Photosensitive controlled release with polyethylene glycol–anthracene modified alginate

Covalent modification of alginate with polyethylene glycol–conjugated anthracene molecules has the potential to both stabilize the alginate and act as a photosensitive crosslinker. Release studies with Coomassie Blue show lengthy release times from the alginate photogels that extend past 70 days with, for example, 17% versus 27% release at 1750 h (73 days) for photogels with and without 365-nm UV light treatment for 30 min at 10 mW/cm2 in the initial release period. Photocrosslinking of the photogels after loading effectively “locks” in drug compounds to control their release. Effective crosslinking densities and controls of polyethylene glycol-crosslinked alginate and physically crosslinked calcium alginate gels suggest strong interactions between Coomassie Blue and both alginate and anthracene. Photogels containing anthracene-capped star-polyethylene glycol show increased photosensitivity with modified release profiles. Ultimately, the covalent modification of alginate with photoactive crosslinkers has the potential to produce a long-term, photosensitive, controlled release system.

Graphical abstractPhotoresponsive alginate – 365-nm UV light causes anthracene dimerization along the alginate polymer backbones of photogels to cause decreases in the release rates of small and large molecules.Figure optionsDownload full-size imageDownload as PowerPoint slide