Amperometric l-lactate biosensor based on screen-printed carbon electrode containing cobalt phthalocyanine, coated with lactate oxidase-mesoporous silica conjugate layer

A novel amperometric biosensor for the measurement of l-lactate has been developed. The device comprises a screen-printed carbon electrode containing cobalt phthalocyanine (CoPC-SPCE), coated with lactate oxidase (LOD) that is immobilized in mesoporous silica (FSM8.0) using a polymer matrix of denatured polyvinyl alcohol; a Nafion layer on the electrode surface acts as a barrier to interferents. The sampling unit attached to the SPCE requires only a small sample volume of 100 μL for each measurement. The measurement of l-lactate is based on the signal produced by hydrogen peroxide, the product of the enzymatic reaction. The behavior of the biosensor, LOD-FSM8.0/Naf/CoPC-SPCE, was examined in terms of pH, applied potential, sensitivity and operational range, selectivity, and storage stability. The sensor showed an optimum response at a pH of 7.4 and an applied potential of +450 mV. The determination range and the response time for l-lactate were 18.3 μM to 1.5 mM and approximately 90 s, respectively. In addition, the sensor exhibited high selectivity for l-lactate and was quite stable in storage, showing no noticeable change in its initial response after being stored for over 9 months. These results indicate that our method provides a simple, cost-effective, high-performance biosensor for l-lactate.

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► l-lactate biosensor based on screen-printed electrode, simple to fabricate and use, has been developed.
► Activated electrode containing cobalt-phthalocyanine lowers operating potential of the biosensor.
► Mesoporous silica and nafion layers ensure excellent stability and high selectivity.
► Only a small sample volume is required for the measurement.
► High-performance l-lactate biosensor is obtained with a simple and cost effective way.