Eectrical Switching Behavior of a [60]Fullerene-Based Molecular Wire Encapsulated in a Syndiotactic Poly(methyl methacrylate) Helical Cavity

1. Dr. Shengli Qi^1,4,*, 
2. Dr. Hiroki Iida¹, 
3. Dr. Lili Liu², 
4. Prof. Stephan Irle^2,*, 
5. Prof. Wenping Hu³, 
6. Prof. Eiji Yashima^1,*

Article first published online: 12 DEC 2012

DOI: 10.1002/anie.201209492

A helical syndiotactic poly(methyl methacrylate) (st-PMMA) encapsulates C₆₀ molecules within its helical cavity to form a supramolecular peapod-like molecular wire. In their Communication (DOI: 10.1002/anie.201208481), S. Qi, S. Irle, E. Yashima, and co-workers report that sandwich devices fabricated using this helical st-PMMA/C₆₀ inclusion complex exhibit an irreversible electrical switching effect, which results from a violent Coulomb explosion in the peapod C₆₀ wires during the charge injection process

Nanoscale Electrochemical Patterning Reveals the Active Sites for Catechol Oxidation at Graphite Surfaces

Anisha N. Patel †, Kim McKelvey †‡, and Patrick R. Unwin *†

^†Department of Chemistry and ^‡MOAC Doctoral Training Centre, University of Warwick, Coventry CV4 7AL, United Kingdom

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/ja3095894

Publication Date (Web): December 4, 2012

Copyright © 2012 American Chemical Society

Graphite-based electrodes (graphite, graphene, and nanotubes) are used widely in electrochemistry, and there is a long-standing view that graphite step edges are needed to catalyze many reactions, with the basal surface considered to be inert. In the present work, this model was tested directly for the first time using scanning electrochemical cell microscopy reactive patterning and shown to be incorrect. For the electro-oxidation of dopamine as a model process, the reaction rate was measured at high spatial resolution across a surface of highly oriented pyrolytic graphite. Oxidation products left behind in a pattern defined by the scanned electrochemical cell served as surface-site markers, allowing the electrochemical activity to be correlated directly with the graphite structure on the nanoscale. This process produced tens of thousands of electrochemical measurements at different locations across the basal surface, unambiguously revealing it to be highly electrochemically active, with step edges providing no enhanced activity. This new model of graphite electrodes has significant implications for the design of carbon-based biosensors, and the results are additionally important for understanding electrochemical processes on related sp²-hybridized materials such as pristine graphene and nanotubes.

Thermolides, Potent Nematocidal PKS-NRPS Hybrid Metabolites from Thermophilic Fungus Talaromyces thermophilu

Ji-Peng Guo , Chun-Yan Zhu , Chuan-Ping Zhang ,Yan-Sheng Chu , Yan-Li Wang , Jun-Xian Zhang , De-Kai Wu , Ke-Qin Zhang *, and Xue-Mei Niu *

Laboratory for Conservation and Utilization of Bio-Resources & Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming 650091, P. R. China

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/ja3104044

Publication Date (Web): December 4, 2012

Copyright © 2012 American Chemical Society

Macrocyclic PKS-NRPS hybrid metabolites represent a unique family of natural products mainly from bacteria with broad and outstanding biological activities. However, their distribution in fungi has rarely been reported, and little has been reported regarding their nematocidal activity. Here we describe an unprecedented class of PKS-NRPS hybrid metabolites possessing a 13-membered lactam-bearing macrolactone, thermolides A–F (1–6) from a thermophilic fungus Talaromyces thermophilus. We showed that 1 and 2 displayed potent inhibitory activity against three notorious nematodes with LC₅₀ values of 0.5–1 μg/mL, as active as commercial avermectins. This work provided a new class of promising lead compounds for nematocide discovery.

