Development of Beta vulgaris L. extract-finished plasma-cured recycled linen fabrics as a chromogenic sensor for...

A novel smart textile swab was developed as an analytical tool for the onsite evaluation of biochemical changes in sweat toward potential applications in healthcare monitoring and drug testing. Betalain (BTA) was extracted from beetroot (Beta vulgaris L.) using a simple procedure. Recycled woven textile waste was recycled to linen fibers for the production of nonwoven textile by the needle punching technology. The betalain probe was applied to the recycled nonwoven linen cloth in the presence of a mordant to fasten BTA to cellulose fibers. The sweat monitoring was performed by generating halochromic mordant (Al)/betalain (BTA/Al) nanoparticles (15-35 nm) on the plasma-treated fabric surface. Increasing the pH of a sweat mimic solution results in a blueshift (hypsochromism) in the absorption spectra of the cellulose sensor, switching the wavelength from 583 nm to 440 nm, demonstrating an isosbestic point of 503 nm. The biochromic efficiency of the BTA-dyed cellulose diagnostic tool mostly depends on the halochromic character of the betalain probe, which exhibited a color switch from red to yellow owing to a pH-driven intramolecular charge delocalization in the BTA chromophore. The fastness properties of the dyed nonwoven fabrics demonstrated satisfactory results. No substantial defects were identified in the air permeability and stiffness of the BTA-finished nonwoven textiles.