![Scheme showing magainin I immobilization on gold by 11-mercaptoundecanoic acid and 6-mercaptohexanol modification (1:3 ratio) of the surface, followed by esterification using NHS/EDC and ultimately coupling of magainin I. Adapted from [43] and reprinted with permission.](https://www.researchgate.net/profile/Edward-Rochford/publication/266029484/figure/fig2/AS:392072755466248@1470488837510/Fig-2-Scheme-showing-magainin-I-immobilization-on-gold-by-11-mercaptoundecanoic-acid_Q320.jpg)
![Schematic representation of the different conformations of polymer chains resulting from PAA at different pH values. At pH 3.0, most of the PAA chains (blue) are uncharged, which results in a conformation of the DMLPEI cation (red) with most of its positive charges available, leading to a high bactericidal effect. As the pH increases the PAA chains become more negatively charged, crosslinking with more of the positive charges of DMLPEI leaving less cations available for interaction with the bacterial cell membrane and hence less bactericidal activity. Adapted from [92] and reprinted with permission.](https://www.researchgate.net/profile/Edward-Rochford/publication/266029484/figure/fig4/AS:392072755466250@1470488837822/Fig-5-Schematic-representation-of-the-different-conformations-of-polymer-chains_Q320.jpg)
![Formation of polydopamine films on polymethylmethacrylate (PMMA) and attachment of DNase I by Michael addition reaction . Reprinted with permission from [67].](https://www.researchgate.net/profile/Edward-Rochford/publication/266029484/figure/fig3/AS:392072755466249@1470488837678/Fig-3-Formation-of-polydopamine-films-on-polymethylmethacrylate-PMMA-and-attachment_Q320.jpg)
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Current Developments in Antimicrobial Surface Coatings for Biomedical Applications
Abstract and Figures
Bacterial adhesion and subsequent biofilm formation on material surfaces represent a serious problem in society from both an economical and health perspective. Surface coating approaches to prevent bacterial adhesion and biofilm formation are of increased importance due to the increasing prevalence of antibiotic resistant bacterial strains. Effective antimicrobial surface coatings can be based on an anti-adhesive principle that prevents bacteria to adhere, or on bactericidal strategies, killing organisms either before or after contact is made with the surface. Many strategies, however, implement a multi-functional approach that incorporates both of these mechanisms. For anti-adhesive strategies, the use of polymer chains, or hydrogels is preferred, although recently a new class of super-hydrophobic surfaces has been described which demonstrate improved anti-adhesive activity. In addition, bacterial killing can be achieved using antimicrobial peptides, antibiotics, chitosan or enzymes directly bound, tethered through spacer-molecules or encased in biodegradable matrices, nanoparticles and quaternary ammonium compounds. Notwithstanding the ubiquitous nature of the problem of microbial colonization of material surfaces, this review focuses on the recent developments in antimicrobial surface coatings with respect to biomaterial implants and devices. In this biomedical arena, to rank the different coating strategies in order of increasing efficacy is impossible, since this depends on the clinical application aimed for and whether expectations are short- or long term. Considering that the era of antibiotics to control infectious biofilms will eventually come to an end, the future for biofilm control on biomaterial implants and devices is likely with surface-associated modifications that are non-antibiotic related.
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... For example, numerous efforts have been made to use antibacterial NPs for surface modification by different fabrications of artificial antibacterial surfaces, such as surface functionalization, derivatization, polymerization, and mechanical architecture modification. Medical devices and implants would be able to resist the adhesion and inhibit the proliferation of bacteria, thus reducing the risk of surgery or implant-associated hospital-acquired infections (Kheiri et al. 2019;Yu et al. 2015;Swartjes et al. 2015;Lv et al. 2014). ...
