title: Disposable MMP-9 sensor based on the degradation of peptide cross-linked hydrogel films using electrochemical impedance spectroscopy.
abstract: Matrix metalloproteinase-9 (MMP-9) plays an important role in both physiological and pathological processes. This enzyme is a peripheral biomarker of neuroinflammation in multiple sclerosis (MS), a chronic autoimmune disease of the central nervous system. Presently, expensive magnetic resonance imaging (MRI) studies are used to monitor subclinical disease activity in MS. An alternative to costly MRI scans could be the detection of MMP-9, using a low-cost, disposable sensor system for MMP-9 suitable for home-monitoring of inflammation. This would allow an early prediction of the failure of anti-inflammatory therapies and more timely clinical intervention to limit neuronal damage and prevent disability. Herein we present the development of a disposable sensor for fast and straightforward detection of MMP-9. Biosensors were produced by coating electrodes with oxidized dextran and subsequent cross-linking with peptides containing specific cleavage sites for MMP-9. Exposure of the films to the enzyme resulted in the degradation of the films, which was monitored using impedance measurements. Sensor response was rapid, a significant impedance change was usually observed within 5 min after the addition of MMP-9. Sensors showed a negligible response to matrix metalloproteinase-2 (MMP-2), a protease which may interfere with MMP-9 detection. The peptide sequence with the highest sensitivity and selectivity Leu-Gly-Arg-Met-Gly-Leu-Pro-Gly-Lys was selected to construct calibration curves. MMP-9 was successfully detected in a clinically relevant range from 50 to 400 ng/ml. Two different processes of hydrogel degradation were observed on electrode surfaces with different roughness, and both appeared suitable to monitor MMP-9 activity. The sensor materials are generic and can be easily adopted to respond to other proteases by selecting peptide cross-linkers with suitable cleavage sites.
authors: School of Engineering and Materials Science, Queen Mary University of London, UK.
authors: Anna
authors: A
authors: Biela
authors: School of Biological and Chemical Sciences, Queen Mary University of London, UK.
authors: Michael
authors: M
authors: Watkinson
authors: Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, UK.
authors: Ute C
authors: UC
authors: Meier
authors: Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, UK.
authors: David
authors: D
authors: Baker
authors: Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, UK.
authors: Gavin
authors: G
authors: Giovannoni
authors: School of Engineering and Materials Science, Queen Mary University of London, UK.
authors: C Remzi
authors: CR
authors: Becer
authors: School of Engineering and Materials Science, Queen Mary University of London, UK. Electronic address: s.krause@qmul.ac.uk.
authors: Steffi
authors: S
authors: Krause
mesh_terms: D000595:Amino Acid Sequence; D015374:Biosensing Techniques; D058266:Dielectric Spectroscopy; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000737:chemistry; D020780:Matrix Metalloproteinase 9 / Q000302:isolation & purification*; D008756:Methylgalactosides / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D059748:Proteolysis
chemical_list: D008756:Methylgalactosides; D010455:Peptides; C109801:hydrogel film; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9
keywords: Electrochemical impedance spectroscopy; Film degradation; Interdigitated gold electrodes; MMP-9 sensor; Multiple sclerosis; Peptide cross-linked hydrogel