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Schematic representation of the avidin-mediated assembly of biotin-attached gold nanoparticles. Chemical structures of the BLT and BSPP are also shown; homemade (left) and commercial BSPP (right).
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Bio-functionalized gold nanoparticles (AuNPs), which bio-specifically interact with biotin-(strept)avidin, were investigated in this study. AuNPs were functionalized with a synthetically-provided biotin-linked thiol (BLT), which was synthesized by amidation of the active ester of biotin with 2-mercaptoethylamine. The BLT-attached AuNP was bio-speci...
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The high affinity (KD ~ 10−15 M) of biotin for avidin and streptavidin is the essential component in a multitude of bioassays with many experiments using biotin modifications to invoke coupling. Equilibration times suggested for these assays assume that the association rate constant (kon) is approximately diffusion limited (109 M-1s-1) but recent s...
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In this work the synthesis, photochemistry, and streptavidin interaction of new [Ru(tpy)(bpy)(SRR')](PF6)2 complexes where the R' group contains a free biotin ligand, are described. Two different ligands SRR' were investigated: An asymmetric ligand 1 where the Ru‐bound thioether is an N‐acetylmethionine moiety linked to the free biotin fragment via...
Citations
... AuNPs are then formulated with a variety of polymer matrices used to fabricate nanocomposites for specific applications; the literature reports the best polymer choices for AuNPs are polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polyethylene glycol (PEO), and the polysaccharide chitosan (CS) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Moreover, interesting chemical reduction methods to produce functional metal nanoparticles have been discussed in the literature; in this regard, Ag [17], Au/Ag [18], Pt/Pd [19], and biofunctionalized Au nanoparticles [20]. These studies reveal the importance of proper synthesis methods for biosensor applications. ...
Nanocomposite engineering of biosensors, biomaterials and flexible electronics demand highly tunable synthesis of precursor materials to achieve enhanced or desired properties. However, this process remains lim-ited due to the need for proper synthesis-property strategies. Herein, we report on the ability to synthesize chi-tosan-gold nanocomposite thin films (CS/AuNP) with tunable properties by chemically reducing HAuCl4 in chitosan solutions and different HAuCl4/sodium citrate molar relationships. The structure, electrical and relaxa-tion properties of nanocomposites have been investigated as function of HAuCl4/sodium citrate molar relation. It was shown that gold particle size, conductivity, Vogel temperature (glass transition) and water content strongly depend upon HAuCl4/sodium citrate relationships. Two relaxation processes have been observed in nanocomposites; the α-relaxation process, related to a glass transition in wet CS/AuNP films and the σ-relaxation related to local diffusion process of ions in a disordered system. The ability to fine-tune both α-, and σ relaxations may be exploited in the proper design of functional materials for biosensors, biomaterials, and flexible electronics applications
... Novel biotin-PEG linkers with deliberately varied numbers of anchors (monothiol, cyclic disulfide, and trithiol) were synthesized for subsequent conjugation to spheril gold nanoparticles through gold-thiol adsorption chemistry [40][41][42][43] (Figure 1). The use of molecular linkers containing multiple anchoring groups has been shown to increase AuNP stability in biological environments through resistance to linker displacement by free thiols 44,45 ( Figure S1). ...
Novel biotin-polyethylene glycol (biotin-PEG) gold nanoparticle probes have been synthesized and used as universal constructs for the detection of protein (prostate-specific antigen, PSA) and nucleic acid targets (microRNAs) from a single sample. Microarray assays based upon these probes enabled sensitive detection of biomarker targets (50 fM for nucleic acid targets and 1 pg/μL for the PSA target). Ways of detecting biomarkers, including nucleic acids and proteins, are necessary for the clinical diagnosis of many diseases, but currently available diagnostic platforms rely primarily on the independent detection of proteins or nucleic acids. In addition to the economic benefits associated with the use of a single platform to detect both classes of analytes, studies have shown that the simultaneous identification of multiple classes of biomarkers in the same sample could be useful for the detection and management of early stage diseases, especially when sample amounts are limited. Therefore, these new probes and the assays based upon them open the door for high-sensitivity combination-target assays for studying and tracking biological pathways and diseases.
The search for novel efficient antibacterial agents is attracting a great attention due to the unregulated use of common antibiotics and development of multidrug‐resistant bacteria strains. This paper proposes an eco‐friendly approach to obtain stable chitosan‐capped silver nanoparticles with controlled physicochemical and biological properties using reducing and stabilizing capacity of chitosan. The study of the influence of chitosan characteristics on the kinetic of Ag+ reduction showed that an increase in polysaccharide molecular weight led to a decrease in their reducing ability. The synthesized silver nanoparticles were characterized by UV and FTIR spectroscopy, TEM, XRD, DLS. The relationships between physicochemical characteristics of the formed silver nanoparticles and the type of used chitosan, as well as synthesis temperature, were determined. It has been demonstrated that spherically‐shaped (13–27 nm) and positively‐charged (zeta‐potential 26.1–29.5 mV) silver nanoparticles with a single symmetric SPR band at 408–418 nm are stable during 6 months in a colloidal form, and can be produced with the assistance of low‐molecular weight chitosan (20–30 kDa) at 95°C. The synthesized silver nanoparticles enhanced the antibacterial activity of kanamycin and ampicillin against both gram‐negative and gram‐positive bacteria. These results revealed the prospects for the application of chitosan‐capped silver nanoparticles to create new effective antibacterial systems (gels, films, etc).
The detection of specific species of interest (i.e., analytes) in samples (blood, urine, saliva, water, and food) at low concentrations is of utmost importance for improving human health and maintaining a high quality of life. While this is mostly achievable in lab-based settings found in the developed world, this is a major hurdle to overcome in resource-limited regions found in developing countries. Therefore, new technologies capable of detecting analytes in these challenging regions need to be developed. This review details the development of point-of-care diagnostics for detecting DNA, proteins, bacteria/pathogens, and other species that show promise for solving this major health issue, and improving the quality of life for those in the developing world.
A simple protocol for covalent immobilization of biotin onto the surface of Fe3O4 magnetic nanoparticles (MNPs) for improving the biocompatibility of original MNPs has been realized. MNPs were first prepared by co-precipitation method which was subsequently anchored
with functionalized biotin. The as-synthesized MNPs were observed to be monocrystalline as evidenced from XRD and TEM images. The covalent grafting of biotin to MNPs was confirmed by FT-IR. The XPS analysis suggested the successful preparation of Biotin-f-MNPs. The as-synthesized Biotin-f-MNPs
were found to be superparamagnetic character as recorded by SQUID. Cell viability studies revealed that the biocompatibility of MNPs was improved upon Biotin immobilization.
In this study, we report on the observation that the particleshape was dependent upon in situ seed-growth time of ourone pot synthesis of gold nanoparticles. It was found that thecube yield increased with the increase of the seed-growthtime while a short seed-growth time (~15 min) resulted inthe formation of high-yield octahedral particles. This canalso be regarded as a simple and convenient method ofsynthesizing octahedral and cubic gold nanoparticles inaqueous solution. Although the synthetic methods usingcetyltrimethylammonium bromide (CTAB) and ascorbicacid have been previously reported, the shape control of goldnanoparticles relied on the adjustment of the concentrationof reducing agent, gold precursor, activators, or seed parti-cles. In this report, shape of gold nanoparticles was con-trolled by tuning only one parameter, the in situ seed-growthtime, without any variation in reactant concentrations or inthe way of a separate seeding.Typically, a 250 μL of 10 mM HAuCl