The rise in drug resistance in pathogenic bacteria greatly endangers public health in the post-antibiotic era, and drug-resistant bacteria currently pose a great challenge not only to the community but also to clinical procedures, including surgery, stent implantation, organ transplantation, and other medical procedures involving any open wound and compromised human immunity. Biofilm-associated drug failure, as well as rapid resistance to last-resort antibiotics, necessitates the search for novel treatments against bacterial infection. In recent years, the flourishing development of nanotechnology has provided new insights for exploiting promising alternative therapeutics for drug-resistant bacteria. Metallic agents have been applied in antibacterial usage for several centuries, and the functional modification of metal-based biomaterials using nanotechnology has now attracted great interest in the antibacterial field, not only for their intrinsic antibacterial nature but also for their ready on-demand functionalization and enhanced interaction with bacteria, rendering them with good potential in further translation. However, the possible toxicity of MNPs to the host cells and tissue still hinders its application, and current knowledge on their interaction with cellular pathways is not enough. This review will focus on recent advances in developing metallic nanoparticles (MNPs), including silver, gold, copper, and other metallic nanoparticles, for antibacterial applications, and their potential mechanisms of interaction with pathogenic bacteria as well as hosts.
... The contamination of hospital surfaces or contaminated medical devices plays a significant role in the spread of pathogens and has been identified as the most likely transmission route [8]. These infections could be effectively prevented by using antimicrobial surface coatings (AMCs), which, while not a definitive solution, can help reduce the risk of infection by preventing viable bacteria from adhering to the surface and/or inhibiting their growth [9]. The mechanisms of action by which AMCs act on surfaces are classified into two categories: antimicrobial-releasing methods and contact-killing methods (i.e., potentiated surfaces and substances that do not allow for bacterial adhesion) [10]. ...
Simple Summary
Standardised antimicrobial testing methods are essential to validate the antimicrobial efficacy of materials and enable their application in real-life settings by providing reliable results that allow for comparison between antimicrobial surfaces while assuring end-use product safety. In this review, the literature on the ISO 22196:2011 protocols used in the published studies will be analysed.
Abstract
The survival and spread of foodborne and nosocomial-associated bacteria through high-touch surfaces or contamination-prone sites, in either healthcare, domestic or food industry settings, are not always prevented by the employment of sanitary hygiene protocols. Antimicrobial surface coatings have emerged as a solution to eradicate pathogenic bacteria and prevent future infections and even outbreaks. Standardised antimicrobial testing methods play a crucial role in validating the effectiveness of these materials and enabling their application in real-life settings, providing reliable results that allow for comparison between antimicrobial surfaces while assuring end-use product safety. This review provides an insight into the studies using ISO 22196, which is considered the gold standard for antimicrobial surface coatings and examines the current state of the art in antimicrobial testing methods. It primarily focuses on identifying pitfalls and how even small variations in methods can lead to different results, affecting the assessment of the antimicrobial activity of a particular product.
... Numerous molecules that inhibit biofilm formation or disperse the resulting biofilms have been identified. Nanoparticles, antibiotics, antimicrobial peptides, enzymes, quaternary ammonium compounds, superhydrophobic coatings, and anti-adhesive polymers are used as antimicrobial strategy types in surface coatings [6][7][8]. With the latest developments in nanotechnology, new opportunities for effective biofilm treatment and control have become the focus of attention. ...
Microbial colonization on various surfaces is a serious problem. Biofilms from these microbes pose serious health and economic threats. In addition, the recent global pandemic has also attracted great interest in the latest techniques and technology for antimicrobial surface coatings. Incorporating antimicrobial nanocompounds into materials to prevent microbial adhesion or kill microorganisms has become an increasingly challenging strategy. Recently, many studies have been conducted on the preparation of nanomaterials with antimicrobial properties against diseases caused by pathogens. Despite tremendous efforts to produce antibacterial materials, there is little systematic research on antimicrobial coatings. In this article, we set out to provide a comprehensive overview of nanomaterials-based antimicrobial coatings that can be used to stop the spread of contamination to surfaces. Typically, surfaces can be simple deposits of nanomaterials, embedded nanomaterials, as well as nanotubes, nanowires, nanocolumns, nanofibers, nanoneedles, and bio-inspired structures.
