The nano‐size autonomous monodisperse silica (AS) particles were prepared by hydrolysis and condensation of tetraethoxysilane using l‐lysine as catalyst. The silica/natural rubber (NR) masterbatches were then produced via latex compounding, in which NR latex was mixed with the above AS dispersion. The commercial precipitated silica (PS) was introduced as a control. The effects of both AS and PS particles on the interfacial and mechanical properties of composites were systematically examined. It was found that the AS formed bead‐like morphology wherein the clear particle edges can be distinguished in rubber matrix. Compared with PS/NR, the AS/NR composites were proved to possess more bound rubber and weaker filler–filler interaction resulting in higher tensile strength, abrasive resistance, and resilience. Meanwhile, the efficiency of premodified AS and PS surfaces using bis‐(3‐triethoxysilylpropyl) tetrasulfide on reinforcing the properties of silica/NR composites was studied. The results presented that the overall properties of modified silica/NR vulcanizates were improved significantly. In special, the values of heating building‐up and compression set showed an evident decline which was of great significance for tire tread or other rubber products. For the dynamic properties, the magic angle spinning/NR composites had lower rolling resistance. In short, AS may be applied as an ideal substitution of PS in rubber. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47449.

Ring-opening polymerization (ROP) of cyclic esters/lactones by efficient catalysts is a powerful method for synthesis of biodegradable and biocompatible polyesters with well-defined structures. To develop catalytic systems that are fast, selective and controlled is a persistent effort of chemists. In this contribution, we report a binary urea/alkoxide catalytic system that could catalyze ROP of rac-LA in a fast (over 90% conversion within 1–2 min), stereoselective (Pi up to 0.93) and controlled manner, indicated by narrow MW distributions, linear relationship between the monomer conversions and Mns, end-group fidelity, and chain extension experiments. Remarkably, the catalytic system described here is simple, easily prepared, and structurally tunable and thus has versatile catalytic performances.

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The synthetic biodegradable polyester-based rigid porous scaffolds and cell-laden hydrogels have been separately employed as therapeutic modality for cartilage repair. However, the synthetic rigid scaffolds alone may be limited due to the inherent lack of bioactivity for cartilage regeneration, while the hydrogels have insufficient mechanical properties that are not ideal for load-bearing cartilage applications. In the present study, a hybrid construct was designed to merge the advantage of 3D-printed rigid poly­(lactic-co-glycolic acid) (PLGA) scaffolds with cell-laden platelet-rich plasma (PRP) hydrogels that can release growth factors to regulate the tissue healing process. PRP hydrogels potentially achieved the effective delivery of mesenchymal stem cells (MSCs) into PLGA scaffolds. This hybrid construct could obtain adequate mechanical properties and independently provide MSCs with appropriate clues for proliferation and differentiation. Real-time gene expression analysis showed that PRP stimulated both chondrogenic and osteogenic differentiation of MSC seeding into PLGA scaffolds. Finally, the hybrid constructs were implanted into rabbits to simultaneously regenerate both articular cartilage and subchondral bone within osteochondral defects. Our findings suggest that this unique hybrid system could be practically applied for osteochondral regeneration due to its capacity for cell transportation, growth factors release, and excellent mechanical strength, which would greatly contribute to the progress of cartilage tissue engineering.

Bioresorbable poly(4-hydroxybutyrate) (P4HB) may fulfill the specific requirements that are necessary for a dural substitute, including its high elasticity, long-term strength retention properties, and the biocompatibility without significant accumulation of acidic degradation products. However, commercial P4HB can only be produced by the bacterial fermentation, which limits its applications in the cerebrospinal system due to higher endotoxin restriction. Meanwhile, P4HB can be prepared via the ring-opening polymerization of -butyrolactone. In this contribution, high molecular weight P4HB from chemosynthesis is electrospun into fibrous membrane, showing good mechanical properties that match the natural dura mater. Such P4HB membrane induces fast cellular migration, adhesion, and proliferation of fibroblasts in vitro. Subcutaneous implantation in rats demonstrates excellent biocompatibility of the P4HB membrane with proper biodegradation behaviors. After implantation in the rabbit dural defect model as an onlay graft, the P4HB membranes prevent cerebrospinal fluid leakage and regenerate dura tissue without detecting any local or systematic infections or foreign body responses. Thus, the electrospun P4HB membranes may be particularly useful as artificial dural substitutes to induce wound closure and tissue regeneration, which will be of great benefit to neurosurgery in the future.