惠斯通桥型微流控抗原检测芯片的构建及其微流体流动特性研究

Inspired by the Wheatstone bridge circuit, here we report on a novel type of microfluidic chip, which allows highly-sensitive, quantitative, and visualized detection of specific antigen based on the microfluidic flow characteristics in the Wheatstone-bridge-like microchannel network. The microfluidic chip consists of Wheatstone-bridge-like microchannels incorporated with a hydrogel microvalve that enables volume swelling in response to trace amounts of specific antigen. The antigen-concentration-dependent volume swelling changes the cross-sectional flow area as well as the flow resistance of the microvalve-incorporated microchannel. Based on the Wheatstone-bridge-like microchannel network, this change can be converted and amplified into changes of flow direction and flow rate of the indicating flow that can be easily observed and detected. Thus, based on magnifier-assisted observation of the location of indicating flow interface on the scales of the microchannel for concentration quantification, highly-sensitive, quantitative, and visualized detection of specific antigen can be achieved. This work focuses on the rational design and fabrication of the microfluidic chip, the study of the synergetic and quantitative relationship between the microfluidic flow characteristics, the structure and dimension of microchannels, the volume transition of microvalve, and the concentration of antigen, and the establishment of methodology with mathematic models for highly-sensitive, quantitative, and visualized detection of specific antigen. This work will provide new models for design and fabrication of novel chips for analysis and detection.

受“惠斯通桥”电路结构和原理启发，本课题提出一种新型的微流控检测芯片，基于其“惠斯通桥”型微通道内的微流体流动特性，实现微量抗原的高灵敏度、简便可视化的特异性定量检测。利用芯片微通道中结合的抗原响应性凝胶微阀在特异性响应微量浓度抗原时发生的相应体积溶胀，改变该微通道的流通横截面和流动阻力；该流动阻力的变化信号由“惠斯通桥”转变并放大为微通道中易观察测量的指示液流向和流速变化，再通过放大镜观察与流速相关的指示液界面在微通道壁面的刻度上的读数，实现对微量抗原的高灵敏度、简便可视化的特异性定量检测。拟重点研究该芯片的设计与可控构建，研究其微流体流动特性与微通道结构尺寸、凝胶微阀体积溶胀及抗原浓度之间的协同机制和定量关系，确立其高灵敏、简便可视化地定量检测抗原的方法，并建立相关数学模型。研究结果将为新型分析检测芯片的设计与构建提供一种全新模式。

受电学中“惠斯通桥”电路结构和检测原理的启发，本课题通过构建具有惠斯通桥型微通道结构的微流控芯片，再将智能微凝胶结合到该芯片微通道中作为微阀以调控流阻，成功构建了具有超灵敏、高选择性和便捷可视化检测性能的惠斯通桥型微流控检测芯片。该微流控检测芯片中的微流体流动行为可以通过智能凝胶微阀响应分析物浓度变化后的体积相变来进行动态调控；通过设置微柱阵列定量观察指示液流形变化或定量检测指示液液流宽度变化，可以实现对痕量分析物的超灵敏、高选择性和便捷可视化检测。确立了凝胶微阀的体积相变行为与分析物浓度之间的关系，探明了凝胶微结构和分析物浓度对凝胶微阀体积相变速率的影响规律；确定了微流控芯片中的微流体流动特性与微通道结构尺寸、凝胶微阀体积溶胀行为及分析物浓度之间的定量关系，探明了检测过程中的信号转换和放大机理，建立了超灵敏、高选择性和便捷可视化的定量检测方法。项目研究过程中，基于独特的高分子结构设计，分别先后构建得到了具有Pb2+响应性和H-IgG抗原响应性的智能凝胶材料，以探明该惠斯通桥型微流控检测芯片系统的检测性能。首先，通过将惠斯通桥型微流控检测芯片与Pb2+响应性智能凝胶微阀相结合，实现了对于Pb2+的超灵敏、高选择性和便捷可视化检测，其检测限低至10-14 M，低于迄今为止文献中报道的最低检测限；而其Pb2+浓度检测范围为10-7~10-14 M，是目前所报道的微流控检测系统中最宽的Pb2+浓度检测范围。同时，关于结合该抗原响应性智能凝胶微阀的惠斯通桥型微流控检测芯片的研究正在继续开展中，而基于该抗原响应性智能凝胶材料对H-IgG的特异响应性体积相变以及惠斯通桥型微流控检测芯片的检测原理，相关研究亦有望在后期取得重要的实验结果。因此，通过对惠斯通桥型微流控检测芯片系统及其智能凝胶材料的设计构建和检测原理及检测性能的研究，相关研究结果将为新一代超灵敏、高选择性、简便可视化定量分析检测芯片的设计与研制提供重要的科学基础和技术支撑。