Size-regulated gold and silver nanorods for discriminating reducing substances: A colorimetric sensor array for Chinese Baijiu

In Chinese food culture, Chinese Baijiu holds an indispensable position. Given its economic and nutritional significance, there is a need to explore rapid and efficient discrimination methods. In this work, a colorimetric sensor array was developed for discriminating Baijiu and reducing substances. This sensor array discriminated by controlling nanoparticle size through the deposition of silver on gold nanoparticles (Au NPs) and etching of silver nanoprism (Ag NPRs). In the present of Baijiu or reducing substance, Ag⁺ was reduced to Ag via a silver mirror reaction and deposited onto the surface of Au NPs. Moreover, the Baijiu or reducing substance could inhibit the etching of Ag NPRs by H₂O₂ or MnO₂ nanosheets (MnO₂ NS). The colorimetric sensor array successfully discriminated among 30 types of reducing substances with a classification accuracy of 94.2 %. This method was subsequently applied to discriminate different types of Baijiu. Sixteen Baijiu samples were successfully discriminated without error. The novel application of the colorimetric sensor array involved manipulating particle size, showcasing promising prospects for Baijiu discrimination.