Synthesis and characterization of new type of polyamidoamine dendrimer

Polyamidoamine(PAMAM) dendrimers are used in molecular recognition agents,catalysts,and biomedical materials for their unique structural features,such as the cavities inside the molecule and a large number of functional groups on the surface.The flexibility of dendrimer molecules exhibits obvious effect on gene transfer and drug delivery.The increase of the core size of the dendrimer efficiently improves its flexibility.By reaction of methyl acrylate with excess ethylenediamine,a compound was synthesized,which has longer molecular structure than ethylenediamine,and the related G1-G4 PAMAM dendrimers were prepared using the compound,through iterative Michael addition and amidation reaction.The products were purified using column chromatography and ether-involved sedimentation,and characterized by fourier transform infrared spectroscopy(FT-IR) and proton nuclear magnetic resonance spectra(1H NMR) spectra.The FT-IR results validate the synthetic procedure,and the 1H NMR spectra confirms the structure of desired core unit and the PAMAM dendrimers.These synthetic compounds not only possess the structural properties of traditional PAMAM dendrimer,but also have a lager core unit with an amide group.This kind of desired core unit increases the flexibility of dendrimer molecule and improves the hydrophilicity of the core section,and may provide reference to dendrimer on gene transfer and drug delivery.