Adsorption of binding peptides on ZnO - towards a quantitative understanding of organic-inorganic interactions

ZnO/肽生物杂化材料具有独特的光化学和光电性能。它们的制造依赖于肽的“材料识别”能力，肽选择性地结合到特定的ZnO晶体面，从而决定材料的微观结构和性质。最终的目标是开发一个合理的协议，工程肽序列，以引导制造ZnO/肽杂交所需的性能，在这个项目中，我们的目标是在一个基本的了解肽的材料识别能力和起源的材料选择性结合强度。为了实现这一目标，我们将在结合亲和力（自由能）和分子结构方面对非极性ZnO晶面和肽之间的相互作用进行精确定量。为了这个目标，我们将采用大量的各种实验技术和联合收割机，它们与定量精确的分子建模。非极性（10-10）ZnO结合序列将通过噬菌体展示来选择，并且它们与ZnO晶体表面的相互作用将通过它们的氨基酸序列的点突变来表征。结合位点将通过NMR表征。将通过石英晶体微天平、等温滴定量热法、AFM力谱和表面等离子体共振方法评价结合亲和力。模拟将采用先进的采样分子动力学（MD）方法的基础上元吸附，复制交换与溶质回火和转向MD。模拟将提供结合自由能的理论估计，可以直接与实验确定的自由能进行比较。这些方法还将预测与ZnO表面上的肽吸附过程相关的结构变化，可以与NMR，圆二色性和红外光谱的实验结果进行比较。互补和相互支持的模拟和实验方法将有助于阐明肽的识别能力，我们希望能够转移到其他材料/肽系统，最终实现基于知识的设计与定制的结合强度的无机结合肽。

Bio-hybrid ZnO/peptide materials present peculiar photochemical and optoelectronic properties. Their fabrication relies on the "materials recognition" capability of the peptides, which bind selectively to specific ZnO crystal facets and thus dictate the materials microstructure and properties. With the ultimate goal to develop a rational protocol for engineering the peptide sequences in order to steer the fabrication of ZnO/peptide hybrids with desired properties, in this project we aim at a fundamental understanding of the peptides' materials recognition capability and the origin of a materials-selective binding strength. To reach this goal we will perform precise quantification of the interactions between non-polar ZnO crystal facets and peptides in terms of binding affinity (free energy) and molecular structure. To this aim we will employ a large variety of experimental techniques and combine them with quantitatively accurate molecular modelling. Non-polar (10-10) ZnO binding sequences will be selected via phage-display and their interactions to ZnO crystal surfaces will be characterized amongst other techniques by point mutations of their amino acid sequences. Binding sites will be characterized via NMR. The binding affinity will be evaluated via Quartz-Crystal-Microbalance, Isothermal Titration Calorimetry, AFM force spectroscopy and Surface Plasmon Resonance methods. Simulations will employ state-of-the art advanced sampling molecular dynamics (MD) methods based on metadynamics, replica-exchange with solute tempering and steered MD. The simulations will deliver theoretical estimates of the free energy of binding that can be directly compared to the experimentally determined ones. These methods will also predict structural changes associated with the process of peptide adsorption on ZnO surfaces, that can be compared with experimental results of NMR, Circular Dichroism and Infrared spectroscopy. The complementary and mutually supportive simulation and experimental approaches will help shed light on the peptides' recognition capability in a way that we expect to be transferable to other material/peptide systems, eventually enabling a knowledge-based design of inorganic-binding peptides with tailored binding strengths.