Sunday, January 20, 2013

Biosynthesis of luminescent quantum dots in an earthworm


  • Nature Nanotechnology
     
    8,
     
    57–60
     
    (2013)
     
    doi:10.1038/nnano.2012.232
    Received
     
    Accepted
     
    Published online
     

Not only do earthworms fertilize soil and help catch fish, but the wriggly creatures are also capable of manufacturing semiconductor nanoparticles called quantum dots, according to researchers at King’s College London (Nat. Nanotechnol., DOI:10.1038/nnano.2012.232). Scientists have previously biosynthesized nanoparticles by hijacking the cellular machinery inside bacteria, viruses, and fungi, but “we’re pretty sure this is the first time this has been intentionally achieved in a higher animal,” says Mark Green, who led the research team. To prove the worms capable of the feat, Green, Stephen R. Stürzenbaum, and coworkers put the animals in soil laced with cadmium chloride and sodium tellurite. When they later cut the worms open, they found 2-nm-diameter CdTe quantum dots. The researchers think the earthworms sequester the heavy metals as part of a detoxification mechanism. After harvesting the worm-made dots, the team demonstrated their utility as imaging agents: The particles are taken up by ovarian cancer cells and emit green light after being excited at blue wavelengths.

Electrical Method to Quantify Nanoparticle Interaction with Lipid Bilayers


 Institute of Materials, École Polytechnique Fédérale de Lausanne, EPFL-STI-IMX-SuNMIL, Lausanne CH-1015, Switzerland
 ITQB, Universidade Nova de Lisboa, Avenida Da Republica, Oeiras, Portugal
ACS Nano, Article ASAP
DOI: 10.1021/nn3036304
Publication Date (Web): December 26, 2012
Copyright © 2012 American Chemical 

Understanding as well as rapidly screening the interaction of nanoparticles with cell membranes is of central importance for biological applications such as drug and gene delivery. Recently, we have shown that “striped” mixed-monolayer-coated gold nanoparticles spontaneously penetrate a variety of cell membranes through a passive pathway. Here, we report an electrical approach to screen and readily quantify the interaction between nanoparticles and bilayer lipid membranes. Membrane adsorption is monitored through the capacitive increase of suspended planar lipid membranes upon fusion with nanoparticles. We adopt a Langmuir isotherm model to characterize the adsorption of nanoparticles by bilayer lipid membranes and extract the partition coefficient, K, and the standard free energy gain by this spontaneous process, for a variety of sizes of cell-membrane-penetrating nanoparticles. We believe that the method presented here will be a useful qualitative and quantitative tool to determine nanoparticle interaction with lipid bilayers and consequently with cell membranes.

A near-infrared fluorophore for live-cell super-resolution microscopy of cellular proteins




The ideal fluorescent probe for bioimaging is bright, absorbs at long wavelengths and can be implemented flexibly in living cells and in vivo. However, the design of synthetic fluorophores that combine all of these properties has proved to be extremely difficult. Here, we introduce a biocompatible near-infrared silicon–rhodamine probe that can be coupled specifically to proteins using different labelling techniques. Importantly, its high permeability and fluorogenic character permit the imaging of proteins in living cells and tissues, and its brightness and photostability make it ideally suited for live-cell super-resolution microscopy. The excellent spectroscopic properties of the probe combined with its ease of use in live-cell applications make it a powerful new tool for bioimaging.

Stimuli Responsive Materials: Biopsy with Thermally-Responsive Untethered Microtools


  1. Evin Gultepe1
  2. Jatinder S. Randhawa1,
  3. Sachin Kadam1
  4. Sumitaka Yamanaka2,
  5. Florin M. Selaru2
  6. Eun J. Shin2
  7. Anthony N. Kalloo2
  8. David H. Gracias1,3



The first biopsy with untethered, sub-millimeter scale grippers is described by David H. Gracias and co-workers on page 514. The cover shows the retrieval of cells from the bile duct of a live pig using thermally responsive tether-free m-grippers. The retrieved tissue was of a high enough quality and quantity to enable both histological and molecular biology analyses which forms the basis of diagnostics. Image created by Martin Rietveld.

The pH Taxis of an Intelligent Catalytic Microbot


  1. Krishna Kanti Dey2
  2. Satyapriya Bhandari1,
  3. Dipankar Bandyopadhyay2,3
  4. Saurabh Basu4
  5. Arun Chattopadhyay1,2,*
Article first published online: 14 JAN 2013
DOI: 10.1002/smll.201202312

A Pd nanoparticle-containing polymer microsphere moves with increasing speed across a pH gradient, following differential catalytic decomposition of aqueous hydrogen peroxide. The directional motion is akin to the pH taxis of living microorganisms. The artificial pH taxis exhibits random walk, translation, vertical, hopping, and pulsed motion, when the size of the motor and the imposed pH gradient are modulated

Sunday, January 13, 2013

Inside Back Cover: Light-Triggered Sequence-Specific Cargo Release from DNA Block Copolymer–Lipid Vesicles

Dr. Alberto Rodríguez-Pulido1, Alina I. Kondrachuk1, Dr. Deepak K. Prusty1, Jia Gao2Prof. Dr. Maria A. Loi2, Prof. Dr. Andreas Herrmann1,*



Sequence-specific cargo release from DNA-encoded lipid vesicles through the stable tagging of a liposome surface with amphiphilic DNA block copolymers (DBCs) is reported by A. Herrmann and co-workers in their Communication on page 1008 ff. Hybridization of anchored DBCs with an oligonucleotide photosensitizer is the key to light-induced singlet oxygen generation close to the lipid membrane, which results in the oxidation of polymer anchors and/or unsaturated phospholipids, leading to release of the vesicle payload.

On-Chip Protein Biosynthesis

M. Sc. Christopher Timm,
Prof. Dr. Christof M. Niemeyer*
Article first published online: 10 JAN 2013
DOI: 10.1002/anie.201208880


 Spot on! Cell-free protein expression on surfaces can be implemented in biosensors and in microfluidic devices like that shown in the picture. Here, proteins are generated and immobilized successively on separated spots in a microfluidic reactor. This approach opens up novel opportunities for basic and applied biomedical research.