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Cytotoxicity of CeO 2 Nanoparticles for Escherichia coli. Physico-Chemical Insight of the Cytotoxicity Mechanism
Abstract
The production of nanoparticles (NPs) is increasing rapidly for applications in electronics, chemistry, and biology. This interest is due to the very small size of NPs which provides them with many interesting properties such as rapid diffusion, high specific surface areas, reactivity in liquid or gas phase, and a size close to biomacromolecules. In turn, these extreme abilities might be a problem when considering a potentially uncontrolled exposure to the environment. For instance, nanoparticles might be highly mobile and rapidly transported in the environment or inside the body through a water or air pathway. Accordingly, the very fast development of these new synthetic nanomaterials raises questions about their impact on the environment and human health. We have studied the impact of a model water dispersion of nanoparticles (7 nm CeO2 oxide) on a Gram-negative bacteria (Escherichia coli). The nanoparticles are positively charged at neutral pH and thus display a strong electrostatic attraction toward bacterial outer membranes. The counting of colony forming units (CFU) after direct contact with CeO2 NPs allows for the defining of the conditions for which the contact is lethal to Escherichia coli. Furthermore, a set of experiments including sorption isotherms, TEM microscopy, and X-ray absorption spectroscopy (XAS) at cerium L3 edge is linked to propose a scenario for the observed toxic contact.
... Lipopolysaccharides create negatively charged regions that electrostatically attract positively charged NPs. Adsorbed directly on the outer cell membrane, NPs change its viscosity and ability to transport substances, and affect ion channels [32]. In work [30] identified various ways that biofilms of gram-negative and grampositive bacteria are inhibited using the example of model bacteria Enterobacter cloacae and Streptococcus mutans. ...
... niger and S. aureus has been studied and it has been shown that the bactericidal effect of NPs increases with a decrease in their size [154]. The influence of cerium NPs on E. coli was studied [32]. At neutral pH, cerium NPs are positively charged and interact with the outer membranes of bacteria due to electrostatic attraction. ...
The review summarizes and analyzes information regarding the effect of nanoparticles (NPs) of metals, metal oxides and carbon on the biofilm formation and mature biofilms of microorganisms. The viability of individual microbial cells, including direct disruption of cell surface structures and oxidative stress associated with the formation of reactive oxygen species (ROS), as well as the effect on the production of the exopolymer matrix and the quorum sensing system are considered as the mechanisms of NPs action on bio-films. The effects of silver NPs, gold NPs, some metal oxides, and carbon nanomaterials on microbial bio-films have been described in more detail. The effects of metal and carbon NPs on microbial biofilms are compared. Both antibiofilm and probiofilm effects of NPs are noted, depending on their nature, and the prospect of their use as antimicrobial agents and carriers for the production of microbial biofilms of biotechnological significance are considered.
... MB (cationic) dye and catalyst surfaces often discourage the positively charged adsorption of dissolved families, which lowers the amount of dye that could be absorbed. 53 The maximum efficiency was observed with 4% Y dopant in all media. wall. ...
... Nanostructures may interact with bacterial cells, altering membrane permeability and harming vital metabolic processes. 53,58 In the present study, molecular docking analyses of synthesized nanostructures were conducted to deeply analyze the interactions responsible for their bactericidal activity and investigate their potential function as inhibitors of the selected enzyme target DNA gyrase E. coli. Both Cs-La 2 O 3 and Y/Cs-La 2 O 3 nanoparticles exhibited a moderate binding propensity within the active pocket (Figure 6d), with scores of 2.65 and 3.45, respectively (Figure 6a,b), and displayed H-bond interactions with Arg136, Glu50, and Asn46. ...
As the population grows, the scientific community remains focused on researching new materials, methods, and devices to ensure the availability of safe drinking water. The main aim of this research was to decrease the recombination rate of the charge carriers of La 2 O 3 and enhance the catalytic and antimicrobial activity by employing Y/Cs-doped La 2 O 3, respectively. In the current study, different concentrations of yttrium (Y) and a fixed amount of carbon spheres (Cs) doped into lanthanum oxide (La 2 O 3) nanostructures (NSs) were synthesized by the coprecipitation technique. Cs are used as a cocatalyst as they have a high surface area and small size attributed to increased active sites and decreased recombination rate. Moreover, Y was further incorporated as it activates the generation of reactive oxygen species in the inhibition zone, enhancing the antibacterial activity and reducing the emission intensity. Advanced techniques were utilized to determine the structural properties, optical emission and absorption, elemental composition, and d-spacing of the synthesized samples. The reported ternary catalyst works efficiently, improving the catalytic activity and bactericidal potential. Moreover, in silico molecular docking studies, Cs-doped La 2 O 3 and Y/Cs-doped La 2 O 3 nanostructures toward DNA gyrase Escherichia coli showed good efficacy for antibacterial activity.
... The primary antibacterial effect is related to a direct contact with bacterial membranes [55]. Positively charged particles are adsorbed onto bacterial membranes, leading to viscosity changes, disruption of ionic pump function, and disruption of transport between the bacterial cell and the environment [56,57]. CeONPs could negatively affect the function of proteins on the outer membranes of bacteria [58]. ...
Cerium oxide nanoparticles (CeONPs), as part of tissue regeneration matrices, can protect cells from reactive oxygen species and oxidative stress. In addition, they can influence the properties of the scaffold, including its electrospinnability and mechanical strength. In this work, we prepared electrospun fiber mats from a chitosan and polyethylene oxide blend (CS-PEO) with the addition of ceria nanoparticles (CS-PEO-CeONP). The addition of CeONPs resulted in a smaller fiber diameter and higher swelling compared to CS-PEO fiber mats. CeONP-modified fiber mats also had a higher Young’s modulus due to the reinforcing effect of the nanoparticles. Both mats had comparable adhesion and cytocompatibility to mesenchymal stem cells, which had a more rounded morphology on CS-PEO-CeONP compared to elongated cells on the CS-PEO mats. Biocompatibility in an in vivo rat model showed no acute toxicity, no septic or allergic inflammation, and no rough scar tissue formation. The degradation of both mats passed the stage of matrix swelling. CS-PEO-CeONP showed significantly slower biodegradation, with most of the matrix remaining in the tissue after 90 days. The reactive inflammation was aseptic in nature with the involvement of multinucleated foreign-body type giant cells and was significantly reduced by day 90. CeONPs induced the formation of the implant’s connective tissue capsule. Thus, the introduction of CeONPs influenced the physicochemical properties and biological activity of CS-PEO nanofiber mats.
... These nanosheets penetrated into the bacteria and deactivated the enzymes and caused death of bacterial cell. [35,40] But here in this case the size of particles is little big to penetrate in to the bacteria's membrane through endocytosis. Therefore, it might be interacted directly to the bacterial cell which is the important cause of this process or produce the secondary products that cause damage. ...
In this work, flower shape cerium oxide (CeO2) nanosheets were synthesized at room temperature through a facile precipitation method without adding any surfactant. The synthesized nanosheets were characterized by scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffractometry (XRD) and X‐ray photoelectron spectroscopy (XPS). Results showed that the CeO2 nanosheets form a petal‐like morphology and have fluorite crystal structure with no crystal phase impurity while the average crystallite size of nanosheets i. e. ~10 nm. The CeO2 nanosheets are applied as an antimicrobial agent and the antibacterial property against G⁺ and G⁻ bacteria i. e. (E. coli and S. Aureus) were studied. The obtained results showed that the synthesized CeO2 nanosheets had good antibacterial performance at different concentrations, which should be attributed to the reversible Ce³⁺/Ce⁴⁺ valence states and greater oxygen vacancies. XPS study of CeO2 nanosheets after antibacterial test confirmed the existence of Ce³⁺ ions and oxygen vacancies. CeO2 nanosheets have showed the greater potential as antibacterial nanomaterials against both the bactericides.
... The strong electrostatic interactions between nanoparticles and the cell membrane cause them to adhere for long periods of time, allowing the Ce 4+ surface atoms to be reduced to Ce 3+ , leading to oxidative stress on major membrane components such as lipids and/or proteins (Thill et al. 2006). Oxidation of the bacterial cell ensures the formation of mesosome-like structures, so some elementary and important functions such as DNA replication and cell division are altered and consequently, the surface area of the bacterial cell membrane increases due to the deformation of the membrane to the interior of the cell . ...
A group of new hydrogel materials combining high physical properties and pronounced antibacterial activity has been developed. These are composite hydrogels "cellulose-polyacrylamide" based on cellulose matrices of two types: bacterial or regenerated plant cellulose. To form biologically active materials, a method of introducing ceria nanoparticles with sizes less than 5 nm was elaborated. The developed technology allows to obtain hydrogels with the content of ceria (in swollen material) up to 0.4–0.5 wt.%. Variations of the ratio of gel components concentrations, type of matrix cellulose and synthesis conditions allow to change the complex of mechanical properties of the material within a wide range, in particular, to obtain both soft, low-modular nanocomposites and hydrogels with record high rigidity. Significant differences in mechanical properties of hydrogels based on different types of cellulose fully correlate with the difference in morphological characteristics of these two groups of materials revealed by SEM. No palpable effect of nanoparticles on the morphological characteristics of the material was revealed. Both ceria nanoparticles and hydrogels containing ceria showed antibacterial activity against S.aureus ATCC 29213, S.aureus ATCC 43300, P.aeruginosa ATCC 27853, K.pneumoniae ATCC 33495. Different intensity of growth depression of the bacterial cells was determined depending on the samples composition and of the bacteria species.
