Competitive capacitive biosensing technique (CCBT): a novel technique for monitoring low molecular mass analytes using glucose assay as a model study.
A novel technique for monitoring of low molecular mass analytes using a flow-injection capacitive biosensor is presented. The method is based on the ability of a small molecular mass analyte to displace a large analyte-carrier conjugate from the binding sites of an immobilized biorecognition element with weak affinity to both compounds. A model study was performed on glucose as the small molecular mass analyte. In the absence of glucose, binding of a glucose polymer or a glycoconjugate to concanavalin A results in a capacitance decrease. Upon introduction of glucose, it displaces a part of the bound glucose polymer or glycoconjugate leading to a partial restoration of capacitance. Experimental results show that the change in capacitance depends linearly on glucose concentration within the range from 1.0 x 10(-5) to 1.0 x 10(-1) M, corresponding to 1.8 microg ml(-1) to 18 mg ml(-1) in a logarithmic plot, with a detection limit of 1.0 x 10(-6) (0.18 microg ml(-1)) under optimized conditions. In addition, by modifying the molecular mass of the glucose polymer, amount of biorecognition element, and buffer composition, we were able to tune the analyte-sensing range. The developed technique has the benefits of expanded dynamic range, high sensitivity, and excellent reusability.
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*; D002241:Carbohydrates / Q000032:analysis; D003208:Concanavalin A / Q000737:chemistry / Q000378:metabolism; D003911:Dextrans / Q000032:analysis / Q000737:chemistry; D025802:Electric Capacitance; D005947:Glucose / Q000032:analysis* / Q000378:metabolism; D057230:Limit of Detection; D011108:Polymers / Q000737:chemistry; D011485:Protein Binding
D002241:Carbohydrates; D003911:Dextrans; D011108:Polymers; D003208:Concanavalin A; D005947:Glucose