Synthesis of bi-phase dispersible core-shell FeAu@ZnO magneto-opto-fluorescent nanoparticles.
Ontology highlight
ABSTRACT:
SUBMITTER: Li XM
PROVIDER: S-EPMC4637858 | biostudies-other | 2015
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Single-chain nanoparticles (SCNPs) are highly versatile structures resembling proteins, able to function as catalysts or biomedical delivery systems. Based on their synthesis by single-chain collapse into nanoparticular systems, their internal structure is complex, resulting in nanosized domains preformed during the crosslinking process. In this study we present proof of such nanocompartments within SCNPs via a combination of electron paramagnetic resonance (EPR) and fluorescence spectroscopy. A novel strategy to encapsulate labels within these water dispersible SCNPs with hydrodynamic radii of ≈5 nm is presented, based on amphiphilic polymers with additional covalently bound labels, attached via the copper catalyzed azide/alkyne "click" reaction (CuAAC). A detailed profile of the interior of the SCNPs and the labels' microenvironment was obtained via electron paramagnetic resonance (EPR) experiments, followed by an assessment of their photophysical properties.
| S-EPMC8048794 | biostudies-literature
Project description:Magneto-fluorescent particles have been recognized as an emerging class of materials that exhibit great potential in advanced applications. However, synthesizing such magneto-fluorescent nanomaterials that simultaneously exhibit uniform and tunable sizes, high magnetic content loading, maximized fluorophore coverage at the surface and a versatile surface functionality has proven challenging. Here we report a simple approach for co-assembling magnetic nanoparticles with fluorescent quantum dots to form colloidal magneto-fluorescent supernanoparticles. Importantly, these supernanoparticles exhibit a superstructure consisting of a close-packed magnetic nanoparticle 'core', which is fully surrounded by a 'shell' of fluorescent quantum dots. A thin layer of silica coating provides high colloidal stability and biocompatibility, and a versatile surface functionality. We demonstrate that after surface pegylation, these silica-coated magneto-fluorescent supernanoparticles can be magnetically manipulated inside living cells while being optically tracked. Moreover, our silica-coated magneto-fluorescent supernanoparticles can also serve as an in vivo multi-photon and magnetic resonance dual-modal imaging probe.
| S-EPMC4264679 | biostudies-literature
Project description:Superparamagnetic nanoparticles have been proposed for many applications in biotechnology and medicine. In this paper, it is demonstrated how the excellent colloidal stability and magnetic properties of monodisperse and individually densely grafted iron oxide nanoparticles can be used to manipulate reversibly the solubility of nanoparticles with a poly(N-isopropylacrylamide)nitrodopamine shell. "Grafting-to" and "grafting-from" methods for synthesis of an irreversibly anchored brush shell to monodisperse, oleic acid coated iron oxide cores are compared. Thereafter, it is shown that local heating by magnetic fields as well as global thermal heating can be used to efficiently and reversibly aggregate, magnetically extract nanoparticles from solution and spontaneously redisperse them. The coupling of magnetic and thermally responsive properties points to novel uses as smart materials, for example, in integrated devices for molecular separation and extraction.
| S-EPMC4559841 | biostudies-literature
Project description:In this work, we report the synthesis and characterization of three magnetic nanosystems, CoFe2O4, CoFe2O4@ZnFe2O4, and CoFe2O4@MnFe2O4, which were developed as potential theranostic agents for magnetic hyperthermia and magnetic resonance imaging (MRI). These nanosystems have been thoroughly characterized by X-ray Diffraction (XRD), Transmission Electron Miscroscopy (TEM), Dark Field-TEM (DF-TEM), Vibrating Sample Magnetometry (VSM), and inductive heating, in order to elucidate their structure, morphology, and magnetic properties. The bi-magnetic CoFe2O4@ZnFe2O4 and CoFe2O4@MnFe2O4 nanoparticles (NPs) exhibited a core-shell structure with a mean average particle size of 11.2 ± 1.4 nm and 14.4 ± 2.4 nm, respectively. The CoFe2O4@MnFe2O4 NPs showed the highest specific absorption rate (SAR) values (210-320 W/g) upon exposure to an external magnetic field, along with the highest saturation magnetization (Ms). Therefore, they were selected for functionalization with the PEGylated ligand to make them stable in aqueous media. After the functionalization process, the NPs showed high magnetic relaxivity values and very low cytotoxicity, demonstrating that CoFe2O4@MnFe2O4 is a good candidate for in vivo applications. Finally, in vivo MRI experiments showed that PEGylated CoFe2O4@MnFe2O4 NPs produce high T2 contrast and exhibit very good stealth properties, leading to the efficient evasion of the mononuclear phagocyte system. Thus, these bi-magnetic core-shell NPs show great potential as theranostic agents for in vivo applications, combining magnetic hyperthermia capabilities with high MRI contrast.
