Self-assembly and morphology transition of amphipathic spiropyran-based random copolymers to control drug release

An amphipathic spiropyran-based random copolymer P(SPMA-co-DMAEMA) was synthesized by atom transfer radical polymerization, and the resulting copolymer was characterized by means of H-1 nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography. The self-assembly behaviors and morphology transition were systematically investigated under single and combined external environmental stimuli by transmission electron microscopy. With coumarin 102 as the model drug molecule, the self-assembly micelles were used to control drug loading, release, and re-encapsulation to some extent. The characterization results indicated the successful preparation of the spiropyran-based random copolymer P(SPMA-co-DMAEMA). The external stimuli had some influences on the morphology of the self-assembly aggregate, and the schizophrenic' behavior was interestingly found in this work. The drug release experiments showed the reversible loading and release process up to a point, which might expand the potential application domain of the amphiphilic spiropyran-based random copolymer in drug delivery.