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News Article | September 6, 2016
Site: www.cemag.us

Rutgers University engineers have found a simple method for producing high-quality graphene that can be used in next-generation electronic and energy devices: bake the compound in a microwave oven. The discovery is documented in a study published online in the journal Science. “This is a major advance in the graphene field,” says Manish Chhowalla, professor and associate chair in the Department of Materials Science and Engineering in Rutgers’ School of Engineering. “This simple microwave treatment leads to exceptionally high quality graphene with properties approaching those in pristine graphene.” The discovery was made by post-doctoral associates and undergraduate students in the department, says Chhowalla, who is also the director of the Rutgers Institute for Advanced Materials, Devices and Nanotechnology. Having undergraduates as co-authors of a Science paper is rare but he says “the Rutgers Materials Science and Engineering Department and the School of Engineering at Rutgers cultivate a culture of curiosity driven research in students with fresh ideas who are not afraid to try something new.’’ Graphene — 100 times tougher than steel — conducts electricity better than copper and rapidly dissipates heat, making it useful for many applications. Large-scale production of graphene is necessary for applications such as printable electronics, electrodes for batteries and catalysts for fuel cells. Graphene comes from graphite, a carbon-based material used by generations of students and teachers in the form of pencils. Graphite consists of sheets or layers of graphene. The easiest way to make large quantities of graphene is to exfoliate graphite into individual graphene sheets by using chemicals. The downside of this approach is that side reactions occur with oxygen — forming graphene oxide that is electrically non-conducting, which makes it less useful for products. Removing oxygen from graphene oxide to obtain high-quality graphene has been a major challenge over the past two decades for the scientific community working on graphene. Oxygen distorts the pristine atomic structure of graphene and degrades its properties. Chhowalla and his group members found that baking the exfoliated graphene oxide for just one second in a 1,000-watt microwave oven, like those used in households across America, can eliminate virtually all of the oxygen from graphene oxide. The Rutgers engineers’ research was funded by the National Science Foundation, Rutgers Energy Institute, U.S. Department of Education, and Rutgers Aresty Research Assistant Program. The study’s lead authors are Damien Voiry, a former Rutgers post-doctoral associate in Chhowalla’s Nano-materials & Devices Group who is now at the University of Montpellier in France, and Jieun Yang, a post-doctoral associate in Chhowalla’s group. Other authors include Jacob Kupferberg, who will be a Rutgers senior this fall; graduate student Raymond Fullon; Calvin Lee, who graduated in 2015; Hu Young Jeong and Hyeon Suk Shin from the Ulsan National Institute of Science and Technology in South Korea; and Chhowalla.

Dunn S.S.,Wyss Institute for Biologically Inspired Engineering | Perry J.L.,Lineberger Comprehensive Cancer Center | Desimone J.M.,Lineberger Comprehensive Cancer Center | Desimone J.M.,Institute for Advanced Materials | And 3 more authors.
ACS Macro Letters | Year: 2013

The complexity of tumor biology warrants tailored drug delivery for overcoming the major challenges faced by cancer therapies. The versatility of the PRINT (Particle Replication In Nonwetting Templates) process has enabled the preparation of shape- and size-specific particles with a wide range of chemical compositions and therapeutic cargos. Different particle matrices and drugs may be combined in a plug-and-play approach, such that physicochemical characteristics of delivery vectors may be optimized for biocompatibility, cargo stability, and release, circulation half-life, and efficacy. Thus, the engineering of particles for cancer therapy with specific biophysical behaviors and cellular responses has been demonstrated via the PRINT process. © 2013 American Chemical Society.

