Confocal mapping of myelin figures with micro-Raman spectroscopy

We employ confocal micro-Raman spectroscopy (CMRS) with submicron spatial resolution to study the myelin structures (cylindrical lamellae) composed of nested surfactant C₁₂E₃ or lipid DMPC bilayers. The CMRS mapping indicates that for a straight C₁₂E₃ myelin, the surfactant concentration increases with the myelin width and is higher in the center region than in the peripheral region. For a curved C₁₂E₃ myelin, the convex side has a higher surfactant concentration than the corresponding concave side. The spectrum of DMPC myelins undergoes a qualitative change as the temperature increases above 60 °C, suggesting that the surfactant molecules may be damaged. Our work demonstrates the utility of CMRS in bio-soft material research.