Some very early testing of fluorescence imaging in our optical tweezers instrument. A 10 kb long piece of DNA (ca 3 um long when stretched) is held between two optically trapped microspheres. The DNA is coated with a fluorescent dye (SYBR-gold) which is exited by a 488 nm blue laser and the fluorescence signal is collected with a CCD camera looking through a narrow-band filter centered on the emission spectrum of SYBR-gold.
At around 1:10 in the video there's a double-tether (two DNA-molecules between the beads). We don't want that but there is not much that we can do about it, except discard the data. At the very end there's an image of QDots on the coverglass surface.
A ~48 000 base-pair long (ca 16 um) piece of DNA is stretched between two optically trapped ca 2 um diameter polystyrene beads. Bright-field real-time view through a 100x microscope. Scale-bar in microns on the right.
Some promising results yesterday with trying to stretch DNA molecules. The molecule is attached between two microspheres, and we are actively moving the smaller sphere while the force acting on the bigger sphere is being measured. The image and video shows the view through a 100x microscope objective on the optical tweezers instrument I am building. Towards the end you can see the construct breaking in two stages, so that probably means there were two molecules of DNA between the beads and not one as intended. This is a control experiment and will hopefully set the stage for bigger and better things to come...