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.