Poly （Caprolactone-Co-Dioxane）:A Potential Shape-Memory Biomaterial Suitable For Human Body Temperature

At present,interventional surgery has gradually replaced traditional open surgery and become an important means of surgical treatment for acute diseases of large arteries such as aortic aneurysm rupture and aortic dissection due to its advantages of less trauma,quick recovery and low risk.But in the current interventional therapy,is often taken permanent metal stents or drug-eluting stents（des）,does not have the functions of shape memory and biodegradable,long-term placement may result in luminal stenosis and thrombosis,under the condition of ideal scaffold should possess permanent shape and in need not be automatic degradation is harmless to human body material.Shape memory materials have been proposed for biomaterial design because they can facilitate minimally invasive surgery and restore to a predetermined shape in vivo.Shape memory materials can complete the shape memory transformation process under the control of light,heat and electromagnetism,which can reduce the injury of surgical approach.Currently,researchers and clinical experts have attracted strong attention.However,there are still few researches on shape memory materials conforming to human deformation temperature.The biggest challenge is how to adjust the glass transition temperature of materials.One strategy for adjusting the glass transition temperature of a material is to form a polymer by adding a substance with a low glass transition monomer.The polymer glass transition temperature is consistent with human body temperature,and it also has shape memory effect,which can make the scaffold compressed into a very fine size before vascular implantation,and send the scaffold to a specific site through a special transport device,reducing the injury of surgical approach.The support can automatically change into design size under the temperature of human body,which can meet the needs of human body.At the same time,due to the subtle differences in human anatomy,the current standard stents on the market cannot meet individual needs.The bracket can be designed into different sizes by software to meet individual customization.At the same time,due to the characteristics of polymers,scaffolds are biodegradable.During self-wound repair,scaffolds are degraded into non-toxic water and CO2,and finally discharged from the body.We have developed a simple method to obtain ε-caprolactone（CL）and dioxanone（DX）hemicrystals and random copolymers with thermal stability similar to that of polycaprolactone（PCL）,but with a faster rate of hydrolysis degradation.CL/DX copolymer is a promising composite material for printing needle-like biomaterials,especially in vivo implants.This copolymer has physical properties similar to PCL and absorbs faster.Copolymer with molecular weight of10000 Mn was synthesized by bulk open ring copolymerization.In vivo degradation time is 9 to 15 months.The microstructure of copolymer is separated by long CL blocks separated by isolated DX elements.Copolymer has the characteristics of quick response,short deformation time at human body temperature,and can be degraded.In addition,it has good histocompatibility and cytocompatibility in vivo,which can meet the needs of implantation.The shape memory performance of the material was also tested.