California NanoSystems Institute
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June 02, 2009

Teri Odom
Northwestern University
Multifunctional Plasmonic Nanopyramids: Opportunities for Biomedical Applications
Nanofabricated pyramids are a new class of asymmetric, metal particles that are an ideal architecture from which to build multifunctional structures. PEEL, our large-scale nanofabrication procedure for creating these particles, enables their structural properties to be controlled so that their optical properties can be tailored from visible to near-infrared wavelengths. For example, starting from a single-crystalline template, pyramids can be generated with variable sizes, thicknesses, and multi-material compositions; they can also be designed with blunt, ultra-sharp, or even without tips. Furthermore, we have achieved site-specific chemical and biological functionality on different portions of these pyramidal particles. Finally, we can readily design hybrid inorganic-organic and core-shell structures by combining assembly methods with PEEL. We will discuss our most recent results on using these pyramids in diagnostics and therapeutics.

May 26, 2009

Jonathan Bird
Electrical Engineering
University at Buffalo
Nano-Magneto Electronics: A Path to Unified Logic & Memory?
In modern microelectronics, semiconductors and ferromagnets both fulfill important roles, with the former being used in the field-effect transistors (FETs) that enable computational logic, while the latter provide the means to realize non-volatile data storage. The physical separation of logic and memory into spatially-separated components of the computer comes at the cost of increased power dissipation, and reduced overall speed of computation, problems that are becoming increasingly acute as the scaling of integrated circuits is continued. Consequently, it has become highly desired to unify logic and memory functions within the same device, and this is a challenge that will likely once again require innovation in fundamental solid-state physics. The physical implementation of any memory scheme requires a material or device that exhibits hysteretic response to some external variable, and magnetic materials are highly attractive for this purpose. In my presentation, I demonstrate a large tunneling magneto-resistance (TMR) effect in field-effect transistors, when their usual nonmagnetic gate is replaced with a nanoscale ferromagnet. I show how the conductance of these devices may be regulated by modulating either the electric or the magnetic fields that emanate from the gate. An analysis based on the Landauer-Büttiker approach yields a TMR amplitude in good agreement with that in experiment, indicating that it arises from the ability of fringing fields to modulate the effective tunnel barrier induced by the gate. The hysteretic TMR effect opens up the possibility of integrating both logic and memory functions within a single semiconductor device.

May 05, 2009

David Kaplan
Biomedical Engineering
Tufts University
Controlling Nanoscale Features of Fibrous Protein Materials Related to Function
Fibrous proteins such as silks provide a useful template from which to design a family of protein-based biomaterials where structure, morphology and chemistry can be tightly controlled. This control allows us to gain insight into the self-assembly process involved in materials formation as well as to control of nanoscale features related to function. We will report on recent studies to gain insight into mechanisms of assembly, and how this insight can provide a useful template upon which to build novel biomaterials. Studies on silk protein structure and stability attained from solution, thermal and structural analysis will be used to describe these fundamental features. Further, these issues impact the formation of novel biomaterials, novel optical devices and new functions, as well as impact degradation profiles of these materials in vitro and in vivo.

April 28, 2009

Koji Ando
Nanoelectronics Research Institute
National Institute of Advanced Industrial Science and Technology (AIST)

Streaming Video

Spintronics: a nanotechnology to control spin for normally-off-computer
Electron has two degree freedom: spin and charge. Spin is a basis of the Magnetics (magnet, magnetic tape, HDD and so on). Charge is that of Electronics (transistor, LSI, laser and so on). Spintronics is a new technology that couples the functionalities of spin and charge. For the coupling, coil, which is a very inefficient device, has been indispensable. Spintronics will kick out the coil by realizing the coupling at quantum mechanical level. Nanotechnology is indispensable for spintronics because the typical spin diffusion length in solid is nano meter scale.

Among some functionalities of spin, we are now interested in its non-volatile functionality. Non-volatile memory already forms a big business. We believe that potential of the non-volatile functionality is far beyond the traditional storage & memory functions. If all the information inside computer can be kept in the power-off state, we can turn off the power during finger moves from one key to another (some 10 ms) while the user does not notice that the power is frequently off/on during tapping in. We call it normally-off-computer (NOC). In order to realize NOC, we must develop a variety of fast non-volatile devices for working memories and logic circuits.

In my talk I will discuss first what the advantages of spintronics are. Then, I will focus on the achievements and challenges of spintronics toward NOC.

