Principles of Biocompatible Nanotube Design for High-Performance Biomaterials.

Nanotubes are one-dimensional tubular structures characterized by nanoscale radial dimensions and micrometer-scale axial lengths. Their hollow inner cavity confers a high specific surface area and distinctive physicochemical properties, enabling remarkable potential in drug delivery, disease diagnostics, and tissue engineering. Extensive research into their biocompatibility and degradability establishes a solid foundation for further development and rational design. A synthesis of current data across relevant systems, including carbon nanotubes (CNTs), boron nitride nanotubes (BNNTs), titanium dioxide nanotubes (TiNTs), halloysite nanotubes (HNTs), anodic aluminium oxide nanotubes (AAOs), lipid nanotubes (LNTs), and polymeric nanotubes (PNTs), reveals how structural features and physicochemical properties govern biological responses and functional performance. This integration supports a unified "structure-property-bioresponse-function" framework, offering a conceptual roadmap and general design principles to guide the next generation of nanotube-based biomaterials.