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 1H 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.