Epigenetic insights of microRNAs: Pioneering cancer detection via advanced biosensors

The epigenetic landscape of cancer reveals how microRNAs (miRNAs) regulate gene expression through epigenetic mechanisms, alongside advancements in miRNA-based biosensor technology for early detection. Epigenetics, which studies heritable gene function changes without altering DNA sequences, has transformed our understanding of cancer by highlighting the complex interaction between genetics and environment. Key mechanisms such as DNA methylation, histone modification, and chromatin remodelling shape gene expression and cellular identity, with dysregulation in these processes often marking cancer development. Within this framework, miRNAs act as crucial epigenetic regulators, influencing gene expression post-transcriptionally and functioning as either oncogenes (oncomiRs) or tumour suppressors. miRNAs interact with epigenetic modifiers like histone deacetylases (HDACs) and DNA methyltransferases (DNMTs), creating regulatory networks that affect cancer cell behaviours such as proliferation, differentiation, and apoptosis. To apply these molecular insights, the chapter reviews innovations in miRNA-targeting biosensors. Electrochemical and photoelectrochemical biosensors, enhanced with nanotechnology, are designed to detect miRNAs at ultra-low concentrations in biological fluids, addressing limitations of conventional cancer diagnostics. These biosensors offer high sensitivity, specificity, and point-of-care potential, with benefits such as rapid response, cost-efficiency, and miniaturization. Case studies showcase miRNA-based biosensors targeting cancer-related miRNAs, underscoring their promise in early cancer detection and monitoring. By bridging epigenetics, miRNA regulation, and biosensor technology, these emerging diagnostic tools offer new possibilities for improving cancer diagnosis and patient outcomes.