Graphene-coated soft elastic substrates for cell adhesion studies: Local nanomechanics and label-free electronic biosensing

长期以来，细胞培养一直在平板中进行，其中刚性的底层基质仅用作支持物。最近的观察表明，细胞与它们的微环境相互作用，底层表面的刚度在细胞生长和增殖中起着积极的作用。改变用于细胞生长的基底的刚度提供了一个通用的手柄来调节局部细胞微环境的机械特性并研究对细胞-细胞和细胞-表面相互作用的影响。大多数研究软弹性基底上的细胞粘附的调查利用光学检测方法，其中标记通常是必要的，并且在界面水平获得实时信息的可能性是有限的。通过放置在细胞和生长基质之间的合适电极的细胞-基质相互作用的电子读出将允许以无标记的方式实时研究细胞粘附的可能性。在这里，我们提出了一种生物材料平台的实现，其中软弹性基板上涂覆有单层石墨烯作为电极材料，用于研究细胞粘附。本提案将利用这一平台调查三个具体方面。首先，该项目旨在通过使用动态纳米机械扫描探针显微镜来更好地理解单个石墨烯片对弹性基底刚度的影响。第二个主要目标是实现基于软衬底上的石墨烯片的传感装置，并利用阻抗检测来真实的实时研究细胞过程。最后，我们将利用石墨烯的化学功能化在界面上提供合适的受体，并研究对细胞行为的影响。虽然拟议的活动将主要集中在乳腺癌细胞上，但这种独特的传感平台可以扩展到其他细胞类型和细胞过程。

Cell culture has long been performed in plates where the stiff underlying substrate has only served as a support. Recent observations have shown that cells interact with their microenvironment and the stiffness of the underlying surface plays an active role in cell growth and proliferation. Varying the stiffness of substrates for cell growth provides a versatile handle to modulate the mechanical properties of the local cellular microenvironment and study the effect on cell-cell and cell-surface interactions. Most of the investigations on studying cell adhesion on soft elastic substrates utilize optical detection methods where labeling is often necessary and the possibility to obtain real-time information at the interfacial level is limited. Electronic readout of cell-substrate interactions by suitable electrodes placed between the cells and the growth substrate will allow the possibility to study cell adhesion in real-time in a label-free manner. Here we propose the realization of a biomaterial platform wherein soft elastic substrates are coated with a single sheet of graphene as electrode material for studying cell adhesion. Three specific aspects will be investigated in this proposal using this platform. First, the project aims at obtaining an improved understanding of the effect of single graphene sheets on the stiffness of elastic substrates by using dynamic nanomechanical scanning probe microscopy. A second principal goal is the realization of sensing devices based on the graphene sheet on soft substrates and utilize impedance detection to study cellular processes in real time. Finally, we will exploit chemical functionalization of graphene to provide suitable receptors at the interface and study the ensuing effect on cell behavior. Although the proposed activities will focus mainly on breast cancer cells, this unique sensing platform can be extended to other cell types and cellular processes.