de Gennes’s mesh size in cartilage-inspired self-repairing alginate LipoGels

Inspired by the exceptional lubricity in living systems (e.g. knee joints and eye blinking), a physically cross-linked hydrogel film has been prepared from sodium alginate, an abundant green biopolymer derived from brown algae. Alginate hydrogels were cross-linked by divalent cations, Ca2+, and liposomes (or lipid vesicles) were embedded into the gel, aiming to generate a lubricious and self-repairing material, also with the potential for therapeutic encapsulation. The lubrication performance of the alginate hydrogels was evaluated with a tribometer (UMT Tribolab), and the results showed that the 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) embedded alginate hydrogel exhibited excellent lubrication with a coefficient of friction (CoF) of 0.058 under water. However, to our best knowledge, no structural characterisation has been reported on such novel lubricious liposome-embedded hydrogels. Here, we propose a small angle neutron scattering (SANS) study of the hydrogel nanostructure, varying the alginate concentration, cross-linking conditions, type of lipids, and temperature. The unprecedented results offer structural insights into alginate hydrogels, enabling a correlation with the mechanical characterisation of the gel using nanoindenter and rheometer. Ultimately, this will underpin the rational design of robust hydrogels with tailored nanostructures for biomimetic lubrication.

受生物系统（如膝关节和眨眼动作）中卓越润滑性的启发，研究人员以海藻酸钠——一种源自褐藻的丰富绿色生物聚合物——为原料制备了物理交联水凝胶膜。海藻酸盐水凝胶通过二价阳离子Ca²+交联，并将脂质体（或脂质囊泡）嵌入凝胶中，旨在制备具有润滑性和自修复性能的材料，同时具备治疗性包封的潜力。利用摩擦磨损试验机（UMT Tribolab）评估了海藻酸盐水凝胶的润滑性能，结果显示，嵌入1,2-二棕榈酰-sn-甘油-3-磷酸胆碱（DPPC）的海藻酸盐水凝胶在水下表现出优异的润滑性，摩擦系数（CoF）为0.058。然而，据我们所知，目前尚无关于此类新型润滑性脂质体嵌入水凝胶的结构表征报道。在此，我们提出通过小角中子散射（SANS）研究该水凝胶的纳米结构，并改变海藻酸钠浓度、交联条件、脂质类型及温度等变量。这些前所未有的结果为海藻酸盐水凝胶提供了结构层面的深入理解，使其能够与利用纳米压痕仪和流变仪获得的凝胶力学表征结果相关联。最终，这将为具有定制化纳米结构的稳定水凝胶的理性设计奠定基础，以实现仿生润滑应用。