California NanoSystems Institute
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March 02, 2010

Paul Rothemund
Computer Science, Bioengineering
California Institute of Technology

Streaming Video

Beyond Watson and Crick: Recent advances in the use of DNA as a nanoscale building material
Nearly 30 years ago, Ned Seeman proposed to use DNA as a set of programmable molecular tinkertoys. His goal was to create three dimensional latticeworks for protein crystallography and scaffolds for nanoelectronic devices. Today, such crystals have been achieved---and much more. We can now fold long strands of DNA, origami-like, into any desired 2D or 3D shape, and these 100 nanometer single molecules can be decorated with components at 5 nanometer resolution. Next questions include: How will we use these structures? How will we turn them into functional devices and integrate them with conventional microfabrication? Initial attempts to answer these questions will be discussed, including the precise positioning of DNA origami on silicon and the use of DNA origami to create a carbon nanotube field effect transistor.

February 23, 2010

Chee Wei Wong
Mechanical Engineering
Columbia University
Nonlinear and Quantum Optics in Photonic Nanostructures
We describe our studies at the intersection of solid-state physics with optical nanosciences and engineering. First, we describe the strong control of dispersion and localization in photonic crystal structures, leading to the observations of negative refraction, zero-index superlattice band gaps, and ultrahigh-Q subwavelength nanocavities. Coherent interactions lead to our observations of an optical analog to electromagnetically-induced-transparency. Second, we report on studies in nonlinear optics through the tight field confinement and long photon lifetimes in photonic crystal structures. Examples include chip-scale femtosecond soliton pulse compression, Fano-type optical bistability at femtojoule levels, slow-light four-wave mixing and Raman scattering. Third, we describe our efforts in quantum optics through these nanostructures. Examples include controlling spontaneous emission through cavity quantum electrodynamics for efficient on-demand single photon sources, single exciton-photon coupling, and theoretical proposals to realize scalable quantum phase gates for quantum information sciences. Biography: Chee Wei Wong enjoys examining nonlinear and quantum optics in nanophotonics. He joined the Columbia faculty in 2004, and is a recipient of the DARPA Young Faculty Award in 2007, the NSF CAREER Award in 2008, and the 3M Faculty Award in 2009. He received his Sc.D. at MIT in 2003, his S.M. at MIT in 2001, and his B. Sc. highest honors at UC Berkeley (1996 - 1999), and his B. A. highest honors at UC Berkeley (1996 - 1999). He was a post-doctoral research associate with the MIT Microphotonics Center in 2003. He is a member of APS, ASME, IEEE, OSA and Sigma Xi.

February 16, 2010

Daniel Nocera

Streaming Video

Personalized Energy for 1 (x 6 Billion)
The capture and storage of solar energy at the individual level - personalized solar energy - drives inextricably towards the heart of this energy challenge by addressing the triumvirate of secure, carbon neutral and plentiful energy. Because energy use scales with wealth, point-of-use solar energy will put individuals, in the smallest village in the non-legacy world and in the largest city of the legacy world, on a more level playing field. Moreover, personalized energy (PE) is secure because it is highly distributed and the individual controls the energy on which she/he lives. Finally, the doubling of global energy need by mid-century and tripling by 2100 is driven by 3 billion low-energy users in the non-legacy world and by 3 billion people yet to inhabit the planet over the next half century. The possibility of generating terawatts of carbon-free energy, and thus providing society with its most direct path to realizing a low GHG future, may be realized by making solar PE available to the 6 billion new energy users by high throughput manufacturing. Notwithstanding, current options to harness and store solar energy at the individual level are too expensive to be implemented, especially in a non-legacy world. The imperative to science is to develop new materials, reactions and processes that enable personalized solar energy to be sufficiently inexpensive to penetrate global energy markets and especially the non-legacy world. Personalized energy at low cost presents new basic research targets. Because personalized energy will be possible only if solar energy is a 24/7 available supply, the key enabler for personalized energy is inexpensive storage. Studies in the Nocera group have led to the creation of a new catalyst that captures many of the functional elements of photosynthesis and in doing so provides a highly manufacturable and inexpensive method to effect a carbon-neutral and sustainable method for solar storage - solar fuels from water-splitting. By developing an inexpensive 24/7 solar energy system for the individual, a carbon-neutral energy supply for 1 x 6 billion becomes available.

