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E. C. Wu, J. Park, L. Cheng, W. R. Freeman, M. J. Sailor; Sustained and Observable Release of Daunorubicin/Doxorubicin Using Porous Si Particles: A Potential Treatment for Proliferative Vitreo-Retinopathy. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5965.
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There is an unmet need for a minimally invasive controlled and observable drug delivery system, enabling long acting local treatment of intraocular diseases. To address challenges in the delivery of drugs with narrow therapeutic indices, we have developed biodegradable and biocompatible porous Si micoparticles with tunable photonic properties. The particles can be loaded with daunorubicin (DNR) and doxorubicin (DOX) through covalent attachment, allowing a slow release of the drugs. The optical properties can be used to monitor release of the drugs in the vitreous.
Porous Si particles were prepared by the electrochemical etching of Si wafers and were subsequently functionalized with DNR or DOX using a covalent linkage. The porous structure of the particles gives rise to an optical reflectance spectrum, which can be tuned by varying the etching conditions. As drugs are loaded in or released from the pores the optical reflectance spectrum changes, resulting in a color shift. In vitro drug release was characterized using fluorescence spectroscopy.
Optical spectra of DOX loaded particles were monitored over a period of 7 days and the amount of drug released was quantified. ~15% of the loaded drug was released during this period. The spectra of the particles shifted ~80 nm.
DNR and DOX can be loaded into porous Si particles via covalent attachment and are slowly released as the porous Si matrix degrades. The unique optical properties of porous Si allow for a simple method of monitoring the extent of release in a clinical non-invasive setting after intravitreal injection. Preliminary release data suggests that drug release can be tuned to occur over a period of months and that it is monitorable by an ophthalmoscope or fundus camera.
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