Intra- and Extracellular chips for cell mechanics

Abstract

The Micro- and NanoTooLs group, as a worldwide pioneer in the development of silicon-based suspended chips, has previously enabled the development of micro- and nanodevices small enough to be internalized by living cells. Passive devices, as barcodes, or active devices as biochemical sensors, electrical stimulators or nanomechanical sensors have been developed for chip-in-a-cell and chip-on-a-cell applications. From the previous achievement of developing and testing an intracellular pressure sensor, motivated by the mechanical analysis of cells, a new line was opened within the group covering one of the most promising current research hot-topic in cell biology: Cell Mechanics. This thesis has been focused on the development of innovative tools to explore cellular mechanical properties from inside and outside the cell. This development consisted in the design, fabrication, characterization, mechanical simulation and biological validation of micro- and nanodevices. Chips were fabricated with the required design using micro and nanofabrication processes based on silicon technologies. Hence, these technologies allow the development of tools with functional parts at the micro- and nanometer scale. The mechanical behaviour of these devices was analysed by finite element method simulations, and was compared with an experimental mechanical characterization of fabricated samples. The biological application of the devices is presented as a final step in most of the tools developed on this thesis, with the analysis of their biocompatibility as a mandatory study. Here, we have demonstrated the integration of multiple functionalities within a single chip. To accomplish this, intracellular magnetic biocompatible barcodes were developed enabling both, the labelling, and the magnetic mechanical-manipulation of living cells. Moreover, the second generation of an intracellular pressure sensor has been designed and fabricated through the advances of the technological development of the sealing of a cavity at room temperature and atmospheric pressure to reach millibar sensitivities. Furthermore, the mechanical characterization of the cytoplasm in mouse one-cell embryo development has been accomplished through the use of an intracellular nanodevice, being the basis for the development of new intracellular tools for mechanical sensing within eukaryotic cells. Finally, an extracellular system based on the mechanical failure of silicon chips anchored to the substrate has been designed, fabricated, characterized and validated as a tool for the sensing of cell ultimate traction forces. Overall, the obtained results highlight the reliability of the silicon micro- and nanotechnologies for the fabrication of mechanical chips for and at the scale of living cells.