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

Abstract

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.