Biosensors for the Detection of Glucose in Human Interstitial Fluid

Biosensors are devices comprising of a selective interface in close proximity or integrated with a transducer, which relays an interaction between the surface and analyte. Additionally, electrochemical biosensors are capable of operating in turbid media, much like the interstitial fluid of the human body. Enzyme-based biosensors are highly effective tools for detecting the presence of a biological molecule in vivo that can be utilized in medical devices and diagnostics. This research project focused on the development of a robust glucose biosensor system that can detect glucose in subcutaneous human interstitial fluid. Large biological molecules, like enzymes or antibodies, can be immobilized to the surface of microelectrodes by forming a stable acyl amino ester on the electrode surface. The co-addition of N'-(3-dimethyaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) forms a stable amino ester. Large biological molecules can be easily intercalated into this network, and will be immobilized in the immediate proximity of the electrode. Glucose oxidase (GOx) was densely substituted into this network by replacing the active NHS esters with the primary amines of the enzyme. When tested and calibrated in a solution designed to mimic the composition of human interstitial fluid, the glucose biosensors accurately measured the concentration glucose over an eight-hour operational period, particularly at glucose concentrations within the hypoglycemic regime.