In drug discovery, vaccine development, cellular therapeutics development, basic biology research, and combinatorial biochemistry, there is a need to controllably and reliably inject reagents into a sufficiently large number of cells to assue statistically significant data about cellular responses. Although micropipettes enable cell injection with a high level of control, their current use requires skillful operators and slow, tedious, manual operation. Batch processes involving transfection, electroporation, photoporation or viral infection, cannot guarantee that all the cells in the ensemble are injected and that the compound that enters the cells retains its intended composition. The lack of a high throughput, reliable, injection methodology remains the bottleneck in many significant projects. To address this need, an interdisciplinary team with expertise in nanotechnology, biochemistry, and medicine proposes to develop components for an automated cell injection system. The system will utilize mass-producible, carbon-based nanopipettes (CNPs) invented by the Bau research group. The CNP consists of a nanoscopic carbon pipe of a diameter ranging from tens to hundreds of nanometers connected seamlessly to a macroscopic glass capillary handle that is compatible with standard cell electrophysiology equipment. The entire inner surface of the glass pipette is lined with a carbon film. Thus, the CNP provides a path for reagent injection through the hollow of the tube and an independent path for electrical measurements through the conductive carbon lining. The CNPs have many advantages over conventional, pulled glass micropipettes. They have good mechanical properties, are biocompatible, do not break or clog easily, are stiff enough to penetrate cell membranes, and, due to their small size, are minimally invasive. The CNPs will be used to inject reagents into cells positioned in a regular array at predetermined locations on a surface patterned with electrodes. The cell positioning will be accomplished with the use of electrical polarization forces (dielectrophoresis). The CNP will sense cell penetration via an AC impedance measurement through its carbon lining to provide a signal to an injector. The system's performance will be tested by automatically injecting donor and acceptor fluorescent tRNAs into cells and then measuring the localized rates of both overall and specific protein synthesis in real time by the intensity of a FRET signal. The proposed automated cell injection system has broad utility and will facilitate advances in many areas of medicine and biology.
The proposed automated, high throughput system for controlled cell injection will assist and accelerate drug discovery, vaccine development, cellular therapeutics development, and combinatorial biochemical studies and thus will facilitate the development of treatments for both acute and chronic illnesses.
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