Microbial virulence and biofilm formation stand as a big concern against the goal of achieving a green and sustainable future. Microbial pathogenesis is the process by which the microbes (bacterial, fungal, and viral) cause illness in their respective host organism. ‘Nanotechnology’ is a state-of-art discipline to address this problem. The use of conventional techniques against microbial proliferation has been challenging against the environment. To tackle this problem, there has been a revolution in this multi-disciplinary field, to address the aspect of bioinspired nanomaterials in the antibiofilm and antimicrobial sector. Bioinspired nanomaterials prove to be a potential antibiofilm and antimicrobial agent as they are non-hazardous to the environment and mostly synthesized using a single-step reduction protocol. They exhibit synergistic effects against bacterial, fungal, and viral pathogens and thereby, control the virulence. In this literature review, we have elucidated the potential of bioinspired nanoparticles as well as nanomaterials as a promising anti-microbial treatment pedagogy and throw light on the advancements in how smart photo-switchable platforms have been designed to exhibit both bacterial releasing as well as bacterial-killing properties. Certain limitations and possible outcomes of these bio-based nanomaterials have been discussed in the hope of achieving a green and sustainable ecosystem.
This study aimed to assess the activity of AgNPs biosynthesized by Fusarium oxysporum (bio-AgNPs) against multidrug-resistant uropathogenic Proteus mirabilis, and to assess the antibacterial activity of catheters coated with bio-AgNPs. Broth microdilution and time-kill kinetics assays were used to determine the antibacterial activity of bio-AgNPs. Catheters were coated with two (2C) and three (3C) bio-AgNPs layers using polydopamine as crosslinker. Catheters were challenged with urine inoculated with P. mirabilis to assess the anti-incrustation activity. MIC was found to be 62.5 µmol l-1, causing total loss of viability after 4 h and bio-AgNPs inhibited biofilm formation by 76.4%. Catheters 2C and 3C avoided incrustation for 13 and 20 days, respectively, and reduced biofilm formation by more than 98%, while the pristine catheter was encrusted on the first day. These results provide evidence for the use of bio-AgNPs as a potential alternative to combat of multidrug-resistant P. mirabilis infections.
The use of Mg‐based biomaterials with a number of their advantageous properties are overshadowed by uncontrollable metal corrosion. Moreover, the use of implants goes alongside with the threat of pathogens‐associated complications. In this study, PEO coated Mg biomaterial loaded with antibacterial Ag(I) and Cu(II) complexes is produced and tested to meet both appropriate protective characteristics as well as sufficient level of antibacterial activity. To achieve a suitable level of anticorrosion protection phosphate and fluoride‐phosphate electrolytes are used in the PEO process. Investigation of the surface thickness and morphology done by means of cross‐section analysis and scanning electron microscopy (SEM), as well as electrochemical impedance spectroscopy (EIS) assay show precedence of the fluoride containing PEO coating and make it the material of choice for further modification with Ag(I) and Cu(II) complexes. The presence of the complexes on the PEO surface is confirmed by energy dispersive X‐ray spectroscopy (EDX). X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and glow discharge optical emission spectroscopy (GDOES) are used to estimate the complexes’ chemical state and depth of penetration in the coating surface. Based on the results of antibacterial assay, the modified coatings are found to be active against both Gram‐positive and Gram‐negative bacteria.
Surface bacterial contamination represents a crucial health and industrial concern which requires new strategies to be continuously developed. Successful antibacterial surfaces are characterized by a combination of durable and broad-spectrum antimicrobial actions. Herein, we present a bio-inspired strategy mimicking natural cellulosome to simultaneously immobilize multiple enzymes with antibacterial activity onto surfaces. The grafting strategy leverages the strong biomolecular interaction between receptors on a scaffold protein anchored on the substrate and ligands added to the enzymes. As a proof of concept, lysozyme and lysostaphin were chosen to target the bacterial cell wall, and DNase I to degrade DNA released during cell lysis, known to promote bacterial adhesion which can later lead to biofilm formation. The specificity of the ligand/receptor interaction was confirmed by biochemical and AFM-based single-molecule force spectroscopy assays, thus demonstrating successful co-immobilization of the three enzymes on the protein scaffold. Then, the antibacterial protection was evaluated against Staphylococcus aureus, Escherichia coli and Micrococcus luteus by viability tests which revealed long-term antimicrobial protection of the multi-enzymatic scaffold on both Gram-positive and Gram-negative bacteria. After 24 hours of contact, the system induced lysis of 71 to 85% of bacteria, and its antimicrobial properties remained effective after 5 days even with several cumulative waves of bacterial contamination. This work demonstrates the relevance of bio-inspired multi-enzymatic scaffolds for antibacterial protection, providing long-term and broad-spectrum action.
