Cell Control via Spatiotemporal Microenvironmental pH Modulation

Microenvironmental pH is a key factor in cell functioning and pathogenesis. To control the function and behavior of cells by modulating pH microenvironments is critical to advancing the development of cell biology and tissue engineering and enabling applications in drug delivery and regenerative medicine. However, pH-based cell control remains a challenge due to the lack of means to real-time, spatioselective modulation of microenvironmental pH. While pH microenvironments in cell systems are highly heterogeneous in time and space, known pH-modulation methods are through CO2/HCO3− buffering and H+ diffusion, which are slow, isotropic, and nonspecific. An urgent need, therefore, is to modulate pH microenvironments in a spatiotemporally specific manner. Failure to do so means that pH, an essential factor that determines cell fate and function, is not in good control. The PI’s long-term goal is microenvironmental pH–based closed-loop regulation of cell function, metabolism, and morphogenesis. The overall goal of this project, a critical step towards the long-term goal, is to control cells by real-time, spatioselective modulation of pH microenvironments. The hypothesis is that cell function and behavior can be regulated with ultra-high spatiotemporal resolutions (10–100 µm, <50 s), compared to conventional, diffusion-based methods (>103 µm, >103 s), in pH microenvironments that are modulated nanoelectrochemically by microelectrodes based on graphene, a two-dimensional nanomaterial with unique outstanding bio-transduction properties that address the primary challenge of on-chip pH modulation of living cell systems for typical microelectrode materials. The approach to test this hypothesis is to quantify real-time responses of model cell systems to arrayed pH microenvironment generated by an array of bidirectional graphene-microelectrode transducers that are optically transparent to allow microscopic characterization and communicate with cellular systems through electrical signal interrogation and rapid nanoelectrochemical microenvironmental-pH modulation. The following milestone goals will be reached in this project: (1) to create densely arrayed pH microenvironment by developing an array of bidirectional graphene-microelectrode transducers and (2) to control the function and behavior of model cell systems (cardiomyocytes and tumor cells) via spatiotemporal microenvironmental pH modulation using the graphene transducer array. The PI is uniquely positioned to conduct the project due to the ability of the PI’s lab to create graphene microelectrodes integrable in a fluidic device for interfacing cellular systems, interrogating electrical/chemical cell signals, and controlling cell behavior by generating microscale pH gradients. To harness and combine these techniques allows the development of arrays of bidirectional graphene transducers for selective, real-time pH-microenvironment modulation and cell control. The expected outcome of the project is pH-based cell-control tools with over two- orders-of-magnitude enhanced spatiotemporal resolutions compared to conventional methods. This outcome is to generate positive impact on bioengineering development, regenerative medicine, and synthetic morphology.