... In addition to their ability to bind with bacterial cells and disrupt cell membrane permeability, metal-doped QDs are also capable of interfering with important metabolic pathways [62]. Microbe toxicity of QDs is thus examined in more depth. ...
Designing efficient catalysts that possess large number of active sites, high catalytic activity and selectivity while also exhibiting strong antimicrobial activity is a challenging task because of poor control over material fabrication. Therefore, developing new and innovative approaches for the synthesis of catalytic materials is crucial for addressing these challenges. Here, we report the controlled fabrication of GQDs/Y-doped MgO nanoparticles achieved by co doping of yttrium (Y) and graphene quantum dots (GQDs) in magnesium oxide (MgO) based nanostructures (NSs) using the co-precipitation method. The co-doping of GQDs and Y was controlled by manipulating the ratio of precursors where introduction of GQD resulted in higher surface area and enhanced conductivity while the doping of Y enhanced the number of active sites in the final product. The GQDs/Y-doped MgO exhibited an average particle size of ~50 nm and a bandgap of 3.6 eV. Owing to these excellent characteristics, the GQDs/Y-doped MgO was utilized as a catalyst for treatment of the organic pollutants from water as well as antibacterial activity. The modified GQDs/Y-doped MgO nanostructure exhibited excellent activity of over 99.9 % for dye removal and versatility in a broad range of pH which clearly indicated the application in a range of different environments. Furthermore, the GQDs/Y-doped MgO exhibited excellent antibacterial activity against Escherichia Coli (E. Coli) bacteria. To gain further insights into the origins of this excellent activity response, the molecular docking simulations (MDS) is utilized against DNA gyrase and FabI (two enzymes critical to nucleic acid and fatty acid biosynthesis, respectively), to uncover the mechanism behind the observed anti-bacterial effects. In summary, the modified catalyst provides a pathway to design highly efficient catalysts for all pH range water treatment as well as good activity against microbes.
... Higher pH levels and H 2 O 2 levels, which produce more hydroxyl radicals and trap electrons from the conduction band, respectively, accelerate the photodegradation reactions [61]. CeO 2 NPs vary in size and oxidation state, with larger particles (420 nm) often being in the Ce(IV) state and smaller particles (a few nm) typically being in the Ce(III) state [62]. CeO 2 NPs show antibacterial properties, but considerably less than other metal oxides. ...
... The use of CeO 2 in industrial and biomedical applications is due to its ability to reduce Ce +4 to Ce +3 on the surface of CeO 2 NPs [15,16]. It has been reported that the Ce 4+ cation of the nanoparticles is reduced to Ce 3+ at the membrane surface of Escherichia coli, resulting in oxidative stress of the main components of the plasma membrane of the microorganism, such as lipids and/or proteins, or during cellular metabolism electron uptake [17]. Another proposed mechanism of antibacterial action is the generation of ROS by metal NPs, which that leads to the induction of oxidative stress and alters the function of the respiratory chain in bacteria [18]. ...
... The prolonged existence of nanoparticles (NPs) on the bacterial surface can be accredited to the electrostatic contact and the obstruction of the bacterial membrane, which suppress their penetration into the membrane. Subsequently, the introduction of nanoparticles (NPs) has the potential to vary the cellular membrane's viscosity, hinder the functionality of particular ionic pumps, and ultimately disrupt the transport processes involved in the interchange of substances between the bacterial cell and its surrounding solution, thereby perturbing bacterial evolution 56 . After adsorption onto the exterior membrane of the bacterial cell, CeO 2 has the potential to interact with and disrupt proteins. ...
In the current report, we have successfully synthesized nanocomposites of PMMA incorporating different doping of CeO2 through a chemical approach. XRD results reflects decent matching for CeO2 nanoparticles with 29 nm crystallite size. FTIR spectroscopy demonstrates the characteristic functional groups validating the successful formation of the composite. The optical study of PMMA and the nanocomposites has proven that the optical properties such as band gap, refractive index, optical permittivity, and loss tangent factor are affected by adding CeO2 to the PMMA matrix.The peak residing around 420 nm by UV measurements is allocated to occurring electrons photoexcitation from the valence to conduction band inherent in CeO2. The dielectric measurements were achieved using broadband dielectric spectroscopy upon a wide span of frequencies (10–1–10⁷ Hz) and within temperatures from − 10 to 80 °C with a step of 10 °C. The permittivity decreases by adding CeO2 and the dielectric parameters are thermally enhanced, however, the temperature influence is based on CeO2 content, the higher the CeO2 amount, the higher the influence of temperature. The results of the nanocomposites revealed antibacterial activity counter to gram-positive bacteria strain (S. aureus, and B. subtilis), and gram-negative bacteria (E. coli, and K. pneumoniae), yeast (C. albicans, as well as fungi (A. niger). Inherently, the change in CeO2 concentration from 0.01 to 0.1 wt% delivers maximum influence against gram-negative bacteria. These PMMA CeO2-doped composites are beneficial for optoelectronic areas and devices.
... The increased permeability of the external membrane of gram − ve bacteria allows the nanoparticles to penetrate more easily and disrupt essential cellular processes. The ceria nanoparticles get electrostatically attracted to the external membrane of the gram − ve organisms [60]. The adsorption to the membrane may cause membrane disruption, exposing the inner membrane and the periplasmic space, making these organisms more susceptible to the nanoparticle. ...
Biofouling, the accumulation of microorganisms, plants, algae on wet surfaces is one of the major issues adversely affecting the overall hydrodynamic performance of the marine vessels. Ceria (CeO 2) nanoparticles (NPs) are effectively used as anti-biofouling agent to prevent the deterioration of steel structures, due to their excellent redox capacity. Various approaches are being investigated to enhance the antifouling activity of ceria NPs. Here, we report the development of novel polydopamine (PDA) functionalised ceria-zirconia nanoparticles filled water-borne epoxy nanocomposite coating to prevent the microbial-induced corrosion of mild steel. Ceria NPs were functionalised with PDA to enhance the dispersibility and improve their ability to resist biofouling in water-borne epoxy resin coatings against microbial species. As the anti-biofouling activity of ceria depends on their oxygen storage capacity, zirconium was incorporated to create a defective crystal structure with more active oxygen storage and release sites. Ceria and ceria-zirconia NPs were synthesised by precipitation method and functionalised with PDA. The functionalisation of ceria-zirconia (CZ) NPs was confirmed by Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), Confocal Raman spectroscopy and X-ray Photon spectroscopy (XPS). Thermogravimetric analysis (TGA) shows that incorporation of zirconium increases the amount of oxygen vacancies in the crystal lattice there by enhancing ceria's redox potential. Anti-biofouling and anti-biocorrosion properties of the coatings were explored against different microbial strains. The antibac-terial tests show that colony-forming units (CFU) of PDA functionalized ceria-zirconia epoxy (EPCZ) nano-composites were suppressed by 93 % and 87 % in the case of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) bacteria, respectively. Biofilm inhibition studies show that EPCZ nanocomposite coatings have higher biofilm inhibition efficiency against gram-negative bacteria (96.37 %) than gram-positive bacteria (62.67 %) due to the differences in their morphology. The practical applicability of the nanocomposite coatings was studied using cultured seawater consortia, and the results reveal that PCZ nanoparticles provide superior biofilm inhibition. Electrochemical impedance spectroscopy (EIS) reveals that the EPCZ coatings exhibit significant enhancement in charge transfer resistance and coating resistance. The synergistic effect of PDA functionalisation and zirconium incorporation in ceria leads to the exceptional biocorrosion resistance in corrosive bacterial environments.
... One of the key demands for the practical use of antibacterial nanoparticles is their safety for humans and the environment. Cerium oxide (CeO 2 ) nanoparticles have excellent antibacterial activity against both Gram-negative and Gram-positive bacteria [25][26][27][28][29][30][31][32], exhibit antiviral properties [33][34][35][36] and possess low cytotoxicity to mammalian cells [37,38]. The particle size of CeO 2 greatly affects its antibacterial [39] and antiviral [40] properties [41][42][43], which allows the desired effect to be fine-tuned. ...
Textiles and nonwovens (including those used in ventilation systems as filters) are currently one of the main sources of patient cross-infection. Healthcare-associated infections (HAIs) affect 5-10% of patients and stand as the tenth leading cause of death. Therefore, the development of new methods for creating functional nanostructured coatings with antibacterial and antiviral properties on the surfaces of textiles and nonwoven materials is crucial for modern medicine. Antimicrobial filter technology must be high-speed, low-energy and safe if its commercialization and mass adoption are to be successful. Cerium oxide nanoparticles can act as active components in these coatings due to their high antibacterial activity and low toxicity. This paper focuses on the elaboration of a high-throughput and resource-saving method for the deposition of cerium oxide nanoparticles onto nonwoven fibrous material for use in airconditioning filters. The proposed spraying technique is based on the use of an aerodynamic emitter and simultaneous suction. Cerium oxide nanoparticles have successfully been deposited onto the filter materials used in air conditioning systems; the antibacterial activity of the ceria-modified filters exceeded 4.0.
