Science

Sunday, July 1, 2012

Nature Materials

(2012)

doi:10.1038/nmat3357

Received

25 October 2011

Accepted

15 May 2012

Published online

01 July 2012

In the absence of perfusable vascular networks, three-dimensional (3D) engineered tissues densely populated with cells quickly develop a necrotic core¹. Yet the lack of a general approach to rapidly construct such networks remains a major challenge for 3D tissue culture^2, 3, 4. Here, we printed rigid 3D filament networks of carbohydrate glass, and used them as a cytocompatible sacrificial template in engineered tissues containing living cells to generate cylindrical networks that could be lined with endothelial cells and perfused with blood under high-pressure pulsatile flow. Because this simple vascular casting approach allows independent control of network geometry, endothelialization and extravascular tissue, it is compatible with a wide variety of cell types, synthetic and natural extracellular matrices, and crosslinking strategies. We also demonstrated that the perfused vascular channels sustained the metabolic function of primary rat hepatocytes in engineered tissue constructs that otherwise exhibited suppressed function in their core.

Remotely Activated Protein-Producing Nanoparticles

Avi Schroeder†‡, Michael S. Goldberg†, ChristianKastrup†‡§, Yingxia Wang‡, Shan Jiang†‡, Brian J.Joseph‡, Christopher G. Levins†‡, Sneha T. Kannan†,Robert Langer†‡

, and Daniel G. Anderson*†‡

^†David H. Koch Institute for Integrative Cancer Research and ^‡Department of Chemical Engineering,Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States

^§ Michael Smith Laboratories and Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver V6T 1Z4 Canada

Harvard MIT Division of Health Science and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States

Nano Lett., 2012, 12 (6), pp 2685–2689

DOI: 10.1021/nl2036047

Publication Date (Web): March 20, 2012

The development of responsive nanomaterials, nanoscale systems that actively respond to stimuli, is one general goal of nanotechnology. Here we develop nanoparticles that can be controllably triggered to synthesize proteins. The nanoparticles consist of lipid vesicles filled with the cellular machinery responsible for transcription and translation, including amino acids, ribosomes, and DNA caged with a photolabile protecting group. These particles served as nanofactories capable of producing proteins including green fluorescent protein (GFP) and enzymatically active luciferase. In vitro and in vivo, protein synthesis was spatially and temporally controllable, and could be initiated by irradiating micrometer-scale regions on the time scale of milliseconds. The ability to control protein synthesis inside nanomaterials may enable new strategies to facilitate the study of orthogonal proteins in a confined environment and for remotely activated drug delivery.

On-chip manipulation of single microparticles, cells, and organisms using surface acoustic waves

Xiaoyun Ding^a,

Sz-Chin Steven Lin^a,

Brian Kiraly^a,

Hongjun Yue^b,

Sixing Li^c,

I-Kao Chiang^a,

Jinjie Shi^a,

Stephen J. Benkovic^b,¹, and

Tony Jun Huang^a,^c,¹

Published online before print June 25, 2012, doi:10.1073/pnas.1209288109PNAS June 25, 2012

Techniques that can dexterously manipulate single particles, cells, and organisms are invaluable for many applications in biology, chemistry, engineering, and physics. Here, we demonstrate standing surface acoustic wave based “acoustic tweezers” that can trap and manipulate single microparticles, cells, and entire organisms (i.e., Caenorhabditis elegans) in a single-layer microfluidic chip. Our acoustic tweezers utilize the wide resonance band of chirped interdigital transducers to achieve real-time control of a standing surface acoustic wave field, which enables flexible manipulation of most known microparticles. The power density required by our acoustic device is significantly lower than its optical counterparts (10,000,000 times less than optical tweezers and 100 times less than optoelectronic tweezers), which renders the technique more biocompatible and amenable to miniaturization. Cell-viability tests were conducted to verify the tweezers’ compatibility with biological objects. With its advantages in biocompatibility, miniaturization, and versatility, the acoustic tweezers presented here will become a powerful tool for many disciplines of science and engineering.

Paintable Battery

Wei Gao,

Arava Leela Mohana Reddy,

Alexandru Vlad

& Pulickel M. Ajayan

Scientific Reports

2,

Article number:

481

doi:10.1038/srep00481

Received

13 April 2012

Accepted

07 June 2012

Published

28 June 2012

If the components of a battery, including electrodes, separator, electrolyte and the current collectors can be designed as paints and applied sequentially to build a complete battery, on any arbitrary surface, it would have significant impact on the design, implementation and integration of energy storage devices. Here, we establish a paradigm change in battery assembly by fabricating rechargeable Li-ion batteries solely by multi-step spray painting of its components on a variety of materials such as metals, glass, glazed ceramics and flexible polymer substrates. We also demonstrate the possibility of interconnected modular spray painted battery units to be coupled to energy conversion devices such as solar cells, with possibilities of building standalone energy capture-storage hybrid devices in different configurations.

