Facile synthesis of inorganic-organic hybrid fluorescent nanoparticles with AIE feature using hexachlorocyclotriphosphazene as the bridge

Abstract In recent 20 years, the functional materials with aggregation-induced emission (AIE) feature have shown huge superiority and great potential in biomedicine field and numerous strategies have been developed to fabricate these AIE-active functional materials. Though delightful developments, facile synthesis of inorganic–organic hybrid fluorescent nanoparticles with AIE feature has seldom reported thus far. In this work, we reported for the first time that novel cross-linked inorganic–organic hybrid polyphosphazene nanospheres with AIE feature could be simply synthesized via conjugation AIE-active fluorophore tetraphenylethylene derivative (TPE-NH2) with hydrophilic polyethylene glycol (PEG-NH2) using hexachlorocyclotriphosphazene (HCCP) as the bridge. This strategy is simple and high-efficient with some advantages (e.g., the reaction can occur under room temperature, the reaction time is short, no surfactant is required and no air-protection is needed). The structure, morphology and spectroscopic properties of TPE-HCCP-PEG nanoparticles (NPs) were characterized by various apparatus. To further evaluate their potential applications in biomedical fields, biocompatibility and cell uptake behavior of TPE-HCCP-PEG composites have been examined. Results demonstrated that TPE-HCCP-PEG NPs possessed intensive fluorescence and high water dispersibility and were of low cytotoxicity. These features endow TPE-HCCP-PEG NPs huge potential in fluorescence imaging. Also, the strategy can be extended for the construction of many other inorganic–organic hybrid polymers taken advantage of their unique features and convenient synthetic method. We expect that this work will open a new avenue for the synthesis of inorganic heterocycles centered AIE-active materials with extensive application prospects.