Polymers of 21st century

Polymers of 21st century. : 

Polymers of 21st century. By Sravan kumar suggala 07U21R0051 B pharmacy IV-I Sree Dattha Institute of pharmacy. 30/09/2010 1

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Definition: : 

A dendrimer is generally described as a macromolecule,which is characterized by its highly branched structure that provides a high degree of surface functionality and versatility. Properties like High degree of branching,Multi valency , Well defined molecular weight clearly distinguishes these as unique and optimum nano carriers. 30/09/2010 3 Definition:

History: : 

FRITZ VOGTEL and Coworkers first synthesized these polymers in 1978. DONALD A.TOMALIA synthesized the first family of dendrimers in 1985. Dendrimer is a greek word DENDRON=Tree and meros =part. NEWKOMES in the same period synthesized these polymers and named them as ARBOROLS a latin word meaning Tree. Dendrimer is preferred over ARBOROLS. 30/09/2010 4 History:

STRUCTURE: : 

Dendrimers are built from a starting atom such as nitrogen to which carbon and other elements are added by a repeating series of chemical reactions that provides a spherical branching structure. A the process repeats successive layers are added ,the sphere can be expanded to the required size . This results in spherical macro molecule. 30/09/2010 5 STRUCTURE:

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COMPONENTS OF DENDRIMER: : 

CORE INTERIOR LAYERS(Generators) SHELL PINCEER END GROUP. 30/09/2010 7 COMPONENTS OF DENDRIMER:

INTERIOR LAYERS (Generators): : 

It is hyper branching when going from the center of the dendrimer towards the periphery, resulting in homo structural layers between the branching points. The number of focal points when going from the core towards the dendrimer surface is the GENERATION NUMBER. If there are 5 focal points then it is 5th generation dendrimer abbreviated as G5. 30/09/2010 8 INTERIOR LAYERS (Generators):

SHELL: : 

The dendrimer shell is the homo structural spatial segment between the focal points , the “generation space”. Outer shell: space between the last outer branching point and the surface. Inner shell: Generally dendrimer interior. 30/09/2010 9 SHELL:

PINCER: : 

In dendrimers the outer shell consists of a varying no of pincers created by last focal point before reaching the dendrimer surface. Number of pincer= Half the number of surface groups because in dendrimers the chain divides in to two chains in each focal point. 30/09/2010 10 PINCER:

END GROUP: : 

The groups that are present at the end are called END GROUPS. TERMINAL GROUP and SURFACE GROUP are synonyms. 30/09/2010 11 END GROUP:

COMPARISION BETWEEN DENDRIMERS AND LINEAR POLYMERS. : 

30/09/2010 12 COMPARISION BETWEEN DENDRIMERS AND LINEAR POLYMERS.

APPLICATIONS: : 

30/09/2010 13 Many potential applications of dendrimers are based on their molecular uniformity, multifunctional surface and presence of internal cavities. These specific properties make dendrimers suitable for a variety of high technology uses and are as follows: PHARMACEUTICAL APPLICATIONS which include Delivery of anti cancer drug Cellular delivery Nano drugs NON PHARMACEUTICAL APPLICATIONS. Dendritic catalysts/Enzymes Industrial processes. APPLICATIONS:

Delivery of Anticancer Drugs by Dendrimers and Dendritic Polymers: : 

The star polymer gave the most promising results regarding cytotoxicity and systemic circulatory half-life (72 h).In addition to improving drug properties such as solubility and plasma circulation time polymeric carriers can also facilitate the passive targeting of drugs to solid tumors. Combined, these factors lead to the selective accumulation of macromolecules in tumor tissue – a phenomenon termed the ‘Enhanced Permeation and Retention’ (EPR) effect .Therefore, the anticancer drug doxorubicin was covalently bound to this carrier via an acid-labile hydrazone linkage. The cytotoxicity of doxorubicin was significantly reduced (80–98%), and the drug was successfully taken up by several cancer cell lines 30/09/2010 14 Delivery of Anticancer Drugs by Dendrimers and Dendritic Polymers:

CELLULAR DELIVERY USING DENDRIMER CARRIERS: : 

Kannan et al. studied the dynamics of cellular entry into human lung epithelial carcinoma cells of a range of PAMAM dendrimers (G4-NH2, G3-NH2, G4-OH, PEGlayted G3 [G3-PEG]) and a hyper branched polymer (polyol). G4-NH2and G4-OH entered cells more rapidly than did G3-NH2, polyol or G3-PEG. It was suggested that the rapid entry of G4-NH2 might be a result of the cationic nature of the amine surface groups, which may interact electrostatically with negatively charged epithelial cells and enter via fluid phase pinocytosis. The lower rate of cellular entry of G3-NH2 compared with G4-NH2may be a result of fewer surface charges on the G3-NH2dendrimer.Because polyol and G3-PEG do not have cationic surface groups, their cellular entry may result from non-specific adsorption to the cell membrane and subsequent endocytosis. 30/09/2010 15 CELLULAR DELIVERY USING DENDRIMER CARRIERS:

DENDRIMERS AS NANO DRUGS: : 

Poly-lysine dendrimers modified with sulfonated naphthyl groups have been found to be useful as antiviral drugs against the herpes simplex virus can potentially prevent/reduce transmission of HIV and other sexually transmitted diseases (STDs) .In earlier studies, it was found that PAMAM dendrimers covalently modified with naphthyl sulfonate residues on the surface, also exhibited antiviral activity against HIV. This dendrimer-based nano-drug inhibited early stage virus/cell adsorption and later stage viral replication by interfering with reverse transcriptase and/or integrase enzyme activities. 30/09/2010 16 DENDRIMERS AS NANO DRUGS:

DENDRITIC CATALYSTS/ENZYMES: : 

The combination of high surface area and high solubility makes dendrimers useful as nanoscale catalysts. Dendrimers have a multifunctional surface and all catalytic sites are always exposed towards the reaction mixture. They can be recovered from the reaction mixture by easy ultra filtration methods. Dendritic shells can be used to create a microenvironment favorable for catalysis or provide shielding for functional groups at the dendritic core. Because of their ‘pseudo’-spherical nature and their resultant conformations the metal sites in these well-defined polymeric catalysts should be easily accessible for substrate molecules and reagents, and therefore exhibit characteristics- fast kinetics, specificity and solubility 30/09/2010 17 DENDRITIC CATALYSTS/ENZYMES:

INDUSTRIAL PROCESSES: : 

Dendrimers can encapsulate insoluble materials, such as metals, and transport them into a solvent within their interior. Cooper and co-workers synthesized fluorinated dendrimers, which are soluble in supercritical CO2 and can be used to extract strongly hydrophilic compounds from water into liquid CO2(13).This may help develop Technologies in which hazardous organic solvents are replaced by liquid CO2. 30/09/2010 18 INDUSTRIAL PROCESSES:

REFERENCE: : 

www.wikipedia.org www.pharmainfo.net 30/09/2010 19 REFERENCE:

ANY QUERIES : 

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