AbstractAt present, the main diagnostic for catheter related bloodstream infection is the presence of fever, often coupled with rigors, which is highly unspecific, unreliable and relies heavily on subjective decision on behalf of the patient or clinical staff to raise an alert. It is clearly imperative therefore to develop readily integratable in situ sensors which could monitor the condition of the catheter line and warn the patient/clinical professionals of the early onset of biofilm formation. The ability to eradicate pathogen contamination would also be an ideal prerequisite for such systems in order to fully minimise the risk of infection, undoubtedly reducing mortality and morbidity rates caused by the infection.
This research project has focused on the use of pH as an indirect method in detecting line contamination. Various carbon-based materials (carbon fibre mesh, carbon-loaded polyethylene film and carbon screen printed electrodes) were used as electrode substrates due to their versatility, mass manufacturability, scalability as well as relatively low production cost – a prerequisite given the emphasis on cost reductions within healthcare systems.
Surface modifications through electrochemical anodisation, electropolymerisation of a custom flavin-phenol derivative as well as adsorption of riboflavin were investigated and their purpose in enhancing the proposed sensor’s electroanalytical performance towards pH detection were critically assessed. A microbial reactor, total parenteral nutrition (TPN) and laked horse blood – all of which present complex media containing a range of potential interferences, were employed to examine the sensitivity, selectivity and repeatability of the various sensor designs. The design and development of a flavin-modified polymer was found to exhibit Nernstian behaviour (55 mV/pH) over pH 2.55 to pH 8.12. This approach was further updated to exploit physisorbed riboflavin (vitamin B2) with similar characteristics (61 mV/pH) but which was intrinsically biocompatible. The riboflavin system was employed with authentic TPN formulations and found to exhibit reversible pH monitoring capabilities (repeated cycling in over 20 scans) with minimal drift (4 mV).
The dual capability of riboflavin in detecting pH as well as electro-generating reactive oxygen species was also exploited and studied. Through the generation of the reactive oxygen species, it was envisaged that the eradication of catheter-contaminating pathogens could be feasible. Ultimately, a riboflavin-based smart catheter system is proposed as a suitable solution to the challenging problem of catheter-related bloodstream infection.
|Date of Award||Jan 2021|
|Supervisor||James Davis (Supervisor) & Patrick Dunlop (Supervisor)|
- pH sensor
- Carbon fibre
- Screen printed electrode