... Although the concentration likely to be found in environmental waters is lower than the lowest concentration (1 µg/L) tested in the current study, CeO 2 NP concentrations in environmental waters are expected to increase, depending on their use. The toxicological effects of CeO 2 NPs on amphibians (Bour et al. 2015), fish (Correia et al. 2019(Correia et al. , 2020, terrestrial invertebrates (Roh et al. 2010), plants (Zhao et al. 2012), algae (Manier et al. 2013), and bacteria (Thill et al. 2006) have been demonstrated by using Table 3). Data are mean ± SE. *, ** and ***: Significant compared to control group at p < 0.05, p < 0.01 and p < 0.001, respectively various biological models. ...
This study evaluated the potential toxic and endocrine-disrupting effects of sublethal concentrations of Fe2O3, CeO2 and ZnO nanoparticles (NPs) on amphibian metamorphosis. Tadpoles were exposed to several NPs concentrations, reaching a maximum of 1000 µg/L, for up to 21 days according to the amphibian metamorphosis assay (AMA). Some standard morphological parameters, such as developmental stage (DS), hind limb length (HLL), snout-to-vent length (SVL), wet body weight (WBW), and as well as post-exposure lethality were recorded in exposed organisms on days 7 and 21 of the bioassay. Furthermore, triiodothyronine (T3), thyroxine (T4) and malondialdehyde (MDA) levels and the activities of glutathione S-transferases (GST), glutathione reductase (GR), catalase (CAT), carboxylesterase (CaE), and acetylcholinesterase (AChE) were determined in exposed tadpoles as biomarkers. The results indicate that short-term exposure to Fe2O3 NPs leads to toxic effects, both exposure periods cause toxic effects and growth inhibition for ZnO NPs, while short-term exposure to CeO2 NPs results in toxic effects and long-term exposure causes endocrine-disrupting effects. The responses observed after exposure to the tested NPs during amphibian metamorphosis suggest that they may have ecotoxicological effects and their effects should be monitored through field studies.
... It should be highlighted that the presence of Ce 3+ and Ce 4+ may be responsible for the improved antibacterial activities observed. The conversion of cerium (IV) to cerium (III) that occurs after ceria particle adsorption at the surface of E. coli cells suggests that oxidative stress may be a plausible mechanism by which cerium particle exerts their toxicity [75]. Because it may act through two different mechanisms: ionic and particle effects, the Ce-doped MBG produced in this work is thought to have antibacterial characteristics during 24 h at 2 mg/mL concentration, as shown in Figure 6. ...
Researchers are concentrating on discovering reducing treatments for bacterial infections due to the worrisome and quick rise of drug-resistant microbial-related illnesses. Metallic ion doping and co-doping mesoporous bioactive glass (MBG) can defend against drug-resistant pathogens of Escherichia coli (E. coli) infection of wounds and solve the issues of bone deformities. In this study, un-doped MBG, silver-doped MBG (Ag-doped MBG), cerium-doped MBG (Ce-doped MBG), and silver–cerium co-doped MBG (Ag-Ce co-doped MBG) have been successfully synthesized via the spray pyrolysis method. In addition, various characterization techniques, including X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption–desorption, were used to investigate the phase compositions, surface morphologies, chemical compositions, inner structure morphologies, chemical bonds/functional groups, and specific surface areas, respectively. The antibacterial efficacy against E. coli was assessed using the colony count technique. All types of MBG with Ag, Ce, and Ag-Ce were effective against E. coli. Furthermore, when immersed in simulated body fluid, the MBGs formed hydroxyapatite and could be used to improve bone defects. Only 5.75 mol% Ag-doped MBG showed toxicity in the MTT assay test. According to our analysis, the 80S-Ag-Ce-MBG was the first Ag-Ce co-doped MBG.
... The mechanisms of action of NPs against various bacteria are not completely elucidated because it depends on two essential factors, physical and chemical properties of NPs and type of bacteria [123]. The literature reports that NPs interact electrostatically with the bacterial membrane, damaging its essential proteins and DNA [124]. Thus, the bactericidal activity comes from the induction of oxidative stress due to the presence of free radicals (reactive oxygen and nitrogen species) after the administration of NPs. ...
Nanoparticles with their various physical and chemical properties are commonly applied in the environmental remediation systems, as well as in the field of biomedicine. We report the recent advances in the biosynthesized metallic nanoparticles (NPs) via eco-friendly, sustainable, and low-cost methods, as well as their use in medicinal strategies. Traditional NPs synthesis approaches are often expensive, harmful to the environment, and do not use clean materials and green energy, which are not good for the environment. On the other hand, in the scientific and technological fields, there is a growing demand/need for the multifunctional and industrially useful NPs, which have aroused interest in the scientific development of simple, eco-friendly, and low-cost strategies that use the alternative, sustainable, and renewable sources. Thus, constituting different scientific and technological advances on the frontier of nanoscience and nanotechnology. In this context, the use of residues from the biomasses as alternative sources for the NPs synthesis appears to be an excellent environmental strategy, which contains secondary metabolites that assist in the process of reduction and oxidation of metallic species for the production of NPs with different morphologies and sizes. In this unusual review, we report the strategic use of nanoparticles obtained via plant and microbial synthesis, as well as their toxic effects on humans, aiming to make a direct relationship with the applications of NPs in the biomedical area.
... As their size is comparable to biological molecules, such as large protein complexes, it is hypothesized that NCs can engage in subcellular reactions. This can enhance the creation of reactive oxygen species (ROS), which can damage and inactivate vital macromolecules such as DNA, proteins, and lipids [65,66]. There are four important groups of things that affect the antibacterial effect based on the size of the particles. ...
Nanomaterials, specifically metal nanoclusters (NCs), are gaining attention as a promising class of antibacterial agents. Metal NCs exhibit antibacterial properties due to their ultrasmall size, extensive surface area, and well-controlled surface ligands. The antibacterial mechanisms of metal NCs are influenced by two primary factors: size and surface charge. In this review, we summarize the impacts of size and surface charge of metal NCs on the antibacterial mechanisms, their interactions with bacteria, and the factors that influence their antibacterial effects against both gram-negative and gram-positive bacteria. Additionally, we highlight the mechanisms that occur when NCs are negatively or positively charged, and provide examples of their applications as antibacterial agents. A better understanding of relationships between antibacterial activity and the properties of metal NCs will aid in the design and synthesis of nanomaterials for the development of effective antibacterial agents against bacterial infections. Based on the remarkable achievements in the design of metal NCs, this review also presents conclusions on current challenges and future perspectives of metal NCs for both fundamental investigations and practical antibacterial applications.
Graphical Abstract
... Studies on the toxicity of silver and zinc oxide nanoparticles to nitrifying bacteria and Escherichia coli showed that the antibacterial effect of these nanoparticles results from the release of silver and zinc ions [75]. Nanoparticles can bind to the membrane of bacteria through electrostatic interaction and disruption of membrane structure [76]. In addition, the close contact between nanoparticles and roots can lead to the absorption of nanoparticles by roots and cause the transfer of nanoparticles to plants [77]. ...
... IONPs heighten the permeability of the cellular barrier through electrostatic attraction and an affinity for thionin. This fosters superior adhesion of metal ions to bacterial cell walls and plasma membrane surfaces, thereby compromising the integrity of bacterial cell membranes [88,89]. IONPs exhibit antibacterial effects on both Gram-positive and Gram-negative bacteria [44,[90][91][92]. ...
Metal nanoparticles play an outstanding role in the field of wound healing due to their excellent properties, and the significance of iron, one of the most widely used metals globally, cannot be overlooked. The purpose of this review is to determine the importance of iron nanoparticles in wound-healing dressings. Prolonged, poorly healing wounds may induce infections; wound infections are a major cause of chronic wound formation. The primary components of iron nanoparticles are iron oxide nanoparticles, which promote wound healing by being antibacterial, releasing metal ions, and overcoming bacterial resistance. The diameter of iron oxide nanoparticles typically ranges between 1 and 100 nm. Magnetic nanoparticles with a diameter of less than 30 nm are superparamagnetic and are referred to as superparamagnetic iron oxide nanoparticles. This subset of iron oxide nanoparticles can use an external magnetic field for novel functions such as magnetization and functionalization. Iron nanoparticles can serve clinical purposes not only to enhance wound healing through the aforementioned means but also to ameliorate anemia and glucose irregularities, capitalizing on iron’s properties. Iron nanoparticles positively impact the healing process of chronic wounds, potentially extending beyond wound management.
