Fluorescence-Magnetism Functional EuS Nanocrystals with Controllable Morphologies for Dual Bioimaging

Abstract

Multiple functions incorporated in one single component material offer important applications in biosystems. Here we prepared a divalent state of rare earth EuS nanocrystals (NCs), which provides luminescent and magnetic properties, using both 1-Dodecanethiol (DT) and oleylamine (OLA) as reducing agents. The resultant EuS NCs exhibit controllable shapes, uniform size, and bright luminescence with a quantum yield as high as 3.5%. OLA as a surface ligand plays an important role in tunable morphologies, such as nanowires, nanorods, nanospheres et al. Another attractive nature of the EuS NCs is their paramagnetism at room temperature. In order to expand the biological applications, the resultant EuS NCs were modified with amphiphilic block copolymer F127 and transferred from oil to water phase. The excellent biocompatibility of EuS NCs is demonstrated as well as preservation of their luminescence and paramagnetic properties. The EuS NCs offer multifunction and great advantages of bright luminescence, paramagnetic, controllable morphologies, and good biocompatibility promising applications in the field of simultaneous magnetic resonance and fluorescence bioimaging.

A Novel Strategy to Synthesize Dual Blue Fluorescent‐Magnetic EuCl2 Nanocrystals via One‐Pot Method with Controlled Morphologies Using Urea

“…And they exhibit good photoluminescence (PL) and paramagnetism properties at room temperature, as shown in Figure B, C. When the EuCl 2 NCs were irradiated at 360 nm, a strong blue emission peak was observed at 400 nm with a full width at half‐maximum (FWHM) of 32 nm. Obviously, the bright blue emission via the 4f‐5d electronic transformation of the Eu II can be attributed to the effective energy transition from their surface passivation, oleyl amine (OLA), and oleic acid (OA) . Picture inserted in Figure B is the photograph of EuCl 2 NCs solution irradiated by 365 nm wavelength of UV light.…”

“…Each HRTEM image inserted in Figure A–D, shows interplanar spacing of ≈4.40 Å in the [220] direction, respectively. The fast Fourier transform (FFT) patterns of the different NCs shapes exhibit almost the same diffuse halos in [220], [400], and [420] directions by the superimposed of many bright diffraction spots (Figure S11, Supporting Information,).…”

“…Rare‐earth nanomaterials have aroused great interests during the last few decades due to their optical, electric, and magnetic properties. They promise many advanced applications in solar cells, biological labeling, and imaging . A lot of these researches focused on the trivalent state europium (Eu III ) with special optical properties because of their active 4f electrons .…”

“…Compared to Eu III compounds, divalent state europium nanocrystals (Eu II NCs) with excellent magnetic and luminescent characters have drawn great attention lately . These advanced materials could be applied in many fields of optical isolators, magneto‐optic devices, catalysis, bioimaging, solar cells, etc. So far, reports on Eu II NCs are mainly on europium chalcogenides, EuX (X = O, S, Se), of which morphology is controlled by the reaction temperature or surface ligand .…”

“…These advanced materials could be applied in many fields of optical isolators, magneto‐optic devices, catalysis, bioimaging, solar cells, etc. So far, reports on Eu II NCs are mainly on europium chalcogenides, EuX (X = O, S, Se), of which morphology is controlled by the reaction temperature or surface ligand . In 2018, Hierarchical Europium (II) oxide tubes were firstly prepared with native ferromagnetism .…”