“Nanotechnology” (Lecture 1) Shagufta Kanwal

2 22 Evolution of Technologies

3 3 Nanotechnology? “Ability to work at the atomic, molecular and even sub-molecular levels in order to create and use material structures, devices and systems with new properties and functions” Source: National Science Foundation (NSF), USA

A Journey to the World of NANOTECHNOLOGY…

What is Nanotechnology? “Art and science of manipulating atoms and molecules to create new systems, materials and devices with at least one feature of less than 100 nm scale (critically 10 nm)”. Richard Feynman Nature employs nanotechnology to build nanoscale DNA, proteins and enzymes etc. Ribosome is an ideal example of nanomachine (nanorobot). What is the function of ribosome? How to differentiate between nano-biotechnology and bio-nanotechnology? Idea given by Richard Feynman in his famous speech in 1959 “There is a plenty of room at the bottom” at Caltech, USA.

EXAMPLE: Nanospheres coated with fluorescent polymers. Researchers are seeking to design polymers whose fluorescence is quenched when they encounter specific molecules. 6 NanoBiotechnology? Nanobiotechnology is the branch of nanotechnology with biological and biochemical applications or uses. Nanobiotechnology often studies existing elements of nature in order to fabricate new devices. Nanobiotechnology usually refers to the use of nanotechnology to further the goals of biotechnology, while bionanotechnology might refer to any overlap between biology and nanotechnology, including the use of biomolecules as part of or as an inspiration for nanotechnological devices. Nanobiotechnology is that branch of one,which deals with the study and application of biological and biochemical activities from elements of nature to fabricate new devices like biosensors. Nanobiotechnology is often used to describe the overlapping multidisciplinary activities associated with biosensors particularly where photonics, chemistry, biology, biophysics nanomedicine and engineering converge.

“Nanotechnology is an enabling technology that will change the nature of almost every human- made object in the next century.” National Science and Technology Council, USA

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Evolution of Nanotechnology: The Nanoscale was initially used by R. P. Feynman, a physicist. “There’s plenty of room at the bottom. But there’s not that much room - to put every atom in its place - the vision articulated by some nanotechnologists - would require magic fingers”. The ability to work at the molecular level, atom by atom, to create structures with fundamentally new molecular organization.”

Nanoscale Measurements!

What Does a Nano Mean? “Nano” – derived from a Greek word “Nanos” meaning DWARF or small. “Nano” = One billionth of something “A Nanometer” = One billionth of a meter = meter

15 Nanotechnology nanometer A nanometer (nm) is one billionth (10 -9 ) of a meter Thickness of a human hair  80,000 nm Nanometer:10 -9 m = 10 x m = 10 atoms in a line (one atom, 2 He 4  m  0.1 nm) Helium Atom, 2 He 4 Size : 0.1 nm Electron Neutron Proton Sub-Nanometer Sizes: Electron  x m  2 x nm Proton  m  nm Neutron  nm  1/1,000,000 nm)

16 0.1nm

17 Nanoscale No.Item Size (Approx.), Scaling down µm to nm Size (Approx.), on nm Scale 1.Human hair (diameter)60 – 120 µm60,000 – 120,000 2.Pollen10 – 100 µm10,000 – 100,000 3.Asbestos fibers (diameter)< 3 µm< 3,000 4.Diesel exhaust particles< 100 nm – 1 µm< 100 nm – Soot< 10 nm – 1 µm< 10 nm – Quantum dots2 – 20 nm2 – 20 7.Nanotubes (diameter)~1 nm~ 1 8.Fullerenes~ 1 nm~ 1 9.Atoms1-3 Å ~ 0.1 nm1-3 Å ~ 0.1

18 Typical Nanosizes of Cellular Species Biological Species Example Typical Size (nm) Typical Molecular Weight Small assemblies Ribosome 20 (sphere)10 5 – 10 7 Nucleic acidstRNA10 (rod)10 4 – 10 5 Small proteinsChymotrypsin 4 (sphere)10 4 – 10 5 Large proteinsAspartate trans- carbamoylase 7 (sphere)10 5 – 10 7 Source: Nanotechnology in Biology and Medicine, Ed: Tuan Vo-Dinh, CRC Press, 2007

