The development of an electrochemical sensor for detecting and measuring circulating tumour DNA in human fluids

Rights statement
Awarding institution
  • University of Strathclyde
Date of award
  • 2021
Thesis identifier
  • T16035
Person Identifier (Local)
  • 201692049
Qualification Level
Qualification Name
Department, School or Faculty
  • The high rates of mortality amongst cancer patients highlights the need for advances in rapid detection and enhanced point of care (PoC) testing. A simple approach tailored towards PoC cancer detection and monitoring using label-free electrochemical biosensors is presented. Screen-Printed Carbon electrodes (SPCEs) have been extensively employed as an economical transducer substrate for electrochemical biosensing applications due to their simplicity, affordability and versatility. In this work, a simple, low-cost DNA biosensor is presented which after initial work with Tp53 was developed specifically to detect mutations in a key oncogene (KRAS). Sensor arrays of SPCEs and carbon-nanotube (CNT) modified SPCEs were used to perform multiplexed measurements of DNA hybridisation. Various amplification techniques for enriching the pool of mutated DNA strands were explored and optimised. Amine-modified ssDNA probes were immobilized by modifying SPCEs and CNT-SPCEs with diazonium and EDC/NHS groups. The sensor performance was characterized using cyclic voltammetry, differential pulse voltammetry, square wave voltammetry and electrochemical impedance spectroscopy all to different extents. The detection principle was evaluated by showing effective on-chip DNA hybridization techniques, discrimination using negative controls, and performing multiple repetitions to ascertain reliability of the system. The developed sensor displayed some sensitivity and selectivity to Tp53, KRAS pG12D, and KRAS pG13D DNA, all of which are important mutations in cancer progression. For the amplified samples, 0.027 ng/µl amplicons were detectable while for the non-amplified samples, 0.85 ng/µl cfDNA concentration was detectable using the assay developed. The importance of these findings lies in the design of future electrochemical assays that are capable of discriminating between circulating tumour DNA in the blood prior to and post cancer therapy. The real-world application of this concept provides not only early diagnostic capability but an avenue for treatment decisions to be guided in such a way that health care providers can initiate, choose, avoid, alter or cease selected therapies when caring for patients that have shown symptoms for cancer or who are at risk of having recurrent cancers.
Advisor / supervisor
  • Corrigan, Damion
  • Baker, Matthew
Resource Type