Preparation of size-controlled poly(cyclotriphosphazene-co-resveratrol) microspheres and their properties as drug delivery carriers

Polymeric materials are used as ideal carriers for drug delivery applications due to their excellent physicochemical properties, however, the controlled preparation and drug release behavior of cross-linked polymeric microspheres are still open to discussion. Hexacyclotriphosphazene (HCCP), as one of the prominent members of polyphosphazene, can be easily treated with many monomers to produce micro/nanospheres. In this research work, cross-linked poly(cyclotriphosphazene- co -resveratrol) (PCTPRS) microspheres were prepared by the precipitation reaction of HCCP and resveratrol (RSV). The apparent peak at 961 cm −1 in FTIR spectra of the microspheres revealed that the polymerization between RSV and HCCP was successful. The TGA results showed that the increase in thermal properties was owing to the highly cross-linked structure of the microspheres. The XRD patterns showed the amorphous nature of the microspheres compared to the monomers. The obtained SEM micrographs dictated that the HCCP:RSV mole ratio had a significant impact on the size of the microspheres. The PCTPRS microspheres were used as carriers for the drug loading and release study of the anti-cancer model drug camptothecin (CPT). The drug loading efficiency of the PCTPRS microspheres was found to be 89.9 mg/g. Whereas the release study revealed that 53.0% of CPT was released at pH 4.0 and 37.5% at pH 7.4 from the drug-loaded microspheres after 11 days. Graphical abstract