Enzyme activity detection and color intensity measurement
After printing and drying biosensors were cut into strips and tested for H2O2, glucose and cholesterol. For this purpose, 5 µl of substrate was applied on the sensitive zone of the test strip, and in 2 minutes the color intensity was measured. Enzymatic activity was measured spectrophotometrically in terms of the absorbance increase compared to a control sample by the formation of yellow colored complex of tetravalent titanium with hydrogen peroxide. Measurements were carried out in the range of 200 to 800 nm. In this case we used Cary 60 UV-Vis with Video Barrelino console for measuring diffuse reflectance. Peroxide aqueous solutions with concentrations from 0.0013 to 1% were applied for testing hydrogen peroxide sensitivity. Glucose aqueous solutions with concentrations from 3 to 100 mg / dL were used to test for glucose determination. Cholesterol alcohol solutions with concentrations from 6 to 200 mg / dL were employed for cholesterol detection testing.