DNA类软物质材料力学性能的跨尺度表征、识别及其应用

Mechanical properties of DNA-like soft matter are closely relevant to the signals of biochip detection, mechanism of virus replication and treatment, and functions of DNA origami nanostructures. The plan is devoted to capturing the statistical rules of DNA conformations on gold substrates, and to developing mesoscopic free energy models for DNA liquid crystals, of which empirical parameters are obtained by microcantilever bending experiments. Thereby, the continuum mechanics method is combined to study the temperature effect and negative modulus effect on mechanical properties of DNA films, and to develop a curvature-relevant surface energy theory to study the clamping end effect and negative modulus effect on nonlinear dynamic signals of microcantilever-based identification. Next, the Lagrangian multiplier method and AFM nano-indentation experiment are used to study the effect of temperature fluctuation on DNA packing pattern and virus stiffness; based on a new theory of bending persistence length for single DNA chain, the effect of environment changes on the mechanical properties of DNA nanotube and its origami nanostructures. The main innovation lies in characterizing the relation between the varieties in macro/meso-scopic mechanical properties and the self-adaptability of microstructure by the nanoscale-related modification of mesoscopic free energy models. The self-consistent trans-scale characterization system will be established for description of mechanical properties of DNA-like soft matter, and the results related to temperature effect and nonlinear effect will give new insights and guidances for biochip design, virus replication and treatment, and function regulation of DNA origami nanostructure.

DNA类软物质力学性能与生物芯片检测信号、病毒传染与防治和DNA折叠结构功能密切相关。采用MD方法捕捉基底上DNA链构象统计规律，为DNA材料发展温度依赖的介观自由能模型，并采用微梁弯曲实验确定经验参数；联合采用连续介质力学方法，研究DNA膜弹性性能的温度效应和负模量效应，发展曲率相关表界面能理论，研究负模量效应和夹支端效应对微梁非线性动态识别信号的影响。其次，采用拉格朗日乘子法和AFM压痕实验，研究温变对DNA封装模式和病毒刚度的影响；基于弯曲持续长度的Manning新理论，研究环境变化对DNA纳米管及其折叠结构力学性能的影响。主要创新点是通过纳尺度关联的介观自由能改造去表征微观结构的自适应与宏介观力学性能多样性之间关系。期待为DNA类材料力学性能描述建立自洽的跨尺度表征体系，有关温度效应和非线性效应的研究成果可为生物芯片设计、病毒传染与防治、DNA折叠结构功能调控提供新的认识和准则。

DNA类软物质力学性能与生物芯片检测信号、病毒传染与防治和DNA折叠结构功能密切相关。本项目通过MD模拟、理论模型和实验测量，跨尺度表征了不同状态下DNA类软物质微观结构、介观液晶自由能、宏观力学性能、DNA-微梁静动态检测信号之间的复杂关系。(1)以基底上短链DNA系统为研究对象，采用MD模拟获得DNA链纳观结构特征，建立或发展介观粗粒化DNA液晶自由能模型，并通过实验测量不同环境条件下DNA膜-微梁挠度，为介观粗粒化模型提供经验参数；(2)以DNA膜-微梁系统为研究对象，基于上述介观粗粒化DNA液晶自由能模型，结合连续介质力学观点，跨尺度建立了DNA膜介观粗粒化自由能、宏观力学性能与微梁静动态检测信号的联系，揭示了尺寸效应、环境条件、边界约束等检测条件对微梁信号的影响；(3)以封装于蛋白衣壳中病毒DNA为研究对象，基于上述介观粗粒化DNA液晶自由能模型，结合反映病毒内部DNA无序和有序区实验新发现，建立了刻画病毒内部DNA微观结构分区模型和尺寸依赖的表观刚度模型，揭示了环境条件对病毒封装/喷出力学性能和表观刚度影响，并开展AFM纳米压痕实验研究；(4)以DNA折纸技术中DNA纳米管为研究对象，基于上述介观粗粒化DNA液晶自由能模型，利用或发展单分子理论中DNA链的WLC模型，建立了单个DNA链不同特征长度之间的关系，揭示了链间微观作用、结点效应和封装模式对DNA纳米管力学性能的影响，并针对典型DNA机械结构研究了设计参数和环境因素等对其执行功能的影响。有关研究结果可为生物芯片设计、病毒传染防治和DNA纳米机械结构的设计等提供深刻的认识与创新的准则。