The study of a disposable reagentless biosensor for fast test of aspartate aminotransferase

A reagentless biosensor for amperometric measurement of aspartate aminotransferase (AST) has been developed. The three-electrode biosensor was modified with two enzyme membrane with an integrated planar Ag vertical bar AgCl reference electrode. With a cellulose membrane containing catalytic substance coated, the reagentless biosensor was used for measurement of serum AST. The optimal sensitive membrane composition and operation conditions were studied. With low polarizing potential (0 V vs. integrated Ag vertical bar AgCl) and appropriate substrate concentration (20 mM alpha-ketoglutarate acid), the response of the biosensor to AST activity was linear over the range of 25-1000 U/L with good relativity (R = 0.9904 and 0.9823 in standard AST solutions and AST serum respectively) and fast response time (120 s). The biosensor also indicated good stability of more than 90% of its original activity for 60 days stored in 4 degrees C, and 90% of the activity was retained after a storage period of 15 days at room temperature (25 degrees C). The biosensor is expected to be used for the diagnosis of heart and liver disease in the future.