Ag/FeCo/Ag Core/Shell/Shell Magnetic Nanoparticles with Plasmonic Imaging Capability

Abstract

Magnetic nanoparticles (NPs) have been used to separate various species such as bacteria, cells, and proteins. In this study, we synthesized Ag/FeCo/Ag core/shell/shell NPs designed for magnetic separation of subcellular components like intracellular vesicles. A benefit of these NPs is that their silver metal content allows plasmon scattering to be used as a tool to observe detection by the NPs easily and semipermanently. Therefore, these NPs are considered a potential alternative to existing fluorescent probes like dye molecules and colloidal quantum dots. In addition, the Ag core inside the NPs suppresses the oxidation of FeCo because of electron transfer from the Ag core to the FeCo shell, even though FeCo is typically susceptible to oxidation. The surfaces of the Ag/FeCo/Ag NPs were functionalized with ε-poly-L-lysine-based hydrophilic polymers to make them water-soluble and biocompatible. The imaging capability of the polymer-functionalized NPs induced by plasmon scattering from the Ag core was investigated. The response of the NPs to a magnetic field using liposomes as platforms and applying a magnetic field during observation by confocal laser scanning microscopy was assessed. The results of the magnetophoresis experiments of liposomes allowed us to calculate the magnetic force to which each liposome was subjected.

Magnetic Separation of Autophagosomes from Mammalian Cells Using Magnetic–Plasmonic Hybrid Nanobeads

“…The MPNBs exhibited superparamagnetic behavior at 300 K with a saturation magnetization value of typically around 33 emu/g. 16 , 23 , 24 …”

“…Therefore, the red shift of the LSPR peak is presumably due to the ligand exchange with PLL-SH which has the higher refractive index than hexane, water, and hydrophobic organic ligands. Because the extinction of the LSPR band is linearly proportional to the concentration of MPNBs, 16 one can precisely estimate the concentration of MPNBs from the UV–vis spectrum. The concentration of the undiluted water dispersion of MPNBs was estimated to be 5.2 mg/mL from the UV–vis spectrum and was used in the following cellular experiment.…”

“… 16 Although the magnetic probe had a magnetically inert Ag core with a mean size of 10 nm, the magnetic beads showed separation capability. 16 If the magnetic bead with the same volume of the FeCo shell was composed of iron oxide, it would be ineffective as a magnetic bead because the saturation magnetization of iron oxide (400–450 emu/cm 3 ) is approximately a quarter that of FeCo (1790 emu/cm 3 ). 17 Therefore, we expect that our magnetic bead would be easily endocytosed and could be used as a separation probe for endosome-related organelles.…”

Исследования свойств наночастиц Ag/FeСo/Ag типа ядро/ оболочка/оболочка

“…Одним из наиболее перспективных ПР ГНЧ являются наночастицы Ag/FeСo/Ag типа ядро/оболочка/оболочка (Я/О/О) [5][6][7][8][9]. Наносеребро в наибольшей степени соот-ветствует требованиям, предъявляемым к материалам в этой области, так как имеют самые низкие плазмонные потери из всех материалов в УФ и видимой области спектра.…”

“…Наносеребро в наибольшей степени соот-ветствует требованиям, предъявляемым к материалам в этой области, так как имеют самые низкие плазмонные потери из всех материалов в УФ и видимой области спектра. Для синтеза таких ГНЧ в [5][6][7][8][9] были ком-бинированы FeСo и Ag в одной гетеро-наноструктуре, обладающей магнитными и плазмонными свойствами. Основной концепцией строения ГНЧ Ag/FeСo/Ag типа Я/О/О является то, что ядро из Ag обеспечивает ло-кализованный поверхностный плазмонный резонанс, а также подавляет окисление ферромагнитной оболочки FeСo из-за переноса электронов от ядра Ag к оболочке FeСo [5][6][7][8].…”