Label-free optical biosensors based on Au2S-coated gold nanorods

Huang, Haowen; Huang, Shaowen; Liu, Xuanyong; Zeng, Yanwei; Yu, Xianyong; Liao, Bo; Chen, Yi

doi:10.1016/j.bios.2009.03.018

Cited by 18 publications

(6 citation statements)

References 23 publications

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“…Aer the deposition of GNRs onto the PGE surfaces the R ct values sharply decreased which is the result of enhanced electron transfer due to the excellent conductive properties of the gold nanoparticles with high surface areas. 11,13,40 The highest conductivity increase and reproducible R ct values were observed for the surfaces prepared with a 1 : 10 dilution (Fig. 3B and Table 1B).…”

Section: This Journal Is © the Royal Society Of Chemistry 2016mentioning

confidence: 80%

Impedimetric detection of pathogenic bacteria with bacteriophages using gold nanorod deposited graphite electrodes

et al. 2016

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Electrochemical impedance spectroscopy (EIS) is applied for the detection of bacteria using bacteriophages as a bioprobe together with gold nanorods (GNRs). Escherichia coli -E. coli K12 was used as a model target bacteria and also for the propagation of its specific T4-phages. Gold nanorods (GNRs) were synthesized via a two-step protocol and characterized using different techniques. EIS measurements were conducted in an electrochemical cell consisting of a three electrode system. Single-use pencil graphite electrodes (PGE) were modified by the physical adsorption of GNRs to increase their interfacial conductivity and therefore sensitivity for impedimetric measurements. Therefore, interfacial charge-transfer resistance values (R ct ) sharply decreased after GNRs deposition. Phages were adsorbed on these electrodes via a simple incubation protocol at room temperature, which resulted in an increase in R ct values, which was concluded to be as a result of nonconductive phage layers. These phage-carrying GNRs-PGEs were used for impedimetric detection of the target bacteria, E. coli. Significant increases at the R ct values were observed which were attributed to the insulation effects of the adsorbed bacterial layers. This increase was even more when the bacterial concentrations were higher. In the case of the non-target bacteria Staphylococcus aureus (S. aureus), conductivity noticeable decreases (due to nonspecific adsorption).However, in the case of E. coli, the R ct value increase is time dependent and reaches maximum in about 25-30 min, then decreases gradually as a result of bacterial lysis due to phage invasion on the electrode surfaces. In contrast, there were no time dependent changes with the non-target bacteria S. aureus (no infection and no lytic activity). It is concluded that the target bacteria could be detected using this very simple and inexpensive detection protocol with a minimum detection limit of 10 3 CFU mL À1 in approximately 100 mL bacterial suspension.

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Section: This Journal Is © the Royal Society Of Chemistry 2016mentioning

confidence: 80%

Impedimetric detection of pathogenic bacteria with bacteriophages using gold nanorod deposited graphite electrodes

et al. 2016

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“…The combination of size and shape provides very unique electronic, magnetic, catalytic, and optical properties to these metal nanoparticles that can be exploitable in the rapidly growing nanoindustries. There are exciting potential of nanoparticles in catalysis [2][3][4][5][6][7], DNA sequence recognition [8][9][10], nonlinear optical devices [11], biological sensors [12,13], information storage [14], and plasmonics [15]. These properties are mainly due to their optical and electronic attributes modulated by their shape and size [16,17].…”

Section: Introductionmentioning

confidence: 99%

Biogenic gold nanotriangles from Saccharomonospora sp., an endophytic actinomycetes of Azadirachta indica A. Juss.

et al. 2013

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Microbial biofabrication is emerging as eco-friendly, simpler, and reproducible alternative to chemical synthesis of metals and semiconductor nanoparticles, allowing generation of rare geometrical forms such as nanotriangles and nanoprisms. Highly confined nanostructures like triangles/prisms are interesting class of nanoparticles due to their unique optical properties exploitable in biomedical diagnostics and biosensors. Here, we report for the first time a single-step biological protocol for the synthesis of gold nanotriangles using extract of endophytic actinomycetes Saccharomonospora sp., isolated from surface sterilized root tissues of Azadirachta indica A. Juss., when incubated with an aqueous solution of chloroaurate ions (AuCl − 4 /1 mM). Thin, flat occasionally prismatic gold nanotriangles were produced when aqueous chloroaurate ions reacted with the cell-free extract as well as with the biomass of endophytic Saccharomonospora. It was evidenced from sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis that proteins of 42 and 50 kD were involved in biosynthesis as well as in stabilization of the nanoparticles. The particle growth process was monitored by UV-vis spectroscopy, and the morphological characterization was carried out by transmission electron microscopy and atomic force microscopy together with X-ray powder diffractions. Although the exact mechanism for this shape-oriented synthesis is not clear so far, the possibility of achieving nanoparticle shape control in a microbial system is exciting.

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“…16. 94 The Au 2 S shell can easily react with mercaptoundecanoic acid (MUA) to form a self-assembled membrane (SAM), which can further covalently link with biomolecules. As shown in Fig.…”

Section: Vis-nir Spectroscopymentioning

confidence: 99%