Chitosan functionalization to prolong stable hydrophilicity of cotton thread for thread-based analytical device application

Cotton thread has been proposed as a new, economically affordable material for the fabrication of microfluidic circuits for use in fast, low-cost, point-of-care diagnostic testing devices. In this work, chitosan, a biocompatible polymer, was used to modify cotton thread to improve its fluidic properties for microfluidic applications. Electrostatic-interaction-mediated adsorption of chitosan on alkaline-scoured thread can effectively increase thread’s solution hydrophilicity and wicking rate. Moreover, the proposed process conserves the thread’s hydrophilicity and fluidic properties even when stored for several months. As a microfluidic platform for enzymatic-reaction-associated colorimetric measurement, the suggested chitosan modification results in the accumulation of more analyte in the detection zone because of the improved flow rate, which enhances the colorimetric signal intensity. In this study, a glucose oxidase-mediated colorimetric glucose assay was demonstrated on a chitosan-modified microfluidic thread-based analytical device (μTAD). A linear range of 1–7.5 mM, a low detection limit of 0.2 mM, and a recovery rate between 93 and 98% was achieved in detecting glucose in artificial urine samples.