DIRECT SENSING PLATINUM ULTRAMICROBIOSENSORS FOR GLUCOSE

Miniaturized glucose biosensors were constructed from disk-shaped ultr amicroelectrodes (UMEs) (diameter = 10 mum and 25 mum), cylindrical UM Es (diameter = 25 mum), and platinum black modified UMEs. Glucose oxid ase (E.C.1.1.3.4) was immobilized by glutaraldehyde cross-linking. All ultramicrobiosensors (UMBs) had response times (100% response) of les s than 1 min, and had linear response over the human clinical range fo r glucose (3-7 mM). Response to glucose was linear over a greater conc entration range at cylindrical UMBs, compared to similarly prepared di sk-shaped UMBs, typically from 3-20 mM glucose. Thin, electrochemicall y polymerized films were used to prevent signals due to interfering sp ecies. A variety of different films, and electropolymerization conditi ons were examined. Poly(1,3-diaminobenzene) (1,3-DAB) was found to be the most effective at preventing signals due to interferents. Poly(1,3 -DAB) was used to protect the biosensor from fouling. A 25 mum biosens or, with poly(1,3-DAB), was used for the direct measurement of glucose in complex samples.