Synthesis and Characterization of Soluble Iron Oxide−Dendrimer Composites

Abstract

Carboxylated poly(amidoamine) PAMAM dendrimers (generation 4.5) have been utilized for the synthesis and stabilization of ferrimagnetic iron oxide nanoparticles. Oxidation of Fe(II) at slightly elevated pH and temperature results in the formation of highly soluble nanocomposites of iron oxides and dendrimer, which are stable under a wide range of temperatures and pH's. Size exclusion chromatography indicates aggregates in the 20-30-nm size regime, consistent with the oligomeric nature of the composite material. Transmission electron microscopy reveals small assemblies of mineral cores with electron diffraction and high-resolution TEM data, indicative of the mineral maghemite. SQUID magnetometry demonstrated that this crystalline composition exhibited superparamagnetism at room temperature. NMR relaxation studies of solvent (water) protons revealed unusually high T1 and T2 relaxivities, which make these materials excellent candidates as contrast agents for MR imaging.

Synthesis and characterization of PVP-functionalized superparamagnetic Fe3O4 nanoparticles as an MRI contrast agent

“…Furthermore, aggregated nanoparticles change their superparamagnetic response [7]. Therefore, in order to minimize biofouling and aggregation of particles and escape from the RES for longer circulation times, the nanoparticles are usually coated with a layer of hydrophilic and biocompatible polymer such as dextran [18], dendrimers [19], poly(ethylene glycol) (PEG) [20], and poly(vinyl pyrrolidone) (PVP) [21][22][23]. Of synthetic polymers, PVP is water-soluble, non-charged, non-toxic, and is used in various medical applications [24].…”

Novel Nanosized Gd3+-ALGD-G2-C595: In vivo Dual Selective MUC-1 Positive Tumor Molecular MR Imaging and Therapeutic Agent

“…Better outcomes obtained by specifically delivering contrast agents to the tumors followed by taking MR imaging modalities. In this regard, application of nanosized cancer specific contrast agents plays an important role in MR imaging for early cancer detection followed by treatment [5][6][7][8][9][10].…”

“…Dendrimers (nanosized polymers) have been explored for the targeting of hydrophobic pharmaceuticals and or for the delivery of anticancer drugs including MR imaging contrast agents [7][8][9][10][11][12][13][14]. Dendrimerbased gadolinium chelates are a new class of macromolecular MR imaging contrast agents with extremely molecular relaxivities [7,9].…”

“…Dendrimers (nanosized polymers) have been explored for the targeting of hydrophobic pharmaceuticals and or for the delivery of anticancer drugs including MR imaging contrast agents [7][8][9][10][11][12][13][14]. Dendrimerbased gadolinium chelates are a new class of macromolecular MR imaging contrast agents with extremely molecular relaxivities [7,9]. The chemico-physical characteristics of dendrimers, including their monodispersity, water solubility, drug loading ability, and large number of functionalizable peripheral groups, make these macromolecules appropriate candidates for evaluation as MR tumor imaging or therapeutic vehicles [7][8][9][10][11][12][13][14].…”

“…Dendrimerbased gadolinium chelates are a new class of macromolecular MR imaging contrast agents with extremely molecular relaxivities [7,9]. The chemico-physical characteristics of dendrimers, including their monodispersity, water solubility, drug loading ability, and large number of functionalizable peripheral groups, make these macromolecules appropriate candidates for evaluation as MR tumor imaging or therapeutic vehicles [7][8][9][10][11][12][13][14]. As dendrimer generation increases, the number of terminal branches increases exponentially, while diameter increases linearly by about 1nm/generation.…”