... It is still unclear exactly how NP acts on different microorganisms. Strong NP interactions with bacterial membranes cause NPs to bind to the wall, which disrupts the membrane's stiffness [106]. The disintegration of the bacterial cell wall due to the creation of ROS from NPs triggering oxidative stress is also hypothesized. ...
Antibiotic consumption is growing more widespread worldwide and so is the problem of antibiotic resistance. According to reports, the projected world’s consumption of antibiotics by 2030 in terms of defined daily dosages (DDD) is 200 % higher than 42 billion DDD’s consumed in 2015 (Klein et al. in Proc Natl Acad Sci U S A 115:E3463–E3470, 2018). Drug-resistant infections pose a serious concern to public health management especially in the backdrop of severe economic strain ever since the outset of COVID-19 pandemic. Metal oxide nanoparticles (MONPs) have proven their credentials in biomedicine due to their unique properties compared to their bulk metallic counterparts. In the present review, we have briefly compiled the methods of synthesis of novel antimicrobial MONPs, and the diverse MONPs that have been reported for their antibiotic application have been presented. The cascade of mechanisms behind the antibiotic activity of MONPs has been listed with specific mentions of the site-specific mechanisms that are operational. The challenges, as well as lapses in the current knowledge in this area of research, have been discussed and recommendations for expanding its application proposed.
... In this case, nanoparticles attach to the bacteria membrane and lead to the destruction of the cell wall, resulting in the killing of bacteria. Smaller size nanoparticles easily attached to the bacteria membrane and lead to killing more bacteria [72].In this study, size of nanoparticles decreases by adding Ni dopant, which leads to an increase in antibacterial activity. The most crucial antibacterial mechanism is the generation of reactive oxygen species (ROS) [73].Denaturalization of protein and DNA destruction is done by bacteria killing agents that are ROS (singlet oxygen O 2 1 , hydrogen peroxide H 2 O 2 , hydroxyl of free radicals OH radicals of super oxide anion O 2 * -) [73][74][75]. ...
The presented study reports the green synthesis of pure and Ni-doped CuO nanoparticles by Allium staivum (Garlic) extract. Cupric nitrate (Cu (NO3)2) and Nickel nitrate (Ni (NO3)2) as intermediate precursors in Allium staivum (Garlic) extract were used to synthesize Pure and Ni-doped CuO nanoparticles. XRD patterns confirmed the absence of any impurity peaks suggesting the monoclinic phase of CuO and successful doping of Ni into the CuO matrix. Tauc’s plots showed an increase in optical band gap energy with the introduction of Ni dopant. The photocatalytic activity of prepared samples was investigated against Methylene blue (MB) dye and Ciprofloxacin (CIP) under the UV light spectrum. The photocatalytic activity results depicted an enhanced photodegradation efficiency of Ni-doped samples against both MB and CIP organic pollutants. The experimental results reveal that the degradation of MB and CIP can reach 70% and 67% respectively. The synthesized samples thus possess a potential for the treatment of antibiotic-contaminated waters for eliminating or reducing antibiotic residues from the environment. Both CuO and CuN nanoparticles at concentrations of 5, 10, 20 and 30 mg/ml were used to investigate bacterial activity against E. coli. CuN refers to nickel doped CuO nanoparticles. Zones of inhibition of the synthesized nanoparticles (derived from green synthesis) against E. coli for CuO and CuN were 11 mm and 28 mm at 30 mg/ml respectively. The large zone of inhibition values reported in this work reveals that the synthesized nanoparticles give better antibacterial activity.
Wound healing is a complex process that can be facilitated through the development of wound dressings satisfying its primary requirements. The present study aims to investigate the wound healing and antibacterial properties of alginate-chitosan nanocomposite carrying eugenol-loaded silver nanoparticles. Alginate-chitosan nanocomposite contains an antibacterial structure, has wound healing properties, and is biocompatible, biodegradable, and cost-convenient. Adding biosynthesized silver nanoparticles coated with eugenol is known to enhance the antimicrobial properties of biofilm and add anti-inflammatory and antioxidant effects to it. Silver nanoparticles were coated with eugenol, and alginate-chitosan nanocomposite-loaded eugenol-silver nanoparticle was prepared. The resulting nanocomposites were assessed with DSC and SEM tests. The antimicrobial properties of silver nanoparticles, silver nanoparticles eugenol loaded, and nanocomposite were investigated against Escherichia coli, Bacillus subtilis, Klebsiella, and Staphylococcus aureus bacteria, and nanocomposite’s wound healing capability was examined in mouse models. Silver nanoparticles were described by UV, XRD, and TEM for an average size of 30 nm. Zeta potential results (− 36 convert to − 25) suggested that the nanoparticles were thoroughly covered with eugenol and had better antibacterial properties against gram-negative bacteria. The nanocomposite with eugenol loader silver nanoparticles showed maximum antibacterial activity against human pathogenic bacteria; and the measured inhibition zones ranged from 2.5 to 5.5 mm. Results of testing the nanocomposite’s antioxidant and antibacterial properties indicated significantly better properties compared to alone composite, which was significantly evident in wound healing (81% in 7 day). The alginate-chitosan nanocomposite containing silver nanoparticles that were loaded with eugenol and biosynthesized with quercetin revealed the opportunity to develop a biocompatible antibacterial wound dressings that could prove a suitable tool to exert antioxidant effects and increase silver nanoparticle activity while reducing its cellular toxicity by preventing the rapid release and dispersion of eugenol-loaded silver nanoparticles.
The symbiotic relationship between nitrogen-fixing cyanobacteria and plants offers a promising avenue for sustainable agricultural practices and environmental remediation. This review paper explores the molecular interactions between nitrogen-fixing cyanobacteria and nanoparticles, shedding light on their potential synergies in agricultural nanotechnology. Delving into the evolutionary history and specialized adaptations of cyanobacteria, this paper highlights their pivotal role in fixing atmospheric nitrogen, which is crucial for ecosystem productivity. The review discusses the unique characteristics of metal nanoparticles and their emerging applications in agriculture, including improved nutrient delivery, stress tolerance, and disease resistance. It delves into the complex mechanisms of nanoparticle entry into plant cells, intracellular transport, and localization, uncovering the impact on root-shoot translocation and systemic distribution. Furthermore, the paper elucidates cellular responses to nanoparticle exposure, emphasizing oxidative stress, signaling pathways, and enhanced nutrient uptake. The potential of metal nanoparticles as carriers of essential nutrients and their implications for nutrient-use efficiency and crop yield are also explored. Insights into the modulation of plant stress responses, disease resistance, and phytoremediation strategies demonstrate the multifaceted benefits of nanoparticles in agriculture. Current trends, prospects, and challenges in agricultural nanotechnology are discussed, underscoring the need for responsible and safe nanoparticle utilization. By harnessing the power of nitrogen-fixing cyanobacteria and leveraging the unique attributes of nanoparticles, this review paves the way for innovative, sustainable, and efficient agricultural practices.
Ceria nanoparticles (CeO2 NPs) have become popular materials in biomedical and industrial fields due to their potential applications in anti-oxidation, cancer therapy, photocatalytic degradation of pollutants, sensors, etc. Many methods, including gas phase, solid phase, liquid phase, and the newly proposed green synthesis method, have been reported for the synthesis of CeO2 NPs. Due to the wide application of CeO2 NPs, concerns about their adverse impacts on human health have been raised. This review covers recent studies on the biomedical applications of CeO2 NPs, including their use in the treatment of various diseases (e.g., Alzheimer’s disease, ischemic stroke, retinal damage, chronic inflammation, and cancer). CeO2 NP toxicity is discussed in terms of the different systems of the human body (e.g., cytotoxicity, genotoxicity, respiratory toxicity, neurotoxicity, and hepatotoxicity). This comprehensive review covers both fundamental discoveries and exploratory progress in CeO2 NP research that may lead to practical developments in the future.
Since the discovery of ferromagnetic nanoparticles Fe 3 O 4 that exhibit enzyme-like activity in 2007, the research on nanoenzymes has made significant progress. With the in-depth study of various nanoenzymes and the rapid development of related nanotechnology, nanoenzymes have emerged as a promising alternative to natural enzymes. Within nanozymes, there is a category of metal-based single-atom nanozymes that has been rapidly developed due to low cast, convenient preparation, long storage, less immunogenicity, and especially higher efficiency. More importantly, single-atom nanozymes possess the capacity to scavenge reactive oxygen species through various mechanisms, which is beneficial in the tissue repair process. Herein, this paper systemically highlights the types of metal single-atom nanozymes, their catalytic mechanisms, and their recent applications in tissue repair. The existing challenges are identified and the prospects of future research on nanozymes composed of metallic nanomaterials are proposed. We hope this review will illuminate the potential of single-atom nanozymes in tissue repair, encouraging their sequential clinical translation.
