A new approach for simple and rapid colorimetric detection of Hg(2+) in aqueous solution is proposed based on Hg(2+)-induced aggregation of mononucleotides-stabilized gold nanoparticles.

Gold nanoparticle (AuNP) based colorimetric aptasensor have been developed for many analytes recently largely because of the ease of detection, high sensitivity, and potential for high-throughput analysis. Most of the target aptamers for detection have short sequences. However, the approach shows poor performance in terms of detection sensitivity for most of the long-sequence aptamers. To addre...

We developed two colorimetric methods for the detection of vancomycin- and oxacillin-resistant Staphylococcus aureus in </=6 h: (i) a nitrate reductase assay and (ii) a resazurin microplate method. MICs agreed with results obtained by CLSI methods for oxacillin. However, detection of vancomycin resistance required a larger inoculum. These methods may be recommended for the detection of vancomyc...

Positively-charged gold nanoparticles can effectively differentiate long DNA and fragmented DNA, thus providing a simple and visual approach to colorimetric detection of nuclease activity.

This study describes the fabrication techniques for two forms of magnetic DNA nanotubes (MDNTs) and their applications as platforms for developing colorimetric assays. The first form of MDNTs was DNTs filled-up with magnetic nanoparticles (MNPs) and the second one was DNTs arayed with MNPs on their extrior surfaces. Then the both forms of MDNTs were employed as platforms for attaching a specifi...

Direct and rapid detection of 1-hydroxypyrene (1-OHP) is of great importance owing to its high carcinogenicity, teratogenicity and toxicity. In this study, a simple colorimetric assay for rapid determination of 1-OHP is reported, which is based on non-crosslinking aggregation of gold nanoparticles (Au NPs) induced by 1-OHP in the presence of formic acid (FA). Initially, Au NPs were synthesized ...

In this report, we present a method for the detection of Pb2+ based on the different adsorption capacity on the surface of gold nanoparticles (AuNPs) between ssDNA (single-stranded DNA) and G-quartet. In the absence of Pb2+, the DNA oligonucleotides probe, which is guanine-rich ssDNA, can be adsorbed on the surface of AuNPs protecting them from aggregation. After adding Pb2+, the DNA oligonucle...

The presence of Escherichia coli (E. coli) in food and drinking water is a chronic problem worldwide. Protecting food against bacterial contamination and rapid diagnosis of infection require simple and rapid assays for detection of bacterial pathogens, including E. coli O157:H7. Here we report a rapid and novel colorimetric method for detecting E. coli O157:H7. This colorimetric method is based...