Galani A.,National and Kapodistrian University of Athens | Efthimiadou E.K.,Advanced Materials and Processes | Theodosiou T.,Institute for Advanced Materials | Kordas G.,Advanced Materials and Processes | Karaliota A.,National and Kapodistrian University of Athens
Inorganica Chimica Acta | Year: 2014

This paper deals with the synthesis, characterization and biological evaluation of mixed ligand zinc complexes with the third generation quinolones' representative, levofloxacin. Two novel zinc (II) complexes of fluoroquinolone drug levofloxacin (H-levo), containing 1,10-phenanthroline (phen) (complex 1) and 2,2′-bipyridine (bipy) (complex 2) were synthesized and evaluated as antimicrobial agents, antitumor antibiotics and fluorescent probes. The highlight of this work is the ability of the aforementioned complexes to penetrate the cell membrane inducing fluorescence. The complexes structural characterization was performed by means of elemental and thermogravimetric analysis, FT-IR, RAMAN, 1H NMR, 13C NMR, and UV-Vis. The complexation of zinc (II) metal ion with the deprotonated ligand levofloxacin and heteroligands reveals that levofloxacin coordinated to zinc through one pyridone and one carboxylato oxygen as well as with two nitrogen atoms from the heteroligands. Additionally, complexes have been tested for their antimicrobial activity, revealing an increased potency in comparison with the free H-levo ligand. The cytotoxic behavior of the synthesized mixed complexes in comparison with the free ligands was performed by MTT assay. It was found that the proliferation rate and viability of MCF-7 cells decreased after treatment with the above complexes. Zinc levofloxacin mixed complex with 1,10-phenanthroline (complex 1) presents the highest effect in comparison with zinc levofloxacin complex with 2,2′-bipyridine (complex 2). Furthermore, it was investigated the ability of mixed zinc complexes to penetrate the cell membrane inducing fluorescence. The results show that both complexes penetrate the cell membrane acting both, as fluorescent probes and as new cytotoxic drugs. © 2014 Elsevier B.V. All rights reserved.

Rezvantalab H.,Rutgers University | Shojaei-Zadeh S.,Rutgers University | Shojaei-Zadeh S.,Institute for Advanced Materials
ACS Nano | Year: 2016

We investigate the response of a single Janus nanoparticle adsorbed at an oil-water interface to imposed shear flows using molecular dynamics simulations. We consider particles of different geometry, including spheres, cylinders, and discs, and tune their degree of amphiphilicity by controlling the affinity of their two sides to the fluid phases. We observe that depending on the shape, amphiphilicity, and the applied shear rate, two modes of rotational dynamics takes place: a smooth tilt or a tumbling motion. We demonstrate that irrespective of this dynamic behavior, a steady-state orientation is eventually achieved as a result of the balance between the shear- and capillary-induced torques, which can be tuned by controlling the surface property and flow parameters. Our findings provide insight on using flow fields to tune particle orientation at an interface and to utilize it to direct their assembly into ordered monolayers. © 2016 American Chemical Society.

Rezvantalab H.,Rutgers University | Shojaei-Zadeh S.,Rutgers University | Shojaei-Zadeh S.,Institute for Advanced Materials
Langmuir | Year: 2013

We study the capillary interactions between ellipsoidal Janus particles adsorbed at flat liquid-fluid interfaces. In contrast to spherical particles, Janus ellipsoids with a large aspect ratio or a small difference in the wettability of the two regions tend to tilt at equilibrium. The interface deforms around ellipsoids with tilted orientations and thus results in energetic interactions between neighboring particles. We quantify these interactions through evaluation of capillary energy variation as a function of the spacing and angle between the particles. The complex meniscus shape results in a pair interaction potential which cannot be expressed in terms of capillary quadrupoles as in homogeneous ellipsoids. Moreover, Janus ellipsoids in contact exhibit a larger capillary force at side-by-side alignment compared to the tip-to-tip configuration, while these two are of comparable magnitude for their homogeneous counterparts. We evaluate the role of particles aspect ratio and the degree of amphiphilicity on the interparticle force and the capillary torque. The energy landscapes enable prediction of micromechanics of particle chains, which has implications in predicting the interfacial rheology of such particles at fluid interfaces. © 2013 American Chemical Society.

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