Fabrication Of Aggregate With Polyamide-amine Denderimers And Alkyl Gadolinium Compound And Study On Release Behavior Of Gadolinium Ions

The PAMAM-PEG dendrimer and the PAMAM-PEG-NAA dendrimer were synthesized with the core of PAMAM dendrimer and HOOC-PEG-NH₂（molecular weight 2000 Da）,HOOC-PEG-NH₂ and1-naphthylacetic acid（NAA）,respectively.They were characterized by Infrared spectrometer,Nuclear magnetic spectrometer,Transmission electron microscope（TEM）,Dynamic Light Scattering（DLS）and Gel Permeation Chromatography（GPC）,and the results were consistent with the theory.Three kinds of polymer aggregates were fabricated with the dendrimers of PAMAM,PAMAM-PEG and PAMAM-PEG-NAA,respectively and the micelle which constructed with gadolinium dodecyl benzene sulfonate（Gd₂（LAS）₃）and the solubilizer of fatty alcohol polyoxyethylene ether（AEO-25）by self-assembly of weak intermolecular interaction and synergetic effect.In a conclusion,the results showed that all of the three aggregates had good water solubility,moreover,the aggregates constructed by PAMAM-PEG were better than others.The release behavior of gadolinium ions in PAMAM-PEG/[Gd₂（LAS）₃/AEO] aggregate was observed in this paper by changing the pH values of the solution and the system temperature.The relationships of relaxation time with pH values,batch ratio and temperature were also studied by low-field NMR spectrometry,and the relaxation rate of the aggregate was 9.233 mM·s^-1.In summary,the aggregate had a high relaxation rate at low magnetic fields and expected to be used for nuclear magnetic resonance molecular imaging contrast agents.