February 09, 2010

Vincent Castranova
Physiology and Pharmacology
West Virginia University

Streaming Video

Pulmonary Responses to Multi-walled Carbon Nanotube Exposure
Multi-walled carbon nanotubes (MWCNT)have unique physicochemical properties which are being explored for applications in targeted drug delivery, bone grafting, electronics, sensors, heaters, structural materials, sporting goods, and water purification. Due to their wide range of applications, there exists the potential for worker exposure during synthesis, transfer, use, and disposal. Therefore, the potential adverse pulmonary effects upon inhalation are a concern. NIOSH scientists have exposed mice by pharyngeal aspiration to a well dispersed suspension of MWCNT (10 - 80 ug/mouse). At 1 - 56 days post-exposure, bronchoalveolar lavage markers of inflammation and damage were monitored. In addition, the deposition, fate, and pulmonary response were evaluated histologically. Pulmonary aspiration of MWCNT resulted in a dose dependent inflammation and injury response which was transient. Exposure also resulted in a granulomas and fibrosis which were both rapid in onset and persistent. Microscopic evaluation indicates the MWCNT enter alveolar macrophages, penetrate alveolar epithelial cells and enter the interstitial space, and penetrate the pleural surface to enter the intrapleural space. Preliminary data indicate the inhalation exposure results in similar pulmonary reactions as exposure by pharyngeal aspiration. In summary, results indicate that MWCNT can cause persistent pulmonary fibrosis. Therefore, it appears prudent to limit exposure of workers to MWCNT.

February 02, 2010

Fraser Stoddart
Northwestern University

Streaming Video

Molecular Nanotechnology in Tomorrow's World
The development of molecular electronic devices (MEDs) for memory and logic applications in computing presents one of the most exciting contemporary challenges in nanoscience and nanotechnology. The lecture will highlight how the concepts of molecular recognition and self-assembly (template-directed synthesis) have been pursued actively during the production of two families of redox-controllable mechanically interlocked molecules-namely, bistable catenanes and bistable rotaxanes-which can be incorporated into a device setting in the form of a two-terminal molecular switch tunnel junction (MSTJ) wherein the bistable molecules can be switched electrically between high- and low-conductance states. In the case of a two-terminal MSTJ, the objective is to design and make a bistable molecule that, collectively in the device at a specific voltage, switches from a stable structure (isomer) to another metastable isomer with a different conductivity. The molecule needs to remain in the metastable state until either another voltage pulse is applied or thermal fluctuations cause a return to the starting state. The two states of the molecule correspond to the ON and OFF states of the switch and the finite stability of the metastable state leads to a hysteretic current/voltage response that forms the basis of the switch. Molecular random access memory (RAM) can be created by fabricating many MSTJs simultaneously into a crossbar type of architecture in a MED.

The lecture will conclude with the description of a 160,000-bit molecular electronic memory circuit based on a bistable [2]rotaxane and fabricated at a density of 100,000,000,000 bits per square centimeter-that is, roughly analogous to the density of a DRAM circuit projected to be available by 2020. The entire 160,000-bit crossbar is smaller than the cross-section of a white blood cell. Arguably, chemical systems are at their best when they are robust and smart. Imagine a device for the specific delivery of an anticancer drug targeted to breast cancer cells that involves a rugged nanoscale container, endowed with nanoscale antennae and associated machinery. The containers we are using consist of mesoporous glass nanoparticles (200-500 nm in diameter) adorned with antennae to seek out diseased cells in preference to healthy ones and interspersed on the surface of the nanoparticles with different models of nanomachinery that can be actuated chemically (pH change), biochemically (enzyme action), or photophysically (light). Alongside a wide variety of drug delivery systems that include polymers, in many different guises, mesoporous silica nanoparticles have several highly attractive features that commend them for use in the delivery of chemotherapeutic agents. The nanoparticles can be made with complete control being exercised, not only on their diameters, but also on the dimensions of the cylindrical cavities that characterize the mesoporous glass in a periodic (often hexagonal) manner. Since the nanoparticles are made of glass they are not only robust and innocuous but they are also biocompatible and nontoxic. They have large surface areas and their porous interiors can be employed as reservoirs for storing (hydrophobic) drugs, usually introduced quite simply under a concentration gradient. The pore sizes can be rather accurately and tightly controlled during the synthesis of the mesoporous glass nanoparticles, while their size and shape can be tuned to maximize their uptake by cells. The lecture will describe the progress we are making in our research with these mechanized nanoparticles.

