Multifunctional gold nanoparticles as signal transducers for fabrication of 1:2 molecular demultiplexer

A label-free and enzyme-free demultiplexer system for the fabrication of 1:2 molecular demultiplexer with luminol functionalized gold nanoparticles (Lum-AuNPs) as signal transducers was developed for the first time. The Lum-AuNPs had both chemiluminescence (CL) activity and surface plasmon resonance property. It was found that organothiols (RSH) could easily induce the aggregation of AuNPs via strong Au–S covalent interactions in the absence of hydrogen peroxide (H 2 O 2 ), generating a red shift in the absorption band of AuNPs. However, the presence of H 2 O 2 would readily oxidize RSH to disulfide (RS-SR), and the aggregation of Lum-AuNPs did not occur due to lack of the sulfhydryl group. Meanwhile, H 2 O 2 could react with Lum-AuNPs, producing a strong CL emission owing to the enhancement effect of RSH on AuNPs-luminol-H 2 O 2 CL system. Thus, RSH, H 2 O 2 , absorbance ratio, and CL intensity served as the signal input, address input, and two different signal outputs of the 1:2 molecular demultiplexer, respectively.