Optical Spectroscopy for Noninvasive Monitoring of Stem Cell Differentiation

Figure 5

Individual Raman spectra within a single mesenchymal stem cell (red: nucleus, black: cytoplasm). The following peaks are specific to DNA and RNA: A (785 cm⁻¹, uracil/cytosine/thymine ring breathing, O−P−O stretch), B (813 cm⁻¹, O−P−O stretch), C (828 cm⁻¹, O−P−O antisymmetric stretch), F (1093 cm⁻¹, O−P−O stretch and C−C stretch), and H (1580 cm⁻¹, adenine/guanine C−N stretch). Peaks specific to proteins are D (854 cm⁻¹, tyrosine ring breathing), E (1004 cm⁻¹, phenylalanine ring breathing), and I (1660 cm⁻¹, amide I alpha helix). Peaks dominated by lipids are G (1448 cm⁻¹, CH₂ deformation) and J (2800–3000 cm⁻¹, C−H stretch).