Abstract Description

Upon an increase in prostate cancer statistics of men aged 50 years and above, there is a need for a development of a biosensor. A biosensor is an analytical device that detects changes in biological processes and converts them into an electrical signal. Biosensors have been applied in many fields such as food industry, medical field, marine sector etc. In this work a novel biosensor made of a dye molecules-metallopthalocyanines (MPcs) and nanomaterials of graphene derives such as graphene oxides (GO), is developed for the detection of prostate-specific antigen (PSA). A PSA is a biomarker for the prostate cancer. UV-Vis, mass spec, XRD and FTIR are used to characterize MPcs and GOs. The glassy carbon electrode (GCE) is modified with these MPcs and GO molecules. DNA molecules (aptamer, and its complementary DNA) are also added onto the GCE. One of the best-known modifications of GCE, is the sequential modification in which MPc is placed on top of GO to give GCE-GO-MPc(sequential). Other modifications involve the use of only one molecule such as to give GCE-GO or GCE-MPc. The electrochemical results are recorded for this work using electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) techniques for the detection of PSA. The GCE-GO-MPc (sequential)-Aptamer-cDNA in the presence of the PSA shows better electrochemical results. The limit of detection was calculated from the electrochemical results of each GCE electrode and were obtained to be below the cut-off value of 4 ng/mL for patients suspected to have prostate cancer. The best electrochemical performing electrode: GCE-GO-MPc(sequential)-Aptamer-cDNA electrode was found to be selective to only the PSA in the presence of interfering molecules such as bovine serum albumin, glucose and cysteine that might be found in normal human blood and was also found to be stable when 50 DPV scans were run. The electrode showed good % recovery (80 % - 100 %) when human serum was spiked with different PSA concentrations.