Fluorescent Superparamagnetic Iron Oxide Core–Shell Nanoprobes for Multimodal Cellular Imaging

Abstract

Multimodal imaging agents that combine magnetic and fluorescent imaging capabilities are desirable for the high spatial and temporal resolution. In the present work, we report the synthesis of multifunctional fluorescent ferrofluids using iron oxide as the magnetic core and rhodamine B as fluorochrome shell. The core-shell structure was designed in such a way that fluorescence quenching due to the inner magnetic core was minimized by an intermediate layer of silica. The intermediate passive layer of silica was realized by a novel method which involves the esterification reaction between the epoxy group of prehydrolysed 3-Glyidoxypropyltrimethoxysilane and the surfactant over iron oxide. The as-synthesized ferrofluids have a high saturation magnetization in the range of 62-65 emu/g and were found to emit light of wavelength 640 nm ( excitation = 446 nm). Time resolved life time decay analysis showed a bi-exponential decay pattern with an increase in the decay life time in the presence of intermediate silica layer. Cytotoxicity studies confirmed the cell viability of these materials. The in vitro MRI imaging illustrated a high contrast when these multimodal nano probes were employed and the R2 relaxivity of these sample was found to be 334 mM −1 s −1 which reveals its high potential as a T2 contrast enhancing agent.

Thermal and mechanical properties of epoxy resin reinforced with modified iron oxide nanoparticles

“…Then, 1 g of citric acid was dissolved in 10 ml distilled water and was added to the above solution and stirred for 2 h. Finally, the solution was sonicated for 5 min to obtain a stable suspension. On the other hand, a pre-hydrolyzed GPTMS solution was prepared by adding a 10 ml mixture of water and isopropanol (1:2) to 107 mg of GPTMS with stirring for 1 h. 33 A 1 ml of the prepared solution was, then, added to 20 ml of the previously prepared suspension and stirred constantly for 6 h. The NPs were magnetically separated and washed/centrifuged with distilled water three times at 4000 rpm. Finally, the particles were dried under vacuum for 16 h at 50 C (Figure 2(b)).…”

Radio frequency plasma assisted surface modification of Fe3O4 nanoparticles using polyaniline/polypyrrole for bioimaging and magnetic hyperthermia applications

“…Similar to other semiconducting materials, presence of defects, oxygen vacancies or excitons are responsible for the optical properties of these Fe 3 O 4 [25]. One of the major challenges in the synthesis of magnetic-fluorescent nanomaterials is the quenching of photoluminescence (PL) emission by the magnetic core, contributed to the electron transfer between Fe 2+ and Fe 3+ ionic states in the tetrahedral and octahedral sites with the ligands [24][25][26][27]. This type of PL quenching can be controlled by coating the ferrite using polymers/silica layer [26,27].…”

“…One of the major challenges in the synthesis of magnetic-fluorescent nanomaterials is the quenching of photoluminescence (PL) emission by the magnetic core, contributed to the electron transfer between Fe 2+ and Fe 3+ ionic states in the tetrahedral and octahedral sites with the ligands [24][25][26][27]. This type of PL quenching can be controlled by coating the ferrite using polymers/silica layer [26,27]. Passivation of magnetite nanoparticles using conjugated polymers can also serve as a good photothermal agent for cancer therapy for both in vivo and in vitro applications [9,10].…”

Sub-Nanometer Controllable Fabrication of Freestanding Hetero-Structures Through Plasma-Matter Interaction During Ion Irradiation

“…Devices based on freestanding micro/nanostructures, including core-shell structures, have shown excellent functionalities that planar nanodevices cannot achieve and various fabrication techniques have been explored to produce functional 3D structures and devices. [1][2][3][4][5][6][7][8][9][10][11][12] Among them, plasma etching techniques have been used widely and intensively studied: on one hand to obtain freestanding micro/nano-structures with high aspect ratio by mask etching; the other is to explore the effects occurred in the processing with the downscaling of the minimum feature size of transistors towards the nanometer range. 13 14 Besides the application for failure analysis, 15 plasma etching techniques have been used in kinds of devices fabrication, including solar cells, 16 double gate Fin-FET devices, 17 and trenches.…”