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Full-Text Articles in Nanoscience and Nanotechnology

Microbiosensors Based On Dna Modified Single-Walled Carbon Nanotube And Pt Black Nanocomposites, Jin Shi, Tae-Gon Cha, Jonathan C. Claussen, Alfred R. Diggs, Jong Hyun Choi, D. Marshall Porterfield Jan 2011

Microbiosensors Based On Dna Modified Single-Walled Carbon Nanotube And Pt Black Nanocomposites, Jin Shi, Tae-Gon Cha, Jonathan C. Claussen, Alfred R. Diggs, Jong Hyun Choi, D. Marshall Porterfield

Jonathan C. Claussen

Glucose and ATP biosensors have important applications in diagnostics and research. Biosensors based on conventional materials suffer from low sensitivity and low spatial resolution. Our previous work has shown that combining single-walled carbon nanotubes (SWCNTs) with Pt nanoparticles can significantly enhance the performance of electrochemical biosensors. The immobilization of SWCNTs on biosensors remains challenging due to the aqueous insolubility originating from van der Waals forces. In this study, we used single-stranded DNA (ssDNA) to modify SWCNTs to increase solubility in water. This allowed us to explore new schemes of combining ssDNA-SWCNT and Pt black in aqueous media systems. The result …


Electrochemical Glutamate Biosensing With Nanocube And Nanosphere Augmented Single-Walled Carbon Nanotube Networks: A Comparative Study, Jonathan C. Claussen, Mayra S. Artiles, Eric S. Mclamore, Subhashree Mohanty, Jin Shi, Jenna L. Rickus, Timothy S. Fisher, D. Marshall Porterfield Jan 2011

Electrochemical Glutamate Biosensing With Nanocube And Nanosphere Augmented Single-Walled Carbon Nanotube Networks: A Comparative Study, Jonathan C. Claussen, Mayra S. Artiles, Eric S. Mclamore, Subhashree Mohanty, Jin Shi, Jenna L. Rickus, Timothy S. Fisher, D. Marshall Porterfield

Jonathan C. Claussen

We describe two hybrid nanomaterial biosensor platforms, based on networks of single-walled carbon nanotubes (SWCNTs) enhanced with Pd nanocubes and Pt nanospheres and grown in situ from a porous anodic alumina (PAA) template. These nanocube and nanosphere SWCNT networks are converted into glutamate biosensors by immobilizing the enzyme glutamate oxidase (cross-linked with gluteraldehyde) onto the electrode surface. The Pt nanosphere/SWCNT biosensor outperformed the Pd nanocube/SWCNT biosensor and previously reported similar nanomaterial-based biosensors by amperometrically monitoring glutamate concentrations with a wide linear sensing range (50 nM to 1.6 mM) and a small detection limit (4.6 nM, 3s). These results combined with …


Nanotechnology Education—First Step In Implementing A Spiral Curriculum, Ganesh Balasubramanian, Vinod K. Lohani, Ishwar K. Puri, Scott W. Case, Roop L. Mahajan Jan 2011

Nanotechnology Education—First Step In Implementing A Spiral Curriculum, Ganesh Balasubramanian, Vinod K. Lohani, Ishwar K. Puri, Scott W. Case, Roop L. Mahajan

Ganesh Balasubramanian

A nanotechnology learning module was implemented into a freshman engineering course at Virginia Tech. The novelty of our approach is that an established spiral curriculum model has been employed, for the first time to the best of authors’ knowledge, to design the nanotechnology option. The module was piloted in a freshman class (180 students) during spring ‘08. The key components included (1) a prior knowledge survey, (2) a 40-minute in-class presentation on basic nanotechnology concepts, (3) an activity that involves nanoscale image analysis and the plotting of molecular forces usingLabVIEWsoftware,and(4)apost-modulesurvey.Lessonslearnedfromthepilotimplementationwereincorporated appropriately to expose roughly 1450 freshmen to nanotechnology basics in …


Effects Of Carbon Nanotube-Tethered Nanosphere Density On Amperometric Biosensing: Simulation And Experiment, Jonathan C. Claussen, James B. Hengenius, Monique M. Wickner, Timothy S. Fisher, David M. Umulis, D. Marshall Porterfield Jan 2011

Effects Of Carbon Nanotube-Tethered Nanosphere Density On Amperometric Biosensing: Simulation And Experiment, Jonathan C. Claussen, James B. Hengenius, Monique M. Wickner, Timothy S. Fisher, David M. Umulis, D. Marshall Porterfield

Jonathan C. Claussen

Nascent nanofabrication approaches are being applied to reduce electrode feature dimensions from the microscale to the nanoscale, creating biosensors that are capable of working more efficiently at the biomolecular level. The development of nanoscale biosensors has been driven largely by experimental empiricism to date. Consequently, the precise positioning of nanoscale electrode elements is typically neglected, and its impact on biosensor performance is subsequently overlooked. Herein, we present a bottom-up nanoelectrode array fabrication approach that utilizes low-density and horizontally oriented single-walled carbon nanotubes (SWCNTs) as a template for the growth and precise positioning of Pt nanospheres. We further develop a computational …


Rh1−Xpdxnanoparticle Composition Dependence In Co Oxidation By Oxygen: Catalytic Activity Enhancement In Bimetallic Systems, James Russell Renzas, Wenyu Huang, Yawen Zhang, Michael E. Grass, Dat Tien Hoang, Selim Alayoglu, Derek R. Butcher, Franklin Tao, Zhi Liu, Gabor A. Somorjai Jan 2011

