Controlled-Release of Dexamethasone via Light-Activated Implant for Potential Vocal Fold Scar Treatment

This study investigates a novel light-activated implant system designed for injectable, dose-controlled, sustained drug delivery. The light-activated implant was developed by incorporating light-activated drug-releasing liposomes into a biodegradable polymeric capsule. The drug release kinetics from the implant at 0, 1, and 2 min of light activation were determined <i>in vitro</i> using a tissue mimic with varying depths. A pulsed near-infrared laser at 1064 nm, connected to an optical fiber, was used as the light source. The dexamethasone sodium phosphate (DSP) release was tunable depending on the laser irradiation time, with an approximately 4% reduction in release as tissue depth increased by 2 mm. The implant was injected using a needle into <i>ex vivo</i> porcine vocal folds, and drug release kinetics were quantified by real-time fluorescence imaging. Mathematical models were also developed to understand diffusion mechanisms of the light-activated, controlled drug release profiles from the cylindrical implant. Finally, <i>in vivo</i> evaluations in a healthy rabbit vocal fold model confirmed comparable drug release through light activation. Histological assessments demonstrated the safety of the drug delivery system and the structural integrity of the implant within biological tissues after 6 weeks of implantation. These results support the potential clinical application of the drug delivery system, offering a promising solution for conditions requiring precise, controlled therapeutic delivery. Future work will focus on scaling the technology for clinical trials, including construct and tissue reactions in human tissue, to enhance treatment efficacy for various medical conditions.