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

Abstract

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 1 H 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 selfassembly 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.

Novel Macromolecular Emulsifiers as Coatings with Water‐Tolerant Antifogging Properties Based on Coumarin‐Containing Copolymeric Micelles

“…Under acidic conditions, i.e., pH < 3.94, O/W emulsion could be stabilized as a result of the protonation of DMAEMA unit, making the emulsifier surface more hydrophilic. When pH was adjusted to more neutral or basic conditions, i.e., pH > 5.80, deprotonation of DMAEMA unit could promote the formation of more lipophilic surface, so the phase inversion from O/W to W/O was observed. Nevertheless, as pH elevated over 9.86, the stability of emulsions significantly decreased and even demulsification occurred due to the disintegration of micelles.…”

Multiple morphologies of a poly(methyl methacrylate)‐block‐poly(N,N‐dimethyl aminoethyl methacrylate) copolymer with pH‐responsiveness and thermoresponsiveness

“…Amphiphilic block polymers can self‐assemble into well‐defined nanostructures with regulatable morphologies and sizes in solution and can act as functional materials in applications such as biotechnology and medical materials . Stimuli‐responsive amphiphilic polymers have captured more and more attention, not only on account of their response to environmental stimuli but also because of their diverse structures .…”

Molecular-Gated Drug Delivery Systems Using Light-Triggered Hydrophobic-to-Hydrophilic Switches

“…This has been achieved by two strategies. One is introducing SP into amphiphilic block copolymers in which SP represents the hydrophobic segment [21][22][23][24][25][26][27][28][29] . These amphiphilic structures selfassemble into micelles in which the drug is encapsulated.…”

“…This has been achieved by two strategies. One is introducing SP into amphiphilic block copolymers in which SP represents the hydrophobic segment. − These amphiphilic structures self-assemble into micelles in which the drug is encapsulated. UV light irradiation induces the isomerization of hydrophobic SP units to hydrophilic zwitterionic MC units, leading to the shift of the hydrophilic–hydrophobic balance, which consequently disassembles and disrupts the micellar structure and releases the encapsulated drug. ,, The second strategy uses SP as a gate molecule on the surface of drug-loaded mesoporous silica. − Exploiting the hydrophobicity–hydrophilicity switch between the closed (SP) and open (MC) isomers allows control and adjustment of the wetting behavior of the surface and release of the drug.…”