A novel competitive capacitive glucose biosensor based on concanavalin A-labeled nanogold colloids assembled on a polytyramine-modified gold electrode.
A highly sensitive competitive capacitive glucose biosensor was constructed based on gold nanoparticles, which were employed as a platform to immobilize concanavalin A (Con A). Gold nanoparticles were fixed on a gold electrode, on which a layer of polytyramine was preformed via electrochemical polymerization. The sensing mechanism is based on the competitive dissociation of a glucose polymer or a glycoconjugate from the glycoligand binding sites of immobilized Con A by the added glucose. To further improve the sensor response, several glucose polymers as well as a synthesized glycoconjugate using the periodate method, were screened. Consequently, dextran (MW 39 kDa) was selected and the feasibility of the proposed biosensor was evaluated for a competitive assay of glucose. Experimental results show that the biosensor responded linearly to glucose in the range from 1.0 x 10(-6) to 1.0 x 10(-2) M, corresponding to 0.18 microg mL(-1) to 1.8 mg mL(-1) of glucose with a detection limit of 1.0 x 10(-6) M under optimized conditions. The studied biosensor exhibited a response time of about 15 min and a neglectable loss in sensitivity after 10 repeated analytical cycles.
Labib
Mahmoud
M
Department of Biotechnology, Lund University, Box 124, 221 00, Lund, Sweden.
Hedström
Martin
M
Amin
Magdy
M
Mattiasson
Bo
B
D015374:Biosensing Techniques / Q000379:methods*; D003102:Colloids / Q000737:chemistry*; D003208:Concanavalin A / Q000737:chemistry*; D004566:Electrodes; D005947:Glucose / Q000032:analysis*; D006046:Gold / Q000737:chemistry*; D055767:Immobilized Proteins / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D015203:Reproducibility of Results; D014439:Tyramine / Q000737:chemistry*
D003102:Colloids; D055767:Immobilized Proteins; D003208:Concanavalin A; D006046:Gold; D005947:Glucose; D014439:Tyramine