微梁上DNA生物膜的界面效应研究

The mechanism of microcantilever deformation induced by DNA adsorption or hybridization remains an open question, which hinders the marketization of DNA-microcantilever biosensor technology. Considering thermal, eletrical, chemical and mechainical factors in the process of DNA adsorption or hybridization, the plan is devoted to carpturing nanoscopic inhomogeneous property of DNA biofilm at solid-solution interface by nolocal DFT, nonlinear Poisson-Boltzmann equation and Langmuir adsorption isotherms,and providing reasonable inhomogenous assuptions of ion concentrations; to developing mesoscopic liquid crystal models for free energy of DNA biofilm by using Yukawa attractive potential,and two-variable method for laminated beams; to establishing multiscale relations among nanoscopic geometrical propety of DNA chain, microscopic interactions such as hydration force,mesoscopic free energy, macroscopic elastic modulus, thermal expansion coefficient of bioflim, and static deflection, surface stress, dynamic frequency of microcantilevers. The innovative point is that we consider the influence of matter inhomogeneity on local defomation of DNA chain, thermo-chemo-electro-mechanical property of biofilm and global deformatiom of microcantilever. The multiscale models containing special properties of solid-solution bio-interface will be provided to reveal the origin of nanomechanical motions of DNA-microcantilevers, and to give some guidances for surface preparations of self assembly, double-beam technology, and integration manufactures of DNA chips.

DNA吸附或杂交引起的微梁变形机理是开放性难题，也是制约无标记DNA-微梁传感器技术市场化重要因素。本项目考虑DNA吸附和杂交过程中热、电、化、力学因素，利用非局部密度泛函理论、非线性Poisson-Bolzmann方程和Langmuir吸附定律，捕捉固-液界面处DNA生物膜非均布纳观特征，形成合理离子浓度非均布假设；采用Yukawa吸引势和课题组提出的层合梁两变量方法，发展DNA生物膜自由能中观液晶模型，进而跨尺度建立DNA分子纳观几何特征、水合力等微观作用和生物膜中观自由能、宏观弹性模量、热膨胀系数以及微梁静态挠度、表面应力、动态频率之间的关系。主要创新点是考虑界面效应引起的物质分布非均匀性对于DNA链局部变形、生物膜热-电-化-力学性能、微梁整体变形的影响。期待给出反映固-液生物界面特性并揭示DNA-微梁纳米运动机理的多尺度模型，为芯片自组装表面处理、双梁技术、集成化制造等提供参考。

DNA 吸附引起的微梁变形机理是开放性难题，也是制约微梁生物传感器技术市场化重要因素。本项目跨尺度表征了基底上粒子的微观分布、DNA吸附膜的电荷状态和电势分布、介观液晶自由能、宏观弹性模量、热膨胀系数和压电系数与微梁表面应力、静态挠度和动态频率之间的复杂关系。(1)对于对粒子的纳观分布，研究了基底曲率、溶液条件和电荷状态等因素对吸附膜内粒子分布和电势分布的影响，获得了不同封装条件下膜电势的分布规律；(2)对于DNA吸附膜的力/热/电学性能，结合高价盐下链间微观吸引作用的实验新发现，发展了反映上述电势非均布特征的DNA介观自由能的新模型，并突破连续介质力学的束缚，跨尺度研究了溶液条件、电荷状态和封装模式等因素对DNA膜弹性模量、压电系数和热膨胀系数的多样性和尺寸效应的影响；(3)对于微梁表面应力和静动态检测信号，构建了吸附膜−微梁层合结构的跨尺度能量模型，给出了检测条件与微梁静态挠度、动态频率之间的解析关系；(4)研究了温变引起的检测信号失效问题和耦合双梁新技术中的非线性效应，揭示了基底种类、碱基对数、温度变化和溶液离子等检测条件对微梁检测失效的影响，给出了避免检测失效的优化条件；(5)实测了不同溶液条件下DNA−微梁的静态挠度，为上述介观自由能新模型提供了拟合数据，并验证了上述部分预测。有关研究结果可为DNA芯片的自组装表面处理、双梁耦合新技术、集成化制造等提供了设计参考。