Hughes Matt D G, West Daniel, Wurr Rebecca, Cussons Sophie, Cook Kalila R, Mahmoudi Najet, Head David, Brockwell David J, Dougan Lorna
School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Leeds, UK.
School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Leeds, UK; Department of Physics, King's College London, London, WC2R 2LS, UK.
J Colloid Interface Sci. 2025 Jan 15;678(Pt C):1259-1269. doi: 10.1016/j.jcis.2024.09.183. Epub 2024 Sep 22.
Folded protein hydrogels are emerging as promising new materials for medicine and healthcare applications. Folded globular proteins can be modelled as colloids which exhibit site specific cross-linking for controlled network formation. However, folded proteins have inherent mechanical stability and unfolded in response to an applied force. It is not yet understood how colloidal network theory maps onto folded protein hydrogels and whether it models the impact of protein unfolding on network properties. To address this, we study a hybrid system which contains folded proteins (patchy colloids) and unfolded proteins (biopolymers). We use a model protein, bovine serum albumin (BSA), to explore network architecture and mechanics in folded protein hydrogels. We alter both the photo-chemical cross-linking reaction rate and the mechanical properties of the protein building block, via illumination intensity and redox removal of robust intra-protein covalent bonds, respectively. This dual approach, in conjunction with rheological and structural techniques, allows us to show that while reaction rate can 'fine-tune' the mechanical and structural properties of protein hydrogels, it is the force-lability of the protein which has the greatest impact on network architecture and rigidity. To understand these results, we consider a colloidal model which successfully describes the behaviour of the folded protein hydrogels but cannot account for the behaviour observed in force-labile hydrogels containing unfolded protein. Alternative models are needed which combine the properties of colloids (folded proteins) and biopolymers (unfolded proteins) in cross-linked networks. This work provides important insights into the accessible design space of folded protein hydrogels without the need for complex and costly protein engineering, aiding the development of protein-based biomaterials.
折叠蛋白水凝胶正成为医学和医疗保健应用中颇具前景的新型材料。折叠的球状蛋白可被模拟为胶体，其表现出位点特异性交联以形成可控网络。然而，折叠蛋白具有固有的机械稳定性，会在施加外力时展开。目前尚不清楚胶体网络理论如何应用于折叠蛋白水凝胶，以及它是否能模拟蛋白质展开对网络性质的影响。为了解决这个问题，我们研究了一个包含折叠蛋白（补丁胶体）和未折叠蛋白（生物聚合物）的混合系统。我们使用一种模型蛋白，牛血清白蛋白（BSA），来探索折叠蛋白水凝胶中的网络结构和力学性能。我们分别通过光照强度和去除蛋白质内强大共价键的氧化还原反应，改变光化学交联反应速率和蛋白质构建块的力学性能。这种双重方法，结合流变学和结构技术，使我们能够表明，虽然反应速率可以“微调”蛋白质水凝胶的力学和结构性能，但对网络结构和刚性影响最大的是蛋白质的力敏感性。为了理解这些结果，我们考虑了一个胶体模型，该模型成功地描述了折叠蛋白水凝胶的行为，但无法解释在含有未折叠蛋白的力敏感水凝胶中观察到的行为。需要替代模型来结合交联网络中胶体（折叠蛋白）和生物聚合物（未折叠蛋白）的特性。这项工作为折叠蛋白水凝胶的可及设计空间提供了重要见解，无需复杂且昂贵的蛋白质工程，有助于基于蛋白质的生物材料的开发。
