Selenium nanostructures in biomedical diagnostics: toward smart and sustainable disease monitoring

Selenium (Se) is a vital trace element responsible for maintaining redox balance, immune modulation, and the preservation of cellular homeostasis. In recent years, selenium nanostructures have been widely used in biomedical diagnosis due to their exceptional physicochemical properties, inherent biological function, and excellent biocompatibility. The nanostructure comprises selenium nanoparticles (SeNPs), selenium quantum dots (SeQDs), and hybrid selenium nanocomposites. It exhibits properties such as tunable optical, electrical, and catalytic activities, allowing sensitive detection of disease-associated biomolecules. This review summarises the updated progress in the design of selenium nanostructures for diagnostic aims, including the synthesis methods, their surface functionalization and sensing mechanism. A new generation of selenium nanomaterials has been combined with carbon-based materials and polymers to enhance the sensitivity, amplification, and multiplexing of detection. Besides having significant potential in experimental studies, challenges such as large-scale production, batch-to-batch consistency, long-term biocompatibility, and obtaining regulatory approval limit clinical translation. The continued improvements in AI-based data analysis, data interpretation-supported automated systems, microfluidic platforms, and smart biosensor design will drive future research in this field. On the whole, selenium nanostructures are a low-cost and environmentally friendly material that shows potential for application in disease diagnostics and point-of-care implementation toward precision medicine.