Design, Synthesis And Property Study Of Dendrimer As Drug Deliver Agent

Dendrimers are highly branched and reactive three-dimensional macromolecules, with all bonds emanating from a central core. Since their introduction in the mid-1980s, this novel class of polymeric materials has attracted considerable attention because of their unique structure and properties. Compared with traditional linear polymers, dendrimers have much more accurately controlled structures, with a globular shape, a single molecular weight rather than a distribution of molecular weights, and a large number of controllable 'peripheral' functionalities. Due to their unique physical and chemical properties, dendrimers provide many exciting opportunities for design of novel drug delivery systems, gene-carriers and imaging agents.To exploit the potential of dendrimers for use as drug delivery systems, we designed and synthesized a new type of water-soluble dendrimers. The dendrimers were synthesized in two steps: first, the poly(amidoamine)(PAMAM) dendrimers were prepared by divergent method, then PAMAM were treated with tris(tri-hydroxymethyl) amino methane(TRIS). PAMAM with ethylenediamine core were prepared, containing 4, 8 and 16 ester terminal groups respectively. Subsequent coupling reactions with TRIS afforded two type water-soluble dendrimers PAMAM-OH and PAMAM-K, dependent on the deffer of reaction media. The dendrimers were characterized by IR.The surface tension of their aqueous solution was measured by drop-volume method. As no CMC was observed, intermolecular aggregation did not occur in the concentration ranges used in solubilization studies. Benzoic acid, salicylic acid and ibuprofen were choiced as hydrophobic drug model. The ability of dendrimers to increase the solubility of hydrophic drug molecules was investigated by UV-VIS spectroscopy. The dendrimers with different end groups all enhanced the solubility of model drug significantly. Since no CMC was observed, the dendrimers in water could been regarded as "unimolecular micelle". The unimolecular micelle has the similar properties to a conventional micelle, but the micellar structure is static rather than dynamic, and it is maintained at all concentrations and in a variety of solvents. The inherent stability of dendritic unimolecular micelles, as well as the ability to encapsulate guest molecules, makes them good candidates for the design of novel drug delivery agents. Additionally we had observed the size recognition between dendrimers and guest molecules.