The micromechanical properties of linear polymer chains such as double-stranded DNA has long been of interest in both life and materials science since many processes in nature and technology involve transport and manipulation of DNA in liquid environment. A novel technique based on attaching a nanometer-sized fluorescent quantum dot (Qdot) specifically to the free end of the native DNA duplex allows its direct observation in flow fields. The thermal fluctuations of single, surface-tethered DNA duplexes have been analysed by fluorescence microscopy. A steady shear flow has been applied in order to stretch the DNA molecule and the positions of the Qdot-labelled end were tracked. From there, the mean fractional extension and the fluctuations parallel and perpendicular to the flow direction were quantified and related to morphological changes.
The micromechanical properties of linear polymer chains such as double-stranded DNA has long been of interest in both life and materials science since many processes in nature and technology involve transport and manipulation of DNA in liquid environment. A novel technique based on attaching a nanometer-sized fluorescent quantum dot (Qdot) specifically to the free end of the native DNA duplex allows its direct observation in flow fields. The thermal fluctuations of single, surface-tethered DNA duplexes have been analysed by fluorescence microscopy. A steady shear flow has been applied in order to stretch the DNA molecule and the positions of the Qdot-labelled end were tracked. From there, the mean fractional extension and the fluctuations parallel and perpendicular to the flow direction were quantified and related to morphological changes.
