Selective glucose detection based on the concept of electrochemical depletion of electroactive species in diffusion layer.
A glucose detection approach based on the concept of electrochemical depletion of electroactive species in diffusion layer was established, using scanning electrochemical microscopy (SECM). By controlling the glucose oxidase (GOD) modified electrode (substrate electrode) at a proper potential of electrochemical oxidation of interfering electroactive species, i.e., ascorbic acid (AA), an interference-free microcircumstance was formed in the diffusion layer of the substrate electrode. Consequently, we could successfully sense hydrogen peroxide generated from an enzymatic reaction by locating a Pt ultramicroelectrode (UME) (tip electrode, 5 microm in radius) into the diffusion layer of the substrate electrode. Properties of this interference-removing approach based on electrochemical depletion were systematically investigated. Results showed that the interference-removing efficiency was significantly determined by the tip-substrate distance and substrate potential. When the tip-substrate distance was 11 microm (2.2 times of the tip electrode radius) and the substrate potential was 0.5 V, nearly 90% of AA (0.5 mM) could be depleted within 30s without consumption of H2O2. Under these conditions, 0.1 mM AA showed no influence on the detection of 0.5 mM glucose. The linear range of glucose detection is 0.01-1 mM with a detection limit (DL) of 0.005 mM (correlation coefficient is 0.9948). This research will open a new way for developing selective micro-biosensors.
Wang
Kang
K
The State Key Laboratory of Coordination Chemistry, Department of Chemistry, Institute of Analytical Science, Nanjing University, Nanjing 210093, China.
Xu
Jing-Juan
JJ
Sun
Da-Cheng
DC
Wei
Hui
H
Xia
Xing-Hua
XH
D015374:Biosensing Techniques; D004566:Electrodes; D005947:Glucose / Q000032:analysis*; D008855:Microscopy, Electron, Scanning
D005947:Glucose