The Department of Engineering Science and Mechanics, The Pennsylvania State University, 212 Earth and Engineering Sciences Building, University Park, PA 16802, USA.
Biosens Bioelectron. 2010 Apr 15;25(8):1963-9. doi: 10.1016/j.bios.2010.01.023. Epub 2010 Jan 25.
The underlying sensing mechanism of single-cell-based integrated microelectrode array (IMA) biosensors was investigated via experimental and modeling studies. IMA chips were microfabricated and single-cell-level manipulation was achieved through surface chemistry modification of IMA chips. Individual fibroblast cells (NIH3T3) were immobilized on either lysine-arginine-glycine-aspartic acid (KRGD) short peptide-modified or fibronectin extracellular-cell-adhesion-molecule-modified microelectrodes to record the impedance variations of cell-electrode heterostructure over a frequency range of 1-10 kHz. By fitting experimental data to an application-specific single-cell-level equivalent circuit model, important sensing parameters, including specific cell membrane capacity, cell membrane resistivity, and averaged cell-to-substrate separation, were determined. It was demonstrated that biofunctionalization of planar microelectrode surface by covalently linking short peptides or fibronectin molecules could achieve strong or tight cell adhesion (with an estimated averaged cell-to-substrate separation distance of 11-16 nm), which, in turn, improves the transduced electrical signal from IMA chips. Analyses on frequency-dependent characteristics of single-cell-covered microelectrode impedance and of IMA sensor circuitry response have revealed an addressable frequency band wherein electrical properties of single cells can be distinctively determined and monitored for cellular biosensing applications. The presented work addresses some major limitations in single-cell-based biosensing schemes, i.e., the manipulation of a single cell, the transduction of weak biological signals, and the implementation of a proper model for data analysis, and demonstrates the potential of IMA devices as single-cell biosensors.
通过实验和建模研究，研究了基于单细胞的集成微电极阵列（IMA）生物传感器的基本传感机制。通过 IMA 芯片的表面化学修饰，实现了 IMA 芯片的单细胞级操作。将单个成纤维细胞（NIH3T3）固定在赖氨酸-精氨酸-甘氨酸-天冬氨酸（KRGD）短肽修饰或纤连蛋白细胞外细胞黏附分子修饰的微电极上，以在 1-10 kHz 的频率范围内记录细胞-电极异质结构的阻抗变化。通过将实验数据拟合到特定于应用的单细胞级等效电路模型，确定了重要的传感参数，包括特定细胞膜电容、细胞膜电阻率和平均细胞-基底分离距离。结果表明，通过共价连接短肽或纤连蛋白分子对平面微电极表面进行生物功能化可以实现强或紧密的细胞黏附（估计平均细胞-基底分离距离为 11-16nm），从而提高 IMA 芯片的转导电信号。对单细胞覆盖微电极阻抗的频率相关特性和 IMA 传感器电路响应的分析表明，存在一个可寻址的频率带，其中可以明显确定和监测单个细胞的电特性，用于细胞生物传感应用。这项工作解决了基于单细胞的生物传感方案中的一些主要限制，即单个细胞的操作、弱生物信号的转导以及适当模型的实现用于数据分析，并展示了 IMA 器件作为单细胞生物传感器的潜力。
