Department of Food Processing Technology and Management

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    TWO DISTINCT FLUORESCENT QUANTUM CLUSTERS OF GOLD STARTING FROM METALLIC NANOPARTICLES BY PH-DEPENDENT LIGAND ETCHING
    (Springer Link, 2008) Madathumpady, Abubaker Habeeb Muhammed; Subramani, Ramesh; Sudarson, Sekhar Sinha; Samir Kumar, Pal; Thalappil, Pradeep
    Two fluorescent quantum clusters of gold, namely Au25 and Au8, have been synthesized from mercaptosuccinic acid-protected gold nanoparticles of 4–5 nm core diameter by etching with excess glutathione. While etching at pH ∼3 yielded Au25, that at pH 7–8 yielded Au8. This is the first report of the synthesis of two quantum clusters starting from a single precursor. This simple method makes it possible to synthesize well-defined clusters in gram quantities. Since these clusters are highly fluorescent and are highly biocompatible due to their low metallic content, they can be used for diagnostic applications.
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    SELF-ASSEMBLY OF A NANOSCALE DNA BOX WITH A CONTROLLABLE LID
    (Nature Publishing Group UK, 2009-05-07) Ebbe S, Andersen; Mingdong, Dong; Morten M, Nielsen; Kasper, Jahn; Ramesh, Subramani; Wael, Mamdouh; Monika M, Golas; Bjoern, Sander; Holger, Stark; Cristiano L. P, Oliveira; Jan, Skov Pedersen; Victoria, Birkedal; Flemming, Besenbacher; Kurt V, Gothelf; Jørgen, Kjems
    The unique structural motifs and self-recognition properties of DNA can be exploited to generate self-assembling DNA nanostructures of specific shapes using a ‘bottom-up’ approach1. Several assembly strategies have been developed for building complex three-dimensional (3D) DNA nanostructures2,3,4,5,6,7,8. Recently, the DNA ‘origami’ method was used to build two-dimensional addressable DNA structures of arbitrary shape9 that can be used as platforms to arrange nanomaterials with high precision and specificity9,10,11,12,13. A long-term goal of this field has been to construct fully addressable 3D DNA nanostructures14,15. Here we extend the DNA origami method into three dimensions by creating an addressable DNA box 42 × 36 × 36 nm3 in size that can be opened in the presence of externally supplied DNA ‘keys’. We thoroughly characterize the structure of this DNA box using cryogenic transmission electron microscopy, small-angle X-ray scattering and atomic force microscopy, and use fluorescence resonance energy transfer to optically monitor the opening of the lid. Controlled access to the interior compartment of this DNA nanocontainer could yield several interesting applications, for example as a logic sensor for multiple-sequence signals or for the controlled release of nanocargos