Real-time Raman spectroscopy of optically trapped living cells and organelles

Abstract

We report on real-time Raman spectroscopic studies of optically trapped living cells and organelles using an inverted confocal laser-tweezers-Raman-spectroscopy (LTRS) system. The LTRS system was used to hold a single living cell in a physiological solution or to hold a functional organelle within a living cell and consequently measured its Raman spectra. We have measured the changes in Raman spectra of a trapped yeast cell as the function of the temperature of the bathing solution and studied the irreversible cell degeneration during the heat denaturation. In addition, we measured the in-vitro Raman spectra of the nuclei within living pine cells and B. sporeformer, Strep. salivarius, and E. coli bacteria suspended in solution and showed the possibility of using LTRS system as a sensor for rapid identification of microbes in a fluid.

Comparison of subcellular responses for the evaluation and prediction of the chemotherapeutic response to cisplatin in lung adenocarcinoma using Raman spectroscopy

“…The Raman bands at 669 cm -1 (Thymine) and 1336 cm -1 (Guanine) are present, both in the mean spectra of the nucleus and cytoplasm which is expected, as their presence in the cytoplasm may be due to cytoplasmic DNA, and are unexpectedly seen in the membrane spectra 110 which may be the contribution from the surrounding cytoplasm 29 . Comparing the mean control spectra of the nucleus of A549 cells with that of the cell membrane and cytoplasm, ideally, there should be no peaks in the nuclear spectra for may be due to the contribution from the surrounding cytoplasm 33 and 29 or on the other hand this band can be assigned, both to lipids and proteins 34 .…”

“…Nevertheless, the spectral changes in the protein extracted from cisplatin exposed compared to control cell cultures confirms a significant modification of 15 the protein structure as a result of the exposure, by direct or indirect means. Normally, in a cell, proteins are folded in a well-ordered structure and the side chains of the proteins are constrained 34 and thus the intensities of these Raman bands are suppressed in the spectrum of the control 20 as compared to the exposed. The increase in the intensities of these bands may be due to the direct binding of the cisplatin to the associated proteins which causes changes in their secondary structure and causes their unfolding, exposing the phenylalanine/tyrosine/tryptophan side ), are also observed.…”

The lag phase and G1 phase of a single yeast cell monitored by Raman microspectroscopy

“…12 The ratio of the RNA (813 cm 1 ) and protein (1005 cm 1 ) peaks in the Raman spectra of murine embryonic stem cells have previously been proposed as an indicator of mRNA translation during differentiation in vitro, 12 and the peak at 1005 cm 1 has been used as an indicator of protein denaturation in the cell. 33,36 However, in yeast cells under trapped and non-stressed conditions, the known protein peaks such as 757, 1005 and 1660 cm 1 do not show any definite upward or downward trends. As an example, the behaviour of the peak at 757 cm 1 with time during the initial lag phase can be seen in Fig.…”

Visible, near‐infrared, and ultraviolet laser‐excited Raman spectroscopy of the monocytes/macrophages (U937) cells

“…The 1090 cm −1 peak is attributed to the vibration of the O-P-O bonds inside DNA. [12,21] The peak centered at 850 cm −1 is weak in the Raman spectra excited with visible light in bacteria or in bakery yeast cells [9,12] ; however, it can be easily detected in keratin fibers [22] and is associated with vibration of tyrosine (ring breathing). [18] All three Raman spectra of the monocyte cell have sharp peaks at 980 cm −1 .…”