Tuning the Biodegradability of Silicon Nanoparticles for Drug Delivery

Porous silicon nanoparticles (PSiNPs) are attractive carriers for in vivo drug delivery, the biodegradation property of PSiNPs provides a pathway for their safe clearance from the body. Particles sizes of 80 - 120 nm are of particular interest because these nanoparticles can take advantage of the enhanced permeability and retention (EPR) effect to deliver drug preferentially to tumors with leaky vasculature, yet large enough to avoid renal clearance. However, the biodegradability rate of such particles is often too fast, which limits the in vivo delivery efficiency. In this work, we study the effect of both thermal oxidation and silica coating on the stability of PSiNPs in phosphate buffered saline solution (a close mimic of a basic biological fluid). Using thermal oxidation, the half-life of PSiNPs can be varied from 10 minutes up to 3 hours. Using silica coating, the half-life can be extended further to 8 hours.