Ferrer J M, Fangyuan D, Brau R R, Tarsa P B, Lang M J
Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Curr Pharm Biotechnol. 2009 Aug;10(5):502-7. doi: 10.2174/138920109788922182.
The combination of optical tweezers force microscopy and single molecule fluorescence has previously been complicated by trap-induced photobleaching. Recent studies have suggested that this effect is caused by a sequential absorption of photons, leading to ionization of the fluorescent singlet state. In this work, we show the range of effects of optical trapping radiation on common fluorescent dyes. Using the interlaced optical force fluorescence (IOFF) laser modulation technique, we show that the removal of simultaneous near infrared radiation dramatically reduces photobleaching effects. However, these studies show that the sequential addition of near infrared radiation in some cases extends photobleaching longevity beyond the natural intrinsic decay. We suggest a refined photoelectronic mechanism that accounts for the possibility of reverse intersystem crossing from a reactive triplet state and explains the nature of trap-induced photobleaching.
光镊力显微镜和单分子荧光技术的结合此前因陷阱诱导的光漂白而变得复杂。最近的研究表明，这种效应是由光子的顺序吸收引起的，导致荧光单重态的电离。在这项工作中，我们展示了光镊辐射对常见荧光染料的影响范围。使用交错光力荧光（IOFF）激光调制技术，我们表明去除同时存在的近红外辐射可显著降低光漂白效应。然而，这些研究表明，在某些情况下，顺序添加近红外辐射会使光漂白寿命延长至超过自然本征衰变。我们提出了一种精细的光电子机制，该机制考虑了从反应性三重态反向系间窜越的可能性，并解释了陷阱诱导光漂白的本质。