January 26, 2010

Mauro Ferrari
Nanomedicine and Biomedical Engineering (nBME), Internal Medicine, Division of Cardiology, The University of Texas Health Science Center

Streaming Video

Cancer Nanotechnologies
I will present a view from the trenches on the use of nanotechnologies applied to the personalization of cancer diagnosis and therapy. In particular, I will discuss the four research platforms in our group: Multistage vectors for directed delivery of therapeutic agents; Implantable nanochannel systems for controlled release; Bio-nanoscaffolds for regenerative medicine; and Proteomic/Peptidomic nanochips for early detection and therapeutic efficacy monitoring.

January 19, 2010

L. Mahadevan
Applied Mathematics,School of Engineering and Applied Sciences
Harvard University

Streaming Video

Continuum and statistical mechanics of ribbons
Ribbons are chimeric geometric creatures - part filament-like and part membrane-like. The large separation in length scales between the thickness, width and length of ribbons leads to some unusual consequences for their mechanical behavior. I will describe theoretical work on two recent examples that we have studied - the statistical and continuum mechanics of ribbons inspired by macromolecular assemblies, and the continuum mechanics of growing blades inspired by the shape of long leaves and algal blades.

January 12, 2010

Chris Voigt
Pharmaceutical Chemistry
University of California,San Francisco

Streaming Video

Programming Cells: Using a Synthetic Light Sensor as a Fast, High-Resolution Input to Signaling Networks
Cells integrate environmental signals and control programs of gene expression using complex and highly integrated regulatory networks. We have constructed a series of light sensing proteins that operate in bacteria and mammalian cells. Light is an ideal means to perturb and control regulatory networks because it offers unparalleled spatiotemporal control. Orthogonal green and red light sensors have been constructed that operate in E. coli. When an image is projected on a lawn of bacteria, the sensors are able to record the image as a pattern of gene expression. We are using this as a platform to combine simple genetic circuits to reconstruct signal processing algorithms. The bacteria present the results of the computation to the user as a visible, printed output at a macroscopic scale. I will describe how this has inspired new computational methods to connect and optimize genetic circuits. This work will help elucidate the design principles by which simple genetic circuits can be combined to produce complex functions. We have constructed an analogous light sensor that controls a protein-protein interaction in mammalian cells. Because protein-protein interactions are one of the most general currencies of cellular signaling, this system can be used to control diverse functions. I will show that this system can be used to precisely and reversibly translocate target proteins to the membrane with micrometer spatial resolution and second time resolution. The system has also been used to control the translocation of rho-family GTPases and their upstream activators. This enables light to be used to control the actin cytoskeleton to precisely reshape and direct cell morphology. The light-gated protein-protein interaction will be useful for the design of diverse light-programmable reagents, potentially enabling a new generation of quantitative perturbation experiments in cell biology.
January 05, 2010

Nai-Chang Yeh,
Professor of Physics
The Kavli Nanoscience Institute, California Institute of Technology

Streaming Video

Spatially Resolved Spectroscopic Studies of Strongly Correlated Electronic Systems at the Nano Scale
The competition among charge, spin, orbital, phonon and spatial degrees of freedom in strongly correlated electronic systems often leads to novel ground states that consist of either coexisting phases or spatial phase separations. Some of the celebrated examples of strongly correlated electrons include the high-temperature superconducting cuprates, colossal magnetoresistive (CMR) manganites and fractional quantum Hall systems. In this talk, I shall review the richness and novelty of physical phenomena revealed by our recent spatially resolved spectroscopic studies of various correlated electronic systems, including the superconducting cuprates [1-3], ferromagnetic manganites, graphene [4], and quantum confined silicon nano-pillars. These experimental investigations based on the cryogenic scanning tunneling microscopy/spectroscopy (STM/STS) and spin-polarized STM/STS (SP-STM/STS) enable direct nano-scale manifestation of the electronic structures, thereby providing useful information about how the ground state and low-energy excitations of correlated electrons evolve with varying competing mechanisms. [1] N.-C. Yeh and A. D. Beyer, Int, J. Mod. Phys. 23, 4543 - 4577 (2009). [2] A. D. Beyer et al., Europhys. Lett. 87, 37005 (2009). [3] M. L. Teague et al., Europhys. Lett. 85, 17004 (2009). [4] M. L. Teague et al., Nano Lett. 9, 2542 - 2546 (2009).