19 Why will nano change the properties of materials? Example: Smaller size means larger surface area diameter 10 µm 50 nm diameter Area 0.22 m 2 /g 44 m 2 /g

Why nano will change the properties of materials? Sphere Volume, V = 4/3 π R 3 Surface Area, S = 4πR 2 Ratio S/V = 3 /R α 1/R He atom, 2R = 0.1 nm. S/V = 6 × R R S/ V RS/V Smaller size means larger surface area

How to Make Nanostructures? Top-down Approach Building something by starting with a larger component and carving away material (like a sculpture) Nanotechnology example: patterning (using photolithography) and etching away material, as in building integrated circuits Rock Statue

How to Make Nanostructures? Brick Bottom-up Building something by assembling smaller components (like building a car engine), atom by atom assembly. In nanotechnology: self-assembly of atoms and molecules, as in chemical and biological systems Building

Why Small is Good? Nano-objects are: - Faster - Lighter - Can get into small spaces - Cheaper - More energy efficient - Different properties at very small scale Surface area increases as size decreases

An example of a molecular self-assembly through hydrogen bonds reported by Meijer and coworkers. 28 Molecular self-assembly Molecular self-assembly is the process by which molecules adopt a defined arrangement without guidance or management from an outside source. There are two types of self-assembly:  Intramolecular self-assembly  folding  Intermolecular self-assembly.

29 Supramolecular Systems Molecular self-assembly is a key concept in supramolecular chemistry since assembly of the molecules is directed through noncovalent interactions (e.g., hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, π-π interactions, and/or electrostatic) as well as electromagnetic interactions. Common examples include the formation of micelles, vesicles and liquid crystal phases.

30 Biological Systems Molecular self-assembly is crucial to the function of cells. It is exhibited in the self-assembly of lipids to form the membrane, the formation of double helical DNA through hydrogen bonding of the individual strands, and the assembly of proteins to form quaternary structures. Molecular self-assembly of incorrectly folded proteins into insoluble amyloid fibers is responsible for infectious prion-related neurodegenerative diseases.

31 Nanotechnology The DNA structure at left will self-assemble into the structure visualized by atomic force microscopy at right.

32 Nanotechnology Molecular self-assembly is an important aspect of bottom-up approaches to nanotechnology. Using molecular self-assembly the final (desired) structure is programmed in the shape and functional groups of the molecules. Self-assembly is referred to as a 'bottom-up' manufacturing technique in contrast to a 'top- down' technique such as lithography where the desired final structure is carved from a larger block of matter. In the speculative vision of molecular nanotechnology, microchips of the future might be made by molecular self-assembly. An advantage to constructing nanostructure using molecular self- assembly for biological materials is that they will degrade back into individual molecules that can be broken down by the body.

33 DNA nanotechnology DNA nanotechnology is an area of current research that uses the bottom-up, self-assembly approach for nanotechnological goals. DNA nanotechnology uses the unique molecular recognition properties of DNA and other nucleic acids to create self-assembling branched DNA complexes with useful properties. DNA is thus used as a structural material rather than as a carrier of biological information, to make structures such as two-dimensional periodic lattices (both tile-based as well as using the "DNA origami" method (DNA origami is the nanoscale folding of DNA to create arbitrary two and three dimensional shapes at the nanoscale. The specificity of the interactions between complementary base pairs make DNA a useful construction material through design of its base sequences) and three-dimensional structures in the shapes of polyhedra. These DNA structures have also been used to template the assembly of other molecules such as gold nanoparticles and streptavidin proteins (bacteria uses are the purification or detection of various biomolecules.

34 Computational Nanotechnology Goal Develop theory, models, and large scale simulations to establish the scientific basis and as cost-effective design tools in meeting grand challenges in - Nanoelectronics and computing - Optoelectronics, photonics - Sensors - Structural materials Approach Modeling and simulation across time and length scales coupling fundamental physics, chemistry, and material science, and validation against experiments