Presentation on theme: "Nanostructures and its Applications"— Presentation transcript:
1 Nanostructures and its Applications N. PonpandianDepartment of Nanoscience and TechnologyBharathiar UniversityCoimbatoreWeb:
2 electron = h / p “De Broglie’s Relationship” ELECTRON WAVES SeparateNanoSCIENCE from MicroSCIENCEThe discovery that electrons = waves led to QUANTUM MECHANICSA weird, new, counter intuitive, non-Newtonian way of looking at the nano worldWith a particular impact upon our understanding of electrons: Electrons => WavesHow do you figure out an electron’s wavelength?electron = h / p “De Broglie’s Relationship”( = electron wavelength, h = Planck’s Constant, p = electron’s momentum)This relationship was based on series of experiments late 1800’s / early 1900’sTo put the size of an electron’s wavelength in perspective:2
3 Planck’s Wavelength = h/p (or) h/mv Quantum MechanicsPlanck’s Wavelength = h/p (or) h/mvWhen mv >> h – Quantum effects are not observablesmv ~ h - Quantum effects are observable3
5 Size of Things (red = man-made things) Millimeters Microns NanometersBall of a ball point pen 0.5Thickness of paperHuman hair – 200Talcum Powder 40Fiberglass fibersCarbon fiber 5Human red blood cell 4 – 6E-coli bacterium 1Size of a modern transistorSize of Smallpox virus – – 300___________________________________________________________________________________________________Electron wavelength: ~10 nm or lessDiameter of Carbon Nanotube 3Diameter of DNA spiral 2Diameter of C60 BuckyballDiameter of Benzene ringSize of one Atom ~0.1
6 Surface Area in Nanomaterials A = 4 x 2 a x a + 2 a2 = 8 a2 + 2 a2 = 10 a2A = 6 x a x a + 6 a x a = 12 a2
10 Surface Energy Surface atoms posses more energy than bulk atoms Consequently, surface atoms are more chemically reactiveNanoparticles posses enhanced chemical reactivityExample: NASA is exploring aluminum nanoparticles for rocket propulsion due to their explosiveness.
11 Nanoparticle Catalysis Research Group, Tsukuba, Japan Macroscopic Gold is chemically inert.Gold nanoparticles are used to catalyze chemical reactions.Example: Reduced pollution in oxidation reactions (i.e., environmentally friendlyNanoparticle Catalysis Research Group, Tsukuba, Japan
12 Macroscopic melting temperature At macroscopic length scales, the melting temperature of materials in size-independent.For example, an ice cube and a glacier both melt at the same temperature (32˚ F)
13 Nanoscale melting temperature Nanocrystal size decreasesSurface energy increasesMeling point decreasesExample: 3 nm CdSe nanocrystal melts at 700 K compared to bulk CdSe at 1678 K
15 What are Quantum dots?Types of materialsMetals – No band gapSemiconductors – low band gapInsulators – very high band gap
16 What are Quantum dots?Quantum dots are nanocrystals of semiconductors that exhibit quantum confinement effects, once their dimensions get smaller than a characteristic length, called the Bohr’s radius.This Bohr’s radius is a specific property of an individual semiconductorBohr’s radius can be equated with the electron–hole distance in an exciton that might be formed in the bulk semiconductor.
