The inflammatory environment of periodontitis with bacteria, excessive reactive oxygen species (ROS) and limited regenerative capacity of alveolar bone makes reconstruction of periodontium become a huge challenge. The present strategies, such as local debridement and antibiotic injection, are difficult to solve above problems completely. Thus, to reverse the progression of the disease, Ca2+-tannic acid nanocomposites loaded into injectable sodium alginate/4-arm polyethylene glycol-lipoic acid hydrogel (CaTA@Gel) were fabricated, including Ca2+‑sodium alginate (SA) ionic crosslinking and radical polymerization of lipoic acid-modified 4-arm polyethylene glycol (PEG-SS4) under UV illumination. In our results, the double networks of hydrogel not only had good mechanical property, but also sustainedly released CaTA nanocomposites which could inhibit bacteria, scavenge ROS due to TA, and promote osteogenesis of bone mesenchymal stem cells (BMSCs) via Ca2+. The antibacterial rates of CaTA (1 mg/mL) against E. coli and S. aureus were 97.3 ± 1.25 % and 96.7 ± 2.57 %, respectively. Meanwhile, ·OH and ·O2- could be inhibited obviously by CaTA (100 μg/mL), whose inhibition rate were 59.6 ± 2.98 % and 62.4 ± 3.12 %, respectively. Finally, the up-regulation of osteogenetic genes and successful alveolar bone regeneration in rat models indicated this injectable nanocomposite hydrogel provided a promising strategy for the treatment of periodontitis.

The controllable and sequential release of kartogenin (KGN) could improve in situ cartilage regeneration due to the intrinsically different windows between endogenous stem/progenitor cells (ESPCs) recruitment and chondrogenesis. In this paper, KGN were loaded into polyamino acid-based scaffolds in two different ways: First, phenylboronic acid ester (PBE) covalent grafting between KGN and poly (L-glutamic acid) (PLG) was built for a responsive release in an inflammatory environment, showing a responsive release of 50 % in 3 days and effectively promoting the migration of bone marrow stem cells (BMSCs) in vitro. Secondly, the conformation shift of silk fibroin (SF), from hydrophilic alpha-helix to hydrophobic beta-sheet, could form physical network for mechanical improvement of hydrogels, as well as embedding KGN for a sustained release of 73 % in 30 days, which promoted chondrogenesis of BMSCs. In vivo rat models proved scaffolds with ROS-responsive release and physical diffusion of KGN could successfully reconstruct hyaline cartilage whose matrix composition, distribution and structure were all consistent with healthy hyaline cartilage. These results proved that this work built a smart scaffold platform with controllable and sequential release of KGN, providing a new idea for cell-free strategy in cartilage regeneration and has great clinic meaning.

The piezoelectric and elastic properties are critical for the performance of AlN-based 5G RF filters. The improvement of the piezoelectric response in AlN is often accompanied by lattice softening, which compromises the elastic modulus and sound velocities. Optimizing both the piezoelectric and elastic properties simultaneously is both challenging and practically desirable. In this work, 117 X0.125Y0.125Al0.75N compounds were studied with the high-throughput first-principles calculation. B0.125Er0.125Al0.75N, Mg0.125Ti0.125Al0.75N, and Be0.125Ce0.125Al0.75N were found to have both high C33 (>249.592 GPa) and high e33 (>1.869 C/m2). The COMSOL Multiphysics simulation showed that most of the quality factor (Qr) values and the effective coupling coefficient (Keff2) of the resonators made with these three materials were higher than those with Sc0.25AlN with the exception of the Keff2 of Be0.125Ce0.125AlN, which was lower due to the higher permittivity. This result demonstrates that double-element doping of AlN is an effective strategy to enhance the piezoelectric strain constant without softening the lattice. A large e33 can be achieved with doping elements having d-/f- electrons and large internal atomic coordinate changes of du/dε. The doping elements–nitrogen bond with a smaller electronegativity difference (ΔEd) leads to a larger elastic constant C33.

In this paper, we demonstrate that V0.027Bi0.973TeI, a material with both giant bulk Rashba effect and ferromagnetism, can reverse its magnetization by self-generated spin–orbit torque. Through first-principles calculation, it is found that the giant bulk Rashba effect arises from both bulk space inversion asymmetry and strong spin–orbital coupling, while the ferromagnetism originates from the itinerant d-electrons of doped element vanadium. More importantly, its field-like spin–orbit torque efficiency is determined to be as high as 4.53 × 10−4 mT/(A cm−2), which is more than two orders of magnitude higher than that typically observed in magnetic heterostructures. It is further shown that by using such magnetic bulk Rashba material to form a homogenous spintronic device, the power consumption for magnetization switching can be significantly reduced.

