A powerful magnetic nanoprobe with folic acid (FA)‐targeting ligands is fabricated by dendrimer functionalization of Fe3O4 nanoparticles (NPs) precoated with crosslinkable and biocompatible polymer multilayer shells. This magnetic probe allows for magnetic resonance imaging of FA receptor‐overexpressing tumor cells in vitro and of an early‐stage tumor model in vivo (see picture).
Polymer-functionalized carbon nanotubes hold great promise for their use in environmental and biomedical applications. In this work, polyethyleneimine (PEI) was covalently bonded to acid-treated multiwalled carbon nanotubes (MWCNTs) through amide bond formation. The amine groups of PEI on the surface of MWCNTs were then reacted with acetic anhydride or succinic anhydride to form MWCNTs with neutral or negative surface charges, respectively. The structural transformation, surface potential, and morphology of the functionalized MWCNTs were characterized by nuclear magnetic resonance, thermogravimetric analysis, zeta potential, and transmission electron microscopy. The functionalized MWCNTs are water-soluble and stable. In vitro cytotoxicity assays using both FRO cells (a human thyroid cancer cell line) and KB cells (a human epithelial carcinoma cell line) reveal that the biocompatibility of these functionalized MWCNTs is largely dependent on their surface potential. Neutral and negatively charged MWCNTs are nontoxic to both cell lines at a concentration up to 100 µg/mL, whereas positively charged MWCNTs are toxic to FRO cells at 10 µg/mL. The results of this study demonstrate that PEI-modified MWCNTs can be chemically modified to alter their surface charges and cytotoxicity, thereby significantly improving the biocompatibility of the materials for a variety of biomedical applications.
We report a facile approach to synthesizing 3-aminopropyltrimethoxysilane (APTS)-coated magnetic iron oxide (Fe(3)O(4)@APTS) nanoparticles (NPs) with tunable surface functional groups for potential biomedical applications. The Fe(3)O(4) NPs with a mean diameter of 6.5 nm were synthesized by a hydrothermal route in the presence of APTS. The formed amine-surfaced Fe(3)O(4)@APTS NPs were further chemically modified with acetic anhydride and succinic anhydride to generate neutral (Fe(3)O(4)@APTS⋅Ac) and negatively charged (Fe(3)O(4)@APTS⋅SAH) NPs. These differently functionalized NPs were extensively characterized by x-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetry analysis, zeta potential measurements, and T(2) relaxometry. The cytotoxicity of the particles was evaluated by in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric viability assay of cells along with microscopic observation of cell morphology. The hemocompatibility of the particles was assessed by in vitro hemolysis assay. We show that the hydrothermal approach enables an efficient modification of APTS onto the Fe(3)O(4) NP surfaces and the formed NPs with different surface charge polarities are water-dispersible and colloidally stable. The acetylated Fe(3)O(4)@APTS⋅Ac NPs displayed good biocompatibility and hemocompatibility in the concentration range of 0-100 µg ml(-1), while the pristine Fe(3)O(4)@APTS and Fe(3)O(4)@APTS⋅SAH particles started to display slight cytotoxicity at a concentration of 10 µg ml(-1). The findings from this study suggest that the Fe(3)O(4)@APTS NPs synthesized by the one-pot hydrothermal route can be surface modified for various potential biomedical applications.
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