3D Nanofabrication: 3D Nanofabrication of Fluidic Components by Corner Lithography

1. Erwin J. W. Berenschot¹, 
2. Narges Burouni¹,
3. Bart Schurink², 
4. Joost W. van Honschoten¹,
5. Remco G. P. Sanders¹, 
6. Roman Truckenmuller², 
7. Henri V. Jansen¹, 
8. Miko C. Elwenspoek¹, 
9. Aart A. van Apeldoorn²,
10. Niels R. Tas^1,*

Article first published online: 15 DEC 2012

DOI: 10.1002/smll.20129013

A pyramid microarray comprising microsized nanowires made by 3D corner lithography is presented by N. R. Tas and co-workers on page 3823. The arrays are integrated into a cell-seeding device for the entrapment of single cells. Polystyrene microspheres are shown efficiently captured from a suspension of homogeneously shaped spheres. The same procedure is done with a suspension of primary bovine chondrocytes, after which their phenotype is studied over 48 h. The magnified electron micrograph shows the efficient entrapment of 1 cell per pyramid after 2 h of cell culture. Cells maintain their native round morphology during entrapment, while the onset of protein deposition starts between these confined cells.

Oxidation Level-Dependent Zwitterionic Liposome Adsorption and Rupture by Graphene-based Materials and Light-Induced Content Release

1. Alexander C.-F. Ip, 
2. Biwu Liu, 
3. Po-Jung Jimmy Huang, 
4. Juewen Liu^*

Article first published online: 13 DEC 2012

DOI: 10.1002/smll.201202710

Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Liposomes may be stably adsorbed or ruptured on graphene-based materials, depending on the oxidation state of graphene. IR-induced liposome leakage is achieved, since graphene oxide does not induce liposome leakage spontaneously.

Molecular Crystallization Controlled by pH Regulates Mesoscopic Membrane Morphology

Cheuk-Yui Leung †, Liam C. Palmer ‡, Bao Fu Qiao §,Sumit Kewalramani §, Rastko Sknepnek §, Christina J. Newcomb §, Megan A. Greenfield , Graziano Vernizzi §, Samuel I. Stupp ‡§¶, Michael J. Bedzyk†§, and Monica Olvera de la Cruz ‡§*

^†Physics and Astronomy, ^‡Department of Chemistry,^§Materials Science and Engineering, and Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States

 Department of Physics, Siena College, Loudonville, New York 12211, United States

^¶ Department of Medicine and Institute for BioNanotechnology in Medicine, Northwestern University, Chicago, Illinois 60611, United States

ACS Nano, Article ASAP

DOI: 10.1021/nn304321w

Publication Date (Web): November 27, 2012

Copyright © 2012 American Chemical Society

Coassembled molecular structures are known to exhibit a large variety of geometries and morphologies. A grand challenge of self-assembly design is to find techniques to control the crystal symmetries and overall morphologies of multicomponent systems. By mixing +3 and −1 ionic amphiphiles, we assemble crystalline ionic bilayers in a large variety of geometries that resemble polyhedral cellular crystalline shells and archaea wall envelopes. We combine TEM with SAXS and WAXS to characterize the coassembled structures from the mesoscopic to nanometer scale. The degree of ionization of the amphiphiles and their intermolecular electrostatic interactions are controlled by varying pH. At low and high pH values, we observe closed, faceted vesicles with two-dimensional hexagonal molecular arrangements, and at intermediate pH, we observe ribbons with rectangular-C packing. Furthermore, as pH increases, we observe interdigitation of the bilayer leaflets. Accurate atomistic molecular dynamics simulations explain the pH-dependent bilayer thickness changes and also reveal bilayers of hexagonally packed tails at low pH, where only a small fraction of anionic headgroups is charged. Coarse-grained simulations show that the mesoscale geometries at low pH are faceted vesicles where liquid-like edges separate flat crystalline domains. Our simulations indicate that the curved-to-polyhedral shape transition can be controlled by tuning the tail density in regions where sharp bends can form the polyhedral edges. In particular, the pH acts to control the overall morphology of the ionic bilayers by changing the local crystalline order of the amphiphile tails

