A sensitive and selective colorimetric sensor for reduced glutathione detection based on silver triangular nanoplates conjugated with gallic acid

Abstract

Silver triangular nanoplates conjugated with gallic acid (AgTNPs⋅GA) was designed and synthesized for colorimetric detection of reduced glutathione (GSH). The surface plasmon resonance (SPR) properties of AgTNPs⋅GA were strongly influenced by the addition of GSH. The detection principle was based on the aggregation of AgTNPs⋅GA, which leads to the significant bathochromic shift of the SPR spectra from 602 nm to 650 nm. The dramatic color changes from the initial dark blue to light blue can be observed, which allowed simple monitoring of GSH ether by naked eye and UV–vis spectrophotometer. With UV–vis spectrophotometer measurements, a quantitative linearity was established in the range of 0.5–5.0 nM (R2 = 0.9919) and with a limit of detection (LOD) of 0.12 ± 0.02 nM. Relative standard deviation (RSD) of 3.46% and 1.82% (n = 10) were achieved for the determination of 1.0 and 3.0 nM, respectively. No interfering substances such as ascorbic acid, glucose, sucrose, citric acid, cysteine, Ca2+, Mg2+, Fe3+ and K+ were revealed in the AgTNPs⋅GA based assay. The proposed colorimetric strategy could be extended as the general platform for detection of GSH in dietary supplements and no significant differences in accuracy and precision were observed compared to HPLC standard method.