Microfluidic elastomeric platforms for probing single cells

Study of biological processes at the single-cell level is important because cells are inherently variable biochemical reactors. New micro- and nanotechnological tools have now opened opportunities for realizing single-cell measurements (biochemical, electrical, mechanical and/or optical). This dissertation is focused on the development of microfluidic devices that can be used for single cell studies, in particular, for probing ion channels on the cell membrane. Ion channels play important roles in cell physiology and underlie a broad spectrum of disorders. However, ion channels remain a largely unexplored class of drug targets due to the low-throughput bottleneck posed by patch clamp technique, the gold standard for studying ion channels. Patch clamping involves careful positioning of a fine-tipped glass micropipette onto the surface of the cell to form a high-resistance seal, a process that is laborious and not scalable to parallel operation in large numbers. We have developed an alternative microfluidic patch clamp chip that is based on elastomer micromolding. A cell is hydrodynamically driven to a microfluidic channel junction to form a high-resistance seal, thus eliminating pipette micropositioning and its vibration sensitivity. High resistance seals (> 1 GO) between the microchannel and the cell membrane of rat basophilic leukemia (RBL) cells were obtained at a rate of 58%. Whole cell recordings from RBL cells expressing endogenous inward-rectifier potassium channels were performed using this device. Whole-cell recordings under extracellular or intracellular solution modulation with reagent dead volume of 0 fL and ∼ 30 fL respectively were demonstrated. The device presented here is simple enough that it could be easily disseminated to the research community and inexpensive enough that it could become an affordable commercial product.