Silica aerogel-based nanocomposites for biomedical nanotechnology: Recent advances, structure-property relationships, and future perspectives

Silica aerogels represent a distinctive class of porous nanomaterials with increasing importance in biomedical science owing to their ultralow density, extremely high specific surface area, and tunable nano to mesoporous architecture. These materials are commonly fabricated through the removal of the liquid phase from a silica gel while preserving the three-dimensional network, enabling precise control over pore size, surface chemistry, and mechanical properties. Such versatility has driven extensive exploration of silica aerogels for healthcare applications, including controlled drug delivery, tissue engineering scaffolds, biosensors, bioimaging, cancer diagnosis and therapy, wound management, and environmentally relevant biomedical technologies. Nevertheless, successful clinical translation requires careful assessment of biocompatibility, cytotoxicity, biodegradation, and long-term interactions with biological systems. Parameters such as surface silanol density, particle morphology, and degradation behavior critically influence cellular responses and inflammatory outcomes. Recent strategies, including polymer reinforcement, surface functionalization, and composite formation with biopolymers, have demonstrated significant potential to mitigate toxicity while improving mechanical integrity and biological performance. This review provides a comprehensive and up-to-date overview of silica aerogel composites for biomedical applications, emphasizing synthesis approaches, structure-property relationships, and functional performance. Particular attention is given to toxicity mechanisms, regulatory considerations, and design strategies for improved safety and efficacy.