Events: NanoSEC Seminars

• Engineered Nanoparticles for Tumor Imaging and Therapy

  Guest: Dr. Jin Xie, Dept. of Chemistry and Bioimaging Research Center, the University of Georgia
  Friday, October 7, 2011 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

  iCal

  Magnetic nanoparticles have long been an important class of biomaterials. Iron oxide nanoparticles, for instance, have been used in clinics as MR contrast probes, mostly for improving the visibility of lesions in reticuloendothelial system (RES) organs, such as liver and lymph nodes. Recently, a new set of chemistry has emerged, which allows one to prepare nanoparticles with fine control over a wide range of parameters, including size, shape, composition, magnetization, hydrodynamic size, surface coating and surface charge. Such a transition does not only affect the conventional applications of magnetic nanoparticles, but also opens many new avenues. The idea is to conceptualize a particle not only as a tiny magnetic crystal, but also as a platform of large surface-to-volume ratio. By harnessing the well-developed surface chemistry, one can load a wide range of functionalities onto the particle surface. These include biovectors--such as peptides and antibodies--which are able to steer the migration of nanoparticles in a living subject and to accumulate them preferentially in areas of interests, such as in tumors. The nanoplatforms can be further loaded with imaging motifs or therapeutic agents, and as a consequence, to be upgraded as multifunctional nanogadgets of multimodal imaging capabilities or theranostic features. In this talk I will introduce some of our recent work in this field.

   

• Curvature-Induced Dielectrophoresis for Particle and Cell Manipulations in Microfluidic Devices

  Guest: Professor Xiangchun Xuan, Department of Mechanical Engineering, Clemson University
  Friday, September 30, 2011 4:00 pm - 5:00 pm
  Location: Riverbend Research South Auditorium

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  Dielectrophoresis (DEP) is a powerful tool that has been widely used to manipulate (e.g., focus, trap, concentrate, and sort) particles and cells in microfluidic devices. Traditional electrode-based DEP (eDEP) arises from the non-uniform high-frequency AC electric field between pairs of electrodes that are fabricated within a microchannel. This method suffers from the problems of fabrication complexity and electrode fouling etc. Such problems are significantly mitigated in the so-called insulator-based DEP (iDEP) devices, where both AC and DC electric fields can be applied through the electrodes that are positioned virtually outside a microchannel. However, in-channel insulating obstacles such as hurdles, posts, and ridges are required to create the electric field gradients. The locally amplified electric field around these micro-obstacles may cause adverse effects on both the sample and the device due to potential Joule heating and particle clogging issues. Our group has recently developed a new method that exploits the curvature of insulating walls for a diverse electrical control of particle and cell motions in microfluidic devices. Due to the variation in path length for electric current, the electric field becomes inherently non-uniform within a microchannel corner. Thus induced DEP can generate both a crossstream and a counter-stream particle motion, which are second-order function of the electric field and are superimposed to the linear electrokinetic motion for flexible particle manipulations. In this talk I will present our recent results on the dielectrophoretic focusing, trapping, concentration, and separation of particles and cells in curved microchannels and microfluidic reservoirs with applications to lab-on-a-chip systems.

• Develop Sensing Technologies for Specialty Crops and Fiber

  Guest: Dr. Changying Li, Dept. of Biological and Agricultural Engineering, the University of Georgia
  Friday, April 22, 2011 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

  iCal

  In his talk “Develop Sensing Technologies for Specialty Crops and Fiber”, Dr. Li will give an overview of his recent research projects and explore opportunities of collaborating with engineers and scientists in the Nano Center.

  In the past four years, Dr. Li has established a research program focusing on developing sensing and automation technologies to enhance the quality and profitability of specialty crops and cotton. Specifically, he has been primarily working on three research areas: enhance the efficiency of vegetable postharvest sorting and storage through hyperspectral imaging and machine olfaction technologies; measure and reduce bruise damages in blueberry mechanical harvest by developing the “electronic blueberry”; and improve cotton fiber quality through optical sensing and effective ginning.

