Bio-Raman Spectroscopy for Real Time,
in vitro Analysis of Cellular Response

 Kathryn Finton¹, Kevin Powers¹, Larry Hench²
Particle Engineering Research Center, Gainesville¹
Imperial College of Science and Technology, London²

Many cellular processes, such as cell division, differentiation, apoptosis, and oncosis involve spatial reorganization and/or degradation of cellular constituents. The chemical composition of the cell can also change over time. Micro Raman spectroscopic measurements are based on vibrational modes specific to a molecule and its environment. In this respect, the spectrum of a cell is a representation of its chemical composition. Raman spectroscopy is unique in that it is noninvasive and does not require labels. Furthermore, virtually any substance can be analyzed in its natural state. The laser excitation wavelength (785 nm) and power at the sample (115 mW) used by our Renishaw InVia spectrometer are not harmful to cells; therefore, time dependent and in vitro or in vivo analysis is possible.

According to recent literature, cell death is said to occur by three alternative modes: apoptotic, or type I programmed cell death, autophagic, or type II programmed cell death, and oncotic cell death. The goal of this study will be to assess whether or not the biological events specific to apoptosis, oncosis, and autophagic cell death can be measured and differentiated by Raman spectroscopy using the Nova Test^{® 2} system. Peak fitting will be used to monitor the spectral changes within the cell during the death process; correlations will be made between spectral and bio-molecular changes. Finally, discriminate analysis will be used to group together different death processes at specified time points; this will allow subsequent Raman measurements of unknown cell death to be classified. This knowledge will then be used for toxicity screening of various pharmaceuticals and nano/biomaterials.