Silica Particles: A Novel Drug-Delivery System

In recent decades, significant advances in drug‐delivery systems have enabled more effective drug administration. To deliver drugs to specific organs, a range of organic systems (e.g., micelles, liposomes, and polymeric nanoparticles) have been designed. They suffer from limitations, including poor thermal and chemical stability, and rapid elimination by the immune system. In contrast, silica particles offer a biocompatible, stable, and “stealthy” alternative. Bioactive molecules can be easily encapsulated within silica particles by combining sol–gel polymerization with either spray‐drying or emulsion chemistry. Spray‐drying faces challenges, including low yield, surface segregation, and size limitations. In contrast, sol–gel emulsions enable the production of nanoparticles with homogeneous drug distribution, and permit ambient temperature processing, necessary for handling biologicals. Independent control of the size and release rate can be readily achieved. Preliminary in‐vivo experiments reveal enhanced blood stability of the nanoparticles, which, coupled with sustained release of anti‐tumor agents, show good potential for cancer treatment. Silica particles present an interesting alternative to organic systems for drug delivery. Combining sol–gel synthesis with emulsion technology can produce particles (see Figure) with independently controlled size and release rates. The particle size is controlled by the emulsion chemistry, while the release rate is controlled by the particle microstructure. Preliminary in‐vivo experiments reveal enhanced blood stability of the nanoparticles, which, coupled with sustained release of anti‐tumor agents, show good potential for cancer treatment.