Verma Nitu, Sharma Paramveer, Jayabal Hemalatha, Dingari Naga Neehar, Gupta Rakesh, Rai Beena
Physical Sciences Research Area, TCS Research, Pune 411013, India.
Physical Sciences Research Area, TCS Research, Pune 411013, India.
J Biomech. 2022 Dec;145:111361. doi: 10.1016/j.jbiomech.2022.111361. Epub 2022 Nov 1.
The dermis, second layer of human skin, is mainly responsible for mechanical response of the skin. The unique viscoelastic nature of this layer arises from the characteristic hierarchical structure of collagen at various length scales. The effect of topical formulation on skin's mechanical properties of great importance for several personal-care applications. Understanding the transport of an active ingredient across skin layer and its effects on the structure of collagen assembly is crucial for successful design of these applications. In this study, we report a multiscale modelling framework mimicking the skin's mechanical behavior. The framework captures the details from the nanoscale (tropocollagen) to microscale (fibers). At first, atomistic molecular dynamics simulations (MDS) of tropocollagen (TC) molecules of various lengths (∼100 nm) were performed to obtain the molecular modulus of TC. The stress-strain response data obtained from these simulations, were utilized in macroscopic models of fibrils and fibers. The modulus obtained from the mentioned framework was in good agreement with earlier reported experimental data. Further, we have utilized this framework to show the effect of dehydrating agent on skin's mechanical response. The hydration effect is utilized in many anti-ageing strategies to improve the overall mechanical property of skin. We showed that on incorporation of hydrating agent, the collagen structure changes significantly at molecular scale which effects the overall response of the skin at macroscopic scale. The reported multiscale framework can further be explored to gain insights into interlinked properties of collagen at much larger scales without extensive molecular simulations and detailed experiments.
真皮是人体皮肤的第二层，主要负责皮肤的机械响应。这一层独特的粘弹性源于不同长度尺度下胶原蛋白的特征层次结构。局部配方对皮肤机械性能的影响在多种个人护理应用中非常重要。了解活性成分在皮肤层中的传输及其对胶原蛋白组装结构的影响对于这些应用的成功设计至关重要。在本研究中，我们报告了一个模拟皮肤机械行为的多尺度建模框架。该框架捕捉了从纳米尺度（原胶原蛋白）到微观尺度（纤维）的细节。首先，对不同长度（约100纳米）的原胶原蛋白（TC）分子进行了原子分子动力学模拟（MDS），以获得TC的分子模量。从这些模拟中获得的应力-应变响应数据被用于原纤维和纤维的宏观模型。从上述框架获得的模量与早期报道的实验数据吻合良好。此外，我们利用这个框架展示了脱水剂对皮肤机械响应的影响。水合作用在许多抗老化策略中被用于改善皮肤的整体机械性能。我们表明，加入水合试剂后，胶原蛋白结构在分子尺度上发生了显著变化，这影响了皮肤在宏观尺度上的整体响应。所报道的多尺度框架可以进一步探索，以在无需广泛分子模拟和详细实验的情况下，深入了解更大尺度下胶原蛋白的相互关联特性。