Despite considerable interest in medical and pharmaceutical fields, there remains a notable absence of functional textiles that concurrently exhibit antibacterial and antioxidant properties. Herein, we introduce a new composite fabric constructed using nanostructured bacterial cellulose covalently‐linked with cerium oxide nanoparticles (BC@CeO 2 NPs). The synthesis of CeO 2 NPs on the BC is performed via a microwave‐assisted, in‐situ chemical deposition technique, resulting in the formation of mixed valence Ce ³⁺ /Ce ⁴⁺ CeO 2 NPs. This approach ensures the durability of the composite fabric subjected to multiple washing cycles. The ROS‐scavenging activity of CeO 2 NPs and their rapid and efficient eradication of >99% model microbes, such as Escherichia coli , Pseudomonas aeruginosa and Staphylococcus aureus remain unaltered in the composite. To demonstrate the feasibility to incorporate the fabric in marketable products, we have fabricated antimicrobial face masks with filter layers made of BC@CeO 2 NPs cross‐linked with propylene or cotton fibers. These masks exhibit complete inhibition of bacterial growth in the three bacterial strains, improved breathability compared to respirator masks and enhanced filtration efficiency compared to single‐use surgical face masks. This study provides valuable insights into the development of functional BC@CeO 2 NPs biotextiles which design can be extended to the fabrication of medical dressings and cosmetic products with combined antibiotic, antioxidant and anti‐inflammatory activities.
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Antibiotic resistance is a global health concern. Strains of pathogenic microorganisms that have developed resistance to multiple antibiotics, such as MRSA, are extremely difficult to treat, and alternative methods for tackling pathogenic microorganisms are in demand. One potential target for new therapeutics is inhibition of quorum sensing: how microorganisms communicate and form biofilms in a density-dependent manner. Inhibiting this system via ‘quorum quenching’ (QQ) is a promising route to new pharmaceuticals and for controlling biofilm formation and growth. Quorum sensing also provides interesting possibilities in synthetic biology for producing novel products, biosensors, bioactive molecules, and so on.
This book covers the biology of quorum sensing and quenching, and potential sources of QQ enzymes and other inhibitors, as well as an overview of their mechanism and potential biotech applications. The book also covers the potential for new drug development from QQ, covering a range of related topics including protein engineering, imaging and computational studies, and integrated systems. This book is an ideal companion to researchers in chemical biology and medicinal chemistry, particularly those interested in biofilm formation, quorum sensing, novel antimicrobial development, synthetic biology and enzymology.
Nowadays, there is a growing interest in multifunctional therapeutic agents as valuable tools to improve and expand the applicability field of traditional bioactive compounds. In this context, the synthesis and main characteristics of dextran-coated iron oxide nanoparticles (IONP-Dex) loaded with both an antioxidant, protocatechuic acid (PCA), and an antibiotic, ceftazidime (CAZ) or levofloxacin (LEV) are herein reported for the first time, with emphasis on the potentiation effect of PCA on drugs activity. All nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry, differential scanning calorimetry and dynamic light scattering. As evidenced by DPPH method, IONP-Dex loaded with PCA and LEV had similar antioxidant activity like those with PCA only, but higher than PCA and CAZ loaded ones. A synergy of action between PCA and each antibiotic co-loaded on IONP-Dex has been highlighted by an enhanced activity against reference bacterial strains, such as S. aureus and E. coli after 40 min of incubation. It was concluded that PCA, which is the main cause of the antioxidative properties of loaded nanoparticles, further improves the antimicrobial activity of IONP-Dex nanoparticles when was co-loaded with CAZ or LEV antibiotics. All constructs also showed a good biocompatibility with normal human dermal fibroblasts.
Cerium (Ce) is a hot topic in the field of materials research due to its electronic layer structure and the unique antioxidant abilities of its oxide (CeO2). Cerium oxide nanoparticles (CeO2 NPs) demonstrate their potential as an antioxidant and antibacterial agent. Current research focuses on whether they can be used to promote wound healing and in what manner. This article provides a systematic review of the various forms of CeO2 NPs that are used in wound‐healing materials over the past decade, as well as the effectiveness demonstrated by in vivo and in vitro experiments, with a focus on the relationship between concentration and effectiveness. CeO2 NPs are expected to become effective ingredients in dressings that require antibacterial, antioxidant, and wound healing promoting properties. This article serves as a reference for further research and clinical applications of nano‐sized CeO2 in wound healing.
(1) Background: An element that has gained much attention in industrial and biomedical fields is Cerium (Ce). CeO2 nanoparticles have been proven to be promising regarding their different biomedical applications for the control of infection and inflammation. The aim of the present study was to investigate the biological properties and antimicrobial behavior of cerium oxide (CeO2) nanoparticles (NPs). (2) Methods: The investigation of the NPs' biocompatibility with human periodontal ligament cells (hPDLCs) was evaluated via the MTT assay. Measurement of alkaline phosphatase (ALP) levels and alizarine red staining (ARS) were used as markers in the investigation of CeO2 NPs' capacity to induce the osteogenic differentiation of hPDLCs. Induced inflammatory stress conditions were applied to hPDLCs with H2O2 to estimate the influence of CeO2 NPs on the viability of cells under these conditions, as well as to reveal any ROS scavenging properties. Total antioxidant capacity (TAC) of cell lysates with NPs was also investigated. Finally, the macro broth dilution method was the method of choice for checking the antibacterial capacity of CeO2 against the anaerobic pathogens Porphyromonas gingivalis and Prevotella intermedia. (3) Results: Cell viability assay indicated that hPDLCs increase their proliferation rate in a time-dependent manner in the presence of CeO2 NPs. ALP and ARS measurements showed that CeO2 NPs can promote the osteogenic differentiation of hPDLCs. In addition, the MTT assay and ROS determination demonstrated some interesting results concerning the viability of cells under oxidative stress conditions and, respectively, the capability of NPs to decrease free radical levels over the course of time. Antimicrobial toxicity was observed mainly against P. gingivalis. (4) Conclusions: CeO2 NPs could provide an excellent choice for use in clinical practices as they could prohibit bacterial proliferation and control inflammatory conditions.
One of the biggest issues for medical professionals and a serious global concern is the emergence of multi-drug-resistant bacteria, which is the result of the overuse or misuse of antimicrobial agents. To combat this urgent problem, new drugs with alternative mechanisms of action are continuously replacing conventional antimicrobials. Nanotechnology-fueled innovations provide patients and medical professionals with hope for overcoming drug resistance. The aim of the present work was to document the antimicrobial potential and mechanisms of action of metallic nanoparticles against bacterial pathogens. Cell wall interaction and membrane penetration, reactive oxygen species (ROS) production, DNA damage, and protein synthesis inhibition were some of the generalised mechanisms recognised in the current study. In vitro and in vivo studies demonstrated that toxicity concerns and the development of bacterial resistance against nanoparticles (NPs) harden the use of metallic NP products for the treatment of drug-resistant bacterial pathogens. Therefore, researchers across the globe should actively engage in solving the above-mentioned issues.
A major clinical challenge today is the large number of bone defects caused by diseases or trauma. The development of three-dimensional (3D) scaffolds with adequate properties is crucial for successful bone repair. In this study, we prepared biomimetic mesoporous bioactive glass (MBG)-based scaffolds with and without ceria addition (up to 3 mol %) to explore the biological structure and chemical composition of the marine sponge Spongia Agaricina (SA) as a sacrificial template. Micro-CT examination revealed that all scaffolds exhibited a highly porous structure with pore diameters primarily ranging from 143.5 μm to 213.5 μm, facilitating bone ingrowth. Additionally, smaller pores (< 75 μm), which are known to enhance osteogenesis, were observed. The undoped scaffold displayed the highest open porosity value of 90.83%. Cytotoxicity assessments demonstrated that all scaffolds were noncytotoxic and nongenotoxic toward osteoblast cells. Moreover, scaffolds with higher CeO2 content promoted osteogenic differentiation of dental pulp stem cells, stimulating calcium and osteocalcin secretion. The scaffolds also exhibited antimicrobial and antibiofilm effects against Staphylococcus aureus (S. aureus) as well as drug delivery ability. Our research findings indicated that the combination of MBG, natural biological structure, and the addition of Ce exhibited a synergistic effect on the structure and biological properties of scaffolds for applications in bone tissue engineering.
Wound care and treatment can be critical from a clinical standpoint. While different strategies for the management and treatment of skin wounds have been developed, the limitations inherent in the current approaches necessitate the development of more effective alternative strategies. Advances in tissue engineering have resulted in the development of novel promising approaches for accelerating wound healing. The use of various biomaterials capable of accelerating the regeneration of damaged tissue is critical in tissue engineering. In this regard, cerium oxide nanoparticles (CeO2 NPs) have recently received much attention because of their excellent biological properties, such as antibacterial, anti-inflammatory, antioxidant, and angiogenic features. The incorporation of CeO2 NPs into various polymer-based scaffolds developed for wound healing applications has led to accelerated wound healing due to the presence of CeO2 NPs. This paper discusses the structure and functions of the skin, the wound healing process, different methods for the synthesis of CeO2 NPs, the biological properties of CeO2 NPs, the role of CeO2 NPs in wound healing, the use of scaffolds containing CeO2 NPs for wound healing applications, and the potential toxicity of CeO2 NPs.