• Functional Polynorbornenes: Membrane-active Agents and Fireretardant Additives

  Guest: Dr. Gregory Gabriel, Department of Chemistry and Biochemistry, Kennesaw State University
  Friday, April 15, 2011 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

  iCal

  Our group has taken advantage of the ease of functionalizing norbornene monomers to make a range of polynorbornenes with designed activities. In our bio-project, one set of water-soluble polymers has been shown to interact with bacterial membranes in several distinct ways including disruption and penetration. We have measured the interactions of three of them with E. coli lipid extract vesicles using a Biacore SPR biosensor. These preliminary binding studies results will be presented. Our materials project involves a set of polymers with promising fire-retardant properties. We have observed how they perform on their own and also as additives in treated paper and polyurethane films. Most recently we have attempted to use our polymers to surface modify magnesium hydroxide which itself is a flame-resistant additive, but only at high loadings. Both of these projects have demonstrated that tuning the properties, of membrane-active agents and fire-retardant additives, can be achieved through facile modifications of the polymer along the
  backbone and side chains.

• Investigating the Interaction of Ultrashort Laser Pulses with Optical Materials and Components

  Guest: Dr. William Dennis, Department of Physics and Astronomy, the University of Georgia
  Friday, April 8, 2011 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

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  Modern table-top laser systems are capable of generating ultrashort optical pulses with sufficiently high intensity to induce nonlinear optical effects in many of the materials (including air!) that are used in the construction of optical components and systems. In this talk we describe how two of the techniques of computational optics can by provide insight into the complex dynamics that occurs at high intensities.

  Firstly we describe how a modified 3+1D nonlinear Schrodinger equation coupled to a rate equation for the plasma density in the dielectric material can be used to simulate pulse propagation and plasma formation in fused silica. In particular we analyze the influence of pulse-shape and beam geometry on the formation of the electron plasma and hence modification in the bulk material. Secondly we use the finite difference time domain (FDTD) technique to simulate ultrashort optical pulse propagation through
  dielectric filters.

• Metal Nanoclusters Tailored by Interfacial Bond Structures and the Transport at Single Nanopores

  Guest: Dr. Gangli Wang, Department of Chemistry, Georgia State University
  Friday, March 25, 2011 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

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  The presentation will briefly discuss our multidentate approach to create uniform metal nanoparticles by tailoring the core-ligand interactions. Exciting electrochemical and optical activities from sub-2-nm Au nanoparticles are reported. The talk will focus on novel mass transport behaviors through a single nanosized pipette or pore, analyzed by time and frequency domain electrochemical measurements and classic simulation. As the pore dimension miniaturizes and approaches that of a single bio-macromolecule, single molecule activities inside the mass transport limiting region perturb the ionic transport current thus be detected. Correlated with the well-known ion current rectification effect observed from various nanodevices, multitime-constant transport processes have been discovered. The knowledge allows us to differentiate the respective contribution to the current signal from substrate charges (coulomb interaction with fixed surface charges) and nanogeometry (volume effect). The transference number of cation and anion, and surface charge density of individual nanodevices, have been determined by combined experiments and simulation.

• Nanoengineered materials: Synthesis, design, functionalization and applications

  Guest: Dr. Simona Hunyadi Murph, Savannah River National Laboratory, Aiken, SC, 735-11A, Room 125
  Friday, February 25, 2011 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

  iCal

           Inorganic nanoparticles are inorganic materials in which the particle diameter is in the 1-100-nm regime. If we classify materials according to their electronic properties and assign them either to metals, semiconductors, or insulators, then metals and semiconductors are by far more interesting to contemplate on the nanoscale. Fundamentally, the mean free path of an electron in a metal at room temperature is ~10-100 nm, and one would predict that as the metallic particle shrinks to this dimension, unusual effects should be observed. In the case of metal nanoparticles, optical properties can be tuned extensively by the size, shape, aggregation, and local environment of the particle. For gold and silver, multiple plasmon bands that give rise to visible colors can occur in the visible and into the infrared for various geometries. Quantum dots are inorganic semiconductor nanoparticles that have a diameter in the 1-10 nm range, coincident with their respective excitonic Bohr radii. These materials are highly photoluminescent, resistant to photobleaching compared to organic fluorophores and their bandgap energies are exquisitely
  tunable with particle diameter, based on quantum confinement effects.

