Non-invasive biosensors in clinical analysis.

Several amperometric biosensors have been developed and applied for the non invasive determination of metabolites in body fluids. Advantages of saliva or sweat analysis are the ease of sample collection and that samples can be collected more frequently with much less stress on the patient. An alcohol biosensor has been developed with a hydrogen peroxide based electrode utilizing immobilized alcohol oxidase. Immobilization parameters have been optimized to increase the stability of the enzyme. An auter hydrophobic gas membrane was used to improve the selectivity of the probe. A hydrogen peroxide based amperometric biosensor has also been developed that utilized the enzyme glucose oxidase. The biosensor was applied to the determination of sera and saliva glucose content. Two hydrogen peroxide based amperometric biosensors that utilized lactate oxidase were also developed for determination of lactate in saliva and sweat. To discriminate against electroactive substances, the biosensor for assay of lactate in saliva utilized a dual electrode with one side active and one inactive, while the biosensor for assay of sweat lactate content utilized a hydrophobic hydrogen peroxide membrane to improve selectivity. Lactate content of saliva and sweat samples were measured after an intense physical exercise. A new procedure to measure glucose via transbuccal mucosa was developed using a dual glucose probe similar to that used for lactate. Correlation between glucose in blood and in transbuccal mucosa has been evaluated.