Bionanomaterials – A Future Material Technology by Lohith T G

OBJECTIVES To familiarize with recent developments in miniature biomaterials To understand the fundamental processes in its design To appreciate needs and benefits of miniature technology

Nanoscience and Nanotechnology Construction and analysis of objects and devices very small on the macroscopic scale Synthetic Chemists manipulating constituents, bonding and stereochemistry of molecules on angstrom scale over a century Physicists theories are based on pico and femto scales

Reasons for impact on Bioworld Biological systems are essentially nanostructures Cellular interactions are in micro and nanoscale level Breakthrough developments in miniature device fabrication and manipulation Potential applications in medical diagnostics, sensors, targeted drug delivery etc.

Molecular and Biochemical Interactions Micro and Nano-structures and Devices Bioengineered Systems Bioactivity Biocompatibility Functionality Influence of microscale on cellular and subcellular function

Attraction of Bionanomaterials Includes Biomaterials like amino acids, lipids, proteins, membranes, cells etc. Endurance to a long period of Evolution Scientists able to manipulate biomolecules Desirable chemical, physical, electrical and optical properties

Synthesis of Nanostructures Top Down Approach –Use of current technologies to fabricate smaller and more precise articles, which in turn will fabricate more smaller products –Demonstrated by AFM Bottom Up Approach –Use of Organic synthetic chemistry, Biochemistry, protein and genetic engineering –Development process of nature –Basically, Self Assembly

Traditional Processing vs. Self Assembly Source:

SELF ASSEMBLY “…process in which atoms, molecules, aggregates of molecules and components arrange themselves into ordered, functioning entities without human intervention.” - George M. Whitesides

BIOLOGICAL SELF ASSEMBLY Monomer molecules - amino acids, lipids  Polymers - DNA, RNA, polysaccharides, proteins  Assemblies - membranes, organelles  Cells  Organs  Organisms

Self Assembly- Bonds and Interactions BOND Inorganic metal-ligand Hydrogen Bonds Electrostatic interactions Hydrophobic interactions Atomic Π -stacking and charge transfer EXAMPLES Metal salts; zinc fingers Nucleotide base pairs Salt bridges in proteins Micelles: LB monolayers on water, lipid bilayers Nucleic acids

Everyday Examples of Self Assembly A raindrop on a leaf (Thermodynamic) Embryo to life (coded) Flat glass processing Silicon crystal growth from melt

TEMPLATED NANOSTRUCTURES Creating initial pattern for subsequent self assembly Original structure can be modified by chemical or physical means to stabilize, or tailor the properties

Template Techniques Photolithography Langmuir-Blodgett Technique Molecular Imprinting AFM Modification Photopatterning

Characterization Microscopy Scanning Probe Microscopy –Atomic Force Microscopy (AFM) –Scanning Tunneling Microscopy (STM) Electron Microscopy –Scanning Electron Microscopy (SEM) –Transmission Electron Microscopy (SEM) –X-ray Photoelectron Microscopy (XPS) Optical Microscopy –Near Field Scanning Optical Microscopy (NSOM) –Dark Field Optical Microscopy

Self Assembled Monolayers One to two nanometer thick film of organic molecules that form a two dimensional crystal on an absorbing substrate EXAMPLES: Alkylsiloxane monolayers Fatty acids on oxidic materials Alkanethiolate monolayers

DNA Nanotechnology for SAM’s DNA is favorable construction medium Ability to construct various shapes with DNA Ability to construct periodic matter with rigidity To date DNA is most successful biomimetic component for Self Assembly

Basics of DNA

DNA 2D ARRAY and 3D LATTICE Left -stable branched DNA molecule Right- a molecule with sticky ends Four of these sticky-ended molecules are shown assembled into a quadrilateral. Cube and truncated octahedron Borromean rings constructed from DNA. Source:

DNA Nanomechanical Device A DNA nanomechanical device based on the B–Z transition.. The device consists of two DX molecules connected by a helix (yellow section) that can undergo the B-Z transition. When this occurs, the bottom domain of the right DX molecule swings from the bottom to the top through a rotary motion

DNA Membrane Self Assembly Source: Diagram of a DNA- membrane complex, a material formed by mixing negatively charged DNA molecules with positively charged artificial versions of the membranes that form the protective coverings of cells.

Negatively charged DNA molecules mixed with positively charged versions of membrane Protective layer covering cells Nanoporous structure is locally aligned Delivery vehicles in gene therapy, electrophoretic media for sorting molecules, templates Features of DNA Membrane Complex

DNA Nanoparticle assembly

DNA –directed nanowires DNA templates used to provide a skeleton on which silver ions can be bound to create a wire with increased conductance.

DNA used as Molecular Switch A Single-stranded DNA attached to each electrode using a linker molecule; B If I > Icritical, joule heating will result in T > Tm (DNA), which will denature the DNA and the current flow will stop flowing. Alternatively, the temperature around the DNA strand can also be increased above Tm by a metal heater/resistor.

KEY APPLICATIONS of DNA Nanotechnology Scaffolding to crystallize biological macromolecules artificially for crystallography To organize the components of nanoelectronics To produce nanomechanical devices To produce membrane complexes with artificial membranes To form Nanonetworks with gold nanoclusters using dithiol connectors In building high conducting DNA-directed nanowires As a molecular switch

Liposomes Modeled after cell membranes Consist of phospholipids –One end is attracted to water –Other end is repelled Phospholipid bilayers grow into spheres with cavities that house drugs Applications include drug delivery and carrier as molecules such as proteins, nucleotides, plasmids, and small drug molecules

Applications of Liposomes Source:

Final Thoughts Biological structures hold a wealth of information for nanomaterial scientists Biological entities as devices Biomimic biological processes and structures to form higher quality nanostructures Integration of biological and synthetic materials Limitless capabilities and applications