Real-time monitoring of papain digestion of antibodies immobilized with various strategies by optical interferometry

Measurement of enzyme activity of insoluble substrates based on ordered porous layer interferometry and the application in evaluation of thrombolytic drugs

The development of innovative methods for real-time surveillance of enzymatic activity determination processes is essential, particularly for insoluble substrate enzymatic assessments. In this work, a novel method for enzymatic activity determination was devised by assembling a 190 nm silica colloidal crystal (SCC) film onto a glass slide, coupled with Ordered Porous Layer Interferometry (OPLI) technology. By fixing the substrate of the enzyme on the surface of the silica sphere, a solid-liquid interface can be formed for monitoring enzymatic activity. The enzymatic activity is gauged by the change in the SCC film's thickness caused by the digestion of the loaded substrate. The procedure of chymotrypsin-mediated casein digestion was documented in real time, facilitating the examination of chymotrypsin's activity and kinetics. The newly-developed enzymatic activity determination method demonstrated exceptional sensitivity towards chymotrypsin activity, with a linear range spanning 0.0505-2.02 units per mg. Additionally, the method was extended to the assessment of fibrinolysis enzyme activity and kinetic analysis, yielding promising results. Therefore, this technique can serve as a real-time, user-friendly, cost-effective novel approach for enzymatic activity determination, providing fresh perspectives for enzymatic activity determination studies.