A nanosol SERS method for quantitative analysis of trace potassium based on aptamer recognition and silver nanorod catalysis of Ag(I)-glucose reaction

Silver nanorods (AgNR) have strong catalysis of the redox reation between AgNO3 and glucose (GLC) to form silver nanoparticles (AgNP) with strong nanoplasmonic effect including surface plasmon resonance (SPR) absorption (RRS) and surface-enhanced resonance Raman scattering (SERS) in the presence of Victoria blue B(VBB) molecular probes. The increased SERS intensity at 1615 cm(-1) responds linearly with the AgNR concentration. The potassium ion aptamers (Apt) can adsorb on the surface of AgNR to inhibit the nanocatalysis. Upon addition of K+, the formed stable G-quadruplex of K-Apt escape from the nanosurface of AgNR to recovery its catalysis. With the increase of K+ concentration, the SERS intensity increased linearly due to producing more AgNP substrates. Thus, a 50-3000 nmol/L K can be analyzed quantitatively by SERS technique, with a detection limit of 25 nmol/L.