Label-free and real time monitoring of adipocyte differentiation by surface infrared spectroscopy

We have investigated in situ real-time monitoring of cell differentiation to adipocytes by using infrared absorption spectroscopy with the multiple internal reflection (MIR-IRAS) geometry. Preadipocyte 3T3-L1 cells were cultured on a silicon prism and their adipogenesis was monitored with MIR-IRAS for seven days. Differentiated cells showed a C=O stretching band of triacylglycerides, together with the protein amide I and amide II bands. The C=O stretching band appeared before optical microscopic confirmation of fat droplet formation, a typical morphological marker for adipocytes, demonstrating that MIR-IRAS is particularly useful for non-destructive monitoring of early adipogenesis. An effect of genistein, an antiadipogenic agent, was also investigated based on the peak intensity of the C=O stretching and amide bands. Thus, MIR-IRAS has a potential to evaluate antiadipogenic agents in terms of their effects on fat and protein synthesis during adipogenesis.