32. REAL-TIME MONITORING OF SUSTAINED DRUG RELEASE WITH PHOTONIC POROUS SILICON PARTICLES
Faculty Advisor(s): Michael Sailor
Name: Elizabeth Chung Pui Wu
Grad Year: 2010
There is a need for a controlled and observable drug delivery system, enabling long-term local treatment of cancer, ocular diseases, and other diseases in which recurring drug administration is necessary. To address challenges in the delivery of drugs with narrow therapeutic indices, we have developed biodegradable and biocompatible porous Si microparticles with tunable photonic properties. Porous Si particles can be degraded in vivo by oxidation to form silicon dioxide followed by hydrolysis to release orthosilicic acid, which is excreted by the kidneys. Drug loading into the porous Si particles can be achieved by covalent attachment using a Si-C linker. The drug is released as the porous Si matrix is degraded by oxidation, providing sustained release of the drug. In addition, the porous structure of the particles gives rise to photonic properties, and their optical reflectance spectrum allows for monitoring of drug release. As the particles degrade and as the drugs are released, the optical reflectance spectrum changes, resulting in an observable color change. The potential for intraocular drug delivery was tested using daunorubicin-loaded particles. Daunorubicin is an anti-proliferative drug that can be used to treat proliferative vitreoretinopathy, but currently its use is limited by its short vitreous-half life and toxicity at high doses. Daunorubicin release from porous Si particles was observed for up to 30 days in vitro. Compared to free daunorubicin, the residence time of daunorubicin attached to porous Si particles is significantly prolonged. The optical spectra of the particles were monitored and a correlation was observed between daunorubicin release and the color change of the particles. The unique optical properties of porous Si allow for a simple and non-invasive method of monitoring the extent of drug release in the vitreous during the treatment of ocular diseases.