Preparation of Tacrolimus loaded micelles based on poly(ɛ-caprolactone)-poly(ethylene glycol)-poly(ɛ-caprolactone)

Self-assembled polymeric micelles are widely applied in drug delivery system. In this study, Tacrolimus (FK506) loaded micelles were prepared based on biodegradable poly(ɛ-caprolactone)-poly(ethylene glycol)-poly(ɛ-caprolactone) (PCEC) copolymers. Micelles were prepared by self-assembly of triblock copolymer PCEC in distilled water triggered by its amphiphilic characteristics. Drug loading and encapsulation efficiency were determined by adjusting the weight ratio of FK506 and PCEC. The particle size distribution and variation of obtained micelles were determined using Malvern laser particle size analyzer, while the spherical geometry was observed on transmission electron microscope (TEM), and the crystallographic assays were fulfilled by X-ray diffractometer (XRD). Besides, in vitro release profile demonstrated a significant difference between rapid release of free Tacrolimus and much slower and sustained release of FK506 loaded micelles. These results suggested that we have successfully prepared Tacrolimus loaded micelles in an improved method which is safer and more efficient. The prepared micelles might be potential carriers for Tacrolimus delivery in immunosuppressive therapy.