Facile synthesis of water-soluble and pH-stable silicon quantum dot and its application in enzyme-free hydrogen peroxide sensing

A sensor for non-enzymatic hydrogen peroxide (H2O2) was developed based on silicon quantum dots (SiQDs). The fluorescent SiQDs were synthesized using a one-pot hydrothermal method. The SiQDs were made water-soluble and pH-stable by covering their surfaces with amino and hydroxyl groups. Additionally, the prepared SiQDs had a large Stokes shift (131 nm), excellent photostability (442 min), and hypotoxicity (e.g., 99% of cell viability was kept after a 24 h-treatment at 8.0 mg/mL of the SiQDs). The dynamic quenching effect induced by H2O2 effectively suppresses the blue fluorescence of SiQDs. Under the optimum conditions, the SiQD-based H2O2 sensor exhibited a wide linear range (10–1000 μM), high sensitivity and selectivity, and a good anti-interference ability. The detection limit and relative standard deviation were 1.7 μM and 4.5% (c = 20 μM, n = 7), respectively. Accordingly, a simple, enzyme-free, and highly efficient method was established for detecting H2O2 in aqueous solutions. Moreover, this eco-friendly fluorescent sensor successfully determined H2O2 in human serum samples with 92%–102% recoveries.