| S-EPMC7279505 | biostudies-literature
Project description:Multifunctional nano-heterostructures (NHSs) with controlled morphology are cardinal in many applications, but the understanding of the nanoscale colloidal chemistry is yet to be fulfilled. The stability of the involved crystalline phases in different solvents at mid- and high-temperatures and reaction kinetics considerably affect the nucleation and growth of the materials and their final architecture. The formation mechanism of manganese ferrite-based core-shell NHSs is herein investigated. The effects of the core size (8, 10, and 11 nm), the shell nature (cobalt ferrite and spinel iron oxide) and the polarity of the solvent (toluene and octanol) on the dissolution phenomena of manganese ferrite are also studied. Noteworthily, the combined use of bulk (powder X-ray diffraction, 57Fe Mössbauer spectroscopy, and DC magnetometry) and nanoscale techniques (HRTEM and STEM-EDX) provides new insights into the manganese ferrite dissolution phenomena, the colloidal stability in an organic environment, and the critical size below which dissolution is complete. Moreover, the dissolved manganese and iron ions react further, leading to an inverted core-shell in the mother liquor solution, paving the way to novel synthetic pathways in nanocrystal design. The MnFe2O4@CoFe2O4 core-shell heterostructures were also employed as heat mediators, exploiting the magnetic coupling between a hard (CoFe2O4) and a soft phase (MnFe2O4).
| S-EPMC9418864 | biostudies-literature
Project description:Functional nanocomposites with biopolymers and zinc oxide (ZnO) nanoparticles is an emerging application of photocatalysis in antifouling coatings. The reduced chemical stability of ZnO in the acidic media in which chitosan is soluble affects the performance of chitosan nanocomposites in antifouling applications. In this study, a thin shell of amorphous tin dioxide (SnOx) was grown on the surface of ZnO to form ZnO-SnOx core-shell nanoparticles that improved the chemical stability of the photocatalyst nanoparticles, as examined at pH 3 and 6. The photocatalytic activity of ZnO-SnOx in the degradation of methylene blue (MB) dye under visible light showed a higher efficiency than that of ZnO nanoparticles due to the passivation of electronic defects. Chitosan-based antifouling coatings with varying percentages of ZnO or ZnO-SnOx nanoparticles, with or without the glutaraldehyde (GA) crosslinking of chitosan, were developed and studied. The incorporation of photocatalysts into the chitosan matrix enhanced the thermal stability of the coatings. Through a mesocosm study using running natural seawater, it was found that chitosan/ZnO-SnOx/GA coatings enabled better inhibition of bacterial growth compared to chitosan coatings alone. This study demonstrates the antifouling potential of chitosan nanocomposite coatings containing core-shell nanoparticles as an effective solution for the prevention of biofouling.
| S-EPMC8123458 | biostudies-literature
Project description:Hydrogen production from water splitting using solar energy based on photoelectrochemical (PEC) cells has attracted increasing attention because it leaves less of a carbon footprint and has economic superiority of solar and hydrogen energy. Oxide semiconductors such as ZnO possessing high stability against photocorrosion in hole scavenger systems have been widely used to build photoanodes of PEC cells but under visible light their conversion efficiencies with respect to incident-photon-to-current conversion efficiency (IPCE) measured without external bias are still not satisfied. An innovative way is presented here to significantly improve the conversion efficiency of PEC cells by constructing a core-shell structure-based photoanode comprising Au@CdS core-shell nanoparticles on ZnO nanowires (Au@CdS-ZnO). The Au core offers strong electronic interactions with both CdS and ZnO resulting in a unique nanojunction to facilitate charge transfer. The Au@CdS-ZnO PEC cell under 400 nm light irradiation without any applied bias provides an IPCE of 14.8%. Under AM1.5 light illumination with a bias of 0.4 V, the Au@CdS-ZnO PEC cell produces H2 at a constant rate of 11.5 μmol h-1 as long as 10 h. This work provides a fundamental insight to improve the conversion efficiency for visible light in water splitting.
