Storing and Releasing Curcumin from Polymer Films

What is it about?

This paper is concerned with storage and release of a therapeutic molecule (curcumin) from a polymer surface treatment. Release of active molecules from such coatings is called surface-mediated drug delivery. It is a method used in biomaterials research (arterial stents, orthopaedic implants) to help the body interact properly with implanted material. Knowing how much of the active molecule can be stored within the film, and the manner in which it is released when the biomaterial is exposed to biological fluids, is essential for the design and adoption of novel surface treatments. The work focuses on a therapeutic molecule from natural sources: curcumin, which is an extract of turmeric. The work was carried out by a number of students from our group: Yongjin Shin, Weng Hou Cheung, and Tracey Ho. They were able to determine, through the use of a range of experiments, that the curcumin is released only when the polymer film is dried and then exposed to solution, rather than from prolonged immersion in a release solution.

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Why is it important?

The key to the impact of this work was the use of an experiment that could probe the uptake (loading) and release of the curcumin without having to remove the coated surface from the loading/release solution. Studies on release of molecules like curcumin (that are hydrophobic - i.e. they cannot easily be dissolved in water) have often used techniques that require the surface coating to be dried before interrogation. As it turns out, the cycling of drying/re-immersion of coated surfaces actually caused the majority of release of curcumin from the surface treatment. When the coating was kept wet, curcumin would not come out. Designing coatings for release of such hydrophobic molecules will thus need to focus on coatings that themselves degrade over time, allowing release to happen via a different mechanism.

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