Bioengineering of novel carbon-based biosensors for real-time biomedical use

Abstract

The aim of this thesis was to develop novel carbon-based biosensors and sensors for real-time metabolite and drug detection, to provide the next generation of medical devices which can give clinicians relevant chemical information in real-time at the patient bedside. An autocalibration system was developed using LabSmith programmable components to give precise fluid delivery and excellent temporal control of multiple liquid streams. This enables a 5-point calibration to be carried out using two solutions in 12 minutes. Systems using chitosan, poly(ethylene glycol)diglycidyl ether hydrogel, electrodeposition and selfassembly to immobilise enzymes on a combined needle electrode surface were studied and their performances were investigated using a microfluidic platform. The autocalibration system was combined with the graphene oxide-based biosensors in a microchip coupled with a microdialysis probe and was examined as a proof-of-concept clinical on-line analysis system. A reduced graphene oxide-based sensor was fabricated using a combined needle electrode for on-line neurotransmitter detection of dopamine. Its performance was compared with that of a platinum electrode. A microfluidic sensor based on a carbon nanotube-epoxy composite was fabricated to detect the presence of carboplatin (anti-cancer drug) in healthy tissue in real time during chemotherapy. Detection of carboplatin was carried out using differential pulse voltammetry firstly in a beaker, in which carbon nanotube-epoxy composite electrodes performed better than glassy carbon electrodes for oxidation of free purine bases and than DNA-modified carbon nanotube-epoxy composite sensors for detection of carboplatin. Carboplatin detection was then performed in a microfluidic platform. The methodology for on-line carboplatin detection was optimised in terms of the analysis time and for the repeated determination of carboplatin using the same electrode. Microdialysis and microfluidic techniques have been combined to give a proof-of-concept system real-time carboplatin detection using the carbon nanotube-epoxy composite sensors.