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. 2012;7(4):e35075.
doi: 10.1371/journal.pone.0035075. Epub 2012 Apr 13.

Micro-Raman spectroscopy of silver nanoparticle induced stress on optically-trapped stem cells

Aseefhali Bankapur  1 , R Sagar Krishnamurthy, Elsa Zachariah, Chidangil Santhosh, Basavaraj Chougule, Bhavishna Praveen, Manna Valiathan, Deepak Mathur
Affiliations

Micro-Raman spectroscopy of silver nanoparticle induced stress on optically-trapped stem cells

Aseefhali Bankapur et al. PLoS One. 2012.

Erratum in

  • PLoS One. 2012;7(7): doi/10.1371/annotation/60f68765-e790-4ab1-b1f2-3867100c6e3e

Abstract

We report here results of a single-cell Raman spectroscopy study of stress effects induced by silver nanoparticles in human mesenchymal stem cells (hMSCs). A high-sensitivity, high-resolution Raman Tweezers set-up has been used to monitor nanoparticle-induced biochemical changes in optically-trapped single cells. Our micro-Raman spectroscopic study reveals that hMSCs treated with silver nanoparticles undergo oxidative stress at doping levels in excess of 2 µg/ml, with results of a statistical analysis of Raman spectra suggesting that the induced stress becomes more dominant at nanoparticle concentration levels above 3 µg/ml.

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Conflict of interest statement

Competing Interests: The authors have the following competing interests: RSK and BC are employees of Stempeutics Research Pvt. Ltd. There are no patents, products in development or marketed products to declare. This does not alter the authors' adherence to all the PLoS ONE policies on sharing data and materials, as detailed online in the guide for authors. The entire data set acquired in the experiments reported in this submission is physically in the custody of the Centre for Atomic and Molecular Physics at Manipal University and is available for sharing with anyone for academic purposes.

Figures

Figure 1
Figure 1. Phase contrast microscope image of control human Mesenchymal stem cells (hMSC) culture after passage 5.
Magnification 4×.
Figure 2
Figure 2. Flow cytometer CD Marker Expression for control hMSC (without Ag NPs).
Figure 3
Figure 3. The experimental apparatus used in the present studies.
(a) Schematic representation of the Raman Tweezers set-up. (b) Picture of the Raman Tweezers set-up showing the geometry of the trapping laser beam and the Raman probe laser beam.
Figure 4
Figure 4. Morphology of hMSC's (A) Control, and Ag NP treated with concentration (B) 1 µg/ml, (C) 2 µg/ml, (D) 3 µg/ml, (E) 4 µg/ml and (F) 5 µg/ml.
Magnification 4×.
Figure 5
Figure 5. Shows a typical baseline-corrected microRaman spectrum of an optically trapped hMSC (an image of which is shown).
The laser power used for trapping (1064 nm wavelength) was 5 mW while the Raman spectrum was measured using a laser power of ∼20 mW (785 nm wavelength); the acquisition time was 120 s and 5 accumulations were made.
Figure 6
Figure 6. Raman spectra of hMSCs.
Top panel shows normalized Raman spectra of hMSCs exposed to different concentrations of Ag nano-particles (1–4 µg/mL). The normalization was with respect to the 999 cm−1 peak. The laser power used for trapping (1064 nm wavelength) was 5 mW while the Raman spectrum was measured using a laser power of ∼20 mW (785 nm wavelength). Each spectrum is an average of spectra from five individual hMSCs. Acquisition time: 120 s and 5 accumulations. The lower panel shows the same spectra over an extended range (see text).
Figure 7
Figure 7. Raman spectrum of Ag NPs recorded using 10 mW power of 785 nm laser beam.
Acquisition time: 30 s with 5 average accumulations. The top panel shows the raw spectrum and lower panels shows the spectrum after appropriate background subtraction.
Figure 8
Figure 8. PCA results in the form of a scatter plot depicting the Score of Factor 1 against the Score of Factor 2.
Control, 1 µg/mL and 2 µg/mL NP treated cell spectra are clustered together (except one datum).
See this image and copyright information in PMC

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