A highly selective solution and film based sensor for colorimetric sensing of arginine in aqueous and blood samples

A benzothiazole-azo based sensor (BTAN) was developed for rapid and on-site detection of arginine. The sensor's selectivity in a semi-aqueous medium was thoroughly investigated, focusing on the colorimetric response to arginine in the presence of 11 different amino acids. Notably, the limit of detection (LOD) for arginine was determined to be 0.7 μM. The underlying sensing mechanism was addressed using ¹H-NMR and UV-vis spectroscopy. BTAN exhibited significant changes in both absorption as well as emission spectra exclusively in the presence of arginine. Furthermore, the arginine sensing capability was extended to the solid state by immobilizing BTAN into a starch-PVA hydrogel matrix as well as paper strips. The hydrogel film of BTAN enabled effective on-site sensing of arginine in a 100% aqueous medium. Moreover, the practicability of the sensor was demonstrated by detecting arginine in human blood samples.