Sensor materials for the detection of proteases

• Published in: Biosensors & bioelectronics 2009-03, Vol.24 (7), p.2113-2118
• Main Authors: Stair, Jacqueline L., Watkinson, Michael, Krause, Steffi
• Format: Article
• Language: English
• Subjects: Biocompatible Materials - chemistry; Biological and medical sciences; Biosensing Techniques - instrumentation; Biotechnology; Cathepsin G; Cross-Linking Reagents - chemistry; Dextrans - chemistry; Enzymatic degradation; Equipment Design; Equipment Failure Analysis; Fundamental and applied biological sciences. Psychology; Human neutrophil elastase (HNE); Hydrogels - chemistry; Materials Testing; Membranes, Artificial; Micro-Electrical-Mechanical Systems - instrumentation; Peptide cross-linked hydrogel; Peptide Hydrolases - analysis; Peptide Hydrolases - chemistry; Peptides - chemistry; Protease; Quartz crystal microbalance (QCM); Reproducibility of Results; Sensitivity and Specificity
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2008.11.002

The concept of generic and tunable sensor materials for the detection of proteases based on the thin film degradation of peptide cross-linked dextran hydrogels was explored. Hydrogel cross-links were formed via simple imine linkages between aldehyde groups in oxidized dextran and a peptide sequence susceptible to protease cleavage. Degradation of the hydrogel films was monitored in this study using a quartz crystal microbalance (QCM). The sensor material was developed using the protease/peptide pair of human neutrophil elastase (HNE) and Ala-Ala-Pro-Val-Ala-Ala-Lys (AAPVAAK). A direct relationship between the hydrogel degradation rate and protease activity was observed; HNE activities from 2.5 to 30Uml−1 were detected using 25% cross-linked films. Film degradation was rapid and was complete in less than 10min for HNE activities ≥10Uml−1. An increase in the rate of degradation by a factor of 3.5 was achieved by increasing the cross-linking density from 25% to 75%. QCM admittance data fitted with a BVD equivalent circuit showed increases in film viscoelasticity upon enzyme addition. A second protease/peptide pair of cathepsin G and Ala-Ala-Pro-Phe-Phe-Lys (AAPFFK) was tested where 25% AAPFFK cross-linked hydrogels demonstrated a rapid response at 100mUml−1. Swapping the protease/peptide pairs to HNE/AAPFFK and cathepsin G/AAPVAAK showed low levels of cross-sensitivity further demonstrating the specificity of film degradation.