E SC 412 Nanotechnology: Materials, Infrastructure, and Safety Wook Jun Nam

Transcription

1 E SC 412 Nanotechnology: Materials, Infrastructure, and Safety Wook Jun Nam

2 Outline 1. The nano-scale: What s different there? 2. Some examples of nano-products.

3 It sometimes is better to be little. As we ll see, new doors open at the Nano-scale New opportunities become accessible!

4 Sources of the opportunities Small size High surface to volume ratio: Surface forces dominate over bulk forces for example, gravity is not important Importance of quantum mechanical effects Dominance of the wave properties of light Sizes corresponding to basic biological structures Sizes corresponding to macro-molecules Unique chemical bonding configurations possible New epistemologies (i.e., new ways of knowing about our world)

5 What s different there? (1) small size

6 What s different there? (2) Large surface area to volume ratio Lower surface to volume ratio Higher surface to volume ratio Courtesy of CNEU

7 What s different there? (3) High surface force Surface forces Gravity s importance decreases with decreasing volume Surface force importance increases with decreasing volume gravity gravity

8 What s different there? (3) High surface force Colloidal particles never settle out so long as surface forces are not present to cause them to agglomerate. If they agglomerated, this would increase particle volume and give gravity a chance to become important.

9 What s different there? (4) Thermal properties The melting temperature of Au gets lower as a nanoparticle gets smaller because higher percentage of atoms are on the surface. Surface atoms are not bound to each other the same way bulk atoms are. Buffat and Borel, Phys. Rev. A 13, 2287 (1976).

10 What s different there? (5) Quantum mechanics can dominate allowed energies for electrons ΔE allowed energies for electrons E 2 E 1 Electrons can only have certain energies in atoms due to quantum mechanics. Nanoparticles are so extremely small that the electrons in semiconductor nanoparticles can have allowed energies* and forbidden energy ranges ΔE just like the electrons in atoms. The energy difference between these allowed energies in nanoparticles gets bigger as R gets smaller. *This phenomenon of energy levels and forbidden energies is part of what is called Quantum Mechanics

11 What s different there? (5) Quantum mechanics can dominate allowed energies for electrons ΔE allowed energies for electrons E 2 E 1 Using the fact that incoming light with energy equal to or bigger than ΔE can excite an electron in the nanoparticle from the ground state band of energies below the energy E1 to the more energetic, excited state band of energies above energy E2. Using the fact that the excited electron can relax back down to the ground state band below E1 and, in a semiconductor nanoparticle, release its extra energy ΔE as emitted light.

12 What s different there? (5) Quantum mechanics can dominate In QDs, the color of the emitted light will depend on the value of ΔE. Therefore same light into a semiconductor QD will produce different colors radiating out depending on particle size because size controls ΔE. Same light in allowed energies for electrons ΔE allowed energies for electrons E 2 E 1 Light out depends on nanoparticle size Relative Size of a Qdot Nanocrystal. Invitrogen Corporation

13 What s different there? (5) Quantum mechanics can dominate

14 What s different there? (6) Physical optics can dominate An electromagnetic wave (e.g., light) has some characteristic wavelength which is determined by energy If L >> wavelength, then geometrical optics works well; i.e., can use ray tracing picture If L ~, then physical optics must be used; i.e., must use wave picture of light. The wavelength of visible light is much larger than the sizes R of nano-scale structures. Light scatters and diffracts off nanostructures

15 What s different there? (6) Physical optics can dominate Plasmonics: Size and physical optics

16 What s different there? (6) Physical optics can dominate Plasmonics: Size and physical optics

17 What s different there? (7) Different chemical bonding possible Graphine In the micro-scale and macro-scale world, pure carbon has two types of chemical bonding between carbon atoms; one is the diamond-type bond and the other is the graphite-type bond. The former is found in diamonds and the latter in pencil lead.

18 What s different there? (7) Different chemical bonding possible At the nanoscale (and only at the nanoscale) carbon has a third type of bonding: the two-dimensional-like carbon nanotube /buckey ball bonding. Using the fact that nature can allow, in such small structures, unusual chemical bonding that is Such unusual chemical bonding not tolerated in the microand macro-scales. can lead to very unusual physical properties (such as amazing mechanical strength).

