Optical tweezers are one of the most effective methods of manipulating micron and sub-micron sized particles. In biological applications, these instruments have been used to trap viruses, bacteria, living cells, organelles and even strands of DNA. We have developed an optical tweezer system for manipulation of mammalian cells. This research activity has been carried out in the frame of a close collaboration with Dr. Ayşe Begüm Tekinay’s group (Nanobiotechnology Group at UNAM, Bilkent University) and EA Technology Ltd. (Turkey).