             This presentation highlights work from its authors’ laboratories on the synthesis, growth
  mechanism, physical properties, reactivity, and applications of silver, gold and platinum nanoparticles and quantum dots. This includes nanomaterials with various designs, geometries and compositions prepared by wet chemical synthesis approaches. These metallic nanoparticles are used as templates for creation of
  complex and ordered engineered nanomaterials with tailored and tunable structural, optical and surface properties. This consists of core-shell, nano-peapods, fluorescent, solid or hollow nanocomposites that can be used for a plethora of applications including (bio)chemical sensing, imaging, molecular-scale
  electronics, environmental implications and energy production applications.

• Synthesis and possible applications of some oxides nanostructures

  Guest: Prof. Zhengjun Zhang, Department of Materials Science and Engineering, Tsinghua University, China
  Monday, February 21, 2011 2:30 pm - 3:30 pm
  Location: Riverbend Research South Laboratory Auditorium

  iCal

  Metal oxides nanostructures can be fabricated on substrates by thermal oxidation approach or by glancing angle deposition. The nanostructures synthesized by thermal oxidation are normally single crystalline and exhibited some interesting properties. For example, vanadium oxide nanostructures exhibited very good photocatalytic activity, tungsten oxide nanostructures exhibited excellent field emission properties. By GLAD, the morphology of the nanostructures can be well controlled which is important for applications such as antireflection coatings.

• Thermoelectric Research at Nanoscale

  Guest: Professor Jin-Cheng Zheng, Department of Physics, Xiamen University, China
  Wednesday, February 9, 2011 3:00 pm - 4:30 pm
  Location: Riverbend Research South Auditorium

  iCal

  By converting waste heat into electricity through the thermoelectric power of solids without producing greenhouse gas emissions, thermoelectric generators could be an important part of the solution to today’s energy challenge. There has been resurgence in the search of new materials for advanced thermoelectric energy conversion applications. In this talk, I will present our recent progress on thermoelectric research such as thermoelectric transport in PbTe nanostructures, pressure-induced
  enhancement of thermoelectric performance in PbTe, SnTe, GeTe materials, strain engineering in graphene sheets and nanoribbons, as well as recent development of thermoelectric theory.

• Nanoscale Science&Engineering at Oxide-Oxide Interfaces

  Guest: Professor Hui-Qiong Wang, Department of Physics, Xiamen University, China
  Wednesday, February 9, 2011 3:00 pm - 4:30 pm
  Location: Riverbend Research South Auditorium

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  The unique characteristics of the outer d electrons lead to an extraordinary range of structural and electronic properties for transition-metal oxides. The interface between two transition-metal oxides is of significant interest in electronics and spintronics. Effort has been focused on the growth of atomically sharp interfaces between these oxides. However, an atomically sharp interface does not necessarily imply electronic abruptness. It is important to investigate the electronic transition at these oxide interfaces. In this talk, I will present our work on two types of oxide-oxide interfaces. For one type of interface, antiferromagnetic and insulating NiO and CoO thin films were grown on ferromagnetic and metallic Fe3O4 single-crystal substrates by molecular beam epitaxy (MBE); for the other type of interface, perovskite EuTiO3 thin films were grown on perovskite SrTiO3 single-crystal substrates by pulsed laser deposition (PLD). Electronic states at the buried interfaces were probed either by photoemission
  spectroscopy (PES) or by electron energy loss spectroscopy (EELS) based on Scanning Transmission Electron Microscopy (STEM).

• Hybrid Nanomaterials for Chemical and Biological Sensing

  Guest: Prof. Junhong Chen, Department of Mechanical Engineering, University of Wisconsin-Milwaukee
  Wednesday, January 5, 2011 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

