Marine mussel plaques are an exceptional model for wet adhesives. Despite advances in understanding their protein composition and strategies for molecular bonding, the process by which these soluble proteins are rapidly processed into load-bearing structures remains poorly understood. Here, we examine the effects of seawater pH on the time evolution of the internal microstructures in plaques harvested from Mytilus californianus. Experimentally, plaques deposited by mussels on glass and acrylic surfaces were collected immediately after foot retraction without plaque separation from the surface, placed into pH-adjusted artificial seawater for varying times, and characterized using scanning electron microscopy and tensile testing. We found a pH dependent transition from a liquid-like state to a porous solid within 30 min for pH ≥ 6.7; these plaques are load-bearing. By contrast, samples maintained at pH 3.0 showed no porosity and no measurable strength. Interestingly, we found cuticle development within 15 min regardless of pH, suggesting that cuticle formation occurs prior to pore assembly. Our results suggest that sea water infusion after deposition by and disengagement of the foot is critical to the rapid formation of internal structures, which in turn plays an important role in the plaques’ mechanical performance.

中文翻译：

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海水pH值对海洋贻贝斑成熟的影响。

海洋贻贝斑是湿粘合剂的特殊模型。尽管在了解它们的蛋白质组成和分子结合策略方面取得了进步，但对这些可溶性蛋白质迅速加工成承载结构的过程仍知之甚少。在这里，我们检查了海水pH值对取自Mytilus californianus菌斑的内部微结构时间演变的影响。。在实验中，脚缩回后立即收集贻贝在玻璃和丙烯酸表面上沉积的斑块，而不会从表面分离出斑块，将其放置在经过pH值调整的人造海水中变化时间，并使用扫描电子显微镜和拉伸测试进行表征。我们发现在pH≥6.7的情况下，在30分钟内从液态到多孔固体的pH依赖性转变；这些斑块是承重的。相比之下，保持在pH 3.0的样品没有孔隙率，也没有可测量的强度。有趣的是，我们发现在15分钟内无论pH值如何，角质层都会发育，这表明角质层的形成要先于孔组装。我们的研究结果表明，足部沉积和脱离后海水注入对内部结构的快速形成至关重要，