Fig. 3. Images taken by confocal Raman microscope for HeLa cells: (Top) after treatment with X2-GO (a1) and X3-GO (b1) for 24 h, bright field. (Bottom) Enlarged areas as detected by Raman spectra (a2 and b2). Reproduced from ref. 20 with permission from Wiley-VCH GmbH & Co., Copyright 2014.