Analysis of Intracellular State Based on Controlled 3D Nanostructures Mediated Surface Enhanced Raman Scattering

Near-infrared surface-enhanced Raman spectroscopy (SERS) is a powerful technique for analyzing the chemical composition within a single living cell at unprecedented resolution. However, current SERS methods employing uncontrollable colloidal metal particles or non-uniformly distributed metal particles on a substrate as SERS-active sites show relatively low reliability and reproducibility. Here, we report a highly-ordered SERS-active surface that is provided by a gold nano-dots array based on thermal evaporation of gold onto an ITO surface through a nanoporous alumina mask. This new combined technique showed a broader distribution of hot spots and a higher signal-to-noise ratio than current SERS techniques due to the highly reproducible and uniform geometrical structures over a large area. This SERS-active surface was applied as cell culture system to study living cells in situ within their culture environment without any external preparation processes. We applied this newly developed method to cell-based research to differentiate cell lines, cells at different cell cycle stages, and live/dead cells. The enhanced Raman signals achieved from each cell, which represent the changes in biochemical compositions, enabled differentiation of each state and the conditions of the cells. This SERS technique employing a tightly controlled nanostructure array can potentially be applied to single cell analysis, early cancer diagnosis and cell physiology research

The effect of cryopreservation on the current response of CaV 3.1 transfected HEK293 cells

The main disadvantage of long-term storage of living cells in liquid nitrogen is its relatively fast evaporation. For this reason, it is necessary to refill Dewar flask quite often. In our experiments, we used low temperature freezer (-80 °C) as more economical option to liquid nitrogen and we would like to show that there is no significant influence of long-term storage of mammalian cell-sat a low temperature. The effect of temperature was studied as the electrophysiological characteristic of the whole-cell Ca2+ current in HEK293 cells. The current responses were measured from cells stored for eight months at -80 °C and compared with previously published papers. The current traces and I-V curves showed that there are no changes in current response between cells frozen at a low temperature and previously published results. From our results can be concluded that the low temperature freezer is an adequate option for storage of mammalian cells for a couple of months