WAVELENGTH DEPENDENCE OF CELL CLONING EFFICIENCY AFTER OPTICAL TRAPPING

A study on clonal growth in Chinese hamster ovary (CHO) cells was cond ucted after exposure to optical trapping wavelengths using Nd:YAG (106 4 nm) and tunable titanium-sapphire (700-990 nm) laser microbeam optic al traps. The nuclei of cells were exposed to optical trapping forces at various wavelengths, power densities, and durations of exposure. Cl onal growth generally decreased as the power density and the duration of laser exposure increased. A wavelength dependence of clonal growth was observed, with maximum clonability at 950-990 nm and least clonabi lity at 740-760 nm and 900 nm. Moreover, the most commonly used trappi ng wavelength, 1064 nm from the Nd:YAG laser, strongly reduced clonabi lity, depending upon the power density and exposure time. The present study demonstrates that a variety of optical parameters must be consid ered when applying optical traps to the study of biological problems, especially when survival and viability are important factors. The abil ity of the optical trap to alter either the structure or biochemistry of the process being probed with the trapping beam must be seriously c onsidered when interpreting experimental results.