Determination of proline in human plasma samples using the encapsulation of proline dehydrogenase enzyme in dendritic silica: a new platform for the enzymatic biosensing of amino acids

An innovative electrochemical biosensor for the sensitive and specific detection of L-proline (L-Pro) in human plasma samples was prepared by the encapsulation of proline dehydrogenase on amine functionalized dendritic fibrous nano-silica KCC-1. Fibrous nano-silica KCC-1-NH2 with its high surface area showed great properties for the encapsulation of proline dehydrogenase. By combining KCC-1-NH2 with proline dehydrogenase and casting it onto a glassy carbon electrode surface, a biosensor for the determination of L-Pro was fabricated. The prepared enzyme biosensor selectively detects L-Pro at physiological pH. The results demonstrate that the catalytic oxidation of L-Pro is diffusion-controlled and irreversible. Using cyclic voltammetry, the oxidation peak current was shown to be compatible with a concentration range of L-Pro from 2.26 to 40 mM and a low limit of quantification was 2.26 mM under physiological-like conditions was obtained. The fabricated biosensor was employed for the determination of L-Pro in unprocessed human plasma samples. It is shown that the prepared enzyme biosensor provides a sensitive and rapid strategy for the detection of L-Pro in plasma samples. The current response of the electrocatalytic oxidation of L-Pro by the engineered biosensor was retained in analytical solution up to 60 °C. The employed approach resulted in superior resistance to temperature in comparison to the free enzyme.