Optical Detection of Thiocyanate in Human Saliva based on the Colorimetric response of (2-(2-hydroxyphenyl)-1H-benzo[d]imidazol-5-yl)(phenyl) methanone (HBPM)/Co2+ ions Conjugate

Abstract Simple colorimetric biosensor was designed for the quantification SCN− ions based on the principle of colorimetric reactions between Co2+ and SCN− ions reaction using synthesized chromophore (2-(2-hydroxyphenyl)-1H-benzo[d]imidazol-5-yl)(phenyl) methanone (HBPM)/Co2+ ions conjugate which was synthesized via greener ultrawave sonication method. The structural characterization of the HBPM chromophore was confirmed by using NMR, ESI-MASS spectral techniques and the photophysical properties, sensor studies were done by using UV–Vis Spectrophotometer. Our designed HBPM/Co2+ ions conjugates have selectively detected SCN− ions qualitatively and quantitatively in the presence of other human salivary interferents. As per clinical point of view, three different ranges of SCN− ions from 0.1 to 2 mM for normal, 3 to 10 mM for disease, and 100–600 µM for below normal ranges were tested successfully by our developed sensor and the LoD was calculated as 5.43 nM. The real potent application of the developed biosensor was tested in human salivary samples of both smokers and non-smokers under different ages and obtained results shown good agreement with existing clinical methods.