Popular science articles

An Implantable Biofuel Cell for a Live Insect

Michelle Rasmussen†, Roy E. Ritzmann‡, Irene Lee†, Alan J. Pollack‡, and Daniel Scherson*†

Departments of ^†Chemistry and ^‡Biology, Case Western Reserve University, Cleveland, Ohio 44106, United States

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/ja210794c

Publication Date (Web): January 3, 2012

A biofuel cell incorporating a bienzymatic trehalase|glucose oxidase trehalose anode and a bilirubin oxidase dioxygen cathode using Os complexes grafted to a polymeric backbone as electron relays was designed and constructed. The specific power densities of the biofuel cell implanted in a female Blaberus discoidalis through incisions into its abdomen yielded maximum values of ca. 55 μW/cm² at 0.2 V that decreased by only ca. 5% after ca. 2.5 h of operation.

Quantitative Analysis of the Role Played by Poly(vinylpyrrolidone) in Seed-Mediated Growth of Ag Nanocrystals

Xiaohu Xia, Jie Zeng, L. Kyle Oetjen, Qingge Li, and Younan Xia

Publication Date (Web): December 28, 2011 (Article)

DOI: 10.1021/ja210047e

Regiospecific Plasmonic Assemblies for in Situ Raman Spectroscopy in Live Cells

Liguang Xu†, Hua Kuang†, Chuanlai Xu†, Wei Ma†‡, Libing Wang*†

, and Nicholas A. Kotov*‡

^† School of Food Science and Technology, State Key Lab of Food Science and Technology, Jiangnan University, Wuxi, JiangSu, 214122, People's Republic of China

^‡ Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States

Hunan Entry–Exit Inspection and Quarantine Bureau, Changsha, 410001, People's Republic China

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/ja2088713

Publication Date (Web): December 18, 2011

wanglb@hnciq.gov.cn; kotov@umich.edu

Multiple properties of plasmonic assemblies are determined by their geometrical organization. While high degree of complexity was achieved for plasmonic superstructures based on nanoparticles (NPs), little is known about the stable and structurally reproducible plasmonic assemblies made up from geometrically diverse plasmonic building blocks. Among other possibilities, they open the door for the preparation of regiospecific isomers of nanoscale assemblies significant both from a fundamental point of view and optical applications. Here, we present a synthetic method for complex assemblies from NPs and nanorods (NRs) based on selective modification of NRs with DNA oligomers. Three types of assemblies denoted as End, Side, and Satellite isomers that display distinct elements of regiospecificity were prepared with the yield exceeding 85%. Multiple experimental methods independently verify various structural features, uniformity, and stability of the prepared assemblies. The presence of interparticle gaps with finely controlled geometrical parameters and inherently small size comparable with those of cellular organelles fomented their study as intracellular probes. Against initial expectations, SERS intensity for End, Side, and Satelliteisomers was found to be dependent primarily on the number of the NPs in the superstructures rationalized with the help of electrical field simulations. Incubation of the label-free NP–NR assemblies with HeLa cells indicated sufficient field enhancement to detect structural lipids of mitochondria and potentially small metabolites. This provided the first proof-of-concept data for the possibility of real-time probing of the local organelle environment in live cells. Further studies should include structural optimization of the assemblies for multitarget monitoring of metabolic activity and further increase in complexity for applications in transformative optics.

Optically Trapped Gold Nanoparticle Enables Listening at the Microscale

Alexander Ohlinger, Andras Deak, Andrey A. Lutich^*, and Jochen Feldmann^†
Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universität München, Amalienstraße 54, 80799 Munich, Germany

We explore a new application of optical tweezers for ultrasensitive detection of sound waves in liquid media. Position tracking of a single gold nanoparticle confined in a three-dimensional optical trap is used to readout acoustic vibrations at a sound power level down to -60 dB, causing a ∼90 μeV increase in kinetic energy of the nanoparticle. The unprecedented sensitivity of such a nanoear is achieved by processing the nanoparticle’s motion in the frequency domain. The concept developed here will enable us to access the interior of biological microorganisms and micromechanical machines not accessible by other microscopy types.

© 2012 American Physical Society
http://prl.aps.org/abstract/PRL/v108/i1/e018101

Silkworms transformed with chimeric silkworm/spider silk genes spin composite silk fibers with improved mechanical properties

+Author Affiliations

Published online before print January 3, 2012, doi:10.1073/pnas.1109420109PNAS January 3, 2012

^aDepartment of Molecular Biology, University of Wyoming, Laramie, WY 82071;
^bCollege of Animal Sciences, Zhejiang University, Hangzhou 310029, People's Republic of China; and
^cEck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556

Edited by David A. Tirrell, California Institute of Technology, Pasadena, CA, and approved November 28, 2011 (received for review June 10, 2011)

Abstract

The development of a spider silk-manufacturing process is of great interest. However, there are serious problems with natural manufacturing through spider farming, and standard recombinant protein production platforms have provided limited progress due to their inability to assemble spider silk proteins into fibers. Thus, we used piggyBac vectors to create transgenic silkworms encoding chimeric silkworm/spider silk proteins. The silk fibers produced by these animals were composite materials that included chimeric silkworm/spider silk proteins integrated in an extremely stable manner. Furthermore, these composite fibers were, on average, tougher than the parental silkworm silk fibers and as tough as native dragline spider silk fibers. These results demonstrate that silkworms can be engineered to manufacture composite silk fibers containing stably integrated spider silk protein sequences, which significantly improve the overall mechanical properties of the parental silkworm silk fibers.