Researchers at University of St Andrews Biophotonics Collaboration have used 4,000 Chinese hamster ovary cells to find the optimal laser settings to blast a hole in a cell so that it allows DNA to enter the cell. The perforated cells were placed in a solution containing plasmid DNA encoding for GFP. By examining pictures such as those shown below the researchers, David Stevenson and Ben Agate, were able to determine how many of the photoporated cells were expressing GFP.

Representative images at 48h of selected Chinese hamster ovary cells at (a) 10 and (b) 60 magnification. Cells optically transfected with GFP are green fluorescent and the blue nuclei surrounding the green targeted cells represent cells that have not been transfected. (Copyright St. Andrews University)