Cartilage injury is a very common joint disease, and cartilage repair is a great challenge in clinical treatment due to the specific structure of cartilage tissue and its microenvironment in vivo. The injectable self-healing hydrogel is a very promising candidate as a cartilage repair material because of its special network structure, high water retention and self-healing properties. In this work, a self-healing hydrogel cross-linked by host-guest interaction between cyclodextrin and cholic acid was developed. The host material was composed of β-cyclodextrin and 2-hydroxyethyl methacrylate-modified poly(l-glutamic acid) (P(LGA-co-GM-co-GC)), while the guest material was chitosan modified by cholic acid, glycidyl methacrylate, and (2,3-epoxypropyl)trimethylammonium chloride (EPTAC) (QCSG-CA). The host-guest interaction self-healing hydrogels, named as HG hydrogels (HG gel), exhibited excellent injectability and self-healable property, and the self-healing efficiency was greater than 90%. Furthermore, in order to enhance the mechanical properties and slow down the degradation of the HG gel in vivo, the second network was constructed by photo-cross-linking in situ. Biocompatibility tests showed that the enhanced multi-interaction hydrogel (MI gel) was extremely suitable for cartilage tissue engineering both in vitro and in vivo. In addition, the adipose derived stem cells (ASCs) in MI gel were able to differentiate cartilage effectively in vitro in the presence of inducing agents. Subsequently, the MI gel without ASCs was transplanted into rat cartilage defects in vivo for the regeneration of cartilage. After 3 months postimplantation, new cartilage tissue was successfully regenerated in a rat cartilage defect. All results indicated that the injectable self-healing host-guest hydrogels have important potential applications in cartilage injury repair.

Aluminum scandium nitride (Al1-xScxN) film has drawn considerable attention owing to its enhanced piezoelectric response for micro-electromechanical system (MEMS) applications. Understanding the fundamentals of piezoelectricity would require a precise characterization of the piezoelectric coefficient, which is also crucial for MEMS device design. In this study, we proposed an in situ method based on a synchrotron X-ray diffraction (XRD) system to characterize the longitudinal piezoelectric constant d33 of Al1-xScxN film. The measurement results quantitatively demonstrated the piezoelectric effect of Al1-xScxN films by lattice spacing variation upon applied external voltage. The as-extracted d33 had a reasonable accuracy compared with the conventional high over-tone bulk acoustic resonators (HBAR) devices and Berlincourt methods. It was also found that the substrate clamping effect, leading to underestimation of d33 from in situ synchrotron XRD measurement while overestimation using Berlincourt method, should be thoroughly corrected in the data extraction process. The d33 of AlN and Al0.9Sc0.1N obtained by synchronous XRD method were 4.76 pC/N and 7.79 pC/N, respectively, matching well with traditional HBAR and Berlincourt methods. Our findings prove the in situ synchrotron XRD measurement as an effective method for precise piezoelectric coefficient d33 characterization.

Lithium sulfur batteries (LSBs) are regarded as one of the most promising energy storage devices due to the high theoretical capacity and energy density. However, the shuttling lithium polysulfides (LiPSs) from the cathode and the growing lithium dendrites on the anode limit the practical application of LSBs. To overcome these challenges, a novel three-dimensional (3D) honeycombed architecture consisting of a local interconnected Co3O4 successfully assembled into a scalable modified layer through mutual support, which is coated on commercial separators for high-performance LSBs. On the basis of the 3D honeycombed architecture, the modified separators not only suppress effectively the "shuttle effects" but also allow for fast lithium-ions transportation. Moreover, the theoretical calculations results exhibit that the collaboration of the exposed (111) and (220) crystal planes of Co3O4 is able to effectively anchor LiPSs. As expected, LSBs with 3D honeycombed Co3O4 modified separators present a reversible specific capacity with 1007 mAh g-1 over 100 cycles at 0.1 C. More importantly, a high reversible capacity of 808 mAh g-1 over 300 cycles even at 1 C is also acquired with the modified separators. Therefore, this proposed strategy of 3D honeycombed architecture Co3O4 modified separators will give a new route to rationally devise durable and efficient LSBs.

