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 (H2O2), generating a red shift in the absorption band of AuNPs. However, the presence of H2O2 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, H2O2 could react with Lum-AuNPs, producing a strong CL emission owing to the enhancement effect of RSH on AuNPs-luminol-H2O2 CL system. Thus, RSH, H2O2, absorbance ratio, and CL intensity served as the signal input, address input, and two different signal outputs of the 1:2 molecular demultiplexer, respectively.