double Tao helix

Letter

Direct Imaging of DNA Fibers: The Visage of Double Helix

Francesco Gentile †‡, Manola Moretti †, Tania Limongi †§, Andrea Falqui , Giovanni Bertoni , Alice Scarpellini, Stefania Santoriello †, Luca Maragliano §, Remo Proietti Zaccaria †, and Enzo Di Fabrizio †‡*

^†Nanostructures, ^§Neuroscience and Brain Technologies, and Nanochemistry Departments, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova, Italy

^‡ BIONEM, Bio-Nanotechnology and Engineering for Medicine, Department of experimental and clinical medicine, University of Magna Graecia Viale Europa, Germaneto, 88100 Catanzaro, Italy

IMEM-CNR, Parco Area delle Scienze 37/A, 43124 Parma, Italy

Nano Lett., 2012, 12 (12), pp 6453–6458

DOI: 10.1021/nl3039162

Publication Date (Web): November 22, 2012

Copyright © 2012 American Chemical Society

Abstract

Direct imaging becomes important when the knowledge at few/single molecule level is requested and where the diffraction does not allow to get structural and functional information. Here we report on the direct imaging of double stranded (ds) λ-DNA in the A conformation, obtained by combining a novel sample preparation method based on super hydrophobic DNA molecules self-aggregation process with transmission electron microscopy (TEM). The experimental breakthrough is the production of robust and highly ordered paired DNA nanofibers that allowed its direct TEM imaging and the double helix structure revealing.

SEM image of a tightrope of DNA between two silicon nanopillars. marker: 1 μm

TEM direct image of DNA double-helix structure.