A disposable immunosensor for the detection of salivary MMP-8 as biomarker of periodontitis.

This work describes the development of a novel voltammetric immunosensor for the detection of salivary MMP-8 at the point-of-care. The electrochemical platform was based on a graphene (GPH) screen-printed electrode (SPE) functionalized by gold-nanospheres (AuNSs) and antibodies against MMP-8 protein (anti-MMP-8). The functionalization with anti-MMP-8 was realized by using 11-mercaptoundecanoic acid (11-MUA), thanks to its ability to give strong sulfur bonds with its -SH end, and to cross-link the -NH groups of the antibody molecule with the other -COOH end, using the traditional EDC-NHS method. The voltammetric sensor showed good performances with a linear range of 2.5-300 ng mL, a LOD value of 1.0 ± 0.1 ng mL and a sensitivity of 0.05 µA mL cm ng. Moreover, the proposed immunosensor was tested in real saliva samples, showing comparable results to those obtained with the conventional ELISA method. The biosensor was single-use and cost-effective and required a small quantity of test medium and a short preparation time, representing a very attractive biosensor for MMP-8 detection in human saliva.