基于原子力显微镜的水凝胶表面的纳米力学性能的研究

Studying on the effects of mechanical properties of the surface of base materials on cell behavior can help us more in-depth understanding of the mechanism of interaction of materials and cells, designing more correctly and reasonably surfaces and the surface with a special function of biological material. However, the characterization of mechanical properties (modulus and viscoelastic) of the surface of base materials is not easy, especially for the hydrogel material, the detection of mechanical properties is more difficult. PeakForce Quantitative Nano-Mechanics (PeakForce QNM) of Atomic force microscope (AFM) based on the force measurement model emerged as the times require. The project selected PEG hydrogel with different stiffness and different pattern as the research objects. The surface morphology and quantitative nano mechanics of the above materials will be characterized using the PeakForce QNM function. The relationship between the measurement parameters, the testing conditions and measured modulus will be intensively studied, the relationship between the molar ratio of the hydrogel monomer and cross linker, molecular weight, pattern type and measured modulus, and the influence of different nano mechanics of the hydrogel on cell biological properties will be also researched. The theoretical basis for the development and application of various biological materials will be further provided.

研究基底材料的表面力学性能对细胞行为的影响，有助于了解材料与细胞之间相互作用规律，设计出更合理和具有特殊功能的材料表面。但是，目前对于材料表面力学（模量、黏弹性等）性能的表征却不理想。尤其是水凝胶材料，它的力学性能检测难度更大。原子力显微镜（AFM）新功能峰值力定量纳米力学模式[PeakForce Quantitative Nano-Mechanics(PeakForce QNM)]应时而生。本项目拟通过制备不同硬度、不同微米图案的聚乙二醇（PEG）水凝胶材料，利用AFM对不同结构的PEG水凝胶材料进行表面形貌和定量纳米力学性能的研究，优化出不同结构的水凝胶的测试条件和力学参数间的关系规律；进而研究不同软硬度、不同金图案修饰的PEG水凝胶的单体与交联剂摩尔比、分子量、图案类型和表面力学性能的关系，以及不同表面力学性能的水凝胶对细胞生物学性能的影响，为生物材料的开发与应用奠定理论基础。

水凝胶材料的表面纳米力学性能一直是近年来研究水凝胶材料课题组渴望探究的问题。本课题在利用AFM研究水凝胶材料的表面纳米力学性能的过程中，得到了很多珍贵的实验结论与规律。具体如下：.1）对原子力的纳米力学性能测试中相对方法与绝对方法做了对不同材料的检测验证，发现AFM的PeakForce QNM模式测定的纳米力学性能结果与宏观力学结果基本一致，该方法的准确度很高，可靠性很好。.2）针对原子力显微镜测试水凝胶中样品固定上的难题做了深入的研究，发明了相应的固定样品台。针对制备的不同软硬度的水凝胶材料，采用AFM探测表面纳米力学性能需要采用不同的探针与仪器参数。.3）AFM探测得到的力学性能结果与纳米压痕仪测定的结果基本一致。材料表面的模量与黏附力影响细胞行为的发生，细胞更喜欢在模量高、黏附力大的材料表面生长，并根据图案形状发生“接触引导”行为。