•A sharp phase transition with a Curie temperature around room temperature.•The nanoparticles turn out to be both hydrophilic and hydrophobic.•The nanoparticles show excellent optical performance and magnetic behavior.•The core-shell nanoparticles could be of interest for potential applications.A free-standing magneto-fluorescent La1–xSrxMnO3@ZnO multifunctional core-shell nanoparticle system with a sharp, tight phase transition from ferromagnetic to superparamagnetic states, was synthesized by a modified nanoemulsion process with poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) as the surfactant. The XRD and TEM/HRTEM show high crystallinity of the La1-xSrxMnO3@ZnO nanoparticles and an average particle size of ∼22.2 nm. The measurements using UV-vis, PL, VSM and PPMS reveal that the nanoparticles exhibit well-behaved absorption bands and multiple visible fingerprint photoluminescent emissions in both aqueous and organic media, and superparamagnetic behavior at room temperature. Particularly, a tight, sharp phase transition from ferromagnetic to superparamagnetic states is observed in the La1-xSrxMnO3@ZnO nanoparticle system for the first time with a Curie temperature around room temperature. The results demonstrate that the multifunctional La1-xSrxMnO3@ZnO core-shell nanoparticles could be of interest for scientific studies and potential applications.A free-standing, magneto-fluorescent La1-xSrxMnO3@ZnO multifunctional core-shell nanoparticle system with a sharp, tight phase transition from ferromagnetic to superparamagnetic states, was synthesized by a modified nanoemulsion process with PEO-PPO-PEO as the surfactant. The nanoparticles show high crystallinity, bi-phase dispersible, excellent optical performance both in organic and aqueous solvent, and superparamagnetic behavior at room temperature. The multifunctional La1-xSrxMnO3@ZnO core-shell nanoparticles have led to enhanced performance and multi-functionalities, offering various possible applications of the nanoparticles.

Multifunctional [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 (HL = pyridine-2-carboxamide) nanocomposites were successfully synthesized by combining [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O and Fe3O4 nanoparticles. The characterization was performed by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray powder diffraction (XRD) and ultraviolet-visible light absorbance spectrometry (UV-vis). The XRD and TEM analyses reveal that the nanocomposites possess high crystallinity with an average particle size of ∼19.43 nm. The VSM and UV-vis demonstrate excellent superparamagnetic behavior and two well-behaved absorption bands of the nanocomposites. The adsorption activity of the nanocomposites was investigated using methylene blue, gentian violet, safranine T, fuchsin basic, methyl orange and Sudan red (III) as probe molecules, and the results reveal that the [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 nanocomposites have selective adsorption behavior for organic dyes. The recycling performance was observed using basic fuchsin, and the results demonstrate that the nanocomposites exhibit good recyclability and high stability. The [Cu(L)2(H2O)]H2[Cu(L)2(P2Mo5O23)]·4H2O/Fe3O4 nanocomposites have a promising future for magnetic, optical and biomedical applications.

•The Fe3O4/Ag nanoparticles were synthesized via non-aqueous nanoemulsion process.•The nanoparticles could be dispersed in both aqueous and organic media.•The nanoparticles show high crystallinity, good magnetic and optical performance.Bi-phase dispersible Fe3O4/Ag core–shell nanoparticles were successfully synthesized via non-aqueous nanoemulsion process using the triblock copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) as the surfactant. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses confirm the structure and morphology of the polymer-capped Fe3O4/Ag nanoparticles. The measurements obtained using ultraviolet-visible light absorbance spectrometry (UV-vis), vibrating sample magnetometry (VSM) demonstrate that the nanoparticles exhibit a surface plasmon resonance (SPR) absorption band around 430 nm from nanostructured Ag and a unique magnetic nature at room temperature. This kind of bifunctional optical-magnetic core–shell nanoparticles could be of interest in interfacial proximity effects due to the unique spatial nanostructure configuration and have potential applications in various areas.Bi-phase dispersible Fe3O4/Ag core–shell nanoparticles were successfully synthesized via non-aqueous nanoemulsion process. The nanoparticles had been characterized by transmission electron microscopy (TEM). As shown in above figure, the nanoparticles apparently are highly crystalline, virtually uniform and nearly spherical or polyhedral in shape.Download high-res image (139KB)Download full-size image

Water-dispersible 2 nm FePt ultrasmall nanocrystals coated by a biocompatible triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) were directly synthesized in a single-step nanoemulsion process. The FTIR investigation proves the PEO-PPO-PEO molecules on the surface of the resulting nanocrystals, which render the nanocrystals hydrophilic for aqueous dispersion without using conventional ligand exchange and offer proper protection of the nanocrystals from oxidation. The structural and morphological analysis reveals both single-crystallinity and high crystallinity of the nanocrystals in the face-centered cubic phase, with an excellent monosize distribution of 1.95 ± 0.18 nm in diameter. Moreover, the polymer-capped nanocrystals possess well-defined magnetic behavior and the aqueous dispersion–collection process of the nanocrystals was demonstrated for application readiness of such ultrasmall nanocrystals in aqueous media.Highlights► Water-dispersible 2 nm FePt ultrasmall nanocrystals were directly synthesized in a single-step nanoemulsion process. ► The surface of the nanocrystals was coated by a biocompatible triblock copolymer, rendering the nanocrystals hydrophilic for aqueous dispersion without using conventional ligand exchange and offering proper protection of the nanocrystals from oxidation. ► Revealing both single-crystallinity and high crystallinity of the nanocrystals, with the excellent monosize distribution of 1.95±0.18 nm in diameter. ► Showing well-defined magnetic behavior of the polymer capped nanocrystals. ► Demonstrating the aqueous dispersion–collection process of the nanocrystals for application readiness in an aqueous medium.

Monosized core–shell Fe3O4/Au magnetic–optic multifunctional nanoparticles were synthesized by a modified nanoemulsion process. The formation of the core–shell nanostructure was accomplished in the presence of poly(vinylpyrrolidone) (PVP) as the surfactant in two consecutive steps. The comparison FTIR study proves the PVP coating on the surface of the resultant nanoparticles, whereas the morphological analysis illustrates the nanoparticle shape, nanostructuring, size and size distribution and shows the excellent monodispersity <10%. The crystal structure of the core–shell nanoparticles is revealed by the XRD patterns, with the single-crystallinity of such individual nanoparticles illustrated by the lattice imaging. Moreover, the nanoparticles manifest soft ferromagnetic behavior with a small coercivity of ∼40 Oe at room temperature and ensuing excellent susceptibility. The magnetic hysteresis curves of the nanoparticles were elucidated by a modified Langevin equation, giving estimation of the effective magnetic dimension of the nanoparticles and reflecting the enhanced susceptibility response as a result of the surface covering. The UV–vis spectroscopic examination reveals the well-behaved surface plasmon at ∼590 nm. Thus, the use of PVP has evidently led to the improved structure and properties, anticipating application potentials of the nanoparticles.