April 21, 2009

Hedi Mattoussi
Optical Sciences Division
US Naval Research Laboratory
Nanoparticle-bioconjugates: Design and Use for Sensing and Imaging
Luminescent quantum dots (QDs), as well as whole array of other inorganic nanoparticles, have a large fraction of their atoms arrayed on their surfaces, and they are capped with bifunctional ligands to promote their compatibility with the surrounding environments (e.g., solvents or polymer matrices). This makes their properties sensitive to that environment. Semiconductor QDs, in particular, exhibit photoemission that can be highly sensitive to potential interactions with proximal dyes and metal complexes, via resonance energy transfer or charge transfer mechanism. We have developed approaches based on non-covalent self-assembly to conjugate a variety of biomolecules to CdSe-ZnS core-shell QDs rendered water-soluble using multifunctional modular ligands. We start with a description of the ligand design we have developed to cap QDs (as well as Au nanoparticles) and promote their transfer to aqueous media, along with the conjugation of these nanoparticles to proteins and peptides. We then describe the use of peptides/proteins as bridges between CdSe-ZnS QDs and fluorescent dyes, Au nanoparticles and redox active metal complexes. These configurations promote QD PL quenching via either energy transfer from QDs to Au-NPs or charge transfer between redox complexes and QDs. For QD-Au-NP pairs the quenching was found to extend over distances beyond those allowed by conventional Förster resonance energy transfer. We will discuss the use of these materials to design sensing assemblies that are specific for target proteins and small molecules in vitro. We will also describe the use of QD-conjugates to image intracellular compartments.

April 14, 2009

James Glazier
Indiana University

Streaming Video

Understanding Early Vertebrate Development using Multi-Cell Simulations
The early embryonic body plan in vertebrates develops in phases beginning with cleavage of the fertilized egg continuing through gastrulation, which defines the main body axis and the three germ layers, and the definition of the segmental structure of the embryo during somitogenesis and ending with the formation of the primary vasculature and the beginning of organogenesis. I will focus on two stages of this development, the formation of the anterior-posterior body axis during primitive-streak elongation (gastrulation) and the subsequent breakup of the continuous presomitic mesoderm tissues into segments (somitogenesis). Multiple biological models have been proposed for both processes partially based on their resemblance to patterning in nonliving materials. Gastrulation produces striking long-range cell movements strongly resembling recirculation vortices in viscous fluids, but the underlying mechanisms generating cell movement remain obscure (chemoattraction, chemorepulsion, oriented cell division, intercalation). Somitogenesis couples a number of subcellular genetic oscillators (in the FGF, Wnt and Planar Polarity pathways) to produce remarkably stable traveling waves. These waves interact with cell-cell oscillator synchronization, cell division, cell migration and subcellular regulation of differentiation states to provide a highly robust and evolvable mechanism to produce controllable numbers and sizes of segments (from ciona to snakes). In both cases, multicell simulations can illuminate underlying mechanisms which are difficult to tease-out experimentally and predict the consequences of experimental perturbations.

April 07, 2009

Miguel Salmeron
Materials Sciences Division
Lawrence Berkeley National Laboratory

Streaming Video

Manipulation of matter at the nanometer scale: the imaging revolution
One of the most important and enabling advances in the field of nanotechnology is the development of Scanning Probe Microscopes. The capabilities of these instruments, for imaging solids, soft matter and liquids are beyond the wildest expectations of the inventors and first practitioners of the field. Surface chemistry at the single molecule level, manipulation of atoms and molecules by excitation of particular vibration and electronic modes is now a reality that opens the way for exquisite control of mater. Among the applications to be discussed are: imaging of nanometer size liquid films and droplets, friction and adhesion phenomena, electrical properties of organic layers for molecular electronic applications, etc.
March 31, 2009

Scott Diamond
Chemical and Biomolecular Engineering
University of Pennsylvania

Streaming Video

Cationic Steroids for Nano-Viroplexes: Anti-inflammatory, Anti-microbial, and Targeted Gene Transfer
Poor delivery remains the central challenge in gene therapy. Inflammatory and immunological responses to vectors reduce transgene expression and limit readministration. Adenovirus, retroviruses, plasmid DNA, lipoplexes, polyplexes, oligonucleotides, siRNA, and shRNA are all associated with substantial inflammatory side effects. Adeno-associated virus (AAV) is one of the least immunogenic viral vectors, yet AAV can display poor tropism and is still difficult to readminister. We developed cationic glucocorticoid-based lipids to deliver virus particles ("viroplexes"), reduce inflammatory/immunological responses, and improve redosing in the context of pulmonary delivery in mouse. These nanoparticle formulations are also bactericidal against E. coli and P. aeruginosa through a rapid cell rupture mechanism that may prove difficult for organisms to evolve resistance against.