CHE5480 Summer 2005 Nanostructures: Introduction

TOPICS: Theory: (Dr. Lee) Experiments (Dr. Newman) Computer: (Dr. Neeman) Attending Nanotechnology Meeting

What size is a nanometer? A nanometer (nm) is meter (1 m = 3.28 ft). Argon 0.3 nm CH nm H 2 O 0.3 nm Red Blood Cell 2000x7000 nm Nanotech: from1 nm to ~100 nm Albumin 6.5 nm Ribosome 25 nm

What size is a nanometer? (2) Argon 0.3 nm CH nm H 2 O 0.3 nm HIV virus 125 nm Red Blood Cell 2000x7000 nm ~1 nm ~100 nm Albumin 6.5 nm Ribosome 25 nm

Definition of Nanotechnology: From NNI (National Nanotechnology Initiative) The Initiative and its Implementation Plan : The essence of nanotechnology is the ability to work at the molecular level, atom by atom, to create large structures with fundamentally new molecular organization. Compared to the behavior of isolated molecules of about 1 nm (10 -9 m) or of bulk materials, behavior of structural features in the range of about to m (1 to 100 nm - a typical dimension of 10 nm is 1,000 times smaller than the diameter of a human hair) exhibit important changes. Nanotechnology is concerned with materials and systems whose structures and components exhibit novel and significantly improved physical, chemical, and biological properties, phenomena, and processes due to their nanoscale size.

22 National Agencies in NNI: (11 of which have R&D budgets.)

National technology for the 21 st century: Leading to a new industrial revolution Initiatives (NTR): 1. Research on fundamental understanding and discoveries. 2. Design of nanostructured materials. 3. Nanodevices: information, bio, medical. 4. Applications of nanomaterials and devices to energy, health, evironment, and security. 5. Education of a new generation of skilled workers.

History of NNI: (National Nanotechnology Initiative) 1998: IWGN (Interagency Working Group on Nanotechnology)— National technology for the 21 st century: Leading to a new industrial revolution. 2001: NNI (Nantional Nanotechnology Initiative)— Funding at ~500 million NSET (National Science, Engineering, and Technology)

Nanostructures: Old and New

Nanostructured Materials: Carbon nanotubes Aerogels Zeolites Dendrimers Self-assembled monolayers Nanoparticles Nanowires NEMS, etc.

NSF Web

Applications of nanotechnology: A new industrial revolution (on the scale of the transistors in 1950s). Potentially it will pervade all sectors of industry and technology. Essentially in the following areas: Information, health, space, environment, defense, etc.

Nature’s Nanodesigns Nature’s Nanodesigns

Mimicry of Nature—1 The Lotus Effect Both surface chemistry and surface topology influence the hydrophobicity -slip. The surface contains “waxy bumps”. Using the “Lotus effect” (that lotus leaves are highly hydrophobic), one can achieve slip flow (Tretheway & Meinhart –UCSB, Silane. Phys. Fluids 2002). Papillae on leaves.Water beads up on papillae. Water runs off.

Mimicry of Nature—2 (The lotus leaf surface) (Feng 2002) Papilla μ

Mimicry of Nature—3 Water Strider μ Gao, X. F. & Jiang, L. Water-repellent legs of water striders. Nature 432, 36 (2004).

Nanosensors:

Nanosensors: Using nanostructued materials for detection of trace amounts of chemical and biological agents. (Medical, space, environmental, homeland security).

Detection of Pathogens— (Homeland Security):

Anthrax: (Woolverton, Kent State U.)

Detect Viruses (Lieber, Harvard)

...and find a Cure!!!

Antimicrobial Nanoemulsion (James Baker, U. Michigan) Use of soybean oil emulsified with surfactants. Drops ~400 – 600 nm. The droplet do not coalesce with themselves. High surface tension make them coalesce with other lipid droplets, killing bacteria. Safe for external use. Not safe for red cells, or sperm.

The droplets fuse with cell membrane of microorganisms resulting in cell lysis. Very effective in killing: – Bacteria, – Bacterial spores, – Enveloped viruses, and – Fungal spores. They are effective at preventing illness in individuals, when used both before and after exposure to the infective agent. They could be used: – Topically, – As an inhalant.

Left: treated with nanoemulsion, Right: untreated. The growth of bacteria colonies has been eliminated by treatment with the nanoemulsion. Antimicrobial Nanoemulsion

Example of Nanostructures : Starburst Dendrimers

What is a dendrimer? Branched polymers ( dendron = tree in Greek) = 3 (Nitrogen) What is a dendrimer? Branched polymers ( dendron = tree in Greek) Functionality = 3 (Nitrogen)

Generations of Dendrimers 2 nd gen. 4 th gen. 5 th gen.