The use of engineered nanomaterials, defined as those smaller than 100 nm, in the health, energy, agricultural, and environmental sectors is expanding rapidly. As such, human and environmental exposure to...
Using SnO and MoO3 as starting materials, a SnO2–MoO2 solid solution (SnMO) was prepared using mechanochemical method. Then its antiviral and antifungal activities were evaluated. The obtained sample was a powder with specific surface area of 5.7 m²/g with a rutile-type crystal structure. The amount of ion elution for SnMO into 1/500NB solution was an order of magnitude lower than that of MoO3. This powder exhibited high antiviral activity against both bacteriophage Qβ and bacteriophage Φ6, suggesting contributions to antiviral activity by both low pH and eluted ions from the powder. Furthermore, a test based on JIS standards revealed that SnMO possesses high antifungal activity. These findings indicate SnMO as an effective material against widely various microorganisms.
Background
It is anticipated that three (3) billion people will experience water stress by 2025 due to limited access to clean water. Water-related diseases and fatalities affect both industrialized and developing countries. Waterborne diseases are challenging worldwide, especially in developing countries. This article evaluates strategies used by various countries, particularly developing countries, to combat waterborne diseases. These strategies have been largely successful in reducing the prevalence of water-related diseases in developing countries.
Main body of the abstract
The effectiveness of these strategies is evaluated in terms of their ability to remove water contaminants such as bacteria, viruses, and chemicals. Different strategies can be used, including traditional water treatment techniques such as boiling, chlorination, flocculation, solar disinfection and ceramic-based water filtration systems. These methods can help improve water quality and safety. The choice of strategy depends on the specific contaminants in the water and the desired outcome. Proper implementation of these strategies is key to ensuring safe drinking water.
Short conclusion
It was revealed that in developing countries, multiple water treatment techniques are used. This has led to the reduction in waterborne diseases from 50 to 90%. Ceramic-based water purification systems are reportedly the modern and least expensive technique, since they are highly efficient and can be made locally. Thus, ceramic water filtration systems are widely used due to their affordability and easy maintenance.
Background:
Cerium ions promote osteoclastogenesis and activate bone metabolism, while cerium oxide nanoparticles exhibit potent anti-inflammatory properties, making them promising for biomedical applications.
Objective:
The purpose of this study was to develop and evaluate a synthesis method for sustained-release cerium-ion bioceramics containing apatite. Substituted apatite was found to be an effective biomaterial.
Methods:
Cerium-containing chlorapatite was synthesized using a mechanochemical method employing dicalcium phosphate, cerium chloride heptahydrate, and calcium hydroxide as raw materials. The synthesized samples were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy.
Results:
Cerium chlorapatite was successfully synthesized in the 10.1% and 20.1% samples. However, at Ce concentrations higher than 30.2%, the samples consisted of three or more phases, indicating the instability of a single phase.
Conclusion:
The method used in this study was found to be more efficient and cost-effective than the precipitation method for producing substituted apatite and calcium phosphate-based biomaterials. This research contributes to the development of sustained-release cerium-ion bioceramics with potential applications in the field of biomedicine.
X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy experiments are used to investigate the oxidation state of cerium ions in ceria nanoparticles. A comparison of results shows that XPS yields a higher concentration of Ce3+ ions, even after analysis with a core–shell model. Three factors are proposed for the discrepancy between results: surface reduction of ceria in the XPS vacuum chamber enhanced by X-ray radiation, fast reduction dynamics associated with ceria nanoparticles, and a diffuse depth profile of the Ce3+ concentration inside ceria particles. Our results suggest that the high-vacuum XPS studies of ceria have overestimated the Ce3+ concentration in ceria nanoparticles under ambient condition. More importantly, we have demonstrated the importance of using complimentary surface analysis techniques to investigate the valence state of ceria nanoparticles.
Here we report the interpretation of all spectral features of Ce L3 x-ray-absorption near-edge structure (XANES) of CeO2 over a 40 eV range. The local partial unoccupied density of states in the initial state and in the fully relaxed final state have been calculated by the full multiple-scattering approach. The wave function of the excited electron in the final states of the Ce L3-edge XANES spectrum is found to be determined by the multiple-scattering processes in a large size cluster formed by at least 45 atoms. We predict, in good agreement with the experimental data, the crystal-field splitting of 5d states in the final state Deltaf=4.0+/-0.2 eV and its variation from the initial to the final state. The many-body final states for the 2p-->5,εd transition, arising from the configuration interaction due to mixing of Ce 4f and O 2p valence orbitals, have been calculated taking into account the crystal-field splitting of the 5,εd states and they give a full explanation for the low-energy shoulder on the Ce L3 x-ray-absorption spectrum white line that was the object of a long-standing discussion. The origin of the pre-edge peak at about 10 eV below the white line maximum is explained as due to transitions at the bottom of the conduction band.
We investigated the adsorption of bovine serum albumin (BSA) on colloidal Al2O3 particles in an aqueous environment. Changes in the zeta potential of the Al2O3 particles upon the adsorption of BSA were measured using an electro-acoustic technique. The mass of protein adsorbed was determined by using UV-vis spectroscopy. The change of the isoelectric point of the Al2O3 powder-protein suspension was found to be a function of adsorbed protein mass. It was shown that approximately one monolayer of BSA was needed to fully mask the surface and to compromise the charge of Al2O3. From titration experiments it follows that about 30-36% of the negatively charged groups of the protein form bonds with the protonated and charged Al2O3 surface. On the basis of our observations we introduced a new adsorption model for BSA on Al2O3 particles.
Cytotoxicity of CdSe and CdSe/ZnS nanoparticles has been investigated for different surface modifications such as coating with mercaptopropionic acid, silanization, and polymer coating. For all cases, quantitative values for the onset of cytotoxic effects in serum-free culture media are given. These values are correlated with microscope images in which the uptake of the particles by the cells has been investigated. Our data suggest that in addition to the release of toxic Cd(2+) ions from the particles also their surface chemistry, in particular their stability toward aggregation, plays an important role for cytotoxic effects. Additional patch clamp experiments investigate effects of the particles on currents through ion channels.
Patients with dysphagia due to oropharyngeal disease or cerebrovascular accident require long-term nutritional support via enteral feeding, which often results in microbial overgrowth in the upper gastrointestinal (GI) tract. Gastric acid is the primary innate defense mechanism in the stomach and has been assumed to provide an effective barrier to microbial colonization at pH values of <4. To evaluate the efficacy of gastric acid as a barrier to overgrowth, the microbiota of gastric and duodenal aspirates was assessed by culturing methods. Additionally, a fermentor-based model incorporating enteral nutrition tubing of the gastric microbiota of enteral nutrition (EN) patients was constructed to assess the effect of pH on the microbiota. Results showed that gastric acidity had a relatively small effect on the numbers of microorganisms recovered from intestinal aspirates but did influence microbiota composition. Similarly, at pH 3 in the fermentor, a complex microbiota developed in the planktonic phase and in biofilms. The effect of pH on microbiota composition was similar in aspirates and in the fermentors. Candidas and lactobacilli were aciduric, while recoveries of Escherichia coli and Klebsiella pneumoniae decreased as pH was reduced, although both were still present in significant numbers at pH 3. Only Staphylococcus aureus and Bifidobacterium adolescentis persisted at higher pH values both in vitro and in vivo. Lactate and acetate were the main organic acids detected in both aspirates and fermentors. These data show that the simulator used in this investigation was capable of modeling the effects of environmental influences on the upper GI microbiota of EN patients and that gastric pH of <4 is not sufficient to prevent microbial overgrowth in these individuals.
Nanomaterials are engineered structures with at least one dimension of 100 nanometers or less. These materials are increasingly
being used for commercial purposes such as fillers, opacifiers, catalysts, semiconductors, cosmetics, microelectronics, and
drug carriers. Materials in this size range may approach the length scale at which some specific physical or chemical interactions
with their environment can occur. As a result, their properties differ substantially from those bulk materials of the same
composition, allowing them to perform exceptional feats of conductivity, reactivity, and optical sensitivity. Possible undesirable
results of these capabilities are harmful interactions with biological systems and the environment, with the potential to
generate toxicity. The establishment of principles and test procedures to ensure safe manufacture and use of nanomaterials
in the marketplace is urgently required and achievable.
The responses of cells exposed to nanoparticles have been studied with regard to toxicity, but very little attention has been paid to the possibility that some types of particles can protect cells from various forms of lethal stress. It is shown here that nanoparticles composed of cerium oxide or yttrium oxide protect nerve cells from oxidative stress and that the neuroprotection is independent of particle size. The ceria and yttria nanoparticles act as direct antioxidants to limit the amount of reactive oxygen species required to kill the cells. It follows that this group of nanoparticles could be used to modulate oxidative stress in biological systems.
There is no doubt that the possible hazards associated with
nanomaterials are significant, and that concern is valid; but how do we
begin to address the challenges that lie ahead? Expanding our scope and
increasing the diversity of subject matter is the key to attaining the
knowledge we will need to protect against the new range of nanohazards.