| S-EPMC5115296 | biostudies-literature
Project description:Increasing use of silica nanoparticles (SiO2 NPs) in consumer products and industrial processes leads to SiO2 NP discharge into wastewater. Thus, there is a need to understand the fate of SiO2 NPs during wastewater treatment. However, the detection of SiO2 NPs in environmental systems is hindered by the elevated background levels of natural silicon. In this work, laboratory-synthesized fluorescent core-shell SiO2 NPs were used to study the fate of these NPs during secondary wastewater treatment. Fluorescent measurements provided an easy and fast method for SiO2 NP tracking. A laboratory-scale activated sludge system consisting of an aeration tank and a settler was fed with synthetic wastewater containing ca. 7.5 mg L(-1) of fluorescent SiO2 NPs for 30 days. SiO2 NPs were effectively removed from the wastewater (>96%) during the first 6 days, however the concentration of SiO2 NPs in the effluent gradually increased afterwards and the NP discharge was as high as 65% of the input after 30 days of NP dosing. The poor removal of the SiO2 NPs was related to the high colloidal stability of the NPs in the wastewater and their limited propensity to biosorption. Although some degree of NP adsorption on the biomass was observed using fluorescence microscopy, the affinity of SiO2 NPs for the activated sludge was not enough for a sustained and effective removal of the SiO2 NPs from the wastewater.
| S-EPMC4426230 | biostudies-literature
Project description:Lanthanide-doped nanoparticles are an emerging class of optical sensors, exhibiting sharp emission peaks, high signal-to-noise ratio, photostability, and a ratiometric color response to stress. The same centrosymmetric crystal field environment that allows for high mechanosensitivity in the cubic-phase (?), however, contributes to low upconversion quantum yield (UCQY). In this work, we engineer brighter mechanosensitive upconverters using a core-shell geometry. Sub-25 nm ?-NaYF4:Yb,Er cores are shelled with an optically inert surface passivation layer of ?4.5 nm thickness. Using different shell materials, including NaGdF4, NaYF4, and NaLuF4, we study how compressive to tensile strain influences the nanoparticles' imaging and sensing properties. All core-shell nanoparticles exhibit enhanced UCQY, up to 0.14% at 150 W/cm2, which rivals the efficiency of unshelled hexagonal-phase (?) nanoparticles. Additionally, strain at the core-shell interface can tune mechanosensitivity. In particular, the compressive Gd shell results in the largest color response from yellow-green to orange or, quantitatively, a change in the red to green ratio of 12.2 ± 1.2% per GPa. For all samples, the ratiometric readouts are consistent over three pressure cycles from ambient to 5 GPa. Therefore, heteroepitaxial shelling significantly improves signal brightness without compromising the core's mechano-sensing capabilities and further, promotes core-shell cubic-phase nanoparticles as upcoming in vivo and in situ optical sensors.
| S-EPMC6613353 | biostudies-literature
Project description:Injectable sensors can significantly improve the volume of critical biomedical information emerging from the human body in response to injury or disease. Optical oxygen sensors with rapid response times can be achieved by incorporating oxygen-sensitive luminescent molecules within polymeric matrices with suitably high surface area to volume ratios. In this work, electrospraying utilizes these advances to produce conveniently injectable, oxygen sensing particles made up of a core-shell polysulfone-polysulfone structure containing a phosphorescent oxygen-sensitive palladium porphyrin species within the core. Particle morphology is highly dependent on solvent identity and electrospraying parameters; DMF offers the best potential for the creation of uniform, sub-micron particles. Total internal reflection fluorescence (TIRF) microscopy confirms the existence of both core-shell structure and oxygen sensitivity. The dissolved oxygen response time is rapid (<0.30 s), ideal for continuous real-time monitoring of oxygen concentration. The incorporation of Pluronic F-127 surfactant enables efficient dispersion; selection of an appropriate electrospraying solvent (DMF) yields particles readily injected even through a <100 μm diameter needle.
| S-EPMC9455784 | biostudies-literature