Coatings of metal–organic frameworks (MOFs) have potential applications in surface modification for medical implants, tissue engineering, and drug delivery systems. Therefore, developing an applicable method for surface-mounted MOF engineering to fabricate protective coating for implant tissue engineering is a crucial issue. Besides, the coating process was desgined for drug infusion and effect opposing chemical and mechanical resistance. In the present review, we discuss the techniques of MOF coatings for medical application in both in vitro and in vivo in various systems such as in situ growth of MOFs, dip coating of MOFs, spin coating of MOFs, Layer-by-layer methods, spray coating of MOFs, gas phase deposition of MOFs, electrochemical deposition of MOFs. The current study investigates the modification in the implant surface to change the properties of the alloy surface by MOF to improve properties such as reduction of the biofilm adhesion, prevention of infection, improvement of drugs and ions rate release, and corrosion resistance. MOF coatings on the surface of alloys can be considered as an opportunity or a restriction. The presence of MOF coatings in the outer layer of alloys would significantly demonstrate the biological, chemical and mechanical effects. Additionally, the impact of MOF properties and specific interactions with the surface of alloys on the anti-microbial resistance, anti-corrosion, and self-healing of MOF coatings are reported. Thus, the importance of multifunctional methods to improve the adhesion of alloy surfaces, microbial and corrosion resistance and prospects are summarized.
Graphical Abstract
The control of microbial infections is a very important issue in modern society. In general there are two ways to stop microbes from infecting humans or deteriorating materials—disinfection and antimicrobial surfaces. The first is usually realized by disinfectants, which are a considerable environmental pollution problem and also support the development of resistant microbial strains. Antimicrobial surfaces are usually designed by impregnation of materials with biocides that are released into the surroundings whereupon microbes are killed. Antimicrobial polymers are the up and coming new class of disinfectants, which can be used even as an alternative to antibiotics in some cases. Interestingly, antimicrobial polymers can be tethered to surfaces without losing their biological activity, which enables the design of surfaces that kill microbes without releasing biocides. The present review considers the working mechanisms of antimicrobial polymers and of contact-active antimicrobial surfaces based on examples of recent research as well as on multifunctional antimicrobial materials.
Hydrogels, such as crosslinked poly(2-hydroxyethyl methacrylate) (pHEMA) have been used extensively in controlled release drug delivery systems. Our previous work demonstrated an ultrasound (US)-responsive system based on pHEMA coated with a self-assembled multilayer of C12-C18 methylene chains. The resulting coating was predominantly crystalline and relatively impermeable, forming an US-activated switch that controlled drug release on-demand, and kept the drug within the matrix in the absence of US. The device, as developed did, however, show a low background drug-leaching rate independent of US irradiation. For some applications, it is desirable to have very low or zero background release rates. This was achieved here by a combination of new processing steps, and by copolymerizing HEMA with a relatively hydrophobic monomer, hydroxypropyl methacrylate (HPMA). These advances produced systems with undetectable ciprofloxacin background release rates that are capable of US-facilitated drug release - up to 14-fold increases relative to controls both before and after US exposure. In addition, these observations are consistent with the hypothesis that US-mediated disorganization of the coating allows a transient flux of water into the matrix where its interaction with bound and dissolved drug facilitates its movement both within and out of the matrix.
