Biodegradable Shape Memory Nanocomposites Based on PCL/PPC/Graphene: As a Proposal Material for Cardiovascular Stent

The limitations of metallic stents have led to the development of absorbable polymer stents in cardiovascular applications. This study focuses on the synthesis of biodegradable shape memory nanocomposites made of polycaprolactone (PCL), poly(propylene carbonate) (PPC) and functionalized graphene nanoparticles (FGNp), designed for medical devices that exhibit shape memory effects at human body temperature. The nanocomposites were synthesized using a solvent casting method. To enhance the performance of graphene nanoparticles (GNPs), chemical modification with polyethylene glycol (PEG) was performed, which was confirmed by energy dispersive X-ray spectroscopy (EDX) and Raman spectroscopy. The effect of modified graphene nanoparticles on the shape memory behavior was discussed in detail and the presence of graphene showed an increase in temporary shape stabilization in the samples. In the nanocomposite with 10 wt% PCL and 0.5 phr FGNp, the shape fixation ratio (Rf) and shape recovery ratio (Rr) of about 90% were achieved with a shape memory transition temperature (Ts) close to human body temperature. This sample was successfully fabricated into a stent by a 3D bioprinter, and the fabricated stent exhibited an improved shape memory effect. Furthermore, comprehensive blood compatibility evaluations including hemolysis, cytotoxicity, and complement activation along with in vitro degradation and drug release behavior evaluations confirmed the potential of the nanocomposite PCL10/PPC90/FGNP0.5 as a promising candidate for the fabrication of biomedical stents.