Preparation And Characterization Of PH-Sensitive Nanoparticles Grafted With1-(3-Aminopropyl)Imidazole

Drug nanocarrier has many promising applications in biomedical field such asdrug delivery, targeting and therapy. The stimuli sensitive nanocarrier, also referred as“smart” nanomaterial, has attracted considerable research due to the capability ofdynamically changing their physical and chemical properties upon exposure toexternal stimuli such as temperature, pH and magnetic field. In this paper, using thebiocompatible dextran as the backbone, a new kind of polymer was synthesized bygrafted with a hydrophobic molecule and a pH-sensitive molecule. then we preparedpH-sensitive self-assembly dextran-based nanoparticles by nanoprecipitation.The main content of this research are shown as follows．The hydrophobical dextran derivative(DCA) was obtained by modified with5β-cholanic acid by using dicy-clohexyl carbodiimide (DCC) as coupling agent and4-dimethylaminopyridine (DMAP) as catalyst. Succinoylation of DCA with succinicanhydride implemented immediately using DMAP as catalyst. Then the pH-sensitive1-(3-aminopropyl) imidazole grafted onto the succinoylated DCA withN-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC) as couplingagent and N-hydroxysuccinimide (NHS) as catalyst. Finally, the obtained derivativesself-assembled into nanoparticles by nanoprecipitation.The morphology of the nanoparticles were analyzed using scanning electronmicroscopy and atomic force microscope. The stability and size distribution ofnanoparticles were measured by zetasizer. The pH-dependent behavior of thenanoparticles was examined by measuring particle size, light transmittance andbuffering behavior.The results showed that the mean diameters of the pH-sensitive nanoparticleswere <150nm, with uniform size distribution and good sphere morphology. Theparticle size, light transmittance and buffering behavior of the nanoparticles werealmost the same at above pH7.4, which showed nanoparticles had a good stability;but changed obviously at below pH7.0, it exhibited nanoparticles had an obviousaggregation behavior and a good buffering capacity.