Laura Wells

Generic, Anthracene-Based Hydrogel Crosslinkers for Photo-controllable Drug Delivery

Light-responsive polymers with controllable, reversible crosslink mechanisms have the potential to create unique biomaterials with stimulus-controlled swelling, degradation and diffusion properties useful in tissue engineering and drug delivery applications. Generic photodimerizing polyethylene glycol-anthracene macromolecules that may be grafted to various polymers to effectively control their crosslinking via a photodimerization mechanism have been developed. These generic crosslinkers were shown to effectively introduce photoresponsive properties into hyaluronate and alginate as model hydrophilic polymers. In vitro testing using human corneal epithelial cells was used to demonstrate cytocompatibility of the resulting photogels. The effective crosslinking density of the photogels could be increased resulting in a decrease in the release rate of small and large molecules from the photogels following exposure to 365 nm light. This tuneable crosslinking has the potential to manipulate the delivery rates of therapeutics resulting in control over treatment profiles and may lend itself to various applications, which may benefit from light induced changes in crosslinking.

Photoresponsive PEG-Anthracene Grafted Hyaluronan as a Controlled-Delivery Biomaterial

Ophthalmic drug delivery to the posterior segment of the eye could benefit from a responsive controlled drug delivery system with light or laser inducible changes. For example, the delivery of age-related macular degeneration drugs requires invasive monthly injections making long-term photoresponsive drug delivery a desirable option. The feasibility of this may be facilitated by both the transparency of the eye and the advanced technology in ophthalmic lasers. Hyaluronic acid photogels that are compatible with retinal pigment epithelial cell lines are shown here to deliver a variety of small and large model drugs over the long term (months). Varying UV exposures resulted in decreases/increases or the turning off and on of delivery, potentially allowing the therapy to be tailored to suit the patient and the disease.