Effect of segment structures on the hydrolytic degradation behaviors of totally degradable poly(L‐lactic acid)‐based copolymers

Self-Reinforced PTLG Copolymer with Shish Kebab Structures and a Bionic Surface as Bioimplant Materials for Tissue Engineering Applications

Green and biodegradable materials with great mechanical properties and biocompatibility will offer new opportunities for next-generation high-performance biological materials. Herein, the novel oriented shish kebab crystals of a novel poly(trimethylene carbonate-lactide-glycolide) (PTLG) vascular stent are first reported to be successfully fabricated through a feasible solid-state drawing process to simultaneously enhance the mechanical performance and biocompatibility. The crystal structure of this self-reinforced vascular stent was transformed from spherulites to a shish kebab crystal, which indicates the mechanical interlocking effect and prevents the lamellae from slipping with a significant improvement of mechanical strength to 333 MPa. Meanwhile, it is different from typical biomedical polymers with smooth surface structures, and the as-obtained PTLG vascular stent exhibits a bionic surface morphology with a parallel micro groove and ridge structure. These ridges and grooves were attributed to the reorganization of cytoskeleton fiber bundles following the direction of blood flow shear stress. The structure and parameters of these morphologies were highly similar to the inner surface of blood vessels of the human, which facilitates cell adhesion growth to improve its proliferation, differentiation, and activity on the surface of PTLG.

Effects on the crystallization behavior and biocompatibility of poly(LLA-ran-PDO-ran-GA) with poly(d-lactide) as nucleating agents

The blends of poly(l-lactide acid-p-dioxanone-glycolide) (PLPG) with poly(d-lactide) (PDLA) (PLPG/PDLA) were prepared by a solution-casting method. The effects of PDLA on the properties of the PLPG were studied. DSC and WAXD results confirmed that PLA stereocomplex (sc-PLA) crystals were formed by blending PLLA segments in PLPG with PDLA, and the melting endotherm for both PLLA and sc-PLA relied on PDLA content. The non-isothermal crystallization results indicated that the crystallization process was remarkably accelerated by the addition of PDLA. Meanwhile, the results of isothermal crystallization indicated that the half-time of crystallization decreased with the increase of PDLA content. Besides, the enzymatic degradation behavior of the samples showed that with the increase of PDLA content, the mass loss gradually decreased. Furthermore, TGA and DTG results indicated that the thermal degradation of the samples was a complex process. Moreover, the biocompatibility of the samples was tested by cell culture and using CCK-8 and live/dead staining. Results showed that the samples possessed lower cytotoxicity. Therefore, the PLPG/PDLA blends are promising candidate materials in biomedical applications.

Sc-PLA crystals in the PLPG/PDLA blends were formed by hydrogen bond between PDLA and PLLA segments, which enhance the crystallization ability of PLLA in the PLPG matrix by decreasing the activation free energy.

A review on biodegradable biliary stents: materials and future trends

Biliary stricture is defined as the reduction and narrowing of the bile duct lumen, which can be caused by many factors such as cancer and inflammation. Biliary stent placement can effectively alleviate benign and malignant biliary strictures. However, the commonly used plastic or metallic biliary stents are far from ideal and do not satisfy all clinical requirements，although several types of biodegradable biliary stents have been developed and used clinically. In this review, we summarized current development status of biodegradable stents with the emphasis on the stent materials. We also presented the future development trends based on the published literature.

•

Summary of current development status of bioresorbable biliary stents with the emphasis on the stent materials.

•

The future development trends based on the published literature.

•

The advantages of bioresorbable biliary stents compared with metallic and plastic biliary stents.

Enhancement of the crystallization and biocompatibility of poly(TMC-b-(LLA-ran-GA)) by poly(lactide) stereocomplex

A series of poly(1,3-trimethylene carbonate-b-(l-lactide-ran-glycolide)) (PTLG) with the three-armed PDLA and PLLA stereoblock copolymer (sc-PLA) acting as the nucleating agent was prepared via the solution-casting method.