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 QMHCCP-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 AIEactive functional materials via a convenient and highly efficient experimental procedure and the resultant AIEactive functional materials are of great potential as fluorescent probes and drug delivery vehicles.

Automated summary

This study presents the synthesis of fluorescent cyclomatrix polyphosphazene spheres with aggregation-induced emission (AIE) feature and biodegradable potential for controlled drug delivery. The resulting micelles exhibit high water dispersibility, desirable fluorescence performance, and high drug loading capacity. They can effectively release the encapsulated drug in physiological solution and show excellent biological imaging ability and cytotoxicity against cancer cells.