A new nano-optical sensor thin film cadmium sulfide doped in sol-gel matrix for assessment of α-amylase activity in human saliva

A novel, simple, sensitive and precise spectrofluorimetric method is developed for measuring the activity of the alpha-amylase enzyme in human saliva. The remarkable quenching of the luminescence intensity at 634 nm of nano CdS doped in a sol-gel matrix by various concentrations of maltose (produced from the reaction of the enzyme with the starch substrate) was successfully used as an optical sensor for the assessment of alpha-amylase activity. The calibration plot was achieved over the concentration range 4.8 x 10(-10) to 1.2 x 10(-5) mol L-1 maltose with a correlation coefficient of 0.999 and a detection limit of 5.7 x 10(-11) mol L-1. The method was used satisfactorily for assessment of the a-amylase activity in a number of human saliva samples collected from various healthy volunteers.