17 What is special in QDs towards nm Below this length scale (Bohr’s radius) the band gap (the gap between the electron occupied energy level, similar to HOMO, and the empty level, similar to LUMO), which are is size-dependent.Band gap is Size DependentValence bandConduction bandtowards nm
30 ? Effect of nanosize on magnetic property D Why nanocrystalline materials t of have excellent soft magnetic propertiesDLexRandom Anisotropy Model?Grain size > exchange lengthsoft magnetic properties as grain size Grain size < exchange lengthsoft magnetic properties as grain size
31 Magnetic properties of nanostructured materials
32 SuperparamagnetismResponse of superparamagnets to applied field described by Langevin modelQualitatively similar to paramagnetsAt room temperature superparamagnetic materials have a much greater magnetic susceptibility per atom than paramagnetic materials
33 Biomedical Applications of Magnetic Nanoparticles
34 Magetism and medicine Iron and living things Many animals use magnetic fields to navigateSynthesize hemoglobinRole of iron in neurodegenerative diseaseMedical applicationsRemoval of iron splinters, shrapnel, etc.Holding prostheticsGuiding instruments through the bodyMRI
35 Magnetic heating (Hyperthermia) Targeted drug delivery Biomedical applications of magnetic nanoparticlesMagnetic imagingMagnetic heating (Hyperthermia)Targeted drug deliveryDetection/purification/isolationManipulation
36 Magnetic SortingGoal: Separate/detect/isolate one type of cell from others, often when the target is present in very small quantities
37 Magnetic Sorting, Detection Functionalized nanoparticlesRLigandO-
39 Magnetic SortingMagnetic nanoparticles bond with targeted cells
40 Magnetic SortingRetain desired cells by applying a magnetic field
41 Hyperthermia Cancer cell growth is slowed or stopped at 42 °C - 46 °C Magnetic materials inside the body generate heat due toHysteresisBrownian motionEddy currentsNanoparticles provideuniform heatingnon-invasive deliverymultiple treatmentsHuman clinical trials in progress (Germany)
43 Magnetic resonance imaging Non-invasive method used to render images of the inside of an objectPrimarily used in medical imaging to demonstrate pathological or other physiological alterations of living tissuesMRI is currently the most efficient imaging procedure used in medicine
46 Problems in MRI Low contrast between different tissues Low contrast between a healthy tissue and tumors
47 Contrast agentsDifferent contrast agents are administered in 40–50% of all MR examinations in order to improve the efficiency of this procedureContrast agents are diagnostic pharmaceutical compounds containing paramagnetic or superparamagnetic metal ions or nanoparticles that affect the MR-signal properties of surrounding tissuesGadolinium chelates are the most widely used extracellular, non-specific contrast agentsOrgan specific contrast agents include superparamagnetic iron oxides nanoparticles stabilized with appropriate biopolymers or biocompatible synthetic polymers
48 Used for intravenous applications Clinically approved superparamagnetic contrastagents stabilized with biopolymersFerumoxide (Endorem, Feridex) dextran stabilizedFerumoxtran (Sinerem, Combidex) dextran stabilizedFerucarbotranum (Resovist) carboxydextran stabilizedUsed for intravenous applications
49 MRI of liver tumorAfter SPIO applicationNormal liver tissue contains phagocytic Kupffer cells darkening after dextran-coated SPIO applicationCancer cells do not contain Kupffer cells after dextran-coated SPIO application tumor is brighter that surrounding tissueBefore SPIO application
50 MRI of gastrointestinal tract Oral application of superparamagnetic nanoparticlesSmall bowel before (left) and after (right) application of the oral contrast agent
51 Commercially available contrast agents: MRI of gastrointestinal tractCommercially available contrast agents:Ferumoxsil (GastroMARK, Lumirem) silicon-coated superparamagnetic iron oxideFerristene (Abdoscan) sulphonated styrene-divinylbenzene latex particles (Ø 3.5 μm) with bound superparamagnetic nanoparticles
54 Nanomedicine : An Overview Nanomedicine is an interdisciplinary field of science, even a simple project needs contributions from physicists, engineers, material chemists, biologists and end users, such as an orthopaedic surgeon.A mature nanomedicine will require the ability to build structures and devices to atomic precision, hence molecular nanotechnology and molecular manufacturing are key enabling technologies for nanomedicine.Medicine must catch up with the technology level of the human body before it can become really effective. The result will be the ability to analyse and repair the human body as completely as we can repair a conventional machine today.If the nanoconcept holds together, it could be the groundwork for a new industrial revolution.BUT: can all different scientists and engineers work together to achieve crossover dreams?
