用于细胞水平药物筛选的微流控芯片对流传质机理研究

Drug screening in the cellular level is the key to the successful clinical research in the process of antitumor drugs discovery. Recently, more and more researchers pay attention to the microfluidic chip based on detecting techniques of SERS because of great advantages of label-free, high-throughput and low cost of drug screening. However, suspended SERS substrates are inapplicable to the adhesion cells in drug screening, while conventional fixed substrate is unable to capture and locate cells. To solve these problems, a novel design of microfluidic chips has been proposed, where the in-situ fabrication of SERS substrates in the microchannels, cellular localization, cell culture and pharmacodynamics Ramman detection will be integrated.By virtue of the theory, simulation and experimental means, basic scientific problems of convective mass transfer in microfluidic chips and relevant control methods will be investigated based on the multiphysics coupling of electrical-thermal-fluidic fields. Specially, controllable fabrication methods of SERS substrates in the microchannel will be established based on the research of mass transport theory of electrochemical reactions under the effect of convective mass transfer. The dielectrophoresis method for cell positioning will be investigated based on the dynamics analysis of the cell assembly influenced by the process of convective mass transport. Finally, prototypes of microfluidic chips used for cellular level drug screening will be developed based on the micro nano integrated manufacturing method, tested and characterized for evaluating its overall performance.

细胞水平药物筛选是抗肿瘤新药研发过程中解决临床研究失败的关键。基于表面增强拉曼散射（SERS）检测技术的微流控芯片因无标识、高通量、大幅降低药物筛选成本等优点而越来越受到重视。然而，悬浮式SERS基底不能适用于粘附性细胞的药物筛选，传统固定式SERS基底又不具备细胞捕获与定位的能力。针对上述问题，本项目提出了一种新型微流控芯片设计方案，实现SERS基底的微流道内原位制备、细胞定位与培养、药效拉曼检测等功能集成。借助理论、仿真与实验手段，项目从电-热-液多场耦合角度研究微流控芯片研制中的对流传质及其控制方法的基础科学问题。具体的，本项目研究对流传质作用下的电化学反应物质输运理论，建立微流道内SERS基底的可控制备方法；研究对流传质作用下的细胞介电泳组装动力学分析模型，建立细胞介电泳可控定位方法；最后，基于微纳集成制造方法，完成用于细胞水平药物筛选的微流控芯片实验样机研制，综合评价器件性能。

项目针对细胞水平药物筛选微流控芯片研制中的对流传质及其控制方法的基础科学问题开展研究。交流电沉积传质机理研究方面，构建了自由基阳离子、中性单体/寡聚物的输运模型，阐释了基于电泳与介电泳的传质调控机理，实现了有机电化学晶体管（OECT）在微流控芯片内的原位制备，通过电压、频率实现了有机半导体层的结构与形貌调控。然后项目引入双极电化学电极制备了阵列化OECT。建立等效电路模型并拟合电化学阻抗谱，明确了OECT的器件性能调控规律。实现了5行1列OECT微流控芯片制备，其最大跨导0.8 mS，开关比182，提出了基于OECT的药物筛选微流控芯片设计与制造方法。细胞介电泳组装机制研究方面，项目组在0.001-1 S/m电导率范围内研究了Hela细胞在二维空间内的负介电泳耦合动力学过程，发现实验中交流电频率与幅值的选择需要综合考虑其引起的跨膜电位及温升对于细胞活性的影响，并且梳齿电极间距需要根据定位细胞的直径进行优化。项目组进一步使用三维耦合动力学模型研究了100 Hz-25 MHz频率范围以及1-20 Vp-p幅值范围内Hela细胞在四电极微流控芯片内的输运规律，表明拖曳力通过交流电渗与电热所产生的涡流影响细胞的运动轨迹，而负介电泳力依然主导着细胞在基底平面上的运动。通过比较“势阱”模型、有限元模型及实验结果，项目组阐明了基于相位调控的细胞负介电泳操控原理。