In situ cartilage regeneration with endogenous stem/progenitor cells (ESPCs) and bioactive scaffolds is attractive in cartilage regeneration. Nevertheless, the optimization of ESPCs recruitment and the establishment of chondrogenic microenvironment are still a huge challenge for better therapeutic outcomes. Herein, a in situ cartilage tissue engineering porous scaffold with enzyme-responsive kartogenin (KGN) release is prepared to not only recruit ESPCs via chemoattractant, but also promote their chondrogenesis. Polyethylene glycol-modified Kartogenin (PEGKGN) and polycaprolactone (PCL) are grafted on poly(L-glutamic acid) (PLGA) to endow the porous scaffolds with good mechanical property, capillarity and enzyme-responsiveness. The scaffolds show a fast absorption of protein solution through capillarity, indicating its capacity of rapid fill with bone marrow blood at the early stage after implantation for the maximum absorption and retention of ESPCs. The release dose of PEGKGN is found to be accelerated by matrix metalloproteinase-2 (MMP-2). And the high-dose PEGKGN can stimulate the migration of bone marrow mesenchyml stem cells (BMSCs) obviously, and the low-dose PEGKGN can promote the chondrogenesis of BMSCs in vitro. The in vivo data demonstrates that the bioactive porous scaffolds enhance in situ cartilage regeneration. The neo-tissues show close structures and components to the healthy cartilages. Thus, the in situ cartilage tissue engineering porous scaffolds with enzyme-responsive KGN release can recruit ESPCs to defects and promote the chondrogenesis effectively, which is a potential treatment for in situ cartilage regeneration.

Temporomandibular joint (TMJ) supports chewing, talking or other daily oral activities. So far, it still remains a great challenge to treat the defected TMJ condyle cartilage through tissue engineering technology. Herein, a bilayered scaffold is designed to fully reconstruct the different cartilage matrices of TMJ condyle under same induction condition. The bilayered scaffold with segregated hydrophobicity-hydrophilicity in top and bottom layer is prepared from a low and high content of polyethylene glycol (PEG) crosslinked poly (L-glutamic acid)-g-polycaprolactone (PLGA-g-PCL). The hydrophobic aggregates in top layer support the adhesion and spread of bone mesenchymal stem cells (BMSCs), thus inducing the differentation towards fibrocartilage; while aggregates (spheroids) are formed on the hydrophlic bottom layer, showing a preferable hyaline differentiation pathway under same chondrogenic induction in vitro. After 14 d in vitro induction, the scaffold/BMSCs construct is implanted in goat TMJ condyle defects. The post-operative outcome after 2 months demonstrates that the defects are fully covered by neo-cartilage. And the regenerated hierarchical TMJ condyle cartilage perfectly consist of ordered fibrocartilage and hyaline cartilage, which is same as natural condyle cartilage. These results corroborate that this bilayered scaffold with segregated hydrophilicity-hydrophobicity carrying induced BMSCs is a promising for treatment of TMJ condyle cartilage defects.

Guided bone regeneration film plays an important role in bone defect reconstruction. In this paper, poly (gamma-benzyl-L-glutamate) (PBLG) was used as raw materials to construct dense films and porous films by solvent casting and particle leaching. And the bilayers guided bone regeneration membrane was constructed by ethanolamine amine membrane modification on the surface. The effect of different modification time on the hydrophilicity and mechanical properties of the films was investigated. The results show that with the increase of the molecular weight of PBLG, the mechanical strength of the film increases and the degradation rate is getting slower. Prolonging the time of amine modification can improve the hydrophilicity of the film and the degradation rate both in vivo and in vitro. Through cell experiments, it was found that the dense layer could effectively block the invasion of fibroblasts, and the porous layer can support adherence and spread of cells. Surface-modified PBLG-based materials were demonstrated to be useful for repair of bone defects in vivo by in vitro bioactivity evaluation. The guided bone regeneration membrane constructed has good mechanical properties, degradation performance, and a certain degree of fit with the tissue. And it could effectively inhibit the infiltration of fibroblasts. The membrane has potential application value.

