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 α-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 α-amylase activity. The calibration plot was achieved over the concentration range 4.8 × 10(-10) to 1.2 × 10(-5) mol L(-1) maltose with a correlation coefficient of 0.999 and a detection limit of 5.7 × 10(-11) mol L(-1). The method was used satisfactorily for assessment of the α-amylase activity in a number of human saliva samples collected from various healthy volunteers.