Development of stimuli-responsive cellulose textile finished with natural extract for detection of ammonia

The aim of this study is to develop an eco-friendly, flexible, sensitive, rapid-response, reversible, portable, cost-effective, and straightforward solid-state colorimetric smart cotton fabric (CF) designed as a vapochromic sensor for detecting ammonia. The natural Betalain (BTL) dye can be derived from Beta vulgaris L. (beetroot). The BTL dye was directly applied to cotton fibers in the presence of a mordant, resulting in the formation of a mordant/BTL coordinated complex nanoparticles. The molecular size, water solubility, sensitivity, and rapid response of BTL make them suitable indicator dyes for cellulose fibers, facilitating the development of diagnostic tests (BTL@CF) for gaseous and aqueous ammonia. The BTL-dyed fabric demonstrated a fast response within a fraction of a second, exhibiting a detection limit ranging from 5 to 400 mg/L. The BTL receptor exhibited ratiometric alterations in the absorption spectra, demonstrating hypsochromism from 574 to 403 nm with an isosbestic point of 477 nm when the ammonia concentration level increased in aqueous solutions. The diameters of the mordant/BTL nanoparticles were found to be 15–55 nm. No significant flaws were noticed in air permeability and bending length during the textile finishing process. The treated cotton fibers exhibited satisfactory colorfastness.