Synthesis and Immobilization of Silver Nanoparticles on Aluminosilicate Nanotubes and Their Antibacterial Properties

A novel colloidal method is presented to synthesize silver nanoparticles on aluminosilicate nanotubes. The technique involves decomposition of AgNO3 solution to Ag nanoparticles in the presence of aluminosilicate nanotubes at room temperature without utilizing of reducing agents or any organic additives. Aluminosilicate nanotubes are shown to be capable of providing a unique chemical environment, not only for in situ conversion of Ag+ into Ag0, but also for stabilization and immobilization of Ag nanoparticles. The synthesis strategy described here could be implemented to obtain self-assembled nanoparticles on other single-walled metal oxide nanotubes for unique applications. Finally, we demonstrated that nanotube/nanoparticle hybrid show strong antibacterial activity toward Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli

Gas transport in aluminosilicate nanotubes by diffusion NMR

Diffusion of tetrafluoromethane in aluminosilicate nanotubes was studied by means of 13C pulsed field gradient (PFG) NMR at 297 K. The measured data allow the estimation of the diffusivity of tetrafluoromethane inside the nanotubes as well as the diffusivity for these molecules undergoing fast exchange between many nanotubes. The results support the assumption about the one-dimensional nature of the tetrafluoromethane diffusion inside nanotubes

Formation and Growth Mechanisms of Single-Walled Metal Oxide Nanotubes

Gulfem Ipek Yucelen presented a lecture at the Nano@Tech Meeting on April 23, 2012 at 12 noon in room 1116 of the Marcus Nanotechnology Building.Ipek is a 4th year graduate student in Materials Science and Engineering. She obtained her undergraduate degree in Metallurgical & Materials Engineering from Istanbul Technical University and a Masters degree in Mechanical Engineering & Energy Processes from Southern Illinois University.Runtime: 22:40 minutesMetal oxide nanotubes have emerged as an important class of ‘building block’ materials for molecular recognition-based applications in catalysis, separations, sensing, and molecular encapsulation due to their well-defined wall structure and porosity, tunable dimensions, and chemically modifiable interior and exterior surfaces. However, their widespread application will depend on the development of synthesis processes that can yield structurally and compositionally well-controlled nanotubes. To this end, we have investigated the mechanisms of formation and growth of single-walled metal oxide nanotubes at multiple length scales, from the molecular scale to the micron-scale. We show how a wide range of quantitative and qualitative information regarding nanotube formation and growth can be obtained by nuclear magnetic resonance (NMR) spectroscopy, electrospray ionization (ESI) mass spectrometry, transmission electron microscopy (TEM), and solvated density functional theory (DFT) calculations. Integration of all this information leads to the construction of the first ‘design rules’ of single-walled metal oxide nanotube formation and growth

Gas transport in aluminosilicate nanotubes by diffusion NMR

Diffusion of tetrafluoromethane in aluminosilicate nanotubes was studied by means of 13C pulsed field gradient (PFG) NMR at 297 K. The measured data allow the estimation of the diffusivity of tetrafluoromethane inside the nanotubes as well as the diffusivity for these molecules undergoing fast exchange between many nanotubes. The results support the assumption about the one-dimensional nature of the tetrafluoromethane diffusion inside nanotubes

Gas transport in aluminosilicate nanotubes by diffusion NMR

Diffusion of tetrafluoromethane in aluminosilicate nanotubes was studied by means of 13C pulsed field gradient (PFG) NMR at 297 K. The measured data allow the estimation of the diffusivity of tetrafluoromethane inside the nanotubes as well as the diffusivity for these molecules undergoing fast exchange between many nanotubes. The results support the assumption about the one-dimensional nature of the tetrafluoromethane diffusion inside nanotubes

Defect Structures in Aluminosilicate Single-Walled Nanotubes: A Solid-State Nuclear Magnetic Resonance Investigation

We report a detailed investigation of the defect structures in aluminosilicate single-walled nanotubes via multiple advanced solid-state NMR techniques. A combination of ¹H–²⁹Si and ¹H–²⁷Al FSLG-HETCOR, ¹H CRAMPS, and ¹H–²⁹Si CP/MAS experiments were employed to evaluate the proton environments around Al and Si atoms in the final nanotube structure. The ¹H CRAMPS spectra of dehydrated aluminosilicate nanotubes revealed the proton environments in great detail. Integration of these results with the findings from the ¹H–²⁹Si and ¹H–²⁷Al FSLG-HETCOR and ¹H–²⁹Si CP/MAS data allows the structural assignment of all the chemical shifts and the identification of various types of defect structures in the aluminosilicate nanotube wall. In particular, we identify five main types of defect structures arising from specific atomic vacancies in the nanotube structure. It is estimated that ∼16% of Si atoms in the nanotube inner wall are involved in a defect structure. The characterization of the detailed structure of the nanotube wall is expected to have significant implications for its chemical properties and applications