Département de chimie moléculaire

The medical diagnostic, industrial, and biotechnol. sectors all require rapid, sensitive, and easy to use methods for trypsin activity detn. A simple approach, which meets all these requirements, based on Quartz Crystal Microbalance (QCM) was developed, anal. characterized and described in the present work. QCM application allows rapid trypsin activity evaluation by real time monitoring of the enzymic degrdn. of the substrate. The new approach suggested in this work employs nanoparticles loaded with the trypsin substrate gelatin, deposited on the QCM crystal. Upon trypsin-mediated proteolysis, the heavy nanoparticles are released from the substrate layer along with the enzymic degrdn. products, thus decreasing the total QCM crystal mass in comparison with the non-charged substrate. As a result, a higher sensor frequency response occurs. A 10-fold improvement of the LOD was achieved for trypsin activity evaluation when applying the proposed method with gelatin-loaded Ag nanoparticles (i.e., 7.5 × 10-4 U mL-1 vs. 7.5 × 10-3 U mL-1 obtained by the classic QCM method). The approach described in this work can be utilized with any substrate-degrading enzyme. [on SciFinder(R)]