The development of Silicon Nano-Tweezers by LIMMS at the University of Tokyo allows direct measurement of the mechanical properties of biopolymers. This is of the highest importance in the understanding of how ions or molecules interact with DNA, change its properties and hence modify cell propagation and cell death. In the first part of the poster we will describe the novel experimental setup of SNTs used in this work. We have undertaken a series of studies using SNTs on the effects of metal ions and upramolecular systems on the mechanical properties of DNA. The results show: Firstly most physiologically common ions have no effect Secondly certain ions such as silver greatly rigidify DNA Thirdly some supramolecular systems are capable of slightly softening DNA Finally combinations of ions and supramolecular systems can act synergistically to dramatically change the mechanical properties of DNA.