Application of Nanopore Single Molecule Detection Technology in Analysis of Xylan Dissolved in Ionic Liquid†

Abstract

Comprehensive SummaryXylan is the most abundant hemicellulose in nature. As a new type of green organic solvent, ionic liquid shows good preservation ability for the functional groups of hemicellulose. In this paper, a single molecule detection technology based on glass nanopore was established to analyze xylan dissolved in ionic liquid. Arabino‐xylan (AX) and beech xylan (BX) are respectively taken as the representatives of heterogeneous xylan and homogeneous xylan. Firstly, unmodified glass nanopore was used to detect the dissolved xylan in ionic liquid, and then poly(ethylene imine) (PEI) was used to modify the nanopore to change the surface charge in the nanopore and further enhance the interaction between the nanopore and the xylan molecule. It was found that before and after nanopore modification, at negative voltage and low positive voltage, AX didn't generate current blocking signal. On the contrary, BX didn't generate current blocking signal at positive voltage. This phenomenon may be due to the current disturbance driven by electrophoresis and electroosmosis of xylan molecules with weak negative charge. After statistics analysis, the current blocking signal of AX showed that the modified nanopore showed multiple peaks. It indicates that heterogeneous xylan and PEI modified nanopore had stronger interaction. The results show that the nanopore detection technology can show the structural difference of heterogenous branched chain and homogeneous straight chain based on the single characteristic current blocking signal and statistical information, providing a research basis for the structural analysis of water insoluble polysaccharides.