Rh1−Xpdxnanoparticle Composition Dependence In Co Oxidation By Oxygen: Catalytic Activity Enhancement In Bimetallic Systems, James Russell Renzas, Wenyu Huang, Yawen Zhang, Michael E. Grass, Dat Tien Hoang, Selim Alayoglu, Derek R. Butcher, Franklin Tao, Zhi Liu, Gabor A. Somorjai

Wenyu Huang

Bimetallic 15 nm Rh1−xPdxnanoparticle catalysts of five different compositions and supported on Si wafers have been synthesized, characterized using TEM, SEM, and XPS, and studied in CO oxidation by O2 in two pressure regimes: atmospheric pressure and 100–200 mTorr. The RhPd bimetallic nanocrystals exhibited similar synergetic effect of increased reaction activity at both atmospheric (760 Torr) and moderate (100–200 mTorr) pressures compared with pure Pd or Rh. The magnitude of the effect depends on the relative pressures of the CO and O2 reactant gases and the reaction temperature. The catalytic activity of the nanocrystals measured at moderate pressure is directly …


Efficient Quantum Cutting In Hexagonal Nagdf4:Eu3+ Nanorods, Pushpal Ghosh, Sifu Tang, Anja V. Mudring Jan 2011

Efficient Quantum Cutting In Hexagonal Nagdf4:Eu3+ Nanorods, Pushpal Ghosh, Sifu Tang, Anja V. Mudring

Anja V. Mudring

An ionic liquid (IL) assisted solvothermal method is employed to prepare single phase, oxygen free, hexagonal NaGdF4:Eu3+ (2 mol%) nanorods with a visible quantum efficiency of 187%. In contrast, for mixed materials containing cubic and hexagonal NaGdF4:Eu3+, the quantum efficiency is much less (127%). Thus, synthesis parameters have to be carefully chosen in order to get the high performance hexagonal material. Not only the influence of the IL but also of the Gd : F ratio during synthesis as well as the temperature were studied. It is found that the IL stabilizes the formation of hexagonal NaGdF4:Eu3+, likewise a fluoride …


Stability And Growth Behavior Of Transition Metal Nanoparticles In Ionic Liquids Prepared By Thermal Evaporation: How Stable Are They Really?, Kai Richter, Alexander Birkner, Anja V. Mudring Jan 2011

Stability And Growth Behavior Of Transition Metal Nanoparticles In Ionic Liquids Prepared By Thermal Evaporation: How Stable Are They Really?, Kai Richter, Alexander Birkner, Anja V. Mudring

Anja V. Mudring

Recently we developed an access to metal- and metal-oxide colloids based on thermal evaporation of metals into ionic liquids (ILs). Here we present systematic studies on the long-time stability of gold and copper nanoparticles (NPs) in different ILs. The influence of metal concentration and temperature on the ripening of the as-prepared gold NPs in different ILs was investigated by transmission electron microscopy (TEM) and UV-vis absorption measurements. Short alkyl chain-length-methyl-imidazolium salts with weakly coordinating perfluorinated counter anions (PF6, BF4 or Tf2N, bis(trifluoromethanesulfonyl)amide) were found to be better stabilizers compared to ILs with cations bearing long alkyl chains (trihexyltetradecylphosphonium, 1-octyl-3-methylimidazolium) and …


Rh1−X Pd X Nanoparticle Composition Dependence In Co Oxidation By No, James Russell Renzas, Wenyu Huang, Yawen Zhang, Michael E. Grass, Gabor A. Somorjai Jan 2011

Rh1−X Pd X Nanoparticle Composition Dependence In Co Oxidation By No, James Russell Renzas, Wenyu Huang, Yawen Zhang, Michael E. Grass, Gabor A. Somorjai

Wenyu Huang

Bimetallic 15 nm Pd-core Rh-shell Rh1−x Pd x nanoparticle catalysts have been synthesized and studied in CO oxidation by NO. The catalysts exhibited composition-dependent activity enhancement (synergy) in CO oxidation in high NO pressures. The observed synergetic effect is attributed to the favorable adsorption of CO on Pd in NO-rich conditions. The Pd-rich bimetallic catalysts deactivated after many hours of oxidation of CO by NO. After catalyst deactivation, product formation was proportional to the Rh molar fraction within the bimetallic nanoparticles. The deactivated catalysts were regenerated by heating the sample in UHV. This regeneration suggests that the deactivation was caused …


Europium(Iii) Fluoride Nanoparticles From Ionic Liquids: Structural, Morphological, And Luminescent Properties, Chantal Lorbeer, Joanna Cybinska, Anja V. Mudring Jan 2011

Europium(Iii) Fluoride Nanoparticles From Ionic Liquids: Structural, Morphological, And Luminescent Properties, Chantal Lorbeer, Joanna Cybinska, Anja V. Mudring

Anja V. Mudring

Inorganic luminescent materials (phosphors) find widespread scientific and industrial applications. For potential applications, nanoscale phosphors are favored because of the reduced scattering and the possibility to miniaturize devices. In such materials, the optical behavior is strongly dependent on impurities or defects in the crystal lattice, so that a well-defined reaction protocol with fixed parameters is compulsory to ensure the quality of the obtained material. The fast and facile conversion of europium acetate via microwave radiation with and in different tetrafluoroborate ionic liquids to oxygen-free, hexagonal EuF3 nanoparticles is investigated in detail. The study of the influence of the different reaction …