Gold/silver-polymer hybrid nanostructures as thermoreversible optical sensors and probes for the quantification radical compounds

Abstract

We present gold (Au) and silver (Ag) nanoparticles (NPs) could be used not only for stimuli- responsive optical sensors but also for the quantification of radical compounds when these nanoparticles are suitably combined with polymeric materials. When Au NPs are assembled 2- dimensionally on the surface of hydrogel NPs which respond to temperatures, the hybrid NPs displayed thermoreversible multiple color swrtching Accordingly, optical bandwidths of the hybnd NP5 are reversibly changed with temperatures with hybrid NPs assembled with SI run Au NPs, prominent optical signals arc recorded at 900 nm at 50 °C while most of extinction signals are shown below 600 nm at room temperatures In addition, we demonstrate the modification of Ag NPs' surfaces (nanocubes and nanospheres) with polyelectrolytes (either positive or negative) could extend the quantifiable detection ranges of radical compounds. Through the surface modification of Ag NPs. the polyelectrolyles protect the Ag NPs by probably either retarding (forming diffusion bamers) or preventing (blocking/entrapptnglscavenging) the arrival of radicals to Ag NPs or both. The roles of the polyelectrolyies are demonstrated by using radical compounds produced from tetrahydrofuran and H202. From the results. we could obtain calibration curves for the wide-range quantification of radical compounds.