Metal–Organic Transmembrane Nanopores

Mariangela Boccalon , Elisabetta Iengo *, and Paolo Tecilla *

Department of Chemical and Pharmaceutical Sciences,University of Trieste, via Giorgieri 1, I-34127, Trieste, Italy

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/ja310425j

Publication Date (Web): November 29, 2012

Copyright © 2012 American Chemical Society

A stable tetraporphyrin metallacycle with Re(I) corners (1) is capable of forming nanopores in a liposomial membrane, provided that the porphyrin units are properly functionalized with peripheral carboxylic acid residues that, by establishing an hydrogen bond network, allow the formation of dimers that span the depth of the membrane.

Ultrasensitive Broadband Probing of Molecular Vibrational Modes with Multifrequency Optical Antennas

Heykel Aouani *†, Hana Šípová ‡, Mohsen Rahmani ¶§,Miguel Navarro-Cia , Kateřina Hegnerová ‡, Jiří Homola ‡, Minghui Hong §, and Stefan A. Maier †

^† The Blackett Laboratory, Department of Physics,Imperial College London, London SW7 2AZ, United Kingdom

^‡ Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Chaberska 57, 18251 Prague, Czech Republic

^¶ Data Storage Institute, (A*STAR) Agency for Science, Technology and Research, 5 Engineering Drive 1, Singapore 117608

^§ Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576

 Department of Electronic & Electrical Engineering, University College London, London WC1E 7JE, United Kingdom

 Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering,Imperial College London, London SW7 2BT, United Kingdom

ACS Nano, Article ASAP

DOI: 10.1021/nn304860t

Publication Date (Web): December 2, 2012

Copyright © 2012 American Chemical Society

Optical antennas represent an enabling technology for enhancing the detection of molecular vibrational signatures at low concentrations and probing the chemical composition of a sample in order to identify target molecules. However, efficiently detecting different vibrational modes to determine the presence (or the absence) of a molecular species requires a multispectral interrogation in a window of several micrometers, as many molecules present informative fingerprint spectra in the mid-infrared between 2.5 and 10 μm. As most nanoantennas exhibit a narrow-band response because of their dipolar nature, they are not suitable for such applications. Here, we propose the use of multifrequency optical antennas designed for operating with a bandwidth of several octaves. We demonstrate that surface-enhanced infrared absorption gains in the order of 10⁵ can be easily obtained in a spectral window of 3 μm with attomolar concentrations of molecules, providing new opportunities for ultrasensitive broadband detection of molecular species viavibrational spectroscopy techniques.

Polymer Brushes: High-Resolution, Large-Area, Serial Fabrication of 3D Polymer Brush Structures by Parallel Dip-Pen Nanodisplacement Lithography

1. 
   

1. Xuechang Zhou^1,2, 
2. Zhilu Liu^1,2, 
3. Zhuang Xie^1,2, 
4. Xuqing Liu^1,2, 
5. Zijian Zheng^1,2,*

Article first published online: 3 DEC 2012

DOI: 10.1002/smll.201290128

Large-area, serial fabrication of 3D polymer structures via parallel dippen nanodisplacement lithography (p-DNL) is demonstrated by Z. Zheng and co-workers on page 3568. p-DNL is a scanning probe-based lithography method that utilizes an array of atomic force microscopy tips to simultaneously displace the inert self-assembled monolayer (SAM) on the surface of a Au substrate with initiator-bearing thiol molecules pre-inked on the tips. By employing p-DNL, 2D patterns of initiator SAMs of rationally designed lateral spacings are readily fabricated in parallel over millimeter scales, and 3D polymer structures are fabricated from such 2D templates owing to different feature densities. This work holds great promise for the engineering of functional structures of high resolution and flexibility over large areas.