NIR-Light Induced Phase Transition of Tunable Biodegradable Composites for On-Demand Healling, Drug Release and Bio-Adhesion

Background: Stimuli responsive biomaterials have a major role in many biomedical applications owing to their ability to change in response to an external stimulus. Among the diverse stimuli existing, light is of particular interest since it possesses many advantages; its parameters are easy to manipulate, and the procedure is safe and rapid. Despite their great potential, these materials are currently limited by the toxicity of the light triggered molecules and/or their by-products, or by the wavelength used to trigger them. Here we design, a unique system based on star-shaped biocompatible copolymers of low melting point, incorporated with gold nanoshells (GNS). We hypothesize that upon near infrared (NIR) irradiation, these materials undergo a melting process and hence a shape transformation.

Methods: The effects of variable irradiation parameters on matrix morphology, melting time, mechanical properties, and release profiles in response to NIR irradiation were examined as well as in-vitro system’s cytotoxicity.

Results: We have successfully synthesized a series of multi-armed polyethylene glycol and poly(ε-caprolactone) copolymers to create a biodegradable system of biocompatible copolymers. Characterization showed that the system melting temperature is tunable and hence may be tailored to a specific application. We have also shown that the system may restore mechanical strength and release drugs in a stepped manner under NIR trigger.

Conclusion: This NIR responsive concept has a great potential in biomedical applications such as drug delivery, repairable tissue scaffolds and tissue adhesives.