19 What s different there? (8) Functionalized nanoparticles Core-Semiconductor - CdSe or CdTe or InAs Shell-Inorganic monolayer - Protects - Enhances optical properties Surface coatings - Organic and polymer coatings - Links to proteins, molecules using conjugation chemistry

20 Outline 1. The nano-scale: What s different there? 2. Some examples of nano-products.

21 On a typical day...

22 Pace Maker Li-Batteries New Materials for Energy Catalyzer Nanoparticles GPS Navigation Functional Materials Air Bag Accelaration Sensors MEMS Cosmetics TiO 2 Nanoparticle Mobile Phone SAW Structures Artificial Hips Biocompatible Materials Glasses and Coatings Optical Materials UV Filter Digital Camera CCD Chip Artificial Lens Biocompatible Polymers Bike Frame Carbon Fibres Composite Materials GMR Read Head Magnetic Multilayers LED Display Photonic Materials Intelligent Credit Card Integrated Circuits Exact Time via satellite Semiconductíng devices Micro-Batteries Taylored Materials at Work.

23 Product Example # 1 (material) Using the fact that gold nanoparticles can be made extremely small so small that they always stay in solution and so small they are no longer gold in color! In fact, the color of these nano-scale pieces of gold depends on their size and their immediate environment. Using the fact gold nanoparticles can have their surface functionalized; i.e., coated. This can be exploited to coat gold nanoparticles with molecules that interact with the hormones present with pregnancy.

24 Product Example # 1 (operation) Urine passes from the flow stick to a central reservoir containing gold nanoparticles and latex microparticles. If pregnancy hormone is present, particles aggregate and are prevented from passing through a down stream filter. This produces a red signal in the viewing window

25 Product Example # 1 (commercial product) The product: First Response Home Pregnancy Test First Response home-pregnancy test manufactured by Carter-Wallace, a New York based biotechnology company. The test uses gold particles (less than 50 nanometers in diameter) to help consumers read test results more easily.

26 Product Example # 2 (material) Using the fact that nanoparticles can be functionalized to attach onto the walls of a cell. This functionalization can be tailored so that they only attach to cancer cells. Using the fact that nanoparticles can also be engineered to carry drug molecules. Drug Molecules Adapted from Whiteside and Love, Scientific American Sept 2001 Nanoparticle

27 Product Example # 2 (operation) Some drugs used for cancer therapy are hard to dissolve in blood. These drugs may be effective against cancer but you can t get them to the tumor! In one application nanoparticles made from the protein albumin have been made and they are found to be easily dispersed in blood---and they can be engineered to carry effective anti-cancer drugs to cancerous cells. These albumin nanoparticles can be engineered to carry anti-cancer drugs that normally will not dissolve in blood. Such drug-carrying albumin nanoparticles are now being used very effectively by physicians to carry anti-cancer drugs to breast cancer tumors.

28 Product Example # 2 (commercial product) The product: Abraxane, the first approved drug to use albumin nanoparticles to improve the therapeutic and safety properties of an anticancer agent. This is a product of American BioScience, Inc., Santa Monica, CA. It was approved on February 7, 2005, by the U.S. Food and Drug Administration for use in patients with metastatic breast cancer who have failed combination drug therapy. National Institutes of Health

29 Product Example # 3 (material) The treatment is based on energy transmission to biocompatible superparamagnetic nanoparticles in an alternating magnetic field, similar to the principles behind magnetic resonance imaging. Functional molecules Iron oxide nanoparticle

30 Product Example # 3 (operation) The functionalized iron oxide nanoparticles suspended in a liquid are brought into the tumor with a regular cannula and then penetrate the tumor cells. When the magnetic field is applied they heat up, up to a temperature of 45 C, if used for boosting of conventional radiation or chemotherapy, or up to 70 C, when used by itself as thermoablation. Because the particles are absorbed by the tumor cells, surrounding healthy tissues are spared.

31 Product Example # 3 (commercial product) The product: MagForce Nanotechnologies AG, from Berlin, Germany, received European regulatory approval for its Nano- Cancer therapy The current approval covers the treatment of brain tumors only and studies in prostate cancer, esophageal cancer and pancreatic cancer are underway.

32 Product Example # 4 (material) Core-Semiconductor - CdSe or CdTe or InAs Shell-Inorganic monolayer - Protects - Enhances optical properties Surface coatings - Organic and polymer coatings - Links to proteins, molecules using conjugation chemistry

33 Product Example # 4 (Operation) allowed energies for electrons ΔE allowed energies for electrons E 2 E 1 The emitted light from a semiconductor nanoparticle is called fluorescence. Nanoparticles can fluoresce very strongly and, as we see, the color of the fluorescence can be adjusted by adjusting the size of the nanoparticles. Semiconductor nanoparticles with this strong fluorescence property are called quantum dots, because of the connection of the light color to ΔE and the connection of ΔE to the allowed energies predicted by quantum mechanics.

