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Jim Gimzewski, CNSI, UCLA
Professor, Chemistry and Biochemistry, Physical Chemistry
Title: Sub-100nm biological particle imaging and characterization with a purpose built nc-AFM
Abstract: Increasingly there is a growing interest in structural, bio-chemical and mechanical characterization of biological systems with dimensions in the sub-100nm range with nm resolution. In particular, liposome structures such as naturally occurring exosomes have been shown to be related to oral and other cancers. To study such particles on a individual basis require microscopy beyond current approaches. Likewise, in recently proposed drug-delivery nanosystems, the ability to image and verify encapsulation and function in liposomic nanocapsules and self-assembled natural protein structures is crucial. Vaults, viruses and other bio-structures all share the crucial sub- 100nm scale. the measurement of single DNA/RNA molecules to identify low copy number in mRNA from a single cell is an ultimate challenge for nanotechnology with disparate length and width scales of 1nm width to microns in length. I will present out latest work in these areas based on ongoing collaboration between CNSI, Pico Lab and the Dental and Medical Schools at UCLA. In particular we show results from a new generation of ultra sensitive low force AFM technologies which are developed at UCLA CNSI specifically for nanomedicine research.
Suneel Kodambaka, UCLA
Assistant Professor, Materials Science and Engineering
Title: In situ Microscopy Studies of 0D, 1D, and 2D Structures- Small Clusters, Nanowires, and Graphene
Abstract:
Progress in nanoscience and technology depends on the ability to systematically organize, manipulate, and characterize matter at the nanoscale. This can only be achieved through a detailed atomic-level understanding of the kinetic processes, mass transport mechanisms, chemical reaction paths, and material thermodynamics controlling the synthesis and stability of materials. Our group focuses on dynamic characterization of materials synthesis as a means to identify the factors influencing the structural, morphological, and compositional evolution of materials at the nanoscale. We use in situ characterization tools such as variable temperature scanning and transmission electron microscopies (SEM and TEM), scanning tunneling microscopy (VT-STM), and low-energy electron microscopy (LEEM), to investigate: thermal/chemical stability of nanocrystals (0D) and surfaces, nucleation and growth of one-dimensional (1D) nanowires, and 2D graphene thin films.
In this talk, I will present a brief overview of our ongoing research efforts in all these areas. Specific examples include:
(1) in situ lattice-resolution TEM studies of structural and morphological evolution of TiO2/C core/shell structures during annealing at temperatures up to 1000 oC. Here, we find several interesting phenomena: a) crystallization of carbon to form graphene layers preferentially on the lowest-energy planes of TiO2; b) shrinking and eventual disappearance of the oxide cores while being encapsulated by carbon, resulting in the formation of hollow-core graphene shell structures; and c) reduction of TiO2 to lower oxides. These studies provide atomic-scale insights into the early stage carbothermal reduction process leading to the synthesis of TiC particles,
(2) in situ TEM investigations of the nucleation and growth of Si and Ge nanowires, which provide new insights into the mechanisms controlling the crystalline structure and morphology as a function of growth flux and temperature, and
(3) in situ STM studies of graphene growth on Pd(111) during ethylene deposition at temperatures between 450 and 750 oC. I'll present first results of the role of substrate on modifying the electronic characteristics of graphene layer. Using scanning tunneling spectroscopy (STS) measurements, we show that graphene islands grown on Pd(111) are semiconducting, with a bandgap of 0.3 - 0.1 eV. Our findings suggest the possibility of preparing semiconducting graphene layers for future carbon-based nanoelectronic devices via direct deposition onto strongly interacting substrates.
