| Enzyme reactions conducted in microdevices for diagnostic applications minimize the enzyme usage. In this research, polydimethylsiloxane microdevices were fabricated and used to study the well studied hydrogen peroxide decomposition reaction using bovine liver catalase. Soft lithography techniques were developed to fabricate custom-made microdevices in-house. High resolution photomasks and oxygen plasma treatment followed by baking for 2--3 hours yielded microdevices with vertical walls that did not leak easily. Flow experiments were conducted with free enzyme, enzyme immobilized on microdevice walls, and carrier-free enzyme aggregates. For free enzyme and carrier-free enzyme aggregate reactions, the average reaction rate showed a maxima at &sim80 mmol/L as predicted from macroscale batch experiments. The trend for average reaction rate was consistent with the model series reactor scheme developed. Covalent binding of enzyme to the microdevice wall was not achieved as the enzyme was found to continuously leach from the microdevice walls. |