Cerium oxide solid samples were prepared via precipitation from aqueous solution of hydrous cerium(III) nitrate in the presence of different percentages of hydrogen peroxide (H2O2) as model corrosion inhibiting coatings materials for aluminum alloys. X-ray absorption spectroscopy at the Ce LIII-edge was applied for the characterization of crystalline anhydrous CeO2, nanocrystalline hydrous CeO2, nanocrystalline CeO2 sample I precipitated in the presence of H2O2, and an amorphous CeO2 sample II precipitated at a higher H2O2 concentration. An analysis by X-ray absorption near-edge structure (XANES) for cerium oxides did not indicate a broad variation in cerium valence state in the precipitated samples as compared to anhydrous CeO2. Furthermore, XANES analysis revealed a decrease in the intensity of the white line peaks for the precipitated samples relative to those in anhydrous CeO2. The EXAFS spectra of the oxides showed that H2O2 reduced the precipitate's particle diameter and bulk crystallinity. Growth in the coordination number of the first, Ce−O, shell was observed with an increased bond distance RCe-O in hydrous and precipitated CeO2 samples. However, the coordination numbers of the second, Ce−Ce, and third, Ce−O, shells were reduced in comparison with anhydrous CeO2. Increasing concentration of H2O2 during alkaline precipitation of cerium oxides caused increased hydration, corresponding to a reduced outer-shell coordination number and reduced bulk crystallinity but no corresponding change in the cerium valence state.
X-ray absorption spectroscopy has been used to study the structural and electronic properties of cerium atoms in nano-crystalline cerium oxide. These nanocrystalline cerium oxides were prepared by precipitation followed by the aging process. To increase the particle size, the as-prepared cerium oxides were calcined at various temperatures. The nanocrystalline phase was retained, even when the samples were calcined at 600°C. The analyses of X-ray absorption near edge structures (XANES) for cerium oxides show that the increase in the relative intensity of the transition to 2p4f15d*L final state and its transition energy shifts toward higher energy are due to the increase in covalence between cerium and oxide ligands with increasing particle size. The extended X-ray absorption fine structure (EXAFS) results for cerium oxide show that the third Ce–O shell is degraded and the coordination number around cerium is decreased, resulting in a decrease in the bond distances of RCe–O and RCe–Ce for particle size
Adsorption isotherms of quaternized polyvinylpyridine on the surface of Escherichia coli bacterial cells were performed using a spectrophotometer. Results show that about 1 mg of polymer can adsorb per m2 of bacterial surface. Electrophoretic mobility measurements of the cells for various quantities of adsorbed polymer indicate that the charge of the cells can be inverted by the cationic polyelectrolyte. Combining the adsorption isotherm and the electrophoretic mobility measurements, we argue that the polymer chains are adsorbed in a very flat configuration on the surface and that they form a strongly entangled network with a mesh size which decreases to a molecular size when the quantity of adsorbed polymer increases to the plateau value of the adsorption isotherm.
The oxide/water interface of nanometric ceria particles has been studied through titration of the surface sites. The adsorption and desorption of protons, hydroxyls, and anions have been measured through potentiometry and chemical analysis. It has been found that these processes cause reactions between surfaces. Conversely, the loss of reactive surfaces which results from chemical treatments changes the charge behavior of the dispersions and reduces it to that of the pure fired oxide.
Stealth liposomes and, today, stealth nanoparticles, constitute a new generation of parenteral therapeutic systems. PLA/ abumin nanoparticles are of particular interest because they constitute fully biodegradable and well tolerated colloidal suspensions. Solvent evaporation and microfluidisation did not damage the albumin molecules; therefore, PLA/albumin nanoparticles are no more immunogenic than native albumin in solution. However, rapid albumin exchanges on the nanoparticle surface probably does not prevent C3-complement binding and phagocytosis by the liver Kupffer cells. Because of their possible intracellular accumulation and toxicity, PLA/albumin nanoparticles are presumably limited to subcutaneous or intramuscular administration. Poly(d,l-lactide)-poly (ethylene glycol) (PLA-PEG) is a new biodegradable hydrophobic dibloc copolymer. The oriented PEG layer, coating the nanoparticle surface, dramatically increases the plasma half-life of the colloidal carrier (‘stealth nanoparticles’ ). In this way, the PLAPEG nanoparticle half-life is about 6 h instead of a few minutes as for PLA/ albumin or PLA/poloxamer 188-coated nanoparticles. The plasma clearance of a water-insoluble hydrophobic drug encapsulated in stealth nanoparticles and administered intravenously, decreases very significantly in comparison with non-stealth nanoparticles. PLAPEG nanoparticles can be considered as a sustained release parenteral (intravenous) dosage form.
With their bright, photostable fluorescence, semiconductor quantum dots (QDs) show promise as alternatives to organic dyes for biological labeling. Questions about their potential cytotoxicity, however, remain unanswered. While cytotoxicity of bulk cadmium selenide (CdSe) is well documented, a number of groups have suggested that CdSe QDs are cytocompatible, at least with some immortalized cell lines. Using primary hepatocytes as a liver model, we found that CdSe-core QDs were indeed acutely toxic under certain conditions. Specifically, we found that the cytotoxicity of QDs was modulated by processing parameters during synthesis, exposure to ultraviolet light, and surface coatings. Our data further suggest that cytotoxicity correlates with the liberation of free Cd2+ ions due to deterioration of the CdSe lattice. When appropriately coated, CdSe-core QDs can be rendered nontoxic and used to track cell migration and reorganization in vitro. Our results provide information for design criteria for the use of QDs in vitro and especially in vivo, where deterioration over time may occur.
The structural basis of the outer membrane permeability for the bacterium Escherichia coli is studied by atomic force microscopy (AFM) in conjunction with biochemical treatment and analysis. The surface of the bacterium is visualized with unprecedented detail at 50 and 5 Å lateral and vertical resolutions, respectively. The AFM images reveal that the outer membrane of native E. coli exhibits protrusions that correspond to patches of lipopolysaccharide (LPS) containing hundreds to thousands of LPS molecules. The packing of the nearest neighbor patches is tight, and as such the LPS layer provides an effective permeability barrier for the Gram-negative bacteria. Treatment with 50 mM EDTA results in the release of LPS molecules from the boundaries of some patches. Further metal depletion produces many irregularly shaped pits at the outer membrane, which is the consequence of progressive release of LPS molecules and membrane proteins. The EDTA-treated cells were analyzed for metal content and for their reactivities toward lysozyme and antibodies specific for LPS. The experiments collectively indicate that the metal depletion procedure did not remove all the LPS molecules despite a dramatic decrease in the metal content. The remaining LPS molecules are present outside the pits, whereas the bottom of the pits is devoid of these molecules. This new structure for the outer membrane exhibits higher permeability than that for the native cells.
The rare earth cerium was found to bind rapidly to Escherichia coli. Cerium inhibited oxygen uptake in the presence of glucose as well as the endogenous respiration of glucose-grown cells. For a cell concentration of 4 mg per ml, maximal inhibition was obtained at 120 mug per ml. Greater concentrations did not increase the inhibitory effect. Cerium inhibited (14)CO(2) evolution and (14)C uptake from uniformly labeled glucose. Marked changes in the distribution of (14)C incorporated into different chemical fractions of the cell were noted. The most striking changes occurred in the alcohol- and alcohol ether-soluble fractions, in which the (14)C activity was increased 5- to 20-fold in the presence of cerium.
The intermediate valence of formally tetravalent compounds has been detected by L3 x-ray-absorption near-edge structure (XANES) in CeO2 and in PrO2 but not in UO2, which have the same CaF2 structure and large f and ligand mixing. The intermediate valence has been found both in CeO2 and in Ce(SO4)2.4H2O, which have similar local structure but different crystal structure. We show that L3 XANES final states are a direct probe of configuration interaction between 4fn and 4fn+1L configurations in the ground state and that the weight of the 4fn+1L in the ground state can be deduced. The many-body final states arise from the characteristic properties of these materials: (i) the presence of localized 4f level above the oxygen 2p band separated by a gap deltaε with relevant correlation energy Uff (Uff>=deltaε) and (ii) mixing of 4f localized states with ligand valence orbitals such that the hybridization energy V is of the same order of magnitude as the energy separation DeltaE between the many-body configuration 4fn and 4fn+1L (V>=DeltaE). These insulating materials, which cannot be classified as standard mixed-valence systems, are called here interatomic intermediate-valence systems.
