Generic protease detection technology for monitoring periodontal disease

Abstract

Periodontal diseases are inflammatory conditions that affect the supporting tissues of teeth and can lead to destruction of the bone support and ultimately tooth loss if untreated. Progression of periodontitis is usually site specific but not uniform, and currently there are no accurate clinical methods for distinguishing sites where there is active disease progression from sites that are quiescent. Consequently, unnecessary and costly treatment of periodontal sites that are not progressing may occur. Three proteases have been identified as suitable markers for distinguishing sites with active disease progression and quiescent sites: human neutrophil elastase, cathepsin G and MMP8. Generic sensor materials for the detection of these three proteases have been developed based on thin dextran hydrogel films cross-linked with peptides. Degradation of the hydrogel films was monitored using impedance measurements. The target proteases were detected in the clinically relevant range within a time frame of 3 min. Good specificity for different proteases was achieved by choosing appropriate peptide cross-linkers.

Disposable MMP-9 sensor based on the degradation of peptide cross-linked hydrogel films using electrochemical impedance spectroscopy

“…However swelling due to a reduced cross-link density caused by the cleavage of peptide cross-links does not explain the increase in impedance as a greater influx of water should also result in an increase in the ferri/ferrocyanide concentration in the film. The increase in impedance was also seen previously when using oxidised dextran films crosslinked with a different peptide (AAPVAAK) on screen printed electrodes for the detection of human neutrophil elastase (HNE) (see general discussion of (Zheng et al, 2011)). In this case, the impedance was also stable in buffer and increased rapidly when exposed to solutions containing HNE.…”

“…Therefore, a thinner layer of dextran was formed with large number of aldehyde groups accessible for subsequent cross-linking with peptide. In the previous studies carried out by Stair et al (2009) and Zheng et al (2011) similar sensor behaviour was detected using quartz crystals and microfabricated IDEs coated with peptide cross-linked hydrogels. They observed an impedance increase and quartz crystal frequency decrease initially after the addition of proteases.…”

“…A two step-coating method, previously developed by our group (Zheng et al, 2011) was adopted to deposit MMP-9 sensitive films. A schematic of the sensor coating process is shown in Scheme 1.…”

“…Good specificity for different proteases was achieved by choosing appropriate peptide cross-linkers. This method was used successfully to produce sensor materials suitable for the detection of three different proteases indicated in periodontal disease, human neutrophil elastase (HNE), cathepsin G and MMP-8 (Zheng et al, 2011). In this work, the generic sensor materials were adapted for the detection of MMP-9.…”

“…Degradation of the hydrogel films was monitored using electrochemical impedance (Zheng et al, 2011) and Quartz Crystal Microbalance (QCM) measurements (Stair et al, 2009). Good specificity for different proteases was achieved by choosing appropriate peptide cross-linkers.…”