Mirsaidov Utkur, Timp Winston, Timp Kaethe, Mir Mustafa, Matsudaira Paul, Timp Gregory
Beckman Institute, University of Illinois, Urbana, Illinois 61801, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Aug;78(2 Pt 1):021910. doi: 10.1103/PhysRevE.78.021910. Epub 2008 Aug 25.
Optical trapping is a powerful tool for the micromanipulation of living cells--especially bacteria--but photodamage induced by the laser beam can adversely affect viability. We have explored optical trapping conditions in the near infrared (840-930 nm) that preserve the viability of E. coli, as measured by gene expression of green fluorescent protein. We have found that time-sharing the optical traps, i.e., dwelling only 10 micros-1 ms on the cell, improves viability relative to continuous wave (CW) exposure for the same exposure time. We have also observed that similar to CW traps the photodamage in a time-shared trap depends weakly on wavelength, but linearly on peak power, implying an effect induced by single photon absorption. Taken altogether, integrating the exposure time and peak power, the data indicate that there is a lethal energy dose of about 5 J for E. coli. Thus a single parameter--the energy--can be used to describe the limitation on viability.
光镊是用于对活细胞（尤其是细菌）进行微操纵的强大工具，但激光束诱导的光损伤会对细胞活力产生不利影响。我们探索了近红外（840 - 930 nm）波段的光镊条件，以绿色荧光蛋白的基因表达来衡量，该条件可保持大肠杆菌的活力。我们发现，分时使用光镊，即在细胞上仅驻留10微秒至1毫秒，相对于相同曝光时间的连续波（CW）照射，可提高细胞活力。我们还观察到，与连续波光镊类似，分时光镊中的光损伤对波长的依赖性较弱，但与峰值功率呈线性关系，这意味着是由单光子吸收引起的效应。综合考虑曝光时间和峰值功率，数据表明大肠杆菌存在约5焦耳的致死能量剂量。因此，单一参数——能量——可用于描述对细胞活力的限制。
