Speaker
Description
Purpose
To develop a high-resolution Raman spectroscopy (RS) technique that can detect biochemical changes induced in MC38 murine colon carcinoma cells exposed to a range of doses of ionizing radiation.
Methods
MC38 cells were cultured on quartz substrates and irradiated using 6 MV X-rays from a medical linear accelerator to doses of 0, 0.25, 0.5, 1, 2, 5 and 10 Gy. The cells were fixed at 24 and 48 hours post irradiation, with two independent sample sets prepared for each timepoint. Confocal Raman measurements were performed using a custom-built microscope with a 785 nm excitation source and a spatial resolution of 1 µm. Raman spectra from individual cells were collected over a 3 x 3 grid with a 3 µm step size over a 7 x 7 µm2 intracellular region of interest. For each dose and timepoint, a total of 25 or 100 cells were sampled from. All data was subjected to standard spectroscopic preprocessing including vector normalization. Partial Least Squares Discriminant analysis was utilized to perform binary classifications between doses, and the subsequent loadings vectors were used to identify specific Raman bands associated with exposure to radiation.
Results
Several features of the MC38 Raman spectrum demonstrated dose-dependent changes in response to radiation. At higher doses (5, 10 Gy) significant decreases of up to 30% compared to controls (0 Gy) were observed for Raman bands corresponding to DNA/RNA (782, 813, 1089, 1336, 1575 cm-1), suggesting a decrease in concentration of DNA/RNA due to exposure to ionizing radiation. Conversely, the relative intensity of some peaks associated with proteins (1001, 1448, 1665 cm-1) increased by up to 20%. Comparing the 24 and 48 hr timepoints shows that some features associated with DNA/RNA (782, 1089, 1575 cm-1) increased by up to 11% for the 48 hr timepoint compared to the 24 hr timepoint.
Conclusions
Our work demonstrates the ability of RS to delineate the biochemical response of MC38 cells to ionizing radiation and has potential applicability to the low-dose exposure range (<0.1 Gy) encountered in environmental, occupational and clinical settings.
| Keyword-1 | Raman Spectroscopy |
|---|---|
| Keyword-2 | Ionizing Radiation |
| Keyword-3 | Radiation Response |