Detection of gingipain activity using solid state nanopore sensors

Abstract

Accurate, robust, and rapid diagnostics is the basis for all well-functioning healthcare. There is a large need in point-of-care biosensors to facilitate diagnosis and reduce the need for cumbersome laboratory equipment. Proteases are key virulence factors in periodontitis. Periodontal disease is very common and characterized by inflammation and infection in the tooth-supporting structures and is linked to many systemic diseases such as cardiovascular disease, diabetes, and Alzheimer’s disease. Proteases present in periodontal disease, gingipains, are highly responsible for the disease onset and progression and are therefore a promising biomarker. Here we show a novel nanopore-based biosensor strategy for protease activity monitoring. Solid-state nanopores were modified with a proteolytic substrate, restricting the ionic current through the apertures of the nanopores. Protease can digest the proteolytic substrate thus enlarge the aperture and the ionic current. Trypsin was used as an initial model protease to investigate the performance of the sensor. We show that the solid-state nanopore-biosensor can detect trypsin with a limit of detection (LOD) of 0.005 ng/mL (0.2 pM). The detection system developed for the model enzyme was then applied to the detection of gingipains. The LOD for detection of gingipains was 1 ng/mL (0.02 nM), with a 27% recovery of the signal at 0.1 µg/mL, indicating that the sensitivity and dynamic range are relevant for the clinical diagnosis of periodontitis. The generic detection of protease activity and high sensitivity make this a promising sensor technology for both diagnosis of periodontal disease and monitoring of other disease-related proteases.