One-Pot, Rapid Self-Assembly of Scalable Xylan-Based Humidity Biosensors via Electrophoretic Deposition

Xylan, the abundant polysaccharide in lignocellulose, manifests remarkable renewability and biodegradability, and is envisaged to be crucial in fabricating eco-friendly, biobased functional materials. However, solvent casting and evaporation-induced self-assembly methods are the most fundamental routes for xylan-based materials, posing challenges such as poor solubility of commercially available xylan, time-consuming procedures, and sensitivity to external factors. To enhance the technological feasibility of xylan, a facile and flexible method suitable for industrial exploitation is developed, using the electrophoretic deposition (EPD)-induced self-assembly of carboxymethylated xylan (CMX). Materials of specific sizes can be generated within a few minutes (<5 min) by controlling CMX’s high surface property (zeta potential of −33.6 mV) and EPD parameters. Notably, CMX exhibits outstanding dispersion stability for carbon nanotubes, reaching 84.4%, enabling their uniform coassembly during the EPD process to one-pot fabricate a humidity biosensor with a reliable, reproducible humidity response (over 13 cycles) and superior humidity sensitivity over a wide relative humidity range of 14–89% RH. This work puts forward a one-pot, rapid self-assembly strategy for the scalable production of high-performance xylan-based materials, which unlocks the potential of EPD with CMX in biosensor applications.