title: Sensor materials for the detection of proteases.
abstract: 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.
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom.
authors.forename: Jacqueline L
authors.initials: JL
authors.lastname: Stair
authors.forename: Michael
authors.initials: M
authors.lastname: Watkinson
authors.forename: Steffi
authors.initials: S
authors.lastname: Krause
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation*; D003432:Cross-Linking Reagents / Q000737:chemistry; D003911:Dextrans / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D020100:Hydrogels / Q000737:chemistry*; D008422:Materials Testing; D008567:Membranes, Artificial; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D010447:Peptide Hydrolases / Q000032:analysis* / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D003911:Dextrans; D020100:Hydrogels; D008567:Membranes, Artificial; D010455:Peptides; D010447:Peptide Hydrolases