Vidvuds Ozolins, CNSI, UCLA
Associate Professor, Materials Science and Engineering
Title: Computational design of new materials using first- principles quantum mechanical calculations
Abstract:
Jacob Schmidt, CNSI, UCLA
Assistant Professor, Bioengineering
Title: Lipid bilayer technologies enabling ion channel sensing and drug discovery
Abstract: Membrane channel proteins are major targets of drug discovery and screening and recent work has also shown their potential as sensors for the detection of small molecules and single molecule DNA sequencing. Although proof-of-concept demonstrations of many of these applications have been made, a significant obstacle toward practical realization of these technologies is the lipid bilayer membrane scaffold containing the ion channel. Conventional freestanding lipid bilayer membranes housing can be problematic to form and are extremely fragile, limiting their technological use. We have developed a number of technologies for membrane formation and stabilization, including hydrogel encapsulation/conjugation, solidification of membrane precursors, materials driven self-assembly in a microfluidic device, and gravity driven bilayer association. With these techniques, we have created membranes that can withstand severe perturbation, support long-term continuous measurements, can be shipped, and are compatible with high throughput robotic systems for drug discovery. I will discuss these technologies and their application to sensing and pharmaceutical research.
Ben Schwartz, CNSI, UCLA
Professor, Chemistry and Biochemistry, Physical Chemistry
Title: Controlling the nanometer-scale architecture of conjugated polymer-based bulk heterojunction solar cells
Abstract:
Ya-Hong Xie, CNSI, UCLA
Professor, Materials Science and Engineering
Title: Momentum and Energy Relaxation Processes of 2-D Electron Systems in Strained Si-SiGe
Abstract: The momentum and energy relaxation processes in 2-dimensional electron systems (2DES) in strained Si are interesting to the fundamental understanding of physics as well as the integrated circuit technology.
In this report, I will discuss our research on the transport of 2DES in strained Si with its unique 2-fold degeneracy of the conduction band. Energy relaxation processes dictate the temperature difference between the 2DES and the lattice and are important considerations in quantum transport experiments. Momentum relaxation processes, on the other hand relate intimately to the achievable electron mobility, which is important for the understanding of correlated electron behaviors. It will be shown that materials science plays a critical role in pushing the limits on the mobility of 2DES at cryogenic temperatures.
Jeff Zink, CNSI, UCLA
Professor, Chemistry and Biochemistry, Inorganic Chemistry, Physical Chemistry
Title: Meso-structured Films, Multifunctional Nanoparticles and Molecular Machines
Abstract: Mesostructured silica thin films and particles prepared by surfactant-templated sol-gel techniques are highly versatile substrates for the formation of functional materials. The ability to deliberately place molecules possessing desired activities in specific spatially separated regions of the nanostructure is an important feature of these materials. Such placement utilizes strategies that exploit the physical and chemical differences between the silica framework and the templated pores, and enables molecular machines to be synthesized. Three types of molecular machines that are based on molecules that undergo large amplitude motion when attached to mesoporous silica are described: impellers, valves and snap-tops. These machines function when activated by light, electrical (redox) and chemical (pH, competitive binding) energy.
Derivatized azobenzene molecules, attached to pore walls by using one of the placement strategies, function as impellers that can move other molecules through the pores. Nanoparticles containing anticancer drugs in the mesopores are taken up by cancer cells. When the impellers are activated by light, the drugs released from the pores and kill the cancer cells. These systems are the first examples of artificial molecular machines operating under remote control inside of living cells.
Rotaxanes and pseudorotaxanes, placed at pore entrances, function as gatekeepers or valves that can trap and release molecules from the pores when stimulated. Examples of these machines and their operation are discussed. Nanoparticles of mesostructured silica containing valve-controlled pores serve as controllable drug delivery vehicles. Uptake of these functional particles by living cells and release of drug molecules upon external command are described.
A new type of biocompatible nanodevice based on mesoporous silica nanoparticles with pore openings controlled by "snap-top" covers will be introduced. The silica functions as both the snap-top's support and as the container for the guest molecules. In general, the snap-top consists of a [2]rotaxane tethered to the surface of the nanoparticle in which a bulky torus encircles a polyethylene glycol thread and is held in place by a cleavable stopper. When closed the snap-top contains the guest molecules but releases them following cleavage of the stopper and dethreading of the torus. A snap-top that is responsive to specific enzymes for self-opening operation inside of cells is described in detail.
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