Highly efficient light-induced reversible micellization of amphiphilic polymer based on photochromism of naphthopyran in aqueous solution

• The naphthopyrans are used as light-responsive group to synthesize amphiphilic polymer with poly(ethylene glycol).
• The amphiphilic polymer can self-assemble to micelles in aqueous solution.
• The photoisomerization of naphthopyrans moieties can tune the disassembly and re-assembly of the micelle fast and reversibly.
• Fluorescent dye nile red is used as the fluorescence probe to monitor the encapsulation and release of micelle.

The photochromic materials of single-molecule naphthopyrans (NP) are first used as hydrophobic and light-responsive group to synthesize amphiphilic polymer with the poly(ethylene glycol) (PEG) via Click-Chemistry. Such an amphiphilic polymer can self-assemble to light-responsive micelles with NP-core and PEG-shell in aqueous solution, as are confirmed by dynamic light scattering and transmission electron microscopy. The photoisomerization of naphthopyrans moieties can fast and reversibly tune the disassembly and re-assembly of the micelle, as are confirmed by UV–Vis spectroscopy. The changes of fluorescent spectra of nile red (NR) in water solution of polymeric micelle within 60 s demonstrate that the polymeric micelle can be used as nanocarriers to encapsulate, release and re-encapsulate guest solutes on demand controlling of light irradiation. The fast and highly efficient photo-control of polymeric micelles is a potential candidate in biomedical area for drug delivery.

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