Yu Tong Han,Da Gang Li,Kang Jie Shi,Dan Ma,Yu Tang,Chao Qun Ma
In the context of carbon neutrality, it is of good economic and ecological value to replace synthetic fibres with natural fibres as reinforcing materials in the preparation of composites. The effect of the hot pressing process parameters on the physical and mechanical properties of the LBF/PP composites was further investigated. The distribution of LBF in the composites was observed by CT. The experimental results show that the hemicellulose content of the BF decreases and the lignin content decreases after the alkali treatment. The mechanical properties of the LBF/PP composites were better at a hot pressing temperature of 180°C, a hot pressing pressure of 8 MPa, a hot pressing time of 15 min and a mass fraction of 70% LBF, with bending strength and bending modulus reaching 226.1 MPa and 15.1 GPa respectively. CT results show that the fibres are evenly distributed in the composites and that the hot pressing process allows the molten PP to penetrate the pores of the LBF surface, forming a good physical and mechanical bond. These composites can be used in various applications such as construction, automotive, consumer goods etc. They are considered to be a suitable alternative to solid plastic products and materials.
Maohua Chen,Yan Hu,Yanhua Hou,Yuting Sun,Maowen Chen,Menghuan Li,Lu Tan,Zhong Luo,Kaiyong Cai
By exploiting the high reactive-oxygen-species(ROS) level in osteoporosis fractured sites, a ROS responsive biomimetic multilayer onto titanium(Ti) implant composed of gelatin(Gel)/dextran amine (DA) and α-melanocyte-stimulating hormone (α-MSH) has been constructed using layer-by-layer spin self-assembled technique, which was further cross-linked with 4-nitrophenyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2) benzyl carbonate (NBC)-grafted-polyethylene glycol (PEG-NBC) for in situ delivery of α-MSH. The PEG-NBC cross-linked Gel/DA multilayer onto Ti substrate (Ti/LBL NBC -MSH) could be broken down when exposed to ROS-rich pathological environment, thus leading to a sustained release of α-MSH from multilayer in a controlled manner. It could maintain the α-MSH concentration at a constant level to promote in situ MSCs differentiation and inhibit osteoclast activity through regulating GSK-3β/β-catenin signal pathways with Runx2 positive feedback regulation loop. Micro-CT analysis, hematoxylin/eosin (HE) staining and Masson's trichrome (MT) staining further confirmed that new bone has fused into mature lamellar bone and trabecularism along the interface of Ti/LBL NBC -MSH in osteoporotic rats. Therefore, this study offers a new perspective on the development of biofunctional Ti implants as supplementary treatment for osteoporotic fracture repair in a clinical context.
Steroid-induced osteonecrosis of the femoral head (SIONFH) is a frequent orthopedic disease caused by long-term or high-dose administration of corticosteroids. Tanshinone I (TsI), a flavonoid compound isolated from Salvia miltiorrhiza Bunge, has been reported to inhibit osteoclastic differentiation in vitro. This study aimed to investigate whether TsI can ameliorate SIONFH. Herein, SIONFH was induced by intraperitoneal injection of 20 μg/kg lipopolysaccharide every 24 h for 2 days, followed by an intramuscular injection of 40 mg/kg methylprednisolone every 24 h for 3 days. Four weeks after the final injection of methylprednisolone, the rats were intraperitoneally administrated with low-dose (5 mg/kg) and high-dose (10 mg/kg) TsI once daily for 4 weeks. Results showed that TsI significantly alleviated osteonecrotic lesions of the femoral heads as determined by micro-CT analysis. Furthermore, TsI increased alkaline phosphatase activity and expressions of osteoblastic markers including osteocalcin, type I collagen, osteopontin, and Runt-related transcription factor 2 and decreased tartrate-resistant acid phosphatase activity and expressions of osteoclastic markers including cathepsin K and acid phosphatase 5. TsI also reduced inflammatory response and oxidative stress and activated the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway in the femoral heads. Taken together, our findings show that TsI can relieve SIONFH, indicating that it may be a candidate for preventing SIONFH.
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