55 HistoryDespite the importance of nanotechnology, literature review of robotics in 1993 included not a single reference to nanotechnology or nanomedicine.The first nanomedical device design technical paper in 1998 by Freitas: Respirocyte – an Artificial Red Cell.
56 Nanostructures in Nature Nature has created nanostuctures for billenia. Biological systems are an existing proof of molecular nanotechnology.Biology is an ingenious form of nanotechnology, even very simple living cells are able to duplicate. So far there is no machine of any size or type, which could do the same.
57 ReplicationReplication is a basic capability for molecular manufacturing. Still some scientists think that medical nanorobots need not ever replicate.It is unlikely that the FDA would ever approve a use of a medical nanodevice that was capable of in vivo replication. Replicators will be very tightly regulated by governments everywhere. In practice you would not want anything that could replicate itself to be turned loose inside your body.
58 NanodreamsNanomedicine will eliminate virtually all common diseases, all medical pain and suffering => theoretically eternal life.Extension of human capabilities.New era of peace. People who are well-fed, well-clothed, well-educated, healthy and happy will have little motivation to make war.Pollution-free industry will guarantee the well-being for the nature.
59 NanohorrorsSelf replicating nanorobots could become massive chemical and biological weapons.Changes to human properties, such as brains, respiration, muscles and DNA will be uncontrolled and may threat the existence of human being.
62 Drug Delivery INanoparticles can deliver drugs in a sophisticated ways, like target specific and trigger based drug dose.Target specific delivery enables the use of lower doses, because the whole body is not saturated with the drug.The side effects will be minimized, and it is possible to use stronger drugs, which could not be used by conventional drug delivery.The use of gold particles in cancer healing is an example target specific action.Gold plated spheres are linked to tumor cells. Nanoshells can be heated from the outside using an infrared source. Heating the shells destroy the cancerous cells, leaving the surrounding tissue unharmed.
63 Improved ImagingUsing magnetic nano particle can Improve imaging with better contrast agents and helps to diagnose diseases more sensitively.The method enables the detection of very small tumors and other organisms which cause disease. When the diagnostics is improved the healing will also be easier.
64 DNA AnalysesSemiconductor nanocrystals, quantum dots, absorb only photons of light omitting just the right wavelength for their size.Use of a variety of sizes and concentrations of quantum dots produces a spectral bar code with distinct spectral lines. Such method allows multiple labels.Fast and accurate DNA testing, comparison of genetic material, rewriting DNA sequences in vivo, and even home DNA test systems.
65 Nanobarcode® Technique I SurroMed company is developing nanobarcode® technique with researchers from the Penn State University.The idea is to use little metallic bars. Consecutively alternating gold- and silver-bands on a bar are interpreted as individual bits.Twenty bands equal twenty bits ≈ 106 alternatives.The bands can be interpreted with an optical microscope.
66 Nanobarcode® Technique II Numerous DNA-testers can be attached to a single bar, the testers combine with receptor molecules. The complex formation results a multiple DNA-sequence analysis. Also antibody molecules can be attached to a surface of a bar, after an immunologic reaction peptide hormones can be analysed.Hundreds of components can be measured from one milliliter of serum, multiple test tubes and plentiful blood samples become unnecessary.
67 Superior Implant Materials The connection between implant material and bone/ surrounding tissues is a key factor to a successful and long-term use of prostheses.Nano-scale modifications of implant surfaces would improve implant durability and biocompatibility.
68 Cleaning Robots ITeeth cleaning robots collect harmful bacteria from the mouth.
69 Cleaning Robots IISimilar cleaning robots can be used in lungs. We have natural macrophages in alveoli, but they are not able to metabolize foreign particles like fibers of asbestos and toxic effects of smoking from the lungs.