Voltage-Gated Ion Transport through Semiconducting Conical Nanopores Formed by Metal Nanoparticle-Assisted Plasma Etching

Teena James†, Yevgeniy V. Kalinin†, Chih-ChiehChan†, Jatinder S. Randhawa†, Mikhail Gaevski§, andDavid H. Gracias*†‡

^†Department of Chemical and Biomolecular Engineering and ^‡Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States

^§ Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08540, United States

Nano Lett., Article ASAP

DOI: 10.1021/nl300673r

Publication Date (Web): June 22, 2012

Nanopores with conical geometries have been found to rectify ionic current in electrolytes. While nanopores in semiconducting membranes are known to modulate ionic transport through gated modification of pore surface charge, the fabrication of conical nanopores in silicon (Si) has proven challenging. Here, we report the discovery that gold (Au) nanoparticle (NP)-assisted plasma etching results in the formation of conical etch profiles in Si. These conical profiles result due to enhanced Si etch rates in the vicinity of the Au NPs. We show that this process provides a convenient and versatile means to fabricate conical nanopores in Si membranes and crystals with variable pore-diameters and cone-angles. We investigated ionic transport through these pores and observed that rectification ratios could be enhanced by a factor of over 100 by voltage gating alone, and that these pores could function as ionic switches with high on–off ratios of approximately 260. Further, we demonstrate voltage gated control over protein transport, which is of importance in lab-on-a-chip devices and biomolecular separations.

Atomic Force Microscopy with Nanoscale Cantilevers Resolves Different Structural Conformations of the DNA Double Helix

Carl Leung*†, Aizhan Bestembayeva†‡, RichardThorogate†, Jake Stinson†‡, Alice Pyne†§, ChristianMarcovich†

, Jinling Yang

, Ute Drechsler#, MichelDespont#, Tilo Jankowski

, Martin Tschöpe

, andBart W. Hoogenboom*†‡

^† London Centre for Nanotechnology, University College London, 17−19 Gordon Street, London WC1H 0AH, United Kingdom

^‡ Department of Physics and Astronomy,University College London, Gower Street, London WC1E 6BT, United Kingdom

^§ National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom

École Polytechnique, 91128 Palaiseau Cedex, France

Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, P. R. China

^# IBM Research Division, Zurich Research Laboratory, Säumerstrasse 4, 8803 Rüschlikon, Switzerland

JPK Instruments AG, Bouchéstrasse 12, 12435 Berlin, Germany

Nano Lett., Article ASAP

DOI: 10.1021/nl301857p

Publication Date (Web): June 26, 2012

Structural variability and flexibility are crucial factors for biomolecular function. Here we have reduced the invasiness and enhanced the spatial resolution of atomic force microscopy(AFM) to visualize, for the first time, different structural conformations of the two polynucleotide strands in the DNA double helix, for single molecules under near-physiological conditions. This is achieved by identifying and tracking the anomalous resonance behavior of nanoscale AFM cantilevers in the immediate vicinity of the sample.

Adiabatic Nanofocusing on Ultrasmooth Single-Crystalline Gold Tapers Creates a 10-nm-Sized Light Source with Few-Cycle Time Resolution

Slawa Schmidt†, Björn Piglosiewicz†, Diyar Sadiq†,Javid Shirdel†, Jae Sung Lee‡, Parinda Vasa†,Namkyoo Park‡, Dai-Sik Kim§, and Christoph Lienau†*

^† Institut für Physik, Carl von Ossietzky Universität, 26111 Oldenburg, Germany

^‡ Photonic Systems Laboratory, School of EECS, Seoul National University, Seoul 151-744, Korea

^§ Center for Subwavelength Optics and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea

ACS Nano, Article ASAP

DOI: 10.1021/nn301121h

Publication Date (Web): June 8, 2012

We demonstrate adiabatic nanofocusing of few-cycle light pulses using ultrasharp and ultrasmooth single-crystalline gold tapers. We show that the grating-induced launching of spectrally broad-band surface plasmon polariton wavepackets onto the shaft of such a taper generates isolated, point-like light spots with 10 fs duration and 10 nm diameter spatial extent at its very apex. This nanofocusing is so efficient that nanolocalized electric fields inducing strong optical nonlinearities at the tip end are reached with conventional high repetition rate laser oscillators. We use here the resulting second harmonic to fully characterize the time structure of the localized electric field in frequency-resolved interferometric autocorrelation measurements. Our results strongly suggest that these nanometer-sized ultrafast light spots will enable new experiments probing the dynamics of optical excitations of individual metallic, semiconducting, and magnetic nanostructures.