以聚L-谷氨酸苄酯(PBLG)为原料,通过溶剂浇铸与粒子沥滤法分别构建PBLG单层致密和PBLG单层多孔膜,利用乙醇胺对薄膜表面改性,构筑双层引导骨再生膜.研究了不同胺解改性时间对PBLG-s-PHEG双层膜亲水性和力学性能的影响,结果表明,随着PBLG分子量的增大,薄膜的力学性能增强而降解速率减缓.延长胺解改性时间可提高薄膜亲水性和体内外降解速率.细胞实验结果表明,双层薄膜的致密结构能够有效阻隔成纤维细胞的侵入,多孔结构能够支持细胞贴壁黏附和铺展.体外生物活性评价结果表明,表面改性的PBLG基材料可用于体内骨缺损修复.本文所构建的双层引导骨再生膜在体外具有良好的力学性能和降解性能,与组织具有一定的贴合性,同时可有效阻碍成纤维细胞侵入,具有潜在应用价值.

ABSTRACTSoft tissues, such as fat and skin, present high flexibility and are capable of withstanding large deformation in various functions. Hydrogels that can resemble the mechanical performance of soft tissue are unique and widely demanded. In this study, micellar hydrogels based on biocompatible poly(l‐glutamic acid) (PLGA) were designed with the enhanced capacity to bear large deformation. Amphipathic triblock copolymer poly(ethylene glycol) acrylate‐co‐poly(ε‐caprolactone)‐co‐poly (ethylene glycol) acrylate (APEG‐PCL‐APEG) with two terminal double bonds was synthesized and self‐assembled into micelles. At the same time, graft copolymers, poly(l‐glutamic acid)‐g‐hydroxyethyl methacrylate (PLGA‐g‐HEMA) with double bonds were synthesized. APEG‐PCL‐APEG micelles and PLGA‐g‐HEMA were mixed to construct micellar hydrogel via radical polymerization. The crystalline structure and hydrophobic aggregation of copolymers (APEG‐PCL‐APEG) were found to associate with PCL molecular weight. Due to the hydrophobic stress dissipation and crystalline structure of the micelles, the softness and toughness of hydrogels were promoted, exhibiting a 25% increase in ultimate strain. Moreover, the micellar hydrogels were able to load proteins with long‐term retention. In addition, under dynamic mechanical stimulation, the release of proteins could be accelerated. Besides, the micellar hydrogels also supported rabbit adipose‐derived stem cells (rASCs) growth, thus exhibiting the potential toward soft tissue engineering. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1115–1125

The key barrier to the clinical application of tissue engineering scaffolds is the limitation of rapid and sufficient vascularization. Adipose-derived stem cells (ASCs), especially multicellular aggregates, exhibited a promising angiogenic activity. Herein, we designed a series of poly(l-glutamic acid) (PLGA)-based hydrogels with tunable hydration to control the in situ formation of multicellular spheroids. Oligo(ethylene glycol)s (OEGs) were employed to regulate the hydration of hydrogels. The hydrogel cross-linked with ethylene glycol (OEG1) supported the most excellent adhesion and proliferation of human ASCs in vitro. However, as the hydration of hydrogels strengthened, the adherent ASCs were gradually replaced with multicellular spheroids. Moreover, the in situ formation of spheroids was more effective in upregulating hypoxia-adaptive signals (e.g., hypoxia-inducible factor-1α, HIF-1α) and enhancing the secretion of angiogenic factors (e.g., vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF-2)) compared to adherent cells in OEG1 hydrogels. The hydrogel cross-linked with oligo(ethylene glycol)400 (OEG9) carrying spheroids induced a high angiogenic response of host tissue in vivo, resulting in an improved system vascularization, compared to adherent cells in the OEG1 hydrogel. These features indicated that the PLGA-based hydrogels were expected to be applied toward bone and fat tissue regeneration.

Using structural materials with high damping property is known as one of the most effective method to solve vibration and noise problem at present, and polyacrylate is one of the most widely polymer damping materials. Polyacrylate was often used as a resin matrix in waterborne damping coating for its excellent weather resistance and oil resistance properties. However, conventional polyacrylate was narrow damping temperature range, which could not meet the requirements to apply practically. In the paper, Methyl methacrylate (MMA) and butyl acrylate (BA), ethyleneglycol dimethacrylate (EGDMA) and phosphate esters of peg monomethacrylate (PAM-100) were used to prepare three layers core-shell acrylate latex interpenetrating polymer networks (LIPN) via surface cross-linking emulsion polymerization. The structure and properties of the latex were characterized by DMA, DLS and AFM. Three layers core-shell acrylate LIPN with 1wt% EGDMA in both layer 1 and layer 2, 4wt% in outmost layer, could be achieved excellent damping property, which the damping peak was high up to 1.12 and the damping temperature range (tan sigma(>)0.3) was 90 oC, and had excellent adhesion to metal substrate and good film-forming property.