Tushar Kumeria1, 4, Joanna Wang2, David Warther1, Kristyn Huffman3, Fangting Li3, Ying Xiao3, Amirali Popat4, Lingyun Cheng3, William Freeman3, and Michael J. Sailor1*


1Dept. of Chemistry and Biochemistry, 2Material Science Engineering Program, 3Shiley Eye Center, University of California, San Diego, La Jolla, CA 92093-0946, U.S.A.
School of Pharmacy, University of Queensland, Brisbane, QLD-4102, Australia.


Self-reporting drug delivery systems can provide a minimally invasive route to accurately determine the amount of drug released/remaining in-vivo. Previously, we developed porous silicon photonic (pSi) crystals based self-reporting drug delivery systems for ophthalmic delivery. However, these tend to be angle and surface roughness dependent, thus interfere with precise reporting of drug amount. Herein, we show a self-reporting drug delivery system using photoluminescent pSi (Figure 1a) with an aim to correlate the decay in photoluminescence (PL) to the amount of drug released from pSi particles. Porous Si microparticles of 50 µm were prepared by electrochemical etching of single crystal Si wafer in a hydrofluoric acid (HF) based electrolyte, ultrasonication, and chemical oxidation (Figure 1b). Triamcinolone acetonide (TA) was loaded into pSi particles from a 10 mg/mL solution, resulting in 10 wt % loading. The in-vitro TA release in HBSS buffer shows a bi-phasic pattern with an initial burst followed by slow release over 30 days. At the same time, the PL also showed a sharp decay followed by a gradual decay, which correlated well with the in-vitro TA release (Figure 1c, d). For in-vivo testing, 4 mg of TA loaded pSi particles were injected into the vitreous of New Zealand rabbits. The in-vivo PL intensity decay of pSi particles was measured by vitreous imaging with a custom modified fundus imaging system, which effectively maps the in-vitro PL intensity decay. Quantification of drug (TA) release from vitreous fractions is in progress to establish in vivo PL-drug release correlations. 
Biographic Details
Name:Tushar Kumeria            
Title: Dr
Affiliation, Country: School of Pharmacy, University of Queensland, QLD-4102, Australia
E-mail: t.kumeria@uq.edu.au
Research interests: porous silicon, nanomedicin, biosensing.