One-step synthesis of AIE-active fluorescent cyclomatrix polyphosphazene spheres as drug delivery carriers

The functional materials with aggregation-induced emission (AIE) feature have been extensively explored for biomedical applications, however, the synthesis of AIE-active functional materials with biodegradable potential and controlled drug delivery behavior have been seldom demonstrated. In this work, we reported for the first time that AIE-active fluorescent cyclomatrix polyphosphazene spheres (named as QM-HCCP-PEG) can be facilely fabricated via a one-step nucleophilic substitution to conjugate hexacyclotriphosphazene (HCCP), amino modified polyethylene glycol (PEG-NH2) and an AIEgen (QM-OH). The resultant QM-HCCP-PEG shows amphiphilicity and can be capable of self-assembling into spheres with high water dispersibility and desirable fluorescence performance. During self-assembly, antitumor drug bortezomib (BTZ) can be encapsulated in the core of QM-HCCP-PEG with a relative high drug loading capacity up to 12.2%. In vitro drug release profile showed that the micelles could successfully release BTZ in physiological solution. Moreover, the QM-HCCP-PEG displayed excellent biological imaging ability for its outstanding AIE feature and BTZ-loaded nanospheres exhibited significant cytotoxicity against MDA-MB-231 cells. Thus, this work provides new perspective for fabrication of AIE-active functional materials via a convenient and highly efficient experimental procedure and the resultant AIE-active functional materials are of great potential as fluorescent probes and drug delivery vehicles.