POROUS SILICA PARTICLES IN BIOLOGY: STUDIES ON CELLULAR UPTAKE, MOLECULAR DELIVERY, AND IMAGING

Inorganic particles with a variety of compositions and sizes are being tested in biological applications by a number of research groups, and interesting and significant differences in biological processing have been found along the spectrum from 1 to 1000 nm. Of the types of materials that can be considered for these applications, amorphous silica prepared in a laboratory environment offer several important advantages. For example, silica is very easily modified with organosilanes, and subsequent organic reactions allow a wide variety of biologically active moieties such as proteins, DNA plasmids, siRNA fragments, or chemotherapeutic drugs to be permanently or temporarily attached to the surface. A porous material can be differentially modified on its internal (pore) and external surfaces to create a transfection device that targets specific tissues or cell types, where it releases large amounts of molecular "cargo" loaded within its pores. This presentation will focus primarily on recent research used for the site-specific modification of porous silica particles, leading to molecular delivery, cellular selectivity, and in vivo MRI imaging. The effect of size, surface modification, and synthesis procedure on cellular uptake and toxicity will be described.