Sol-Gel-Based Advanced Porous Silica Materials for Biomedical Applications

Porous silica-based materials have burgeoning applications ranging from fillers and additives, to adsorbents, catalysts, and recently therapeutic agents and vaccines in nanomedicine. The preponderance of these materials is made by sol-gel processing wherein soluble silica precursors are reacted to form amorphous networks composed of siloxane bonds. The facile sol-gel approach allows for an unlimited variety of binary tertiary and more complex chemical compositions including organic ligands and networks resulting in so-called organic-inorganic hybrid materials. Here, a brief review of the recent progress in sol-gel-derived silica materials prepared as particles, thin films, biosilica/silica bioreplicas (of molecules, cells and organisms), and their related preparation, properties, and bioapplications is provided. First, it highlights the recent achievements of mesoporous silica nanoparticles in biomedical applications, including therapeutic agent delivery, multimodal imaging and theranostics, and bone tissue engineering and repair. Second, the research in evaporation-induced self-assembly (EISA)-based mesostructured silica thin films and cell-directed EISA in bio/nano interfaces for various bioapplications, such as bioactive coatings, biosensing, and living cell immobilization, has been reviewed. Third, the pioneering work in biomimetic silicification/immobilization of biomolecules and bio-organisms and silica bioreplication of complex bio-organisms is summarized. Finally, it is concluded with personal perspectives on the directions of future work on this field.