A new method has been proposed to realize the visual detection of D-amino acids （DAAs） via the antiaggregation of 4-mercaptobenzoic acid modified gold nanoparticles （AuNPs） in the presence of D-amino acid oxidase ...A new method has been proposed to realize the visual detection of D-amino acids （DAAs） via the antiaggregation of 4-mercaptobenzoic acid modified gold nanoparticles （AuNPs） in the presence of D-amino acid oxidase （DAAO）. The negatively charged AuNPs were prepared using sodium citrate as a reducer and stabilizer. The presence of 4-mercaptobenzoic acid （4-MBA） and Cu2＋ induces the aggregation of AuNPs, resulting in a color change from ruby red to royal purple. However, DAAO could oxidize DAAs to generate H2O2. In the presence of H2O2, the mercapto （-SH） group in 4-mercaptobenzoic acid can be oxidized to form a disulfide （-S-S-） bond. Based on these facts, the pre-incubation of DAAs and 4-mercaptobenzoic acid with DAAO would significantly reduce the concentration of free 4-mercaptobenzoic acid molecules, thus the aggregation of AuNPs was interrupted since due to the lack of inducer. As the concentration of DAAs increases, the color of the AuNPs solution would progress from royal purple to ruby red. Consequently, DAAs could be monitored by the colorimetric response of AuNPs using a UV-vis spectrophotometer or even naked eyes. This DAAO mediated visual detection method could determine D- alanine （D-Ala） as a representative DAA with concentrations ranging from 1.5 × 10^-7mol L 1 to 3.0 × 10^-5 mol L^-1, and the detection limit was as low as 7.5 × 10^-8 mol L^-1. The proposed method is convenient, low-cost and free of complex equipment, making it feasible to analyze the concentration of D-AIa in real samples of β-amyloid peptide （Aβ1-42）.展开更多
基金supported by the National Natural Science Foundation of China(No.21272263)the State Key Laboratory of Natural and Biomimetic Drugs(No.K20130206)+1 种基金the University of Chinese Academy of Sciences(No.08JT011J01)the Twelfth Five-Year Plan for National Sciences&Technology Support Project(No.2012BAI37B03)
文摘A new method has been proposed to realize the visual detection of D-amino acids （DAAs） via the antiaggregation of 4-mercaptobenzoic acid modified gold nanoparticles （AuNPs） in the presence of D-amino acid oxidase （DAAO）. The negatively charged AuNPs were prepared using sodium citrate as a reducer and stabilizer. The presence of 4-mercaptobenzoic acid （4-MBA） and Cu2＋ induces the aggregation of AuNPs, resulting in a color change from ruby red to royal purple. However, DAAO could oxidize DAAs to generate H2O2. In the presence of H2O2, the mercapto （-SH） group in 4-mercaptobenzoic acid can be oxidized to form a disulfide （-S-S-） bond. Based on these facts, the pre-incubation of DAAs and 4-mercaptobenzoic acid with DAAO would significantly reduce the concentration of free 4-mercaptobenzoic acid molecules, thus the aggregation of AuNPs was interrupted since due to the lack of inducer. As the concentration of DAAs increases, the color of the AuNPs solution would progress from royal purple to ruby red. Consequently, DAAs could be monitored by the colorimetric response of AuNPs using a UV-vis spectrophotometer or even naked eyes. This DAAO mediated visual detection method could determine D- alanine （D-Ala） as a representative DAA with concentrations ranging from 1.5 × 10^-7mol L 1 to 3.0 × 10^-5 mol L^-1, and the detection limit was as low as 7.5 × 10^-8 mol L^-1. The proposed method is convenient, low-cost and free of complex equipment, making it feasible to analyze the concentration of D-AIa in real samples of β-amyloid peptide （Aβ1-42）.