Bacteria that adhere to implanted medical devices or damaged tissue can encase themselves in a hydrated matrix of polysaccharide and protein, and form a slimy layer known as a biofilm. Antibiotic resistance of bacteria in the biofilm mode of growth contributes to the chronicity of infections such as those associated with implanted medical devices. The mechanisms of resistance in biofilms are different from the now familiar plasmids, transposons, and mutations that confer innate resistance to individual bacterial cells. In biofilms, resistance seems to depend on multicellular strategies. We summarise the features of biofilm infections, review emerging mechanisms of resistance, and discuss potential therapies.
In this work, longa term antibacterial, antiadhesion, and antibiofilm activities are afforded to industrial stainless steel surfaces following a green and bioa inspired strategy. Starting from catechol bearing synthetic polymers, the film crossa linking and the grafting of active (bio)molecules are possible under environmentally friendly conditions (in aqueous media and at room temperature). A bioa inspired polyelectrolyte, a polycationa bearing catechol, is used as the filma anchoring polymer while a poly(methacrylamide)a bearing quinone groups serves as the crossa linking agent in combination with a polymer bearing primary amine groups. The amine/quinone reaction is exploited to prepare stable solutions of nanogels in water at room temperature that can be easily deposited to stainless steel. This coating provides quinonea functionalized surfaces that are then used to covalently anchor active (bio)molecules (antibiofilm enzyme and antiadhesion polymer) through thiol/quinone reactions.
Coated layers of biologically active molecules on synthetic biomaterials and biomedical devices can promote a variety of desirable biological reactions by the host body or the biological medium, such as cell and tissue attachment or deterring bacterial biofilm formation. Such coated layers should be immobilised covalently in order to avoid competitive displacement phenomena, and the use of surface-activating plasmas or plasma polymer interlayers with suitable chemical surface groups has proved to be very convenient means of grafting bioactive molecules onto solid materials surfaces. We review selected work on the covalent immobilisation of proteins and peptides onto solid biomaterial surfaces and describe efforts towards plasma methods that allow biomolecules to be covalently captured in a single step. After reviewing a number of approaches, we discuss in more detail the use of plasma polymer interlayers that possess aldehyde or epoxide surface groups; these groups react readily with amine groups on proteins and peptides without undesirable side reactions, and avoid other issues such as crosslinking. We also emphasise the importance of detailed surface analysis to verify that covalent grafting has indeed taken place, and to assess the surface density of grafted molecules. With suitably chosen peptides or proteins, such covalently grafted layers can support the surface attachment of delicate cells, or combat bacterial biofilm formation.
Negatively charged gold nanoparticles (GNP) and positively charged lysozyme (Lys) were alternately deposited on negatively charged cellulose mats via layer-by-layer (LBL) self-assembly technique. The fabricated multilayer films were characterized by energy-dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FT-IR), and wide-angle X-ray diffraction (XRD). Morphology of the LBL film coated mats was observed by scanning electron microscopy (SEM). Thermal degradation properties were investigated by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). Additionally, the result of microbial inhibition assay indicated that the composite nanofibrous mats had excellent antibacterial activity against Escherichia coli and Staphylococcus aureus, which could be used for antimicrobial packing, tissue engineering, wound dressing, etc.
The treatment of biofilm infections is particularly challenging because bacteria in these conditions become refractory to antibiotic drugs. The reduced effectiveness of current therapies spurs research for the identification of novel molecules endowed with antimicrobial activities and new mechanisms of antibiofilm action. Antimicrobial peptides (AMPs) have been receiving an increasing attention as potential therapeutic agents, since they represent a novel class of antibiotics with a wide spectrum of activity and a low rate in inducing bacterial resistance. Over the past decades a large number of naturally occurring AMPs have been identified or predicted from various organisms as effector molecules of the innate immune system playing a crucial role in the first line of defence. Recent studies have shown the ability of some AMPs to act against microbial biofilms, in particular during early phases of biofilm development. Here we provide a review of the antimicrobial peptides tested on biofilms, highlighting their advantages and disadvantages for prophylactic and therapeutic applications. In addition, we describe the strategies and methods for de novo design of potentially active AMPs and discuss how informatics and computational tools may be exploited to improve antibiofilm effectiveness. This article is protected by copyright. All rights reserved.
Cited By (since 1996):1, Export Date: 24 January 2014, Source: Scopus