Wettability Switching of Electrode for Signal Amplification: Conversion of Conformational Change of Stimuli-Responsive Polymer into Enhanced Electrochemical Chiral Analysis

Signal amplification of chiral interaction is a much needed task for sensing of enantiomers due to nearly identical chemical and physical properties of the chiral isomers. In this article, we established an electrochemical chiral sensing method with high sensitivity and selectivity for monosacharrides based on the stimuli-responsive copolymer/graphene hybrid-modified screen-printed carbon electrodes. The hybrid synthesized by the "grafting from" atom transfer radical polymerization (ATRP) process not only acted as a chiral recognition element but also provided a chiral signal amplification strategy. This occurs due to high sensitivity of conformational transition of copolymer on graphene to the weak chiral interactions that greatly facilitating the diffusion of electroactive probes and monosaccharides to the electrode surface. The described method can quantify monosaccharides, even the concentration of one enantiomer is as low as 1 nM. Apart from the demonstrated chiral distinguish ability, good selectivity toward monosaccharides in comparison to potential interference molecules was also observed. The electrodes with significant analytical performance were successfully applied for discriminating glucose enantiomers in live cells and studying their different transport mechanism. Together, the results show that the coupling of amplification-by-wettability switching concept with electrochemical method offers great promises in providing a sensitive, facile, and cost-effective solution for chiral recognition of molecules in biological process.