Ha-Young Lee

Stanford Medicine, Stanford, California, United States

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Publications (3)20.68 Total impact

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    ABSTRACT: The purpose of this study was to observe the pharmacokinetic behavior of newly synthesized biocompatible polymers based on polyhydroxyethylaspartamide (PHEA) to be used to coat an iron oxide core to make superparamagnetic iron oxide nanoparticles (SPION). The isotopes [(14)C] and [(59)Fe] were used to label the polymer backbone (CLS) and iron oxide core (FLS), respectively. In addition, unradiolabeled cold superparamagnetic iron oxide nanoparticles (SPION/ULS) were synthesized to characterize particle size by dynamic light scattering, morphology by transmission electron microscopy, and in vivo magnetic resonance imaging (MRI). CLS and FLS were used separately to investigate the behavior of both the synthesized polymer and [Fe] in Sprague Dawley (SD) rats, respectively. Because radioactivity of the isotopes was different by β for CLS and γ for FLS, synthesis of the samples had to be separately prepared. The mean particle size of the ULS was 66.1 nm, and the biodistribution of CLS concentrations in various organs, in rank order of magnitude, was liver > kidney > small intestine > other. The biodistribution of FLS concentrations was liver > spleen > lung > other. These rank orders show that synthesized SPION mainly accumulates in the liver. The differences in the distribution were caused by the SPION metabolism. Radiolabeled polymer was metabolized by the kidney and excreted mainly in the urine; [(59)Fe] was recycled for erythrocyte production in the spleen and excreted mainly in the feces. The MR image of the liver after intravenous injection demonstrated that [Fe] effectively accumulated in the liver and exhibited high-contrast enhancement on T2-weighted images. This newly synthesized, polymer-coated SPION appears to be a promising candidate for use as a liver-targeted, biocompatible iron oxide MR imaging agent.
    International Journal of Nanomedicine 01/2013; 8:4077-89. · 4.20 Impact Factor
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    ABSTRACT: Biocompatible poly-[N-(2-hydroxyethyl)-d,l-aspartamide]-methoxypoly(ethyleneglycol)-hexadecylamine (PHEA-mPEG-C(16)) conjugated with 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid-gadolinium (DOTA-Gd) via ethylenediamine (ED) was synthesized as a magnetic resonance imaging (MRI) contrast agent. Amphiphilic PHEA-mPEG-C(16)-ED-DOTA-Gd forms micelle in aqueous solution. All the synthesized materials were characterized by proton nuclear magnetic resonance ((1)H NMR). Micelle size and shape were examined by dynamic light scattering (DLS) and atomic force microscopy (AFM). Micelles with PHEA-mPEG-C(16)-ED-DOTA-Gd showed higher relaxivities than the commercially available gadolinium contrast agent. Moreover, the signal intensity of a rabbit liver was effectively increased after intravenous injection of PHEA-mPEG-C(16)-ED-DOTA-Gd.
    Nanoscale Research Letters 12/2010; 5(12):1970-1976. · 2.48 Impact Factor
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    ABSTRACT: The purpose of this study was to develop a bifunctional iron oxide (IO) nanoparticle probe for PET and MRI scans of tumor integrin alphavbeta3 expression. Polyaspartic acid (PASP)-coated IO (PASP-IO) nanoparticles were synthesized using a coprecipitation method, and particle size and magnetic properties were measured. A phantom study was used to assess the efficacy of PASP-IO as a T2-weighted MRI contrast agent. PASP-IO nanoparticles with surface amino groups were coupled to cyclic arginine-glycine-aspartic (RGD) peptides for integrin alphavbeta3 targeting and macrocyclic 1,4,7,10-tetraazacyclododecane-N,N',N'',N''',-tetraacetic acid (DOTA) chelators for PET after labeling with 64Cu. IO nanoparticle conjugates were further tested in vitro and in vivo to determine receptor targeting efficacy and feasibility for dual PET/MRI. PASP-IO nanoparticles made by single-step reaction have a core size of 5 nm with a hydrodynamic diameter of 45 +/- 10 nm. The saturation magnetization of PASP-IO nanoparticles is about 117 emu/g of iron, and the measured r2 and r2* are 105.5 and 165.5 (s.mM)(-1), respectively. A displacement competitive binding assay indicates that DOTA-IO-RGD conjugates bound specifically to integrin alphavbeta3 in vitro. Both small-animal PET and T2-weighted MRI show integrin-specific delivery of conjugated RGD-PASP-IO nanoparticles and prominent reticuloendothelial system uptake. We have successfully developed an IO-based nanoprobe for simultaneous dual PET and MRI of tumor integrin expression. The success of this bifunctional imaging approach may allow for earlier tumor detection with a high degree of accuracy and provide further insight into the molecular mechanisms of cancer.
    Journal of Nuclear Medicine 08/2008; 49(8):1371-9. · 5.56 Impact Factor
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    ABSTRACT: We report a direct synthesis of ultrasmall c(RGDyK) peptide-coated Fe3O4 NPs (<10 nm in hydrodynamic diameter) and demonstrate their in vivo tumor-specific targeting capability. The Fe3O4 NPs are synthesized by thermal decomposition of iron pentacarbonyl in the presence of 4-methylcatechol (4-MC), and the peptide is coupled to the nanoparticles through 4-MC via Mannich reaction. The c(RGDyK)-MC-Fe3O4 NPs have an overall diameter of approximately 8.4 nm and are stable in physiological conditions. When administrated intravenously, these c(RGDyK)-MC-Fe3O4 NPs accumulate preferentially in the integrin alphavbeta3-rich tumor area, which are readily tracked by MRI.
    Journal of the American Chemical Society 07/2008; 130(24):7542-3. · 11.44 Impact Factor
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    ABSTRACT: The purpose of this study was to synthesize biocompatible polyvinylpyrrolidone (PVP)-coated iron oxide (PVP-IO) nanoparticles and to evaluate their efficacy as a magnetic resonance imaging (MRI) contrast agent. The PVP-IO nanoparticles were synthesized by a thermal decomposition method and characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), and a superconducting quantum interface device (SQUID). The core size of the particles is about 8–10 nm and the overall size is around 20–30 nm. The measured r2 (reciprocal of T2 relaxation time) and r2* (reciprocal of T2* relaxation time) are 141.2 and 338.1 (s mM)−1, respectively. The particles are highly soluble and stable in various buffers and in serum. The macrophage uptake of PVP-IO is comparable to that of Feridex as measured by a Prussian blue iron stain and phantom study. The signal intensity of a rabbit liver was effectively reduced after intravenous administration of PVP-IO. Therefore PVP-IO nanoparticles are potentially useful for T2-weighted MR imaging.
    Nanotechnology 03/2008; 19(16):165101. · 3.67 Impact Factor