PAMAM Dendrimer (polyamidoamine) Alternating (B)-AB-AB-AB-... Ethylenediamine (B) H 2 N-C-C-NH 2 Methylacrylate (A) C=C-CO-OCH 3

PAMAM Moieties: Acrylate Diamine NH 3 or Diamine

Size of PAMAM Dendrimers Generation M.W. Angstrom (dia.) End Gps (1 nm = 10 Angstroms)

Equivalent Sizes with Cells:

Applications of Dendrimers Gas and chemical sensors Catalysts Drug delivery and gene therapy Surface modifiers (tribology, and information storage) Bio compatible materials Electronic devices and antennae

Dendrimers as Drug Delivery Agents: An Example

James R. Baker Jr. University of Michigan Professor, Internal Medicine and Bioengineering Chief, Division of Allergy Director, Center for Biologic Nanotechnology Co-Director, Center for Biomedical Engineering Biotechnology, Nanotechnology and Immunology

Drug Delivery Research in the area of autoimmune endocrine disease. He has helped define the basis of the autoimmune response to thyroid auto antigens. Gene Delivery Work concerning gene transfer; developing a new vector system for gene transfer using synthetic polymers (dendrimers). Anti-microbial research Work on preventing pathogens from entering the human body. This research project seeks to develop a composite material that will serve as a pathogen avoidance barrier and post-exposure therapeutic agent to be applied in a topical manner to the skin and mucous membranes.

Receptors and Ligands

Drug Delivery by Dendrimers Dendrimers (code named “smart bombs”) Targeting cancer cells (ignore normal ones) Able to enter cells Little toxicity Focus: High energy lasers or sound wave to trigger the release of the drug out of the dendrimer.

Polyfunctional Tecto-dendrimers: (connected PAMAM units) Each “spore” in this “smart bomb” has its function: Sensing and binding the target (cancer cells). Emitting a signal (imaging). Drug delivery in situ. Dendrimer’s structure tricks the immune system, avoiding response. Low toxicity

Economist, Dec. 2001

Professor Chris Gorman: NCSU

Electron transfer dedndrimers

Example of Nanostructures : Aerogels

TEM of SiO 2 Aerogels

Different aerogels: (95% air)

Excellent heat insulator:

Heat Insulating Jacket inlaid with aerogels

Example of Nanostructures: Carbon Nanotubes

Types of Carbon Nanotubes: 1.Armchair. 2. Zigzag. 3. Chiral

A Graphene Sheet n=m  Armchair. m=0  Zigzag. others  Chiral.

Gas absorbed in carbon nanotubes

Gas adsorption on banks of carbon nanotubes

Example of Nanostructures: Zeolites

Silicate-Aluminate: Faujasite

Inclusion in zeolites

Mercury-removal on SAM in Zeolite

Nanofluidics: Flows in channels of nanometer dimension

Nanofluidics : Examples of MEMS & NEMS : (Micro- & Nano-electromechanical systems) Lieber (Harvard)

(“Laboratory-on-a chip”) Lieber (Harvard) MEMS

Flow behavior in nanofluidics:

Flow behavior in nanofluidics: (2) LOCOMOTION? difficult to make fluid flow in small channels. Driving forces: 1. Pressure 2. Surface-capillary force 3. Electric (electroosmotic, electrophoretic, electrohydrodynamic, electrowetting), and magnetic (magnetohydrodynamic) 4. Sound—acoustic 5. Centrifuge (rotation)

Making Circuitry by Nanofluidics: (Lieber, Harvard) Purpose: using viscous flow in nanochannels. to orient and assemble nanowires (to make logical circuitries). Note: at nanoscale, the surface effects are large (due to large surface-to-volume ratio). Thus viscous forces dominate in the flow.

(1) Make a mold of channels (PDMS-polydimethylsiloxane). (2) Disperse nanowires (GaP, InP, Si) in ethanol, the carrier solvent. (3) Flow the suspension through the nanochannels.

SEM images of aligned nanowires. Charles Lieber (Harvard)--2 SEM: bar = 2 μm bar = 50 μm

Nanocircuitries : Examples of NEMS Lieber (Harvard)

hydrophobic surfaces Harvard OTS

What happens to the flow when the interface is hydrophobic? --Slip Velocity at wall is 10% of the center (NOT zero, i.e. Slip). This increases the total volumetric flow Phys. Fluids

On what theories to use for nanoscale flows?

2. Nanostructured materials: dendrimers

2. Nanostructured materials: Gas adsorption in dendrimers

Dendrimer: PAMAM

2. Nanostructured materials: Gas adsorption in dendrimers

3. Nanostructured materials: Gas adsorption in aerogels

5. Self-Assembled Monolayers

Alkylatedthiols on Gold Foil

TOPICS: continued High-performance computing (Dr. Neeman) Experimental program (Dr. Newman)

5. Acid gas treating in natural gas processing

6. Electrolyte solutions: An integral equation approach

7. Liquid crystals: Structure and properties

8. Biofluids: Colloidal systems, sol-gel transition

9. Biofluids: Polyelectrolytes and electrical double layers

10. Natural gas hydrate: Formation and inhibition

11. Polymer solutions: Free energy models and statistical mechanics