Dendrimer
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Dendrimer

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Dendrimer Dendrimer Presentation Transcript

  • Dendrimes
  • Overview
  • Dendrimers are the new artificial macromolecules which have the structure like a tree. consist of a series of chemical shells built on a small core molecule. Each shell consists of two chemicals, always in the same order and is called a generation Fig. A: Schematic 2D presentation of dendrimer Fig. B: 3D presentation of dendrimer
  • Properties Structure Compact and Globular synthesis Careful and stepwise growth Structure control Very high Shape spherical Crystallinitty Non crystalline, amorphous material, lower glas temperature Nonpolar solubility high Aqueous solubility high viscosity Non liner relationship with molecular weight reactivity high
  • Dendrimer Components - Dendrimers consist of three main components… Interior Surface: functional peripheral group Interior: affects host-guest properties Core: affects 3D shape of dendrimer Core Surface
  • - Count branching points as the “generation” This is a “G2 dendrimer.” Higher generation dendrimers form more dense, dimensional shape.
  • How do we make a dendrimer? We make the nanodevice by modeling it first. Modeling then drives synthesis, which produces materials for testing. Test results, in turn, drive further modeling and synthesis.
  • Synthesis of Dendrimers Divergent strategy convergent strategy
  • Divergent strategy http://www.fda.gov/nanotechnology/powerpoint_conversions/chbsa-nanotech-presentation06-05_files/textonly/slide10.html
  • convergent strategy Lee J. W., Kim J.H., Kim Byung-Ku. Synthesis of azide-functionalized PAMAM dendrons at the focal point and their application for synthesis of PAMAM-like dendrimers, Tetrahedron Letters, 2006. 47:2683–2686
  • Organic Synthesis Dendrimers have been prepared via click chemistry, employing Diels-Alder reactions,thiol-yne reactions and azide-alkyne reactions.An example is the synthesis of certain polyphenylene dendrimers is shown in this figure http://en.wikipedia.org/wiki/Dendrimer
  • Supramolecular Dendrimers Supramolecular systems are rarely designed from first principles. Rather, chemists have a range of wellstudied structural and functional building blocks that they are able to use to build up larger functional architectures. Many of these exist as whole families of similar units, from which the analog with the exact desired properties can be chosen. The molecule shown here is a combination of traditional organic synthetic compounds using significant steric hinderence to achieve a particular shape/conformation
  • Dendrimers (Arborols)
  • Size scale of Dendrimers of different generations vs. Biological Proteins
  • Dendrimers vs. Proteins Similarities Size Weight Well defined chemical structure (known bonding structure) 3 dimensional position of each atom is difficult to determine - yet a consistent specific 3 dimensional structure exists Difficult to perform chemical analysis Easy for cell to uptake Main Difference Proteins are polymers made from 20 different monomers, while dendrimers are polymers made from two monomers.
  • Dendrimer Applications This light-harvesting dendrimer performs some functions of artificial photosynthesis. White light is gathered through chain-ends that behave like antennae and funneled into a chromophore in the dendrimer's core that then emits a single color of amplified light
  • 1- Bioactive Dendrimers Dendrimers can be functionalized for surface activity., such as attaching to cells, and using a quantum dot interior core for imaging. Dendrimers can contain metal atoms including gold which can absorb radiation at a particular wavelength, and used in cancer treatment. The relatively short lifetime of a dendrimer enures that it won’t bioaccumulate in the body, or concentrate potentially toxic cadmium (CdS quantum dots). Dendrimer
  • 2- Dendrimer as magnetic resonance imaging contrast agents Dendrimer based metal chelates act as a magnetic resonance imaging contrast agent. Dendrimers are highly suited and used as image contrast media because of their properties. Many tests carried on dendrimers have shown that dendrimers are stronger contrast agent than conventional ones. The effect of sepsis on dendrimer-enhanced magnetic resonance imaging (MRI) of the kidney. MRI scans 1, 9, and 17 minutes after intravenous injection of G4 dendrimer. (A) Sham-operated mouse 20 hours after surgery. (B) Cecal ligation and puncture (CLP)-operated mouse 20 hours after surgery.
  • 3- Dendrimers in Antitumor Therapy Dendrimers molecule has found use as diagnostic reagent for tumour imaging by magnetic resonance imaging and as contrast agent; by varying the size and hydrophilicity and by combining with tumour targeting antibodies, these compounds can be used for a range of specific imaging purpose The drug used should be non-toxic, under non- irradiative condition, thus acting as prodrug when not irradiated.
