Calcein release from polymeric vesicles in blood plasma and PVA hydrogel.

Purpose: The main goal of this study was to show the long-term stability of vesicles from poly(2-methyl oxazoline-block-polydimethylsiloxane-block poly(2-methyl oxazoline) (PMOXA-PDMS-PMOXA) in PBS, blood plasma and the feasibility to use these vesicles for drug release from PVA hydrogels.
Methods: The vesicle formation properties and loading efficiency was evaluated using fluorescent dyes. The stability of the vesicles was evaluated in buffer at pH 7 at room temperature and in 50% blood plasma at 37 degrees C. The calcein loaded vesicles were dispersed in a UV crosslinked PVA hydrogel. The stability of the vesicles in the hydrogel was observed over one week, before the vesicles were ruptured with Triton X-100.
Results: The vesicles are very stable in buffer, blood plasma, and the PVA hydrogel. In plasma 50% of the calcein is released in 48 h in the presence of sodium azide. The vesicles can be evenly dispersed in PVA and are stable. The release can be triggered and the calcein diffuses afterwards quickly throughout the gel.
Conclusion: Polymeric vesicles can be used as diffusion barrier in hydrogels for the controlled release of water soluble drugs.