Electrochemical evaluation of lactate dehydrogenase immobilized in polyacrylamide gels

Lactate dehydrogenase (EC 1.1.1.27) has been immobilized in polyacrylamide gels over a platinum grid matrix. The immobilized enzyme is used to oxidize L‐lactate in the presence of nicotinamide adenine dinucleotide (NAD⁺) and femcyanide. The NADH produced is then chemically oxidized back to NAD⁺by ferricyanide. The coupled reduction of ferricyanide ions to ferrocyanide ions results in a measurable electrochemical potential. This measurable zero‐current potential is found to be Nernstian in nature and directly proportional to the logarithm values of L‐Iactate concentration over the range of 2 × 10⁻⁵to 5 × 10⁻²M. The results indicate that immobilized lactate dehydrogenase can be incorporated into a system to detect L‐Lactate acid in aqueous solutions.