  iCal

  Hybrid nanomaterials comprising nanoparticles (NPs) distributing on the surfaces of carbon nanotubes (CNTs) or graphene/graphene oxide (GO) represent a new class of materials. These materials could potentially display not only the unique properties of NPs and those of CNTs/graphene/GO, but also additional novel properties due to the interaction (e.g., electronic) between the NP and the CNT/graphene/GO. Such hybrid nanostructures are promising for various innovative technological applications, including chemical sensors, biosensors, water treatment, nanoelectronics, photovoltaic cells, fuel cells, and lithium ion batteries. This talk will introduce a material-independent, dry route based on the electrostatic force directed assembly (ESFDA) to assemble both aerosol and colloidal NPs onto CNTs/GO to form NP-CNT/GO hybrid structures. The areal density and the size distribution of NPs onthe CNT/GO can be controlled. Moreover, the non-covalent attachment of NPs preserves the intrinsic properties of CNTs/GO. Due to the inherent material-independence nature of the electrostatic force, various compositions of such NP-CNT/GO hybrids can be produced using this technique. Applications of such hybrid nanomaterials will also be presented for the detection of chemical and biological species. Through the combination of high-performance CNTs/GO and NPs of popular sensing materials, hybrid nanostructures exhibit high sensitivity to low-concentration chemical and biological species at room temperature. For instance, hybrid SnO2 NP-CNT platform allows for the room-temperature sensing of various gases, including those (CO and H2) known to be undetectable by either CNTs or SnO2 NPs alone at room temperature. Such superior sensing performance is attributed to the effective electronic transfer between NPs and the CNT, which facilitates the detection of gases through the change in the electrical conductivity of the hybrid nanostructure. Similarly, a specific biosensing platform based on Au NP and thermally-reduced GO (TRGO) has been demonstrated to successfully detect protein binding events (IgG to anti-IgG). The lower detection limit of the biosensor is on the order of 0.1 ng/ml (~1 pM) and could be further improved by optimizing the device structure. This performance is among the best of all carbon nanomaterial (e.g., CNT, graphene, GO)-based protein sensors.

• Biological micro-fluidics: lessons from insects

  Guest: Prof. David Hu, Department of Mechanical Engineering and Biology, Georgia Institute of Technology
  Friday, December 3, 2010 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

  iCal

  The future of engineering is in the small. The past decade has shown numerous advances in manufacturing science that bring lab-on-a-chip applications closer to reality. How can we control the motion of droplets cheaply, easily and robustly? As a biologist and an engineer, the speaker presents experiments demonstrating how insects manipulate fluid surfaces to their advantage. Social insects (fireants) link their bodies to together to weave hydrophobic surfaces in order to keep their colonies dry in rainstorms and floods. On dry surfaces, they excrete oily drops from their feet to scale smooth surfaces. Other insects, such as water striders, have evolved such mastery of surface tension that they can live atop water surfaces indefinitely. We use basic principles (energetics, Cassie and Wenzel laws) to provide a
  unified view of capillarity in the insect world. Particular attention is paid to rationalizing insect waterrepellency in terms of passive surface properties and active behaviors. Applications of our work towards building small-scale machines are also discussed.

• Reproductive Effects of Carbon Nanotubes for Ceriodaphnia dubia

  Guest: Marsha Black, Department of Environmental Health Science, University of Georgia
  Friday, November 19, 2010 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

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  Large amounts of carbon nanotubes are already being manufactured, which will lead to increasing concentrations of nanomaterials in the environment through accidental spills, product use and degradation, or known releases. Previous research has used acute toxicity tests to assess the potential toxicity of CNTs to freshwater invertebrates and fish, yet few chronic studies have been conducted to assess nonlethal effects. We studied chronic effects of 14C-labeled multi-walled carbon nanotubes (MWNTs) on Ceriodaphnia dubia, an aquatic invertebrate. For chronic exposures 14C- MWNTs were solubilized in moderately hard water (MHW) by four different methods: bath sonication, probe sonication, bath sonication followed by addition of Sewanee River natural organic matter (NOM, 2.3 mg C/L), and by stirring nanotubes overnight in NOM dissolved in MHW. Standard 3-brood chronic toxicity tests were conducted following EPA protocol. Reproductive effects (number and size of broods) and
  accumulation of nanotubes by adults and neonates were measured in replicated experiments for each solubilization treatment.

  Ceriodaphnia exposed to bath-sonicated MWNTs had significantly smaller brood numbers and size at the 2.5 mg/L concentration (LOEC), compared with controls. Exposures with probe-sonicated nanotubes showed less reproductive toxicity, with a LOEC of 5 mg/L. No reproductive toxicity was observed for nanotube exposures with added NOM (LOEC > 5 mg/L). Reproductive toxicity of the bathsonicated nanotubes may be related to association of the MWNTs onto the body surfaces of the adults,
  which likely interfered with molting and prevented neonate release (Fig. 1).