70 Cleaning Robots IIIExtra fat can be removed from the arteries with cleaning robots.
71 RespirocyteIt is an artificial mechanical red blood cell floating along in the bloodstream. A spherical (d = 1 μm) nanomedical device is made of 18*109 atoms (mostly carbon).The design of respirocyte was the first technical paper on nanomedical device design. It was published in 1998 by Robert A. Freitas.It is important to notice that molecular nanotechnology violates no physical laws and there are technical paths leading to useful results.Respirocyte device cannot be built today
72 Improving BrainsA nanostructured data storage device measuring a volume about the size of a single human liver cell can store an amount of information equivalent to the entire library.
73 Artificial Tissues and Organs Researchers hope to figure out ways to regenerate skin, bone and more sophisticated organs.At present auto-, allo- and xenografts plus some artificial materials are being used for reconstruction of damaged tissues and organs.The amount of auto- and allografts is limited, and allo- and xenografts carry a risk of infection (HIV or BSE).So the need and interest for artificial regeneration definitely exists!
74 Properties of Medical Nanodevices Shape and sizeBiocompatibilityPoweringCommunicationNavigation
75 Modern Storage Devices Magnetic Thin FilmsforModern Storage Devices
76 The Nobel Prize in Physics 2007 for the discovery of Giant MagnetoresistanceAlbert FertUniversité Paris-SudUnité Mixte de Physique CNRS/THALES Orsay, FrancePeter GrünbergForschungszentrum Jülich Jülich, Germany
78 Magnetic TrilayersTrilayer is a prototype to study magnetic interlayer exchange coupling.System Studied : Co/Cu/Ni/Cu(100)Two trivial limits:(i) dCu = 0 direct coupling (Ni-Co alloy)(ii) dCu = large no coupling (NiCo powder)Objectives:To study the interlayer exchange coupling effects between the magnetic layers as a function of the thickness of Cu and Ni layersA. Scherz, S. Sorg, M. Bernien, N. Ponpandian et. al. , Physical Review B 72 (2005)
79 Ferromagnetic coupling Antiferromagnetic coupling Magnetic Trilayers in Current TechnologyFerromagnetic couplingResistance = lowFM1FM2Antiferromagnetic couplingResistance = high
80 MRAM = Fast + Dense + Non-Volatile Why MRAM?MRAM combinesSilicon technology &Magnetic thin film technologyTo acheiveFast, Dense, Non-VolatileSolid state memoryDRAMMRAM = Fast + Dense + Non-VolatileSRAMFlash
81 Effect of Interlayer Exchange Coupling XMCD probe the sign of JinterExcellent agreement between experiment and theory in TC shiftA. Scherz, S. Sorg, M. Bernien, N. Ponpandian et. al. , Physical Review B 72 (2005)
82 Switching in Fe-Porphyrin Why Organic Molecules?Miniaturization of information storage systemOrganic semiconductors have been used to fabricate promising devices such as OLEDs, FETs and photovoltaic cellsOrganic molecules contain only lighter elements and soSpin – orbit coupling is minimaltransport of spin-polarized current over long distancesObjectives:To combine organic semiconductors with magnetic materials to develop novel devices such as MMRAM and MMSDsMMRAM – molecular magnetic random access memoryMMSDs – molecular magnetic spin devices
83 Fe-octaethylporphyrin chloride (Fe-OEP) molecule Fe-PorphyrinThermally and chemically stableChemical properties can be modified through synthesis with different ‘centre atom‘ and substituent groupsPresent Study:To asses the orientation of the Fe OEP molecules on the surfaces of ferromagnetic Ni (or) Cotype of magnetic orderingthe magnetic orientationSytem Studied:Fe-porphyrin/15ML Ni (or) 5 ML Co on Cu(100)Fe-octaethylporphyrin chloride (Fe-OEP) moleculeNature Materials 6, (2007)
84 Orientation of Fe-Porphyrin Angular dependent NEXAFS**Corbon K-edgeNitrogen K-edgeSame fine structures (Co and Ni)Very similar absorption geometryNormal incidence - * resonance dominatesGrazing incidence - * resonance dominatesFrom N K–edge - molecules are intact with surfacesPlane of the four nitrogen atoms are aligned parallel to the surafceNature Materials 6, (2007)