Surface functionalization of low-cost textile-based microfluidics for manipulation of electrophoretic selectivity of charged analytes

Textile-based microfluidics offer new opportunities for developing low-cost, open surface-assessable analytical systems for the electrophoretic analysis of complex chemical and biological matrixes. In contrast to electrophoretic fluidic transport in typical chip-based enclosed capillaries where direct access to the sample zone during analysis is a real challenge. Herein, we demonstrate that electrophoretic selectivity could be easily manipulated on these inverted low-cost bespoke textile substrates via a simple surface-functionalization to manipulate, redirect, extract, and characterize charged analytes. This simple approach enables significant improvement in the electrophoretic separation and isotachophoretic (ITP) preconcentration of charged solutes at the surface of open surface-accessible 3D textile constructs. In this work, polyester 3D braided structures have been developed using the conventional braiding technique and used as the electrophoretic substrates, which were modified by dip-coating with polycationic polymers such as chitosan and polyethyleneimine (PEIn). The surface functionalization resulted in the modulation of the electroosmotic flow (EOF) and electrophoretic mobilities of the charged solutes with respect to the unmodified substrates. Chitosan outperformed PEIn in terms of efficient electrophoretic separation and isotachophoretic stacking of an anionic solute. However, PEIn modification resulted in significant suppression of the EOF over a broad range of pH values from 3 to 9 and exhibited fast EOF at acidic pH compared to controlled polyester, which could be promising for the analysis of basic proteins. These findings suggest a great potential for the development of affordable surface-accessible textile-based analytical devices for controlling the specific migration, direction, analysis time, and separation and preconcentration of charged analytes. Graphical abstract: [Figure not available: see fulltext.]