Advances in Urinary Liquid Biopsy: A Review of Emerging Sensing Platforms for Early Cancer Screening and Diagnosis.

Early screening of many types of cancers remains limited by the invasiveness of gold-standard tissue biopsies and the poor specificity of traditional clinical biomarkers like prostate-specific antigen (PSA). Non-invasive liquid biopsies are the emerging alternatives. Urine is one of the preferred body fluids for liquid biopsy as it offers a rich, easily accessible and large-volume source of cancer-specific metabolites, proteins, nucleic acids, extracellular vesicles, and cancer cells. This review reports the recent advancements in urinary cancer (bio)sensing technologies, including mainly optical and electrochemical platforms. To overcome the low specificity and detectability of the existing systems, novel nanomaterials, such as metal-organic frameworks, carbon dots, metal nanoparticles, and molecularly imprinted polymers, that offer increased surface area, cost-effectiveness and enzyme-free platforms, as well as accelerated electron transfer, were introduced to provide lower detection limits to the femtomolar and attomolar levels. Additionally, the integration of machine learning and artificial intelligence for biochemical "fingerprint" analysis enhanced diagnostic accuracy. Finally, we discuss the gap between novel sensing systems and robust diagnostic devices for decentralized point-of-care testing (POCT) and personalized medicine in clinical routine.