  We hypothesize that the surface association and reproductive toxicity of the bath-sonicated nanotubes is related to the larger nanotube size and higher degree of aggregation in these treatments. Probe sonicated MWNT solutions were more transparent and may have contained smaller-sized nanotubes. Solubilization of MWNTs in NOM likely increased their water solubility, reducing their potential to associate with adult body surfaces. However, neonates exposed to the NOM-solubilized nanotubes accumulated 14C-nanotubes in a concentration-dependent manner, suggesting ingestion of these more soluble nanotubes. Neonates and adults exposed to bath-sonicated MWNTs randomly accumulated 14C-MWNTs, likely by adherence of larger aggregates to body surfaces. This is one of the first known studies to document reproductive effects and accumulation of MWNTs in aquatic invertebrates and emphasizes the need to assess chronic, non-lethal effects of nanomaterials in aquatic organisms.

• Nanotechnology and Infectious Diseases: Opportunity Knocks

  Guest: Professor Duncan Krause, Department of Microbiology, Faculty of Infectious Diseases, University of Georgia
  Friday, November 12, 2010 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

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  Mycoplasmas are significant pathogens in humans, food animals, and wildlife. Existing antibody- and nucleic acid-based methods for detection and diagnosis have severe limitations, the consequences of which range from continued spread and increased risk for development of secondary complications in humans, to increased production costs for food animals. Thus, the inability to provide rapid, sensitive, and expedient detection of mycoplasmas in the complex biochemical backgrounds of clinical specimens is a major obstacle to the control of mycoplasma disease. Nanorod array-surface-enhanced Raman spectroscopy was applied to the detection and identification of Mycoplasma pneumoniae, a leading cause of bronchitis and atypical pneumonia in humans, in simulated and true clinical throat swab samples. Results from those studies will be presented, followed by general observations regarding the interface between nanotechnology and infectious disease research.

• Advanced Electron Microscopy at CAUR

  Guest: Jianguo Fan, Center for Advanced Ultrastructural Research, Department of Physics and Astronomy, Department of Geology, The University of Georgia
  Friday, October 29, 2010 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

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  Electron microscopy has become a key element in many research activities. In this talk, I will give an introduction to various microscopy instruments and techniques at CAUR (Center for Advanced Ultrastructural Research) for your research needs. A few examples will be illustrated.

• Rational Design Protein-based MRI Contrast Agents (ProCAs) with High Relaxivity and Target Capability to different types of Biomarkers

  Guest: Jenny J. Yang, Ph.D., Departments of Chemistry, Center for Drug Design and Advanced Biotechnology Georgia State University
  Friday, October 22, 2010 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

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  We have developed a new class of protein-based MRI contrast agent (ProCA) by de novo design of Gd3+ binding site(s) into a stable host protein with significantly improved MRI relaxivity at medical application field strengths. Designed proteins show strong Gd3+ affinity and selectivity over excess Ca2+ and other metal ions and a significant improvement in in vivo dose efficiency over clinically approved small molecule based contrast agents such as DTPA. These design ProCAs also exhibit a large improvement in blood retention time and pharmokinetics with excellent enhancement in angiography. Furthermore, we have successfully designed targeted MRI contrast agents to specifically recognize various biomarkers such as gastric release peptide receptors and HER2/EGFR overexpressed in different types of cancers and cell types without using antibodies. These developed targeting MRI contrast agent exhibit strong receptor-specific MRI enhancement both in tumor cells and xenograft mice models with desirable penetration of tissue and the endothelial boundary with applications in monitoring the level of expression and distribution of biomarkers in vivo and examining the response upon treatment by the targeted therapeutics.

• Nanostructure Multiband Detectors for UV to Far Infrared

  Guest: Dr. Unil Perera, Georgia State University, Department of Physics and Astronomy
  Friday, October 1, 2010 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

