Enzyme-free hydrogen peroxide sensor from dual-shaped plasmonic silver nanoparticles

Abstract

A novel growth-based strategy for the determination of hydrogen peroxide has been developed using a mixture of silver nanospheres (AgNSs) and citrate-capped silver nanoprisms (AgNPrs). The unique ability of hydrogen peroxide to oxidize silver nanoparticles and reduce silver metal consequently was exploited to produce a highly sensitive and selective sensor (AgNSs/NPrs). Citrate-capping of the AgNPrs only allows the lateral growth that resulted in a red shift and intensity enhancement of the in-plane dipole plasmon resonance (IPDPR) band. Consequently, distinct hues from yellow, orange, red, purple to blue were produced from the diluted sensors. Ratiometric analysis was employed to quantify H2O2 using absorbance values at the decreasing dipole plasmon resonance (DPR) band of the AgNSs and the increasing IPDPR of the AgNPrs. A detection limit of 4.8 μM was achieved with concentrated hydrogen peroxide determination. Selectivity of the sensor was evaluated using common anions. According to the results of the interference testing, the sensor can only tolerate micromolar levels of bromide and iodide which is not an issue for fresh water or biological samples. The detection of diluted H2O2 was further simplified by using an optimized AgNSs/NPrs sensor concentration and ratio of 20:10 ppm. Colorimetric readout can be achieved at higher sensor concentrations that also provides a broad linear range from 10 to 800 mM. Accuracy and precision testing on concentrated hydrogen peroxide and spiked drinking water show excellent results. Thus, growth-based sensing using dual-shaped silver nanoparticles is a promising alternative as it enables a quick, highly selective, and sensitive colorimetric determination of hydrogen peroxide with high accuracy and precision.