Introduction Of Dendrimers, Properties & Advantages Of Dendrimers In Brief - Part 1
INTRODUCTION:Over the past few years, nanotechnology has emerged as a new and exciting research field that deals with the design, synthesis and fabrication of structures at the molecular scale. There are approximately 130 nanopharmaceutical products in development including nanoparticles, nanocrystals, dendrimers, liposomes and micelles. Their basic aim is to improving pharmacokinetic of drug with especially bioavailability and its delivery to specific target site to body.
Nan pharmaceuticals are fall into five categories: nanoparticles, nanocrystals, dendrimers, liposomes and micelles. Dendrimers are a unique class of polymers, which play an important role in emerging nanotechnology1. Because of their compact, tree-like molecular structure, they provide a rich source of surface functionality, which makes them useful building blocks, and carrier molecules at the nanometer level. They are also important in more traditional technologies such as coatings and inks, as the spherical molecular shape imparts unusual viscosity characteristics.
Dendrimers, in particular, have attracted attention for their drug-delivery applications because of the ease of their synthesis, the ability to achieve well-defined shapes and sizes2. Dendrimers are well-suited for use as carrier molecules in drug delivery, because of its interior void space and surface functional groups. Dendrimers such as poly(amidoamine) (PAMAM) have been widely studied, and researchers have found diverse applications for them in biomedical and biological sciencesDendrimers are versatile, derivatisable, well-defined, compartmentalised chemical polymers with sizes and physicochemical properties resembling those of biomolecules e.g. proteins. The present critical review (citing 158 references) briefly describesdendrimerdesign, nomenclature and divergent/convergent dendrimer synthesis.
The characteristic physicochemical features of dendrimers are highlighted, showing the effect of solvent pH and polarity on their spatial structure. The use of dendrimers in biological systems are reviewed, with emphasis on the biocompatibility of dendrimers, such as in vitro and in vivo cytotoxicity, as well as biopermeability, biostability and immunogenicity.
The review deals with numerous applications of dendrimers as tools for efficient multivalent presentation of biological ligands in biospecific recognition, inhibition and targeting.Dendrimers may be used as drugs for antibacterial and antiviral treatment and have found use as antitumor agents. The review highlights the use of dendrimersas drug or gene delivery devices in e.g. anticancer therapy, and the design of different host–guest binding motifs directed towards medical applications is described.Other specific examples are the use of dendrimers as ‘glycocarriers’ for the controlled multimericpresentation of biologically relevant carbohydrate moieties which are useful for targeting modified tissue in malignant diseases for diagnostic and therapeutic purposes.
Nanotechnology is a new field, and these are the first working biologically active nano devices. These nano devices are undergoing tests to determine their operating parameters and biological activity. Currently the Institute is testing nano devices as smart therapeutics for cancer. The Institute is building a catalog of components, each of which individually performs a particular biological task and each of which can be combined with others to produce a vast array of nano devices.
Figure: Image Of Dendrimers
Dendrimers are spherical polymeric molecules. Dendrimers and proteins share several characteristics:
• Size
• Weight
• Well-defined chemical structure where every atom and its bonds to other atoms is known
• Difficulty in determining the 3-dimensional position of each atom, yet a consistent, specific
3-dimensional structure exists
• Difficulty in performing chemical analysis
• Ease of cellular uptake
Figure: Nanoscopic sizes of dendrimers.
Dendrimers and proteins differ in that proteins are polymers made from 20 different monomers, while dendrimers are polymers made from two monomers: acrylic acid and a diamine. Dendrimers are polymers, as are all plastics. Nylon is a very well-known polymer that is made from a diacid and a diamine. Nylon and dendrimers share a very similar chemical heritage and structure, yet nylon differs in a most important way from dendrimers. Nylon and all plastics have very poorly defined chemical structures. These traditional polymers are mixtures of many different molecules, tangled together to give an average molecular structure and constant bulk properties. The distribution of the constituent molecules is probabilistic. In contrast, dendrimers are precisely defined chemical structures; all of the chemical bonds between the atoms can be accurately described. It is this consistency of structure that makes dendrimersthe ideal (and to date the only) building block for creating a biologically active nano-material.
Using dendrimers, the Michigan Nanotechnology Institute for Medicine and Biological Sciences has demonstrated several biologically active nano-materials. The goal of the Institute is to create a catalogofnano-components which can be used as building blocks in the creation of a vast array of larger, more sophisticated nanodevices, which the Institute names Tecto-Dendrimers.
PROPERTIES OF DENDRIMERS:
- High degree of structural symmetry
- Density gradient (dense core, loose shell)
- Well defined terminal groups that can be chemically different from the interior
- Polyvalent
- Significantly increased solubility compared to linear polymers
- Low intrinsic viscosity
ADVANTAGES OF DENDRIMERS:
Some of the advantages of dendrimer technology include:-
- Biocompatibility
- Non-toxicity
- Non-irritability
- Thermodynamically stable in the body
- Ability to reach places in the body inaccessible to more massive red blood cells
- High solubility in water.
- High oxygen solubility
- Efficient rate of oxygen transfer into an aqueous phase.