Design, Synthesis And Characterization Of Nano-carrier Based On Dendritic Polymers

Dendrimers have attracted great attention for their mono-dispersed molecular weights and well-defined structure. In addition, they can be used as nano-carriers because there are inner pockets in the molecules. PEGlyted dendrimers are developing rapidly recently owing to their excellent biocompatibility and increased EPR effect which is related with the ability for passive targeting in cancer treatment. Introduction of a hydrophobic shell on the surface of dendrimer can improve the complex stability. Besides, comparing with dendrimers, hyperbranched polymers have similar characteristics of structures and properties except for lower degree of branching and higher polydispersity of molecular weight. More interestingly, they are synthesized via a simple and convenient approach. Hyperbranched polymers obtained via improved approaches including employing multi-reactional molecule as core and multi-step polymerization are also attractive and have many potential applications, such as host-gest chemistry.A pH-sensitive nano-carrier system based on PAMAM dendrimer was designed and synthesized. The molecular structure and weight of the novel nano-carrier was characterized using IR, NMR and GPC/LS. Its properties in solution were studied using DLS and zeta potential. It was proved that the nano-carrier had relatively stability and could hydrolysis rapidly in acidic solution. We used p-NA as a hydrophobic molecule and Rose Bengal as a hydrophilic molecule to reserch ththeir encapsulating and releasing properties. The result shows that p-NA was readily released from the polymer; while the release behavior of RB is depend on pH. The hydrobobic group on the surface of dendrimer can act as barriers to keep RB inside. This function can also be presented even when the electrostatic interation between the protonated PAMAM core and negative RB molecules was diminished by adding NaCl. When the pH was decreased, the hydrophobic groups on the surfaces of dendrimer were cleavaged, which caused different release behavior of RB.Amphiphilic hyperbranched polyesters have intriguing biocompatibility and biodegradability. An amphiphilic nano-carrier system based on hyperbranched polyester was designed and synthesized. We prepared hyperbranched polyester using pseudo one pot method. The structure, hydroxyl value and thermo-properties of hyperbranched polyester are studied. The amphiphilic nano-carrier is synthesized via PEGlytion on the surface of hyperbranched polyester. The carrier can improve the solubility of highly hydrophobic guest molecules in water and its release profile presents diffusion-controlled behavior.