Recent advances in plasmonics for liquid biopsy: A short review

Identification of tissue malignancy via biopsy is the widely accepted method in conventional oncology. However, tissue biopsy suffers from inherent limitations such as invasiveness, detection at a later stage, sampling error, patient discomfort, cost and time of analysis, and among others. With technological advancements various alternatives of tissue biopsy have emerged such as intracellular, liquid, radiological, and AI based biopsy methodologies. These advanced biopsy tools are often integrated with portable, lab on a chip, or similar devices for real time monitoring and detection. Different technologies like optical, electrochemical, conductometry, and imaging are utilized for the detection of appropriate signals to foretell biopsy results. In the present article focuses on the recent plasmonic based liquid biopsy detection researches that has been performed to aid early cancer detection. Liquid biopsy is a method for the identification of malignancy from bodily fluids like blood, urine, tear, and saliva. The most notable biomarkers specific to malignant tissues which are available in different bodily liquid are circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), microRNA (miRNA), exosomes, extracellular vesicles (EVs) and more. In general, these biomarkers are minutely present in the biological fluids, which demands the detection principle to be very specific, precise, and reliable. Multiple techniques have been reported for single cell or trace biomarker detection, and plasmonic detection is one of the forerunners among these. Herein, recent literatures have been compiled to review the plasmonic detection techniques for liquid biopsy specific biomarkers, namely - CTCs, ctDNA, EVs, exosomes, and miRNA. The detailed plasmonic principles, detection efficiency, and challenges are reported in this short-focused review. This review will assist the researchers working in medical diagnostics, malignant cancers, and other allied areas of biomedical engineering.