ISSN   1004-0595

CN  62-1224/O4

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高强度、低摩擦脂质润滑水凝胶材料的构建及其摩擦行为研究

Construction and Friction Behavior of High Strength and Low Friction Lipid Lubricated Hydrogel Materials

  • 摘要: 关节软骨是人体关节部位承担支撑、缓冲以及润滑的重要组织. 随着年龄的增长、先天性疾病和创伤等因素,关节软骨会发生损伤及退化,最终会导致骨关节炎的发生,目前骨关节炎是世界上头号致残性疾病之一. 然而,关节软骨周围几乎没有血管与神经组织,损伤后难以自愈. 临床上,人工关节置换是治疗关节损伤最有效的方法之一,传统的人工关节材料主要为金属材料、陶瓷材料和高分子材料,接触方式主要为硬-硬接触和硬-软接触,植入人体后容易产生磨损,会产生异物反应最终导致松动失效. 受到天然关节表面软骨有效减缓冲击和降低磨损的启发,解决人工关节材料磨损和松动等问题的首要任务是构建高性能的软骨替代材料. 水凝胶类似于生物软组织兼具固液两相特性,具有天然软骨微观结构相似性、高含水率、优异的生物相容性和稳定的理化性能等特性,已发展成为关节软骨最佳的替代材料. 然而传统水凝胶的润滑性能和机械性能较差,限制了其在人工关节软骨替代材料领域的应用. 本文中基于关节软骨非流体以及脂质润滑的特性,以二肉豆蔻酰磷脂酰胆碱(DMPC)脂质体为润滑相,将其引入PVA/PAA(聚乙烯醇/聚丙烯酸)水凝胶中,通过冷冻解冻和退火技术构建了具有优异机械强度和润滑性能的脂质体复合水凝胶. 研究结果表明:脂质体复合水凝胶具有优异的机械强度(拉伸强度为10.4±1.2 MPa、拉伸模量为4.1±0.8 MPa、压缩强度9.5±1.0 MPa、压缩模量为8.2±0.9 MPa)和良好的抗疲劳性能(100循环压缩下其最大应力也能保留首次循环应力的93%). 此外,脂质体复合水凝胶表面存在脂质囊泡小球,显著降低了水凝胶的摩擦系数(0.049),并且在很宽滑动速度和法向载荷下具有良好的润滑性能. 润滑性能的增强主要是由于水凝胶中的脂质在载荷的作用下暴露在凝胶表面,随着时间的延长润滑脂就会扩散到整个水凝胶接触区域,形成脂质边界层通过水合润滑机制降低了摩擦. 因此,本研究中为构建高强度以及低摩擦仿软骨材料开辟了1条新途径,为软骨置换和人工关节提供潜在的应用.

     

    Abstract: Articular cartilage is an important tissue for the support, cushioning, and lubrication of human joints. Articular cartilage will be damaged and degenerated with age, congenital diseases, trauma, and other factors, and eventually lead to the occurrence of osteoarthritis, which is currently one of the world's leading disabling diseases. However, there are almost no blood vessels and nerve tissue around the articular cartilage, which is difficult to heal after injury. Clinically, artificial joint replacement is one of the most effective methods to treat joint injury. Traditional artificial joint materials are mainly metal, ceramic, and polymer materials, and the contact modes are mainly hard-hard contact and hard-soft contact, which are easy to wear and cause foreign body reactions and eventually lead to loose failure after implantation. Inspired by the effective mitigation of impact and wear of natural joint surface cartilage, the primary way to solve the problems of wear and loosening of artificial joint materials is to construct high-performance cartilage replacement materials. Hydrogels are similar to biological soft tissues with both solid-liquid phase properties, and have the characteristics of natural cartilage microstructure similarity, high water content, excellent biocompatibility, stable physical and chemical properties, etc., and have been developed as the best alternative materials for articular cartilage. However, the lubrication and mechanical properties of traditional hydrogels are poor, which limits their application in the field of artificial cartilage replacement materials. In this paper, based on the non-fluid and lipid lubrication characteristics of articular cartilage, 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) liposomes were introduced into PVA/PAA hydrogels, and liposome composite hydrogels with excellent mechanical strength and lubrication properties were constructed by freezing-thawing and annealing methods. The findings suggested that liposome composite hydrogel had excellent mechanical strength (tensile strength was 10.4±1.2 MPa, tensile modulus was 4.1±0.8 MPa, compressive strength was 9.5±1 MPa, compressive modulus was 8.2±0.9 MPa), good fatigue resistance (the maximum stress could retain 93% of the first cyclic stress under 100 cycles of compression). In addition, the presence of lipid vesicles on the surface of the liposome composite hydrogel significantly reduced the friction coefficient of the hydrogel (0.049), and the friction reduction was observed under a wide range of sliding velocities and normal loads. The improvement of lubrication performance was mainly because the lipids in the hydrogel were exposed to the gel surface under the action of load. With the extension of time, the grease would spread to the entire hydrogel contact area, forming a lipid boundary layer and reducing the friction through the hydration lubrication mechanism. Therefore, this study opened up a new way to construct high-strength and low-friction cartilage imitation materials, providing potential applications for cartilage replacement and artificial joints.

     

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