title: Colorimetric assay for sulfate using positively-charged gold nanoparticles and its application for real-time monitoring of redox process.
abstract: A flexible nanoparticle-based sulfate assay is demonstrated in which the positively-charged gold nanoparticles (cysteamine-AuNPs) act as indicator. The aggregation of cysteamine-AuNPs is selectively induced by sulfate, which allows the rapid colorimetric sensing of sulfate without any precipitant, sample preparation and specific instruments. In this work, the cysteamine-AuNPs probe has been successfully applied to the colorimetric detection of sulfate and demonstrates superior sensitivity with a detection limit of sulfate of ~50 ppb. A surprise finding is that the proposed probe can achieve the goal of real-time monitoring and translating a redox process into an appreciable color change via the aggregation of nanoparticles. This is a novel application of a positively-charged AuNPs-based nanoprobe for sulfate detection, kinetic study of the redox process, and opens up new opportunities for design of more novel colorimetric strategies and expansion of AuNPs-based application in different fields.
authors.affiliation: Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Meilong RD 130, Shanghai 200237, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.forename: Yu-Qiang
authors.initials: YQ
authors.lastname: Liu
authors.forename: Bang-Ce
authors.initials: BC
authors.lastname: Ye
mesh_terms: D015374:Biosensing Techniques; D003124:Colorimetry / Q000295:instrumentation / Q000379:methods*; D006046:Gold; D053768:Metal Nanoparticles; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity; D013431:Sulfates / Q000032:analysis*; D014867:Water / Q000737:chemistry
chemical_list: D013431:Sulfates; D014867:Water; D006046:Gold