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Analysis of intracellular state based on controlled 3D nanostructures mediated surface enhanced Raman scattering.

El-Said WA, Kim TH, Kim H, Choi JW - PLoS ONE (2011)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul, Republic of Korea.

ABSTRACT
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.

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SERS spectra of different cell lines.(A) SERS spectra of (1) HeLa, (2) HepG2, and (3) MCF-7 cells. (B) SERS spectra of (blue) MCF-7 and (black) HMEC cells. (C) SERS spectra of living HeLa cells (black curve) and dead HeLa cells (blue curve). Inset contains the confocal microscopic images of living and dead HeLa cells. (D) SERS spectra of living HepG2 cells (black curve) and dead HepG2 cells (blue curve). Inset contains the confocal microscopic images of living and dead HepG2 cells. (E) SERS spectra of living HMEC cells (black curve) and dead HMEC cells (blue curve). Inset contains the confocal microscopic images of living and dead HMEC cells. Circles in Figs. C, D, and E indicate the primary differences between the SERS spectra of living and dead cells.
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pone-0015836-g004: SERS spectra of different cell lines.(A) SERS spectra of (1) HeLa, (2) HepG2, and (3) MCF-7 cells. (B) SERS spectra of (blue) MCF-7 and (black) HMEC cells. (C) SERS spectra of living HeLa cells (black curve) and dead HeLa cells (blue curve). Inset contains the confocal microscopic images of living and dead HeLa cells. (D) SERS spectra of living HepG2 cells (black curve) and dead HepG2 cells (blue curve). Inset contains the confocal microscopic images of living and dead HepG2 cells. (E) SERS spectra of living HMEC cells (black curve) and dead HMEC cells (blue curve). Inset contains the confocal microscopic images of living and dead HMEC cells. Circles in Figs. C, D, and E indicate the primary differences between the SERS spectra of living and dead cells.

Mentions: Figure 4A shows SERS spectra from three different cancer cell lines (HeLa, HepG2, and MCF-7) that produce different spectra due to inherent molecular differences [22]. The MCF-7 cell line contains a relatively low level of nuclear material and unordered proteins when compared to the two other cell lines, which is indicated by changes in the intensity of peaks at 721, 783, 1305, 1381, and 1450 cm−1, as well as those of the DNA backbone (PO2) (827 and 1095 cm−1), and of unordered proteins (1250 and 1655 cm−1). The changes in the Raman spectra at several Raman shifts also represent varying amounts of α-helix proteins (935, 1265, and 1655 cm−1), phospholipids (721, 1095, 1125, and 1335 cm−1), and lipids (1095 and 1305 cm−1). Several Raman peaks at 1611, 1212, 1153, and 959 cm−1 were observed from the HeLa and MCF–7 cell lines. However, for the MCF–7 cell line, the peak intensities of the Raman shift were much weaker than those from HeLa cells. Raman peaks at 783, 721, and 673 cm−1 were detected from MCF–7 and HepG2 cells, but not from HeLa cells. Moreover, differences in the intensity of Raman peaks representing the amide III, CH2, and other chemical bands were observed (Tables S2, S3, S4). Therefore, our substrate was able to differentiate cancer cell lines successfully.


Analysis of intracellular state based on controlled 3D nanostructures mediated surface enhanced Raman scattering.

El-Said WA, Kim TH, Kim H, Choi JW - PLoS ONE (2011)

SERS spectra of different cell lines.(A) SERS spectra of (1) HeLa, (2) HepG2, and (3) MCF-7 cells. (B) SERS spectra of (blue) MCF-7 and (black) HMEC cells. (C) SERS spectra of living HeLa cells (black curve) and dead HeLa cells (blue curve). Inset contains the confocal microscopic images of living and dead HeLa cells. (D) SERS spectra of living HepG2 cells (black curve) and dead HepG2 cells (blue curve). Inset contains the confocal microscopic images of living and dead HepG2 cells. (E) SERS spectra of living HMEC cells (black curve) and dead HMEC cells (blue curve). Inset contains the confocal microscopic images of living and dead HMEC cells. Circles in Figs. C, D, and E indicate the primary differences between the SERS spectra of living and dead cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3044723&req=5

pone-0015836-g004: SERS spectra of different cell lines.(A) SERS spectra of (1) HeLa, (2) HepG2, and (3) MCF-7 cells. (B) SERS spectra of (blue) MCF-7 and (black) HMEC cells. (C) SERS spectra of living HeLa cells (black curve) and dead HeLa cells (blue curve). Inset contains the confocal microscopic images of living and dead HeLa cells. (D) SERS spectra of living HepG2 cells (black curve) and dead HepG2 cells (blue curve). Inset contains the confocal microscopic images of living and dead HepG2 cells. (E) SERS spectra of living HMEC cells (black curve) and dead HMEC cells (blue curve). Inset contains the confocal microscopic images of living and dead HMEC cells. Circles in Figs. C, D, and E indicate the primary differences between the SERS spectra of living and dead cells.
Mentions: Figure 4A shows SERS spectra from three different cancer cell lines (HeLa, HepG2, and MCF-7) that produce different spectra due to inherent molecular differences [22]. The MCF-7 cell line contains a relatively low level of nuclear material and unordered proteins when compared to the two other cell lines, which is indicated by changes in the intensity of peaks at 721, 783, 1305, 1381, and 1450 cm−1, as well as those of the DNA backbone (PO2) (827 and 1095 cm−1), and of unordered proteins (1250 and 1655 cm−1). The changes in the Raman spectra at several Raman shifts also represent varying amounts of α-helix proteins (935, 1265, and 1655 cm−1), phospholipids (721, 1095, 1125, and 1335 cm−1), and lipids (1095 and 1305 cm−1). Several Raman peaks at 1611, 1212, 1153, and 959 cm−1 were observed from the HeLa and MCF–7 cell lines. However, for the MCF–7 cell line, the peak intensities of the Raman shift were much weaker than those from HeLa cells. Raman peaks at 783, 721, and 673 cm−1 were detected from MCF–7 and HepG2 cells, but not from HeLa cells. Moreover, differences in the intensity of Raman peaks representing the amide III, CH2, and other chemical bands were observed (Tables S2, S3, S4). Therefore, our substrate was able to differentiate cancer cell lines successfully.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul, Republic of Korea.

ABSTRACT
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.

Show MeSH
Related in: MedlinePlus