Challenges for the development of surface modified biodegradable polyester biomaterials: A chemistry perspective

Nonmulberry silk fibroin-based biomaterials: Impact on cell behavior regulation and tissue regeneration

Silk fibroin (SF) is a promising biomaterial due to its good biocompatibility, easy availability, and high mechanical properties. Compared with mulberry silk fibroin (MSF), nonmulberry silk fibroin (NSF) isolated from typical nonmulberry silkworm silk exhibits unique arginine-glycine-aspartic acid (RGD) sequences with favorable cell adhesion enhancing effect. This inherent property probably makes the NSF more suitable for cell culture and tissue regeneration-related applications. Accordingly, various types of NSF-based biomaterials, such as particles, films, fiber mats, and 3D scaffolds, are constructed and their application potential in different biomedical fields is extensively investigated. Based on these promising NSF biomaterials, this review firstly makes a systematical comparison between the molecular structure and properties of MSF and typical NSF and highlights the unique properties of NSF. In addition, we summarize the effective fabrication strategies from degummed nonmulberry silk fibers to regenerated NSF-based biomaterials with controllable formats and their recent application progresses in cell behavior regulation and tissue regeneration. Finally, current challenges and future perspectives for the fabrication and application of NSF-based biomaterials are discussed. Related research and perspectives may provide valuable references for designing and modifying effective NSF-based and other natural biomaterials. STATEMENT OF SIGNIFICANCE: There exist many reviews about mulberry silk fibroin (MSF) biomaterials and their biomedical applications, while that about nonmulberry silk fibroin (NSF) biomaterials is scarce. Compared with MSF, NSF exhibits unique arginine-glycine-aspartic acid sequences with promising cell adhesion enhancing effect, which makes NSF more suitable for cell culture and tissue regeneration related applications. Focusing on these advanced NSF biomaterials, this review has systematically compared the structure and properties of MSF and NSF, and emphasized the unique properties of NSF. Following that, the effective construction strategies for NSF-based biomaterials are summarized, and their recent applications in cell behavior regulations and tissue regenerations are highlighted. Furthermore, current challenges and future perspectives for the fabrication and application of NSF-based biomaterials were discussed.

Strategies for Enhancing Polyester-Based Materials for Bone Fixation Applications

Polyester-based materials are established options, regarding the manufacturing of bone fixation devices and devices in routine clinical use. This paper reviews the approaches researchers have taken to develop these materials to improve their mechanical and biological performances. Polymer blending, copolymerisation, and the use of particulates and fibre bioceramic materials to make composite materials and surface modifications have all been studied. Polymer blending, copolymerisation, and particulate composite approaches have been adopted commercially, with the primary focus on influencing the in vivo degradation rate. There are emerging opportunities in novel polymer blends and nanoscale particulate systems, to tune bulk properties, and, in terms of surface functionalisation, to optimise the initial interaction of devices with the implanted environment, offering the potential to improve the clinical performances of fracture fixation devices.

Photocrosslinked natural hydrogel composed of hyaluronic acid and gelatin enhances cartilage regeneration of decellularized trachea matrix

Repair of long segmental trachea defects is always a great challenge in the clinic. The key to solving this problem is to develop an ideal trachea substitute with biological function. Using of a decellularized trachea matrix based on laser micropore technique (LDTM) demonstrated the possibility of preparing ideal trachea substitutes with tubular shape and satisfactory cartilage regeneration for tissue-engineered trachea regeneration. However, as a result of the very low cell adhesion of LDTM, an overly high concentration of seeding cell is required, which greatly restricts its clinical translation. To address this issue, the current study proposed a novel strategy using a photocrosslinked natural hydrogel (PNH) carrier to enhance cell retention efficiency and improve tracheal cartilage regeneration. Our results demonstrated that PNH underwent a rapid liquid-solid phase conversion under ultraviolet light. Moreover, the photo-generated aldehyde groups in PNH could rapidly react with inherent amino groups on LDTM surfaces to form imine bonds, which efficiently immobilized the cell-PNH composite to the surfaces of LDTM and/or maintained the composite in the LDTM micropores. Therefore, PNH significantly enhanced cell-seeding efficiency and achieved both stable cell retention and homogenous cell distribution throughout the LDTM. Moreover, PNH exhibited excellent biocompatibility and low cytotoxicity, and provided a natural three-dimensional biomimetic microenvironment to efficiently promote chondrocyte survival and proliferation, extracellular matrix production, and cartilage regeneration. Most importantly, at a relatively low cell-seeding concentration, homogeneous tubular cartilage was successfully regenerated with an accurate tracheal shape, sufficient mechanical strength, good elasticity, typical lacuna structure, and cartilage-specific extracellular matrix deposition. Our findings establish a versatile and efficient cell-seeding strategy for regeneration of various tissue and provide a satisfactory trachea substitute for repair and functional reconstruction of long segmental tracheal defects.