蛋白质纳米孔内电渗现象的数值模拟

Numerical calculation study of electroosmotic flow in protein nanopores

电渗现象是在外加电场下,电解质溶液通过带电多孔介质或毛细管时的液体运动。电渗现象提供了一种高效、可控的液体输运方式,广泛应用于微流控、生物医学检测、化学分析、土壤修复和水处理领域,尤其是高通量基因测序。电渗现象受电场强度、液体黏度、电导率和介质孔隙结构影响,系统研究纳米限域内电渗流的物理性质对优化其应用非常重要。由于纳米级研究的挑战,实验上测量电渗流性质较为困难,理论和数值模拟成为研究电渗现象的有效方法。该研究通过数值模拟探究了蛋白质纳米孔内电渗流(EOF)的物理性质,尤其是在不同电场强度和溶液盐浓度条件下的行为。采用Poisson-Nernst-Planck和Navier-Stokes方程组耦合模型,结合有限元方法,详细分析了电解质溶液中离子的分布和流体流动。研究发现,电渗流速度和电场强度的分布在纳米孔中极不均匀,且受到外加电势和溶液盐浓度的显著影响。在高盐浓度环境下,电渗流速度显著增加,尤其是在孔的中心区域。此外,电场强度的梯度显著影响了电渗流速度的分布,揭示了通过调控电场控制电渗流的可能性。该研究为深入理解纳米孔内的电动特性提供了视角,并指出了其在分子分离和生物医学检测中的应用潜力。

[Objective]This study aims to investigate the physical properties of electroosmotic flow in protein nanopores using numerical simulations,particularly under varying electric field strengths and solution salt concentrations.This research is remarkable because electroosmosis is an efficient and controllable method for liquid transport,which is widely utilized in microfluidics,biomedical detection,chemical analysis,soil remediation,and water treatment,especially in high-throughput gene sequencing.By systematically examining the physical properties of nanoconfined electroosmotic flow,these applications can be optimized to enhance their performance and efficiency.However,owing to the challenges associated with nanoscale research,it is extremely difficult to directly measure the properties of electroosmotic flow in experiments.Therefore,employing theoretical and numerical simulation methods has emerged as an effective approach to address this issue.This study aims to gain a deeper understanding of the dynamic characteristics of electroosmotic flow in protein nanopores through numerical simulations,offering theoretical support and technical guidance for molecular separation and biomedical detection.[Methods]This study employed a coupled model of the Poisson-Nernst-Planck and Navier-Stokes equations to numerically simulate the electroosmotic flow in protein nanopores using the finite element method.This research focused on charged protein nanopores,considering the effects of varying electric field strengths and solution salt concentrations.The model was established by coupling the Poisson-Nernst-Planck and Navier-Stokes equations to obtain a mathematical representation of the nanopore system.The proposed model includes charged nanopores,electrolyte solutions containing free ions and water molecules,and external electric fields applied to both sides of the nanopore.[Results]The distribution of electroosmotic velocity and electric field strength within protein nanopores is highly uneven and substantially influenced by external potential and solution salt concentration.The specific findings are as follows:1)Electroosmotic flow velocity distribution:in environments with high salt concentrations,the electroosmotic flow velocity considerably increases,particularly in the central region of the nanopores.The velocity profile of the electroosmotic flow along the z-axis exhibits nonlinear characteristics,with the velocity varying from the center to both ends of the nanopore.2)Electric field intensity distribution:The electric field intensity is highest in the central region of the nanopore and shows notable nonuniformity in the surrounding areas.The electric field strength gradient greatly influences the distribution of electroosmotic flow velocity,with an increase in electric field strength leading to a substantial increase in the electroosmotic flow velocity in the central nanopore.3)Salt concentration effect:As the salt concentration in the solution increases,the electroosmotic flow rate rises remarkably,and the velocity curve becomes steeper,particularly in the central nanopores,indicating that the electroosmotic flow rate is directly related to the ionic strength of the solution,with high salt concentrations promoting the passage of more ions through the nanopores under the influence of an electric field and enhancing electroosmotic flow.These findings deepen our understanding of the dynamics of electroosmotic flow at the nanoscale and provide a theoretical foundation for optimizing the performance of nanopore-based sensing and separation devices.[Conclusions]This study systematically investigated the electroosmotic characteristics of protein nanopores under varying potentials and salt concentrations using numerical simulations.Results indicate that the nonuniformity of electroosmotic flow velocity and electric field distribution is a key factor in determining electroosmotic flow characteristics.The electric field strength and solution salt concentration considerably affect the electroosmotic flow rate,with high salt concentration and electric field strength leading to a substantial increase in the flow rate within nanopores.By precisely controlling the electric field strength and distribution,the behavior of the electroosmotic flow can be effectively manipulated,which is crucial for optimizing the performance of nanopores in molecular separation and biomedical detection.These research findings offer deeper insights into the electrical properties within nanopores and underscore their potential applications in molecular separation and biomedical detection.In summary,this study offers theoretical support and methodological guidance for optimizing nanopore-based technologies,demonstrating notable application value.Future research can further explore the relationship between the structural characteristics and electroosmotic behavior of different protein nanopores,expanding their applications across various fields.