  iCal

  Semiconductor quantum dots are nano-particles showing remarkable optical properties from ultraviolet (UV) to infrared (IR) regions. Most of the quantum dots operating in visible or near-infrared regions utilize the electronic transitions between the valence and conduction sub-bands across the fundamental band-gap of the semiconductor material. In the infrared region, quantum dots are operated utilizing the electronic transitions between the sub-bands within the conduction (or valence) band. Here, various quantum dot infrared photodetector (QDIP) structures are presented. These can be operated as multi-band detectors in the mid-long-and far-infrared regions (terahertz). Specific QDIP architectures include dots-in-a-well (DWELL), tunneling quantum dot (T-QDIP), and superlattice quantum dot (SL-QDIP) structures. DWELL exhibits multi-color characteristics and offers wavelength tunability based on well parameters, instead of the quantum dot size. The main idea of T-QDIP is to reduce the dark current without reducing the photocurrent but can also be used for bias-selectable multi-band detectors, as well as for terahertz detectors. Similar to quantum dots, quantum ring photodetector structures (QRIPs) will also be presented, which were specifically designed for terahertz detection. As a second approach to achieve bias-selectable response peaks, a quantum well photodetector (QWIP) structure, known as npn-QWIP which also assembles two back-to-back connected p-i-n diodes with the p-region being common is discussed. A theoretical work supported by some preliminary experiments on the polarization sensitivity of QWIP coupled to 1D metal grids will also be discussed presented. The polarization extinction ratio is based on the polarization sensitivity of the diffraction grid, which depends on grid parameters, as well as the intrinsic polarization sensitivity of the photodetector itself. A low-cost photoconductive dual-band detector based on a ZnO film sensitized with lead sulfide quantum dots (PbS-QDs) is also presented. The UV response arises from the interband absorption of UV radiation by ZnO, and the IR response is due to the absorption in the PbS-QDs. Finally, as time permits, homojunction/heterojunction detector structures will be discussed with an emphasis on spin split-off detectors, which are operated based on light/heavy hole to split-off band transitions in p-type doped emitter layers at the interface of a heterojunction structure.

• Molecules and Materials for 21st Century Needs

  Guest: Prof. Tina T. Salguero, UGA, Department of Chemistry
  Friday, September 24, 2010 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

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  With our perspective at the beginning of a new decade, it seems clear that the 21st century will be an age when custom-tailored molecules and materials will reach an unprecedented level of importance. In this talk, I will describe several examples of custom-tailored molecules and materials that range across the fields of organometallic chemistry and materials science and have applications in catalysis, chemical synthesis, and energy production.

• Targeted Delivery of Therapeutics

  Guest: Prof. Shanta Dhar, Department of Chemistry, University of Georgia
  Friday, September 10, 2010 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

  iCal

  Three platinum(II) complexes, cisplatin, carboplatin, and oxaliplatin, have been approved by the US FDA for the treatment of cancer. Structural and mechanistic studies have elucidated four early steps that describe their action, cell entry, activation, DNA binding, and transcription inhibition while eluding repair. In spite of the clinical success of cisplatin, there are many occasions where treatment must be discontinued due to drug resistance, acquired or intrinsic, arises from reduced cellular uptake, enhanced DNA repair, drug deactivation, or a combination of these mechanisms. One strategy to overcome resistance is to design specific functionalities onto platinum to enhance uptake and delivery via drug targeting. Oxidation of cisplatin affords Pt(IV) species, known as prodrugs, that can be derivatized with axial ligands for attaching the resulting complexes to carriers for targeted delivery to cancer cells. Upon entry into the cell, the platinum(IV) is reduced, liberating cisplatin and the axial ligands, which can potentiate the cell-killing properties of the construct. In this manner we have functionalized single-walled carbon nanotubes as “longboat” carriers of Pt(IV) constructs into cells, specifically targeted the folate receptor on cancer cells and delivered platinum complexes with extraordinary potency against folate receptor overexpressing cancer cells.1 Dose limiting toxicities or resistance also limit application of cisplatin in many types of cancer including prostate. We devised a unique strategy to deliver cisplatin to prostate cancer cells by constructing Pt(IV)-encapsulated prostate-specific membrane antigen (PSMA) targeted nanoparticles (NPs) of poly(D,L-lactic-co-glycolic acid) (PLGA)-poly(ethylene glycol) (PEG)-functionalized controlled release polymers. By using PLGA-b-PEG nanoparticles with PSMA targeting aptamers (Apt) on the surface as a vehicle for a platinum(IV) prodrug, a lethal dose of cisplatin was delivered specifically to prostate cancer cells.2 By appending axial ligands that destroy the mitochondrial function of the cancer cell while platinum simultaneously impeding DNA-mediated processes in the nucleus, we have synthesized a novel compound mitaplatin, and this new construct is currently being evaluated for anticancer activity vs. normal cells.3 Our technologies provide a potentially important platform for spatiotemporal, controlled release of two or more drugs for future applications in human cancer chemotherapy.4
  1. Dhar, S.; Liu, Z.; Thomale, J.; Dai, H. and Lippard, S. J. “Targeted Single Walled Carbon Nanotube Mediated Pt(IV) Prodrug Delivery using Folate as Homing Device”, J. Am. Chem. Soc. 2008, 130, 11467‐11476.
  2. Dhar, S.; Gu, F. X.; Langer, R.; Farokhzad, O. C. and Lippard, S. J. “Targeted Delivery of Cisplatin to Prostate Cancer Cells by Aptamer Functionalized Pt(IV) Prodrug‐PLGA–PEG Nanoparticles”,Proc. Natl. Acad. Sci. USA, 2008, 105, 17356‐17361.
  3. Dhar, S. and Lippard, S. J. Proc. Natl. Acad. Sci. USA, 2009, 106, 22199‐22204.
  4. Kolishetti, N.; Dhar, S.; Pedro, V.; Lin, L.; Karnik, R.; Lippard, S. J. Langer, R.; Farokhzad, O. C. and “Engineering of Self‐assembled Nanoparticle Platform for Precisely‐controlled Combination Drug Therapy”, Proc. Natl. Acad. Sci. USA, 2010, in press.

