Homochiral light-sensitive metal-organic framework photoelectrochemical gated transistor for enantioselective discrimination of monosaccharides.

As pure antipodes may differ in biological interactions, pharmacology, and toxicity, discrimination of enantiomers is important in the pharmaceutical and agrochemical industries. Two major challenges in enantiomer determination are transducing and amplifying the distinct chiral-recognition signals. In this study, a light-sensitive organic photoelectrochemical transistor (OPECT) with homochiral character is developed for enantiomer discrimination. Demonstrated with the discrimination of glucose enantiomers, the photoelectrochemically active gate electrode is prepared by integrating Au nanoparticles (AuNPs) and a chiral Cu(II)-metal-organic framework (c-CuMOF) onto TiO nanotube arrays (TNT). The captured glucose enantiomers are oxidized to hydrogen peroxide (HO) by the oxidase-mimicking AuNPs-loaded c-CuMOF. Based on the confinement effect of the mesopocket structure of the c-CuMOF and the remarkable charge transfer ability of the 1D nanotubular architecture, variations in HO yield are translated into significant changes in OPECT drain currents (I) by inducing a catalytic precipitation reaction. Variations in I confer a sensitive discrimination of glucose enantiomers with a limit of detection (LOD) of 0.07 μM for L-Glu and 0.05 μM for D-Glu. This enantiomer-driven gate electrode response strategy not only provides a new route for enantiomer identification, but also helps to understand the origin of the high stereoselectivity in living systems.