34 Product Example # 4 (Operation) - continued 100W mercury lamp excitation study for 3 minutes showed a degradation of the Alexa 488 dye molecule while the quantum dot signal maintained the initial intensity. Green : organic dye Red: quantum dot

35 Product Example # 4 (Operation) - continued Sentinel Lymph Node (SLN) mapping is a common procedure used to identify the presence of cancer in a single, sentinel lymph node, thus avoiding the removal of a patient s entire lymph system. SLN mapping currently relies on a combination of radioactivity and organic dyes but the technique is inexact during surgery, often leading to removal of much more of the lymph system than necessary, causing unwanted trauma. Kim et al. Nature Biotech. Vol. 22, pp. 93 (2004)

36 Product Example # 4 (Operation) - continued The imaging system and quantum dots allowed the pathologist to focus on specific parts of the SLN that would be most likely to contain malignant cells, if cancer were present; and the imaging system and quantum dots minimized inaccuracies and permitted real-time confirmation of the total removal of the target lymph nodes, drastically reducing the potential for repeated procedures. Kim et al. Nature Biotech. Vol. 22, pp. 93 (2004)

37 Product Example # 4 (Operation) - continued Type II near-infrared-emitting quantum dots were injected into a primary tumor in a nearhuman sized pig (Panel A, large green region at right). The false-color image clearly shows transport of the quantum dots through lymph vessels to a nearby lymph node (smaller green area at left) even when imaged non-invasively through the skin. Kim et al. Nature Biotech. Vol. 22, pp. 93 (2004)

38 Product Example # 4 (Operation) - continued In Panels B-D are depicted the surgical removal of the lymph node. A visible light color image is given in B. The black and white image in C is the same image as viewed through a NIRsensitive camera. In Panel D, the images have been merged and the NIR signal false-colored green as in Panel A. Kim et al. Nature Biotech. Vol. 22, pp. 93 (2004)

39 Product Example # 4 (commercial product) The Product: Quantum dots These are available commercially and used in, for example, medical research for their very strong fluorescence color. The color they give off when excited can be changed simply by buying different sized dots which changes ΔE and thereby the fluorescing color. This picture of vials containing actual quantum dots was captured after the samples were placed in front of a UV hand lamp which excited the electrons from below E 1 to above E 2.

40 Product Example # 5 (material) Silver ions from silver nanoparticles can be ingested into a microbe, interrupting RNA replication and preventing the microbe from reproducing. Such silver ions are also attracted to microbial cell walls and thereby affect transport. The ions suppress respiration and metabolism of microbes. And silver nanoparticles can be put into clothing! Bacteria are the reason for clothing odors. Silver nanoparticles in textiles kill the bacteria making clothing odor resistant.

41 Product Example # 5 (operation) Using the fact that nanoparticles are very, very small and that many of their atoms are on the surface as opposed to being inside the particle. In other words they have a very large surface to volume ratio.

42 Product Example # 5 (operation) - continued Using the fact that some metal nanoparticles are antimicrobial (e.g., kill bacteria). Actually, it is the ions of these metals which do the killing. Using the fact that atoms on the surface of a nanoparticle can easily get ionized--and high surface to volume ratio nanoparticles have most of their atoms on the surface a big potential supply of ions for little metal (i.e., little cost). Using the fact that metal nanoparticles can be included into textiles.

43 Product Example # 5 (operation) - continued A silver nanoparticle attached to a textile fiber

44 Product Example # 5 (commercial product) The Product: A number of companies are manufacturing and selling shoes and clothing containing silver nanoparticles for odor control.

45 Product Example # 6 Everyone wants faster computers and more memory. This has forced engineers to make transistors smaller and smaller today transistors are at the nanoscale. This results in millions of transistors per square inch, giving more processing per square inch and more memory per square inch. Also, since these transistors are so close, they can communicate rapidly. This means your computer also gets faster.

46 Product Example # 6

47 Product Example # 6 Today microelectronics has moved from the microscale to the nanoscale. It now really should be called nanoelectronics. Today s transistors are so small that we now make more transistors in a year than we grow grains of rice!

48 Product Example # 6 (commercial products) The Product: Companies are manufacturing microelectronics circuits with more speed and more functionality due to the nanoscale transistors used in these circuits.

49 Key Ideas Nanotechnology is already making an impact and it is just getting started. Impact areas vary from cancer treatments to cooking oil and from bikes to textiles. The impact is caused by the unique properties of the small things of the nanoscale.

50 Key Ideas (continued) The unique properties we saw arose from a. small size b. large surface to volume ratio c. quantum mechanics d. unique chemical bonding These are just some of the unique properties of nanoscale things. There are even more!