• Nano-Carbon: Fundamental Exploration and Technological Development

  Guest: Prof. Ya-Ping Sun, Department of Chemistry and Laboratory for Emerging Materials and Technology, Clemson University
  Friday, September 3, 2010 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

  iCal

  Nanoscale carbon materials, including fullerenes, carbon nanotubes, graphene nanosheets, and small carbon nanoparticles, have interesting and/or unique properties. We have been studying these nanomaterials, from fullerene conjugates with anticancer drugs and bulkseparated metallic/semiconducting single-walled carbon nanotubes for electrical/electronic materials and applications to more recently graphene nanosheets for thermal and mechanical nanocomposites and carbon-based photoluminescent nanoparticles (“carbon dots”) as effective imaging agents. In this talk, some interesting and representative results from our research will be highlighted.

• Present Challenges in Electrochemical Power Sources Research

  Guest: Prof. Ramaraja Ramasamy, Faculty of Engineering, and Member of NanoSEC University of Georgia
  Friday, August 27, 2010 4:00 pm - 5:00 pm
  Location: Riverbend Research South Laboratory Auditorium

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  Electrochemical energy constitutes only a small portion of America’s energy portfolio but is well poised to make a big impact in the nation’s energy independence and sustainability in the 21st century. Electrochemical power sources such as photovoltaic cells, batteries, super-capacitors, fuel cells and biological fuel cells have made visible impact in the field, and yet face tremendous technical and economical challenges to overcome before they can achieve commercial success. The seminar will focus on some of the key technical challenges in lithium ion batteries, fuel cells, hydrogen generation and biological fuel cells and discuss approaches to address these challenges.

• Microcantilever Based Sensors for Detection of Biological and Chemical Species

  Guest: Dr. Pranav Shrotriya, Department of Mechanical Engineering, Iowa State University
  Friday, August 13, 2010 1:30 pm - 2:30 pm
  Location: Auditorium, Riverbend Research Laboratory South

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  Micromechanical cantilever based surface stress sensors have demonstrated tremendous sensitivity to
  non-labeled detection of chemical and biochemical compounds. The sensing strategy involves coating
  one surface of a microcantilever with a receptor species that has high affinity for the analyte molecule of
  interest. The presence of the analyte is detected by resolving the surface stress change associated with
  absorption/adsorption of analyte molecules on the sensitized surface. While a number of studies have
  been undertaken to explore potential uses of the cantilever sensors, their widespread application is
  severely limited due to: 1) lack of integration of all the components in a single miniature device; and 2)
  incomplete understanding of the molecular mechanisms governing the sensor response. We address these
  limitations through development of an interferometry based surface stress sensing approach and
  multiscale models to identify mechanism governing surface stress generation. I will discuss our results on
  surface stress changes associated with two model systems: 1) formation of monomolecular alkanethiol
  films on gold surfaces; and 2) hybridization of surface immobilized DNA molecules. Insight gained from
  the results on the model systems is currently being used to investigate aptamer-modified microcantilevers
  for detection of controlled substances and novel approach on immobilizing receptor molecules that
  maximizes the surface stress changes.

