Etching and anti-etching strategy for sensitive colorimetric sensing of H₂O₂ and biothiols based on silver/carbon...

In this paper, the colorimetric sensing of H₂O₂ related molecules and biothiols based on etching and anti-etching strategy was firstly proposed. Ag/carbon nanocomposite (Ag/C NC) was served as the sensing nanoprobe, which was synthesized via carbon dots (C-dots) as the reductant and stabilizer. The characteristic surface plasmon resonance (SPR) absorbance of Ag nanoparticles (AgNPs) was sensitive to the amount of hydrogen peroxide (H₂O₂). It exhibited strong optical responses to H₂O₂ with the solution colour changing from yellow to nearly colourless, which is resulted from the etching of Ag by H₂O₂. The sensing platform was further extended to detect H₂O₂ related molecules such as lactate in coupling with the specific catalysis oxidation of L-lactate by lactate oxidase (LOx) and formation of H₂O₂. It provides wide linear range for detecting H₂O₂ in 0.1-80μM and 80-220μM with the detection limit as low as 0.03μM (S/N=3). In the presence of biothiols, the etching from the H₂O₂ can be hampered. Other biothiols exhibit anti-etching effects well. The strategy works well in detecting of typical biothiols including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH). Thus, a simple colorimetric strategy for sensitive detection of H₂O₂ and biothiols is proposed. It is believed that the colorimetric sensor based on etching and anti-etching strategy can be applied in other systems in chemical and biosensing areas.