RESUMO
Highly emissive fluorophores based on polyaromatic hydrocarbons with tunable emission properties and aggregated structures play a very important role in relevant functional studies. In this study, a novel alkynylpyrene derivative 1 was synthesized, which exhibits unimolecular to excimer emission in methanol with an increasing concentration accompanied by the formation of nanovesicles via the π-π stacking, hydrogen bond and hydrophobic interaction. The self-assembly behavior as well as emission properties of 1 in aprotic polar solvents (ACN, acetone, DMF and DMSO) can also be adjusted by the volume fraction of the poor solvent H2O, which can induce 1 self-assembly to excimer state and could be applied in information transfer. Moreover, upon visible light irradiation, photoswitchable performance of nanovesicles of 1 was observed in which the emission markedly changes from yellow to blue; this is attributed to the cycloaddition reaction of alkynyl groups and singlet oxygen, which can be generated without the addition of external photosensitizers. The multi-responsive and fluorescence behavior of the alkynylpyrene derivative show that the self-assembly can be used to expand the development of this type of fluorophores, and the novel photoinduced tunability of the fluorescence emission provides an effective strategy to obtain high-performance transmitting and sensing materials.
RESUMO
Mixed micelles made of Pluronic P105 (P105) and poly(ethylene glycol)-phosphatidyl ethanolamine conjugate (PEG-PE) were prepared. The interaction of Pluronic and PEG-PE was studied and the interaction parameter beta and critical micelle concentration (CMC) were used to evaluate the micellar stability toward dilution. The results showed that certain mixed micelles were more stable than pure Pluronic micelles upon dilution. The mixed micelles were used to trap the poorly soluble anticancer drug camptothecin (CPT). The cytotoxicity of the CPT-loaded mixed micelles against MCF-7 cancer cell was higher than that of CPT-loaded P105 micelles and much higher than that of the free drug.