Disposable electrochemical biosensor for amperometric measurement of β-hydroxybutyrate and total cholesterol

A new type of disposable thin-film amperometric biosensor has been developed for measurement of beta-hydroxybutyrate and total cholesterol in serum. The biosensor consists of two plain gold electrodes mounted on a Polyethylene terephthalate (PET) substrate. The reagent solution contains bienzymes (cholesterol oxidase and cholesterol esterase for total cholesterol, beta-hydroxybutyrate dehydrogenase and diaphorase for beta-hydroxybutyrate respectively) with mediator (ferricyanide) were absorption at the surface of electrodes coated by electrodepositing platinum black. The presence of the mediator lowers the applied potential and eliminates the interference from other oxidizable species enhancing the sensitivity and selectivity of the biosensor without modifying the dynamic parameters of the response. The enzymes stably retains in the matrices of platinum black film improving the performance of the mediated sensor. The linearity is observed in the concentration range from 10 x 10(-4) to 10 x 10(-2) mM and 10 x 10(-4) mM to 4.99 x 10(-3) mM with sensitivity of 1.958 mu A/mM and 2.447 mu A/mM respectively. The optimized biosensor exhibits excellent reproducibility and stability retaining more than 90% of its original activity over a period of one month. The simple operation of the biosensor mass-produced at low cost is expected to find clinical application and homecare.