Biomolecular probe-encapsulated into polysaccharide nanofibrous membrane for determination of ammonia

Abstract

Exposure to high ammonia concentration can cause lung damages, burns to throat, nose, eyes, and respiratory tract, and can even cause death. Herein, we reported the development of colorimetric cellulose acetate nanofibers (CANF) to function as a colorimetric sensor for ammonia. Red cabbage plant is a natural source of spectroscopic probe known as anthocyanin (CYN). In order to create mordant/anthocyanin (M/CYN) nanoparticles, the CYN direct dyestuff was immobilized into cellulose acetate fibers in the presence of a mordant (potash alum). Anthocyanins have been suitable indicators for ammonia because of their small molecular size, water solubility, high sensitivity, and rapid detection. CIE Lab coordinates and absorption spectra were utilized to investigate a purple-to-green color change in the smart CANF fabric after being exposed to aqueous ammonia. The colorimetric cellulose acetate nanofibrous fabric displayed a detection limit range of 50–800 mg/L for aqueous ammonia. The anthocyanin probe showed hypsochromic alterations in absorption spectra, with a decrease in wavelength from 568 nm to 437 nm as a function of ammonia concentration in an aqueous solution. This could be explained by modifications to the molecular structure of anthocyanin as a result of intramolecular charge transfer. TEM analysis revealed that the nanoparticles of M/CYN had diameters of 5–7 nm, whereas SEM images showed that the nanofibers of CANF had diameters of 50–150 nm. Moderate variations in stiffness and air-permeability were detected after immobilization of M/CYN into CANF.