Simultaneous optical tweezing and laser-induced fluorescence of DAPI stained chromosomes

In this paper, we describe methods to increase the functionality of conventional optical tweezer techniques through the use of a 410 nm laser diode to induce fluorescence in biological samples. For the first time, to our knowledge, we demonstrate the use of a violet diode laser to induce fluorescence in particles, which are simultaneously tweezed by an infrared laser. Using this technique we demonstrate the sorting of fluorescent polymer spheres and DAPI-stained chromosomes.