• Enhancement of Magnetic Resonance Imaging using Contrast Agents, Qun Zhao

  Friday, April 9, 2010 3:00 pm - 4:00 pm
  Location: Auditorium, Riverbend Research Laboratory South

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  Dr. Qun Zhao of the University of Georgia Department of Physics and Astronomy will be presenting his talk entitled, "Enhancement of Magnetic Resonance Imaging using Contrast Agents."

  Magnetic Resonance Imaging (MRI) has been increasingly used in biological/biomedical
  research and clinical practices. Despite its wide applications, MRI has been facing challenges of
  increasing demand for high sensitivity and specificity. Contrast agents, e.g. superparamagnetic
  iron oxides (SPIOs), are excellent candidates for changing properties such as longitudinal and
  transversal relaxation time, resulting in a signal contrast change among different types of
  materials/tissue in a living body. In this talk, a brief MRI review and the physical principles on
  relaxation time will be introduced first. Then, applications in biomedicine/biology are presented
  for tumor research including generation of positive contrast mapping using SPIOs for early
  detection.

• Nanostructured Metals and Metal Oxides for Anodes of Li-Ion Batteries, Ming Au

  Friday, March 19, 2010 3:00 pm - 4:00 pm
  Location: Auditorium, Riverbend Research Laboratory South

  iCal

  Dr. Ming Au of the Savannah River National Laboratory, will be presenting her talk entitled, "Nanostructured Metals and Metal Oxides for Anodes of Li-Ion Batteries" this week.

  Currently, carbon base anodes are being used for Li-ion rechargeable batteries through Li ion intercalation process. The theoretic capacity is limited at 372 mAh/g. The volume expansion and breakdown of solid electrochemical interface (SEI) of carbon anodes during overcharging is one of the reasons of thermal runaway and fire ignition. Searching for new anode materials that possesses higher energy storage capacity and inherent fire safety is not only scientist’s passion, but the mandate of industries and customers, particularly for plug-in hybrid vehicles and portable power sources.

  It is found that metal oxides and metals can host Li ions through conversion process that changes lattice structure of metal oxides or forms metal alloys. The theoretic capacity of metal oxides and metals is in the range of 500 ~ 4000 mAh/g. The metal oxides do not react with polymer electrolyte and generate exceed heat. The aligned nanostructure, such as nanorods, creates large inter-rods space that is capable to store the charges and accommodates the volume expansion caused by conversion. It is expected the aligned nanorods of metal oxides will offer high energy density and power density and inherent safety. Growing free standing nanostructured anode materials on current collectors directly without additives and binders represent a new trend of anode fabrication with simplified process and low cost. In other hand, the nanoparticles of metal oxides can be assembled as the hollow spheres that offers unique feature for anodes of Li-ion rechargeable batteries. We will present our experimental results and discuss the aspects related to practical applications in the conference.

• Magnetic Liquids for Lab-on-a-Chip Applications, Leidong Mao

  Friday, February 26, 2010 3:00 pm - 4:00 pm
  Location: Auditorium, Riverbend Research Laboratory South

  iCal

  Professor Leidong Mao of the University of Georgia Faculty of Engineering will be presenting his talk entitled "Magnetic Liquids for Lab-on-a-Chip Applications."

  Magnetic liquids (stable colloidal suspensions of magnetic nanoparticles), also called ferrofluids, offer attractive alternatives to moving mechanical components in industrial machinery. When made biocompatible, they are also used in dilute forms as contrast agents for magnetic resonance imaging, or in drug delivery platforms. Recently, we have proposed and begun implementing a series of micro-scale pumping, separation, mixing, particle/cellular manipulation, and droplet generation platforms, all based on magnetic liquids. Our approach involves creating localized magnetic fields within microfluidic devices to manipulate ferrofluids. The ultimate goal is to create assays that are portable, cheap, disposable, rapid and completely label free. Magnetic liquid offers a practical solution to overcome the diffusion barrier in micro- and nanoscale biosensor assays. In this talk, we present some of the exciting results that depict our progress to date.

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