Photo-responsive interpenetrating network beads of alginate/polyvinyl alcohol-coumarin conjugate.

Interpenetrating network (IPN) beads composed of alginate and poly(vinyl alcohol)-epoxypropoxy coumarin (PVA-EPC) conjugate were prepared by dropping the mixture solution into CaCl2 solution under UV irradiation (λ = 365 nm). EPC residues of PVA-EPC could readily be dimerized by λ = 365 nm and de-dimerized by λ= 254 nm even in the presence of alginate. In addition, the viscosity of the mixture solution increased with the time of UV irradiation due to the photo-dimerization. The percentage release in 360 min of FITC-dextran loaded in the beads, which were prepared using the mixture solutions of which alginate/PVA-EPC concentrations were 0.5%/0.5%, 0.5%/1%, and 0.5%/2.5%, were about 2%, 11%, and 5%, respectively. Interestingly, in case of beads prepared using the mixture solution of which alginate/PVA-EPC concentration was 0.5%/2.5%, the release was a little but significantly promoted by the irradiation of λ= 254 nm.