Synthesis and characterization of elastic star shape-memory polymers as self-expandable drug-eluting stents

Abstract

Elastic shape-memory polymers as self-expendable polymeric drug-eluting stents are developed for the first time, with good mechanical properties, fast self-expansion, and sustained drug release. Novel star block co-polymer PCTOPDs containing hyperbranched poly(ε-caprolactone) (PCL) switching segment and poly(2-oxepane-1,5-dione) (POPD) hard segment were synthesized in high yield and characterized by NMR, GPC, DSC, tensile test and cyclic thermomechanical tensile test. PCTOPD containing 15-27 wt% POPD (PCTOPD-15-27) are found to be non-cytotoxic thermoplastic elastomers (T m of 39-40 and 120-129 °C, ε b of 908-1060%, σ m of 12-20 MPa, and E of 60-91 MPa) with good shape-memory properties at 40 °C (R f of 95-97%, R r of 97-99%, and shape recovery time of 35 s). The stent made from PCTOPD-27 gives nearly full self-expansion at 37 °C within 45 s. The collapse pressure at a compressive strain of 30% is 1.7 bar. A stent containing 3.0 wt% paclitaxel releases 42% drug linearly in the first 9 days and 67% drug in 30 days with a slower but nearly linear release for the period of 10-30 days. The developed SMP-based drug-eluting stents might be useful in biomedical application such as the treatment of coronary artery disease. © 2012 The Royal Society of Chemistry.