Synthesis and characterization of functionalized magnetic maghemite nanoparticles with fluorescent probe capabilities for biological applications

Abstract

Nanoparticles with innovative optical, chemical, and magnetic properties combined in a single nanoparticle may be useful as biosensors, targeting agents, and therapeutic agents in the biomedical field. This study describes new magnetic nanoparticles (MNPs) containing the fluorescent dye rhodamine isothiocyanate (RITC) covalently encapsulated within the nanoparticles. These nanoparticles have been prepared by nucleation followed by controlled growth of iron oxide layers onto iron oxide/gelatin-RITC nuclei. The formed RITC labeled MNPs (R-MNPs) are of narrow size distribution, exhibit the fluorescent spectrum of RITC, yet are more photostable. Because of the covalent encapsulation of RITC within the MNPs no detectable leakage of the fluorescent dye into the aqueous continuous phase was observed. This manuscript also demonstrates that the surface of the R-MNPs retains similar ligand binding efficiency as the equivalent nonfluorescent MNPs. Specific cell labeling was obtained by incubating glia cells with R-MNPs conjugated to glial cell line-derived neurotrophic factor (GDNF) protein. We further showed that the R-MNPs may be used for pH sensing between the pH range of 5 and 9. This feature may enable the use of the R-MNPs as a pH sensor of animal tissues and cell compartments. Thus, these functional narrow size distribution R-MNPs with both magnetic and fluorescent properties may provide an important research tool for biological sensing.

Metal Oxide/Polymer Hybrid Nanoparticles with Versatile Functionality Prepared by Controlled Surface Crystallization

“…The modification of polymer particles with metal oxide nanocrystals can indeed be applied to prepare materials with unique properties. Magnetic iron oxides, which have drawn for years the attention of many research groups,19–22 are used to produce composites sensitive to magnetic stimuli for magnetic resonance imaging,23 magnetoresponsive release applications,24 and for an easier sample treatment 25, 26. Zinc oxide, one the most prominent semiconducting metal oxides,27–29 has been especially studied for the preparation of luminescent materials30 and quantum dots 31, 32.…”

Fluorescent Silica Nanoparticles for Medical Imaging

“…These NPs are typically synthesized by co-precipitation under inert gas environments to prevent oxidation, 3 however other procedures have been established that can produce high quality MNPs such as the solvothermal 62 and gelatin growth methods. 94 The final products are usually covalently linked to the FSNP but since their metallic composition can interfere with fluorescence emission of the encapsulated organic dye, many techniques have been developed that allow for dissociation of the MNP from the FSNP to enhance or stimulate the FSNP's fluorescence. 2 In addition to better imaging capabilities, MNP-FSNPs are capable of separating bound targets through simple magnetic separation.…”

Design of near-infrared fluorescent bioactive conjugated functional iron oxide nanoparticles for optical detection of colon cancer

“…Encapsulation of the dye probably protects the dye against reactive oxygen species, thereby reducing photobleaching. 23,41 Tumor growth on CAM A chicken embryo CAM model was used in this work for testing specific tumor detection by both nonbioactive and bioactive peanut agglutinin-conjugated and αCEA-conjugated NIR fluorescent IO-HSA nanoparticles. LS174T and SW480 cell lines evaluated in this study formed solid tumors 3-5 mm in diameter within 6 days.…”

“…[18][19][20][21][22] Previously, a unique type of uniform IO nanoparticles was prepared and characterized in our laboratory. 23,24 These IO nanoparticles were formed by controlled nucleation of IO onto gelatin, dissolved in an aqueous solution, and followed by stepwise growth of thin layers of IO films onto gelatin-IO nuclei. The same IO nanoparticles have been widely investigated in biological applications, and have been shown to be nontoxic.…”