Lipopolysaccharide (LPS), the primary lipid on the surface of Gram-negative bacteria, is thought to act as a protective and permeability barrier. X-ray diffraction analysis of osmotically stressed LPS multilayers was used to determine the structure and interactive properties of LPSs from strains containing the minimum number of sugars necessary for bacterial survival (Re chemotype) to the maximum number of sugars found in rough bacteria (Ra chemotype). At 20 degrees C in the absence of divalent cations, LPS suspensions gave a sharp wide-angle reflection at 4.23 A and a broad low-angle band centered at 50-68 A depending on the chemotype, indicating the presence of gel phase bilayers separated by large fluid spaces. As osmotic pressure was applied, the apposing bilayers were squeezed together and lamellar diffraction at 6 A resolution was obtained. At low applied pressures (<10(6) dyn/cm2), the total repulsive pressure between bilayers could be explained by electrostatic double layer theory. At higher applied pressures, there was a sharp upward break in each pressure-distance relation, indicating the presence of a hydrophilic steric barrier whose range depended strongly on the LPS chemotype. The positions of these upward breaks, along with electron density profiles, showed that the sugar core width systematically increased from 10 A for the Re chemotype to 27 A for the Ra chemotype. In excess buffer, the addition of divalent cations brought the bilayers into steric contact. Electron density profiles were used to determine the locations of cation binding sites and polar substituents on the LPS oligosaccharide core. The area per hydrocarbon chain was approximately 26 A2 in liquid-crystalline LPS bilayers, an indication of an acyl chain packing that is much tighter than that found in bilayers composed of typical membrane lipids. This unusually tight packing could be a critical factor in the permeability barrier provided by LPS.
Superparamagnetic magnetite nanoparticles were surface-modified with poly (ethylene glycol) (PEG) and folic acid, respectively, to improve their intracellular uptake and ability to target specific cells. PEG and folic acid were successfully immobilized on the surfaces of magnetite nanoparticles and characterized using fourier transform infrared spectra. The nanoparticle internalization into mouse macrophage (RAW 264.7) and human breast cancer (BT20) cells was visualized using both fluorescence and confocal microscopy, and quantified by inductively coupled plasma emission spectroscopy (ICP). After the cells were cultured for 48 h in the medium containing the nanoparticles modified with PEG or folic acid, the results of fluorescence and confocal microscopy showed that the nanoparticles were internalized into the cells. The ICP measurements indicated that the uptake amount of PEG-modified nanoparticles into macrophage cells was much lower than that of unmodified nanoparticles. while folic acid modification did not change the amount of the uptake. However, for breast cancer cells, both PEG and folic acid modification facilitated the nanoparticle internalization into the cells. Therefore, PEG and folic acid modification of magnetite nanoparticles could be used to resist the protein adsorption and thus avoid the particle recognition by macrophage cells, and to facilitate the nanoparticle uptake to specific cancer cells for cancer therapy and diagnosis.
The structure and properties of gold nanoparticles make them useful for a wide array of biological application. Toxicity, however, has been observed at high concentrations using these systems. MTT, hemolysis, and bacterial viability assays were used to explore differential toxicity among the cell types used, using 2 nm core particles. These studies show that cationic particles are moderately toxic, whereas anionic particles are quite nontoxic. Concentration-dependent lysis mediated by initial electrostatic binding was observed in dye release studies using lipid vesicles, providing the probable mechanism for observed toxicity with the cationic MMPCs.
The photocatalytic peroxidation of E. coli cell, lipo-polysaccharide (LPS), phosphatidyl-ethanolcholine (PE), and peptidoglycan (PGN) of the E. coli membrane wall has been investigated on TiO2 porous films by ATR-FTIR spectroscopy. The fast reactions of the photogenerated charge carriers in TiO2 with E. coli, LPS, and PE were monitored by laser kinetic spectroscopy. ATR-FTIR spectroscopy allowed the identification of E. coli, LPS, PE, and PGN as photocatalytic peroxidation products. The PGN was observed to be the most resistant membrane wall component. Shorter peroxidation times were observed for LPS and PE. Laser photolysis shows that E. coli, LPS, and PE compete in the scavenging of a surface trapped holes (h+) with the recombination reaction of h+ with the generated electrons (e-) within times > 50 ns. This scavenging leads to the formation of organic radicals initiating the radical chain peroxidation of E. coli, LPS, PE, and PE.
The ability of engineered cerium oxide nanoparticles to confer radioprotection was examined. Human normal and tumor cells were treated with nanoceria and irradiated, and cell survival was measured. Treatment of normal cells conferred almost 99% protection from radiation-induced cell death, whereas the same concentration showed almost no protection of tumor cells. For the first time, nanoceria is shown to confer radioprotection to a normal human breast line but not to a human breast tumor line, MCF-7.
Quantitative studies on the uptake of nanoparticles into biological systems should consider simultaneous agglomeration, sedimentation, and diffusion at physiologically relevant concentrations to assess the corresponding risks of nanomaterials to human health. In this paper, the transport and uptake of industrially important cerium oxide nanoparticles, into human lung fibroblasts is measured in vitro after exposing thoroughly characterized particle suspensions to a fibroblast cell culture for particles of four separate size fractions and concentrations ranging from 100 ng g(-1) to 100 microg g(-1) of fluid (100 ppb to 100 ppm). The unexpected findings at such low but physiologically relevant concentrations reveal a strong dependence of the amount of incorporated ceria on particle size, while nanoparticle number density or total particle surface area are of minor importance. These findings can be explained on the basis of a purely physical model. The rapid formation of agglomerates in the liquid is strongly favored for small particles due to a high number density while larger ones stay mainly unagglomerated. Diffusion (size fraction 25-50 nm) or sedimentation (size fraction 250-500 nm) limits the transport of nanoparticles to the fibroblast cells. The biological uptake processes on the surface of the cell are faster than the physical transport to the cell at such low concentrations. Comparison of the colloid stability of a series of oxide nanoparticles reveals that untreated oxide suspensions rapidly agglomerate in biological fluids and allows the conclusion thatthe presented transport and uptake kinetics at low concentrations may be extended to other industrially relevant materials.
By considering risk in the early stages of a technology, costs of identifying important health and environmental impacts after a technology has widely diffused can be avoided. Nanotechnology, involving materials and objects less than 100 nm in size, is an important case in point. In this paper we analyze the research priorities discussed by various interest groups concerned with the environmental risks of nanotechnology, evaluate the distribution of federal environmental nanotechnology R&D funding, and discuss research in this field. Overall federal environmental R&D funding to date is limited and focuses more on the positive environmental applications of nanotechnology than on basic knowledge/research, tools for nanoenvironmental research, or the potential risks of nanotechnology. The situation began to change in 2004 when a significant increase occurred in federal R&D funding for the environmental implications of engineered nanomaterials. Though literature exits on the exposure, transport, and toxicity of incidental nanoparticles, little work has been published on the environmental risks of engineered nanoparticles.
Early indicators for nanoparticle-derived adverse health effects should provide a relative measure for cytotoxicity of nanomaterials in comparison to existing toxicological data. We have therefore evaluated a human mesothelioma and a rodent fibroblast cell line for in vitro cytotoxicity tests using seven industrially important nanoparticles. Their response in terms of metabolic activity and cell proliferation of cultures exposed to 0-30 ppm nanoparticles (microg g(-1)) was compared to the effects of nontoxic amorphous silica and toxic crocidolite asbestos. Solubility was found to strongly influence the cytotoxic response. The results further revealed a nanoparticle-specific cytotoxic mechanism for uncoated iron oxide and partial detoxification or recovery after treatment with zirconia, ceria, or titania. While in vitro experiments may never replace in vivo studies, the relatively simple cytotoxic tests provide a readily available pre-screening method.
Although the current production of oxide nanoparticles may be modest, the wide range of proposed applications and forecasted growth in production has raised questions about the potential impact of these nanoparticles on the environment and human health. Iron oxide nanoparticles have been proposed for an increasing number of biomedical applications although in vitro toxicity depending on the particles coating has been evidenced. The aim of this study was to examine the potential in vitro cyto- and genotoxicity on human dermal fibroblasts of DMSA-coated maghemite nanoparticles (NmDMSA) as a function of well-defined physicochemical states. Well-stabilized NmDMSA produced weak cytotoxic and no genotoxic effects. This is attributed in part to the DMSA coating, which serves as a barrier for a direct contact between nano-oxide and fibroblasts, inhibiting a potential toxic effect.
Lipopolysaccharide bilayer structure: effectofchemotype,coremutations,divalentcations, and temperature Received for review April 26 Revised manuscript re-ceived July 6
- S Snyder
- D Kim
- T J Mcintosh
Snyder, S.; Kim, D.; McIntosh, T. J. Lipopolysaccharide bilayer structure: effectofchemotype,coremutations,divalentcations, and temperature. Biochemistry 1999, 38, 10758-10767. Received for review April 26, 2006. Revised manuscript re-ceived July 6, 2006. Accepted July 21, 2006. ES060999B 61569ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 40, NO. 19, 2006
ThestudyofnanocrystallineceriumoxidebyX-Rayabsorption spectroscopy
- P Nachimuthu
- W.-C Shih
- R Liu
- S Jang
- L.-Y Chen
Nachimuthu, P.; Shih, W.-C.; Liu, R.-S.; Jang, L.-Y.; Chen, J.-M. ThestudyofnanocrystallineceriumoxidebyX-Rayabsorption spectroscopy. J. Solid State Chem. 2000, 149, 408-413.
- C Kirchner
- T Liedl
- S Kudera
- T Pellegrino
- A M Javier
- H E Gaub
- S Stolzle
- N Fertig
- W J Parak
Kirchner, C.; Liedl, T.; Kudera, S.; Pellegrino, T.; Javier, A. M.;
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