Fullerenes May Induce Physical Changes of DNA - an Optical Tweezers Study

Abstract

Fullerenes are fascinating symmetric carbon nanostructures. Nowadays, they are widely used because of their characteristic physical and chemical properties. Until now research has mainly focused on commercial applications of fullerenes. Only a few investigations have addressed the potential biological hazards, one of which is that fullerenes are believed to alter the elastic properties of DNA upon (irreversible) binding.In our experiments we use optical tweezers with sub-piconewton and nanometer resolution to probe the structural changes and the potential damages that fullerenes may induce on single DNA molecules. Force-extension relations of these molecules are obtained under physiological conditions while varying the concentration of different types of fullerenes, through well-defined microfluidics, in order to assess hypothesized damages. Custom-made Labview software allows for precise equipment control, various feedback options, and very fast on-the-fly data streaming.It has been theoretically predicted [1] that certain fullerenes can function as a minor-groove binder to double-stranded DNA, thus altering its elastic properties significantly. This may be why fullerenes are capable of causing severe damage inside living organisms. They form DNA regions that are inaccessible which prevents proper enzymatic catalysis. A further goal of the study is to establish fullerenes as a tool for a more detailed investigation of DNA-minor-groove binding as well as DNA-protein interactions, such as the traffic of polymerases or the packing by prokaryotic proteins.[1] Zhao, Striolo, and Cummings: BiophysJ (89):3856-62, 2005.