Development of a Novel Nanostructured Biosensor Platform for Early Detection of Cervical Cancer Biomarkers in Resource-Limited Nigerian Clinical Settings

Cervical cancer is the second most common female cancer in Nigeria, with the majority of cases diagnosed at late stages due to absence of accessible early detection technologies, and nanostructured electrochemical biosensors offer a pathway to affordable, sensitive, and specific point-of-care biomarker detection that addresses this diagnostic gap. This dissertation develops and characterises a novel nanostructured biosensor platform for early detection of cervical cancer biomarkers, targeting high-risk human papillomavirus E7 oncoprotein and methylated tumour suppressor gene fragments as complementary biomarker targets. The biosensor platform is constructed on gold nanoparticle-functionalised reduced graphene oxide electrodes deposited on flexible polyethylene terephthalate substrates, enabling conformal application to paper-based analytical devices. Nanostructure synthesis and characterisation employed transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and electrochemical impedance spectroscopy for surface area and conductivity characterisation. Aptamer selection for HPV E7 oncoprotein using the SELEX process yielded two high-affinity aptamers validated by surface plasmon resonance with dissociation constants below 10 nanomolar. Aptamer-functionalised biosensor analytical performance for HPV E7 detection was characterized, demonstrating a linear detection range of 0.1 to 100 nanograms per millilitre, a detection limit of 0.08 nanograms per millilitre, and selectivity against non-target proteins. Methylated DNA detection using a bisulfite-modified DNA hybridization assay was integrated on the same platform. Analytical validation in cervical swab eluate samples from fifty patients at Lagos State University Teaching Hospital showed 94 percent concordance with conventional PCR reference assay. The study provides a complete platform characterisation from nanostructure synthesis through clinical sample validation. Keywords: nanostructured biosensor, cervical cancer biomarkers, HPV detection, point-of-care, Nigeria.