Rare-Earth-Encapsulated SIV-TeIV-Templated Polyoxotungstate for Photoelectrochemical Enzyme Biosensor for Glucose Detection.

By utilizing a [SIVO3]2- and [TeIVO3]2- mixed-heteroanion strategy, a rare-earth encapsulated SIV-TeIV-templated polyoxotungstate [N(CH3)4]14K2.5Na7.5{[Er2W4(H2O)7O9][SW9O33][TeW9O33][S0.5Te0.5W9O33]}{[Er2W4(H2O)7O9][S0.5Te0.5W9O33]2[TeW9O33]}·98 H2O (1) was synthesized, whose polyoxoanion skeleton is composed of two discrete trimeric ErIII-encapsulated SIV-TeIV-templated polyoxotungstate {[Er2W4(H2O)7O9][SW9O33][TeW9O33][S0.5Te0.5W9O33]}12- and {[Er2W4(H2O)7O9][S0.5Te0.5W9O33]2[TeW9O33]}12- units. It is worth noting that 1 represents the first polyoxotungstate simultaneously incorporating SIV and TeIV heteroatoms in the polyoxometalate family. Moreover, its application in photoelectrochemical (PEC) biosensor was explored by sonicating 1 into nanosized crystals (nano-1). Subsequently, a Au/nano-1/PbS composite material comprising nano-1, lead sulfide (PbS) and Au nanoparticles (AuNPs) was prepared, which was utilized to construct a PEC sensor for detecting hydrogen peroxide with a detection limit of 2.331 μM and the detection range from 5 × 10-6 to 5 × 10-4 M. Soon afterward, by immobilizing glucose oxidase, an enzyme-based PEC sensor was developed for glucose detection, demonstrating outstanding performance with a low detection limit of 3.142 nM. This work not only provides a new strategy for synthesizing complicated polyoxometalates containing different heteroatoms, but also highlights the potential of polyoxometalate-based materials for PEC biosensor applications.