A Comprehensive Review on Nanosphere-Based Drug Delivery System for the Identification and Prevention of Cancerous Cells.

Nanospheres are sub-micron-sized solid colloidal particles, typically ranging from 10 to 200 nm in diameter, that have emerged as highly effective carriers for targeted drug delivery and diagnostic applications. Owing to their unique physicochemical properties, including high surface area, tunable particle size, controlled drug release, and excellent biocompatibility, nanospheres have gained considerable attention in pharmaceutical research. These nanocarriers can encapsulate, adsorb, or conjugate therapeutic agents within a polymeric matrix, thereby protecting drugs from premature enzymatic and chemical degradation and enhancing their stability, bioavailability, and therapeutic efficacy. Researchers have used various biodegradable and biocompatible materials, such as albumin, gelatin, starch, polylactic acid, poly(lactic-co-glycolic acid), and dextran-based polymers, to fabricate nanospheres. Surface modification strategies, including polymer coating and ligand conjugation, have been extensively explored to overcome the challenges associated with opsonization and rapid clearance by the reticuloendothelial system, thereby prolonging systemic circulation and improving site-specific drug accumulation. Advanced nanosphere platforms, including magnetic, immunological, and immunomagnetic nanospheres, show strong potential in precision medicine by enabling targeted delivery, enhanced cellular uptake, and real-time monitoring of therapeutic responses. In oncology, nanosphere-based delivery systems have revolutionized cancer diagnosis and treatment by selectively transporting anticancer agents to tumor tissues while minimizing off-target toxicity and adverse effects on healthy cells. Furthermore, nanosphere-assisted biosensing technologies have shown significant promise for early cancer detection by identifying tumor- associated biomarkers, circulating tumor cells, nucleic acids, and specific proteins. These multifunctional nanoplatforms integrate diagnostic and therapeutic capabilities, paving the way for personalized, theranostic approaches to cancer management. This review comprehensively discusses the classification, preparation methods, physicochemical characteristics, and biomedical applications of nanospheres, with a particular focus on their emerging roles in cancer diagnosis, targeted drug delivery, and precision therapeutics. It also critically examines current challenges, recent technological advances, and future perspectives on the clinical translation of nanosphere-based systems.