Nanochannel-Gating Electrochemical Sensor Functionalized with Triethoxysilane-Modified 5-Methyluridine for Highly Selective Hg2+ Detection via T−Hg2+−T Coordination

A mesoporous silica nanochannel-gated electrochemical sensor, functionalized with a triethoxysilane-modified 5-methyluridine, has been developed for the highly sensitive and selective detection of trace Hg2+ in real water samples. The sensing mechanism hinges on the formation of specific T−Hg2+−T coordination complexes mediated by triethoxysilane-modified 5-methyluridine. This interaction induces steric hindrance within the nanochannels, which impedes mass transfer and effectively excludes the methylene blue from the pores, thereby resulting in a substantial attenuation of the redox current. The Hg2+ concentration is linearly correlated with the degree of attenuation of the methylene blue electrochemical signal. Under optimized conditions, the sensor demonstrates a broad detection range from 1 nM to 50 μM, with a low detection limit of 0.56 nM. Moreover, for the analysis of tap water and river water samples, the recovery rates range from 95.4% to 104.6% with relative standard deviations between 0.52% and 1.57%. Notably, this electrochemical sensor delivers high sensitivity and selectivity while requiring only a portable setup, highlighting its great promise for the on-site environmental Hg2+ monitoring.