Voltammetric lipase activity assay based on dilinolein and a modified carbon paste electrode

In this work, a novel electrochemical assay for characterizing both lipases and lipase inhibitors as well as for the determination of lipase activity is described. It is based on a carbon paste electrode, modified with cobalt(II)phthalocyanine, and multi-walled carbon nanotubes (MWCNTs). As reaction media, a sodium borate buffer was used (0.1 M, pH 9). The measurements were carried out in a batch system using differential pulse voltammetry (DPV) and 1,3-dilinolein as standard substrate. The activity assay showed a linearity for porcine pancreas lipase activity in a range between 20 and 300 U L −1 (per min) with a limit of detection (LOD) of 7 U L −1 and a limit of quantification (LOQ) of 20 U L −1 . The kinetic behavior of the lipase reaction was investigated, resulting in a K M value of 0.29 mM. The applicability of the activity assay could be shown by investigating the activity of lipases from Aspergillus oryzae and Candida rugosa , and the results were confirmed by a reference method. The inhibitory effects were characterized with Orlistat. Graphical abstract