GRAPHENE-BIOINTERFACE BIOSENSOR PLATFORMS FOR BIOMEDICAL APPLICATIONS USING THE QUARTZ CRYSTAL MICROBALANCE TECHNIQUE

Abstract

In this thesis, graphene derivatives were used as a coating material for sensor chips to improve their surface functionalities. There are three main articles presented in this thesis ranging from the study of graphene-biomolecule interactions to real-world applications. In the first publication, the quartz-crystal microbalance with dissipation monitoring (QCM-D) technique was employed to study the interaction dynamics of a typical protein, bovine serum albumin (BSA) and graphene materials of varying degrees of functionalisation. The results present significant differences in molecular orientation and confirmation, mass adsorption and antibody binding function of BSA on different graphene surfaces. The binding function of adsorbed BSA was investigated through the interaction with its anti-BSA antibody counterpart. Based on these findings, highly hydrophobic rGO was selected to develop a sensing platform for immunochemical detection, as presented in the second publication. Both the route to functionalize rGO with a specific receptor protein along with a sensitive and low-cost immunoassay tool based on a customised open-source QCM are also presented. Graphene biointerface QCM sensors (G-QCM) were employed to quantify antibodies in undiluted patient serum. We demonstrate its efficacy for a specific antibody against the phospholipase A2 receptor (anti-PLA2R), a biomarker in idiopathic membranous nephropathy. Furthermore, we have explored using our graphene-QCM sensing tool with single-domain antibodies, also called nanobodies, as receptors for antigen proteins, as presented in the third article (ongoing publication). Methods for the functionalisation of nanobodies on graphene-family materials have been explored based on physical adsorption, amine crosslinking, and streptavidin (SA)-biotin interaction. The nanobody against lysozyme was used as a model protein pair. The QCM-D technique was used to monitor the adsorption of the nanobody on different surfaces, its biomolecular recognition and selectivity against other proteins and animal serum. Altogether, the collected knowledge from a series of systematic studies on the biomolecular interactions with graphene led to the development of graphene-biointerface immunosensing platforms. The prototype of a point-of-care QCM immunosensor was developed and tested with patient serum emphasizing the potential to be a real-world disease screening tool.

Date of Award	1 Aug 2022
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Thomas Jowitt (Supervisor) & Aravind Vijayaraghavan (Supervisor)