Li Yiran, Qin Meng, Li Ying, Cao Yi, Wang Wei
National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University , 22 Hankou Road, Nanjing, Jiangsu, China 210093.
Langmuir. 2014 Apr 22;30(15):4358-66. doi: 10.1021/la501189n. Epub 2014 Apr 9.
3,4-Dihydroxyphenylalanine (DOPA) is the noncanonical amino acid widely found in mussel holdfast proteins, which is proposed to be responsible for their strong wet adhesion. This feature has also inspired the successful development of a range of DOPA-containing synthetic polymers for wet adhesions and surface coating. Despite the increasing applications of DOPA in material science, the underlying mechanism of DOPA-wet surface interactions remains unclear. In this work, we studied DOPA-surface interactions one bond at a time using atomic force microscope (AFM) based single molecule force spectroscopy. With our recently developed "multiple fishhook" protocol, we were able to perform high-throughput quantification of the binding strength of DOPA to various types of surfaces for the first time. We found that the dissociation forces between DOPA and nine different types of organic and inorganic surfaces are all in the range of 60-90 pN at a pulling speed of 1000 nm s(-1), suggesting the strong and versatile binding capability of DOPA to different types of surfaces. Moreover, by constructing the free energy landscape for the rupture events, we revealed several distinct binding modes between DOPA and different surfaces, which are directly related to the chemistry nature of the surfaces. These results explain the molecular origin of the versatile binding ability of DOPA. Moreover, we could quantitatively predict the relationship between DOPA contents and the binding strength based on the measured rupture kinetics. These serve as the bases for the quantitative prediction of the relationship between DOPA contents and adhesion strength to different wet surfaces, which is important for the design of novel DOPA based materials.
3,4-二羟基苯丙氨酸（DOPA）是一种广泛存在于贻贝固着蛋白中的非标准氨基酸，据推测它是贻贝具有强湿附着力的原因。这一特性也激发了一系列含DOPA的合成聚合物在湿附着力和表面涂层方面的成功开发。尽管DOPA在材料科学中的应用日益广泛，但其与湿表面相互作用的潜在机制仍不清楚。在这项工作中，我们使用基于原子力显微镜（AFM）的单分子力谱技术，一次研究一个键的DOPA与表面的相互作用。通过我们最近开发的“多鱼钩”方案，我们首次能够对DOPA与各种类型表面的结合强度进行高通量定量。我们发现，在1000 nm s⁻¹的拉伸速度下，DOPA与九种不同类型的有机和无机表面之间的解离力都在60 - 90 pN范围内，这表明DOPA对不同类型表面具有强大且通用的结合能力。此外，通过构建破裂事件的自由能景观，我们揭示了DOPA与不同表面之间几种不同的结合模式，这些模式与表面的化学性质直接相关。这些结果解释了DOPA通用结合能力的分子起源。此外，基于测量的破裂动力学，我们可以定量预测DOPA含量与结合强度之间的关系。这些为定量预测DOPA含量与对不同湿表面的粘附强度之间的关系奠定了基础，这对于新型基于DOPA的材料设计很重要。
