title: Fluorosurfactant-capped gold nanoparticles-based label-free colorimetric assay for Au³⁺ with tunable dynamic range via a redox strategy.
abstract: Gold nanoparticles-based colorimetric assay possesses several unique advantages, and has been applied for a wide range of targets, varying from nucleic acids to different metal ions. However, due to the lack of proper coordinating ligand, gold nanoparticles-based colorimetric sensing system for Au³⁺ has not been developed so far. It is well-known that Au³⁺ could induce the oxidation transition of thiol compounds to disulfide compounds. In this article, for the first time we converted such thiol masking reaction into colorimetric sensing system for label-free detection of Au³⁺ via a target-controlled aggregation of nanoparticles strategy. In the new proposed sensing system, fluorosurfactant-capped gold nanoparticles were chosen as signal reporter units, while an Au³⁺-triggered oxidation of cysteine (Cys), which inhibited the aggregation of gold nanoparticles, acted as the recognition unit. By varying the amount of Cys, a tunable response range accompanied with different windows of color change could be obtained for Au³⁺, illustrating the universality of the sensing system for Au³⁺ samples with different sensitivity requirements. Under optimized condition, the proposed sensing system exhibits a high sensitivity towards Au³⁺ with a detection limit of 50 nM, which is lower than previously reported spectroscopic methods. It has also been applied for detection of Au³⁺ in practical water samples with satisfactory result.
authors: Molecular Science and Biomedicine Laboratory, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, College of Biology, Hunan University, Changsha 410082, China.
authors: Bin
authors: B
authors: Yang
authors: Xiao-Bing
authors: XB
authors: Zhang
authors: Wei-Na
authors: WN
authors: Liu
authors: Rong
authors: R
authors: Hu
authors: Weihong
authors: W
authors: Tan
authors: Guo-Li
authors: GL
authors: Shen
authors: Ru-Qin
authors: RQ
authors: Yu
mesh_terms: D002412:Cations / Q000032:analysis; D003124:Colorimetry / Q000379:methods*; D003545:Cysteine / Q000737:chemistry; D005618:Fresh Water / Q000032:analysis*; D006046:Gold / Q000032:analysis*; D054879:Halogenation; D057230:Limit of Detection; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D013438:Sulfhydryl Compounds / Q000032:analysis; D013501:Surface-Active Agents / Q000737:chemistry
chemical_list: D002412:Cations; D013438:Sulfhydryl Compounds; D013501:Surface-Active Agents; D006046:Gold; D003545:Cysteine