Preparation and photochromic properties of layer-by-layer self-assembly films and light-responsive micelles based on amphiphilic naphthopyran derivative.

An amphiphilic naphthopyran derivative (DSNP) with negative-charged di-sulfatoethoxy was first designed and synthesized. DSNP was used to prepare the LBL self-assembly films with cationic quaternized poly(4-vinylpyridine) (P4VPQ). The multilayer assembly process was monitored via UV-Vis spectra and the DSNP displayed a significant slow fading rate in film. In addition, DSNP was also used as the light-responsive group to fabricate light-responsive micelles with polyethylene glycol-triethylamine bromide (PEG-NEt3). The photoisomerization of naphthopyran moieties can rapidly and reversibly tune the disassembly and re-assembly of the micelles. The changes of fluorescent spectra of Nile Red (NR) in water solution of polymeric micelles demonstrated that the polymeric micelle can be used as nanocarriers to encapsulate, release and re-encapsulate guest solutes on demand controlling of light irradiation. The results indicate that the amphiphilic naphthopyran can be used in both optical-switches and biomedical area for drug delivery.