Screen-printed amperometric microcell for proline iminopeptidase enzyme activity assay

A microfabricated amperometric microcell was designed and used for the determination of proline iminopeptidase (PIP) enzyme activity in 2-10-microl samples. The measurements were made in the range of 10.3-841.5 mU/ml enzyme activities. The sensitivity of the determinations was between - 0.0195 and - 0.0203 microA ml/mU per min. The coefficient of variation of the determined values ranged between 2.8 (at 561.2 mU/ml) and 24.1% (at 10.3 mU/ml). The microcell was manufactured on an alumina substrate using screen-printed graphite working and Ag/AgCl reference electrodes. Elevated PIP activity in the vaginal fluid is a biochemical indicator of bacterial vaginosis. The method is appropriate to differentiate between normal (66+/-145 mU/ml) and elevated, diseased (704+/-145 mU/ml), values.