Light cells, damaging effects

For the application of QDs to three-dimensional biological imaging, a large two-photon absorption cross section is required to avoid cell damage by light irradiation. For application to optoelectronics, QDs should have a large nonlinear refractive index as well as fast response. Two-photon absorption and the optical Kerr effect of QDs are third-order nonlinear optical effects, which can be evaluated from the third-order nonlinear susceptibility, or the nonlinear refractive index, y, and the nonlinear absorption coefficient, p. Experimentally, third-order nonlinear optical parameters have been examined by four-wave mixing and Z-scan experiments. 

Cultured mammalian cells and isolated hepatocyte studies. There have been several recent reports of the damaging effects of visible light exposure (>400 nm) on various microorganisms (9,10) and cultured mammalian cells (11-13). We have reported that human diploid cells on exposure to visible light (14) and oxygen (>10%) (15) lost the ability to proliferate, while ultrastructural studies showed the presence of numerous damaged mitochondria in the illuminated cells (16). WI-38 human fibroblasts show a grad-... 

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