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Cho E.-J.,Yonsei University | Yang J.,Yonsei University | Mohamedali K.A.,University of Texas M. D. Anderson Cancer Center | Lim E.-K.,Yonsei University | And 8 more authors.
Investigative Radiology | Year: 2011

Objectives: To investigate the efficiency of magnetic resonance imaging (MRI) contrast agents employing vascular endothelial growth factor (VEGF 121)/rGel conjugated MnFe2O4 nanocrystals for imaging of neovasculature using a bladder tumor model. Materials and Methods: VEGF121/rGel was conjugated to MnFe2O4 nanoparticles (MNPs). The targeting efficiency and detection capability of the VEGF121/rGel-MNPs were investigated in both KDR-deficient (253JB-V) and KDR-overexpressing (PAE/KDR) cells using MRI. The internalization of VEGF121/rGel-MNPs into cells was confirmed by electron microscopy. Their phosphorylation ability and cytotoxicity were compared with unconjugated VEGF121/rGel. The orthotopic tumor mice were established by implanting low KDR-expressing 253JB-V cells into the bladder dome. After tail-vein injection of VEGF121/rGel-MNPs, the MR signal enhancement of intratumoral vessels by VEGF121/rGel-MNPs was observed and inhibition test using VEGF121 was also conducted. Ex vivo MR imaging of tumor tissue, and a fluorescence immunostaining study was also performed. Results: The water-soluble VEGF121/rGel-MNPs (44.5 ± 1.2 nm) were stably suspended in the biologic media and exhibited a high relaxivity coefficient (423 mM-1s-1). They demonstrated sufficient targeting capability against KDR-overexpressing PAE/KDR cells, as confirmed by dosedependent MR images and VEGF121 inhibition tests The phosphorylation activity of KDR and cytotoxicity of VEGF121/rGel-MNPs were evaluated. VEGF121/rGel-MNPs successfully targeted the tumor and provided accurate anatomic details through (i) acquisition of clear neoangiogenic vascular distributions and (ii) obvious enhancement of the MR signal in T2*-weighted images. Immunostaining and blocking studies demonstrated the specific targeting ability of VEGF121/rGel- MNPs toward intratumoral angiogenesis. Conclusions: Synthesized VEGF 121/rGel-MNPs as targeted MR imaging contrast agents can be specifically delivered to tumors and bind to KDR-expressing angiogenic tumor vessels. Copyright © 2011 by Lippincott Williams & Wilkins.

Hong Y.,Yonsei University | Huh Y.-M.,Yonsei University | Huh Y.-M.,Severance Biomedical Science Institute SBSI | Yoon D.S.,Yonsei University | Yang J.,Yonsei University
Journal of Nanomaterials | Year: 2012

Localized surface plasmon resonance (LSPR) is induced by incident light when it interacts with noble metal nanoparticles that have smaller sizes than the wavelength of the incident light. Recently, LSPR-based nanobiosensors were developed as tools for highly sensitive, label-free, and flexible sensing techniques for the detection of biomolecular interactions. In this paper, we describe the basic principles of LSPR-based nanobiosensing techniques and LSPR sensor system for biomolecule sensing. We also discuss the challenges using LSPR nanobiosensors for detection of biomolecules as a biomarker. © 2012 Yoochan Hong et al.

Lim E.-K.,Yonsei University | Jang E.,Yonsei University | Kim B.,Yonsei University | Choi J.,Yonsei University | And 8 more authors.
Journal of Materials Chemistry | Year: 2011

We fabricated dextran-coated magnetic nanoclusters (Dex-MNCs) for targeted magnetic resonance (MR) imaging of inflammatory macrophages. Dex-MNCs were prepared through encapsulation of hydrophobic magnetic nanocrystals (MNCs) by pyrenyl dextran in order that MNCs could achieve increased colloidal stability in aqueous phase as well as strongly interact with macrophages. Dex-MNCs exhibited biocompatibility and sufficient targeting efficiency against macrophages with strengthened MR contrast effect from in vitro/in vivo studies. Considering these results, we confirmed that Dex-MNCs could accurately detect inflammatory macrophage via MR imaging. © 2011 The Royal Society of Chemistry.

Jang E.,Yonsei University | Lim E.-K.,Yonsei University | Choi J.,Yonsei University | Park J.,Yonsei University | And 8 more authors.
Crystal Growth and Design | Year: 2012

In nanomaterials synthesis, Ostwald ripening is a postsynthetic problem that is one obstacle for common utilization of nanomaterials. Herein, we report an unprecedented Ostwald ripening mechanism resulting from the simple combination of hydrogen peroxide (H 2O 2) and cetyltrimethylammonium bromide (CTAB)-stabilized gold nanoparticles (AuNPs) at room temperature. In this ripening process, H 2O 2 redox induces simultaneous dissolution and growth of AuNPs where bromide (Br -) from CTAB helps to form AuBr 2 - in aqueous solution at room temperature. This understanding will provide basic strategies for advanced designs and development of various nanomaterials. © 2011 American Chemical Society.

Lim E.-K.,Yonsei University | Lim E.-K.,Korea Research Institute of Bioscience and Biotechnology | Jang E.,Yonsei University | Kim J.,Yonsei University | And 10 more authors.
Journal of Materials Chemistry | Year: 2012

A facile method to produce dextran-coated gold nanoparticles (DGNPs) for atherosclerosis detection using computed tomography (CT) imaging is developed. DGNPs are prepared using only pyrenyl dextran as a reducible stabilizer chemically conjugated with hydroxyl groups of dextran and carboxyl groups of pyrenyl molecules, which can reduce gold ions to gold particles and stably form gold nanoparticles in the aqueous phase. The physical properties of DGNPs can be controlled by the reaction time. DGNPs, where gold particles were stably covered with dextran, exhibit targeting ability against inflammatory macrophages with the help of strong interactions between dextran on their surface and scavenger receptors in the macrophages with good biocompatibility without cell damage. From the in vivo studies, DGNPs can be used to accurately detect atherosclerosis via CT imaging. © 2012 The Royal Society of Chemistry.

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