  • 4- Dendrimers as Gene Transfer agents Dendrimers as Gene Transfer agents because • Unmodified PAMAM and PPI dendeimers an form complexes with DNA. • Partially degraded or fragmented ( activated) dendrumers help transfection efficiency • Slight excess of primaryamines is benefiocail
  • 5- Dendrimers in targeted drug delivery Dendrimers have multifunctionality and high potential for drug delivery applications as they possess high density and wide variety of functional groups on its surface 9-11. Its well defined molecular structure, segmental spherical construction of dendrimers offers an interesting architecture for dendrimers. If one of these segments is attached with active drug molecule, the other can be highlighted as targeting group. Due to this double functional group, the plasma level of the drugs will stay at desired level for longer time period and increase its Pharmaceutical efficiency.
  • 6- Dendrimers in drug delivery Dendrimers in drug delivery because • Enhance the aqueous solubility • Increase circulation half life • Target certain tissue. • Improve transit across biological barrier . • Slow drug metabolism
  • 7- Dendrimers in transdermal drug delivery Transdermal drug delivery has come into existence long back. To improve the effectiveness of the drug transdermal drug delivery system was emerged. Drug delivery through skin to achieve a systematic effect of drug is known as transdermal drug delivery.
  • 8- Dendrimers in oral drug delivery Oral drug delivery is the most popular and has received more attention in the pharmaceutical field because of ease of production, low cost, convenience of ease of administration and flexibility in designing of dosage. The oral drug delivery depends on various factors such as type of delivery system, the disease being treated, and the patient, the length of the therapy and properties of the drug.
  • 9- Dendrimers in ocular drug delivery
  • 10- Dendrimers Fighting the Spread of Diseases The dendrimers (blue and red) in VivaGel interact with The dendrimer (blue and red) attaches to multiple receptors protein structures (yellow) on the surface of HIV, blocking (pink) on cell membranes or other biological structures such the interaction of HIV (purple) with healthy human cells as a virus. (pink) that results in HIV infection.
  • 11-Dendrimers used for enhancing the solubility PAMAM dendrimers are expected to have potential applications in enhancing the solubility for drug delivery systems 1, 2. Dendrimers have hydrophilic exteriors and hydrophilic interiors, which are responsible for its unimolecular micelle nature.
  • 12- Dendrimers for additives, printing inks and paints Dendrimers can be used in toners material with additives which require less material than their liquid counterparts. Xerox Corp. Patented a dry toner compound dendrimers as charge enhancing species in the form of an additive
  • 13- Dendrimers in light harvesting material
  • 14- Dendrimers as Catalyst
  • 15- Supramolecular Architectures A schematic illustration of supramolecular architectures of self-assembled extended amphiphilic dendrons, developed at Cornell by Ulrich Wiesner, professor of materials science and engineering , and his research team. The illustration shows (A) cubic micelles, (B) two-dimensional lamellar layers, (C) hexagonally arranged cylindrical columns and (D) three-dimensional continuous cubic structures.
  • 16- Dendrimers as a separating agent A study of variety of compounds synthesized to determine suitability for enhancing boron rejection by reverse osmosis and nanofilteration membrane to separate born from sea water has been developed. For separation, compound must have amphiphile chemical structure and form micelle in aqueous solution. As a new compound dendrimers with a high density of functional moiety, is able to form micelle structure which can be easily separated and recovered by ultra filtration membrane.
  • Dendrimer Superstructures Dendrimers are repetitively branched molecules. [1] [2] The name comes from the Greek word "δένδρον" (pronounced dendron), which translates to "tree". Synonymous terms for dendrimer include arborols and cascade molecules. However, dendrimer is currently the internationally accepted term. A dendrimer is typically symmetric around the core, and often adopts a spherical three-dimensional morphology. The word dendron is also encountered frequently. A dendron usually contains a single chemically addressable group called the focal point. The difference between dendrons and dendrimers is illustrated in figure one, but the terms are typically encountered interchangeably.[3]
  • Organic Light Emitting Diodes (OLEDs)
  • Re f e r e n c e s • http://www.nature.com/ki/journal/v67/n6/full/4495293a.html#fig1 • http://www.chemistry.ohio-state.edu/cgi-bin/brochure?Faculty=parquett • http://nano.med.umich.edu/Dendrimers.html#dendrimer_introduction • http://nano.med.umich.edu/Dendrimers.html • http://www3.interscience.wiley.com/cgi-bin/fulltext/106558159/PDFSTART • http://www.lbl.gov/Science-Articles/Research-Review/Magazine/2001/Fall/features/02Dendrimers.html • http://perceco2.chem.upenn.edu/~percec/inthenews/denx.html • http://www.gade.uni-hd.de/research.php • http://www.fda.gov/nanotechnology/powerpoint_conversions .com • http://www.news.cornell.edu/releases/Sept04/Wiesner.supermolecules.deb.html • http://en.wikipedia.org/wiki/Dendrimers http://pubs.acs.org/doi/abs/10.1021/nl202220q • http://www.ncbi.nlm.nih.gov/pubmed/21864902