Analytical Sciences

Abstract − Analytical Sciences, 25(8), 1013 (2009).

Highly Sensitive and Selective Uric Acid Biosensor Based on Direct Electron Transfer of Hemoglobin-encapsulated Chitosan-modified Glassy Carbon Electrode
Changzhi ZHAO, Li WAN, Qin WANG, Shufeng LIU, and Kui JIAO
Key Laboratory of Eco-chemical Engineering, Ministry of Education, College of Chemistry & Molecular Engineering, Qingdao University of Science & Technology, 53 Zhengzhou Road, Qingdao 266042, China
A uric acid biosensor based on the direct electron transfer of a hemoglobin-encapsulated chitosan-modified glassy carbon electrode was developed for a highly sensitive and selective analysis in urine samples. The modified electrode was prepared by the encapsulation of hemoglobin and uricase in a chitosan matrix. The hydrogen peroxide produced from the catalytic oxidation of uric acid by uricase was reduced electrocatalytically by immobilized hemoglobin and used to obtain a sensitive amperometric response to uric acid. The linear response of the uric acid concentrations ranged from 2.00 to 30.0 μM with a correlation of 0.9982, the detection limit of uric acid was estimated to be 0.85 μM at a signal/noise ratio of 3. The uric acid biosensor can efficiently exclude the interference of commonly coexisted ascorbic acid, dopamine, epinephrine, etc. The relative standard deviation was under 2.56% (n = 5) for the determination of real samples. This biosensor is satisfactory for the determination of human urine samples compared with the HPLC-UV method.