Hollow nanoarchitectures: Materials engineering, nanochemistry, and biomedical applications

The realm of drug delivery has traditionally centered on the exploration of structural and compositional characteristics of solid nanomaterials. Recent investigations have illuminated the significance of voids within nanomaterials, underscoring their multidimensional characteristics. In particular, the hollow nanostructures or nanoarchitectures, characterized by their porous/nonporous shells and empty interiors, possess unique advantages for the confinement of therapeutic agents and biomolecules, facilitating targeted delivery through functionalization with active ligands. Despite considerable strides in research surrounding these advanced materials, the overarching organization of existing studies remains suboptimal. Unlike existing review literature, this balanced review article aims to establish a coherent and progressive framework for the development of advanced hollow nanostructures by addressing critical design and engineering strategies applicable in the field of nanomedicine and theranostics. A selection of seminal works has been integrated to provide foundational knowledge, while ensuring that the application sections reflect the latest developments in the field, the literature examined is restricted to high-quality publications from the preceding five years. Additionally, this review includes a commentary on patents and clinical implications. Our findings suggest that hollow nanostructures exhibit substantial potential for future biomedical applications, thereby warranting further investigation and development in this promising domain.