Silica Particles: A Novel Drug-Delivery System


  • We would like to thank Erden Sizgek, Mark Blackford, David Cassidy, Elizabeth Drabarek, Rachel Trautman, Renée Beyer, Jeanette Chapman, Vu Nguyen, and Patrice Ballantyne (ANSTO) for experimental help and Laurent Rivory, Mac Christie, and Kim Chan from University of Sydney for useful discussions regarding the biodistribution of silica particles.


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.