Katsura S, Hirano K, Matsuzawa Y, Yoshikawa K, Mizuno A
Department of Ecological Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580, Japan.
Nucleic Acids Res. 1998 Nov 1;26(21):4943-5. doi: 10.1093/nar/26.21.4943.
A sharply focused laser is able to trap small particles at the laser focal point due to the difference in refractive index of the particles and that of the surrounding medium. This technique, called laser trapping, can be used to manipulate animal or bacterial cells without any contact and has been widely applied in biological research. However, it has been difficult to trap biological macromolecules such as DNA molecules, because these molecules give a low difference in refractive index and cannot overcome Brownian motion. DNA molecules can be transformed to a condensed globular state. This transformation results in a higher refractive index of DNA due to its increased density. We demonstrate in this paper that a single DNA molecule can be optically trapped using a Nd:YAG laser (1064 nm wavelength) upon transformation from the coiled state to the globular state.
由于粒子与周围介质的折射率存在差异，聚焦良好的激光能够在激光焦点处捕获小粒子。这种技术称为激光捕获，可用于在无任何接触的情况下操纵动物或细菌细胞，并且已在生物学研究中得到广泛应用。然而，捕获诸如DNA分子之类的生物大分子一直很困难，因为这些分子的折射率差异很小，无法克服布朗运动。DNA分子可以转变为凝聚的球状状态。这种转变由于其密度增加而导致DNA具有更高的折射率。我们在本文中证明，单个DNA分子从卷曲状态转变为球状状态后，可以使用Nd:YAG激光（波长1064 nm）进行光学捕获。
