Selective delivery of laser energy to ester bonds of triacylglycerol in lipid droplets of adipocyte using a quantum cascade laser.

The recent development of quantum cascade lasers (QCLs) has facilitated the irradiation of a mid-infrared laser beam that is specifically absorbed by a target molecular bond. Aiming for a selective delivery of laser energy to a specific absorption at 1,738 cm-1 by the ester bonds of triacylglycerol (TAG), a QCL beam with a wavenumber of 1,710 cm-1 was irradiated to 3T3-L1 adipocytes and preadipocytes. Neutral red staining, and FITC-labeled annexin V and ethidium homodimer-III assays revealed the occurrence of adipocyte-specific cell death 24 h after QCL irradiation. The selective delivery of laser energy to endogenous molecules can affect biological processes in a living organism.