Eu NCs Research Articles

Electrochemiluminescent immunoassay for insulin by using a quencher pair consisting of CdS:Eu nanoclusters loaded with multiwalled carbon nanotubes on reduced graphene oxide nanoribbons and gold nanoparticle-loaded octahedral Cu2O

A sensitive electrochemiluminescence (ECL) immunosensor was constructed for detection of insulin. It is based on the quenching effect of octahedral cuprous oxide decorated with gold nanoparticles (Cu2O@Au NPs). A composite constructed from multiwalled carbon nanotubes/reduced graphene oxide nanoribbons provides a large specific surface that promotes electron transfer on the surface of electrodes. In parallel, CdS nanoclusters were loaded with europium(III) to get CdS:Eu NCs. The Eu(III) ions exert a large enhancement in ECL intensity of the CdS NCs. Cu2O is biocompatible and has a large specific surface. It was used as a quencher for the ECL immunosensor. If Au NPs are loaded onto Cu2O, the green fluorescence of the CdS NCs (with emission peaks at 525nm) is quenched. The Cu2O@Au NPs also can be employed as a label for the secondary antibodies (Ab2) to improve the sensitivity of the ECL immunosensor. The assay works in the 0.5pg·mL-1 to 50ng·mL-1 insulin concentration range and has a detection limit of 40 fg·mL-1. Graphical abstract The multiwalled carbon nanotubes/reduced graphene oxide nanoribbons (MWCNT/rGONRs-CdS: Eu NCs) was used as substrate. Europium(III) (Eu3+) improves the ECL intensity of CdS NCs. The synergistic effect between Cu2O and Au NPs decreases the electrochemiluminescence of MWCNTs/rGONRs-CdS:Eu NCs.

Synthesis of Eu2+/Eu3+ Co-Doped Gallium oxide nanocrystals as a full colour converter for white light emitting diodes

Eu2+ and Eu3+ co-doped Ga2O3 nanocrystals (Ga2O3:Eu NCs) were synthesized in an organic phase at a low reaction temperature of 300 °C. The surface of Ga2O3:Eu NCs was passivated by oleylamine (OAm) and acetylacetone (acac). The coexistence of Eu2+ and Eu3+ as well as passivation by acac and OAm enable Ga2O3 to be excited in the broad spectral range of 200–500 nm. The broadened absorption band is attributed to the strong acac → Ln(III) ligand to the metal charge transfer transition at ∼370 nm, Eu(III) f-f allowed 7F0 → 5L6 transition at 395 nm, and 7F0 → 5D2 transition at 465 nm, as well as the efficient electronic transition of Eu(II) 4f → 5d at ∼400 nm. Under near-ultraviolet excitation, white light emission can be achieved by combining orange-red light from f-f electronic transition of Eu(III) with blue-green-yellow light from Ga2O3 oxygen defects levels. Furthermore, the resultant Ga2O3:Eu NCs with optimized quantum yield of 14.5% were coated onto 395 nm near-ultraviolet chips to fabricate a white light emitting diode. It exhibits a luminous efficiency of 34 lm/W, CIE colour coordinate of (0.2964, 0.2831) and high colour rendering index of 80.

Dual-signal ratiometric electrochemiluminescence assay for detecting the activity of human methyltransferase.

In this paper, a dual-signal ratiometric electrochemiluminescence (ECL) assay was developed to detect human DNA (cytosine-5)-methyltransferase1 (DNMT1) activity. Mercaptopropionic acid (MPA)-modified Eu3+-doped CdS nanocrystals (MPA-CdS:Eu NCs) and luminol were used as two different ECL emitters, which showed ECL signals at different electrochemical potentials. The resultant ECL peaks exhibited opposite trends in the DNMT1 system. According to the ratio of the ECL responses of CdS to luminol, the DNMT1 activity was detected in the range of 1.0-30.0 U mL-1 in buffer solution. The limit of detection (LOD) was estimated to be 0.07 U mL-1 at a signal-to-noise ratio of 3. The assay was extended to detect the DNMT1 activity from crude lysates of cancer cells, along with the effect of DNMT1 inhibitors such as 5-aza and 5-aza-2'-dC.

A Structural Investigation of Trivalent and Divalent Rare Earth Thiocyanate Complexes Synthesised by Redox Transmetallation

AbstractA wide range of reactive trivalent and divalent rare earth thiocyanate complexes with 1,2‐dimethoxyethane (dme), tetrahydrofuran (thf) and acetonitrile namely [RE(NCS)3(dme)3] [RE = La (1a), Nd (1b)], [RE(NCS)3(dme)2(μ‐dme)0.5]2 [RE = Dy (1d), Er (1e)], [RE(NCS)3(thf)4]2 [RE = Y (3a), La (3b), Nd (3c), Sm (3d), Dy (3e), Ho (3f)], [Ca(NCS)2(dme)3] [rac‐(4a)], [RE(NCS)2(dme)3] (RE = Sm (rac‐4b), Eu (rac‐4c), [Ca(Yb)(NCS)2(NCMe)5]·NCMe [Ca (6a), Yb (6b)], and [Eu(NCS)2(thf)4]2 (7) have been prepared in good to high yield by redox transmetallation between rare earth metals and the commercially available Hg(SCN)2. In addition [Eu(NCS)3(dme)2(μ‐dme)0.5]2 (1c) and [Yb(NCS)3(dme)2] (1f) have been prepared by oxidation of rac‐4c and [Yb(NCS)2(thf)2], respectively, with Hg(SCN)2 in dme. Crystallisation of 1e from dme/diglyme (diglyme = bis(2‐methoxyethyl) ether) and thf yields [Er(NCS)3(diglyme)(dme)] (2) and [Er(NCS)3(thf)4]2 (3g), respectively, and prolonged storage of rac‐4a in cold dme gave [Ca(NCS)2(dme)2(H2O)] (5). All undergo rapid hydrolysis on exposure to air. Two structural breaks are observed for [RE(NCS)3(dme)n] complexes, all of which have solely RE–NCS binding. Compounds 1a,b are nine‐coordinate monomers that differ in the arrangement (T or Y) of the RE(NCS)3 moiety, 1c–e are eight coordinate dinuclear complexes being bridged by a single η1:η1‐(O,O′)‐dme and 1f is a seven coordinate monomer. 2 is an eight coordinate monomer with, unusually for the present complexes, a facial RE(NCS)3 array. By contrast 3a–g are all dimeric, eight coordinate complexes with two unusual RE–NCS–RE bridges. The RE–S bonds are very weak and show little variation with RE3+ radius, and Er–S of 3g increases by 0.18 Å between 123 K and room temperature), foreshadowing a change to a seven coordinate monomer with [Yb(NCS)3(thf)4]. Monomeric eight coordination with transoid (N–RE–N ≈ 149°) SCN–RE–NCS bonding is observed in rac‐4a–c and Λ‐4c, whilst 5 is a seven‐coordinate monomer with a cis‐Ca(NCS)2 array. Single crystals of 6,a,b contain seven‐coordinate, pentagonal bipyramidal monomers with trans‐NCS ligands, whereas 7 is dimeric with two Eu–NCS–Eu bridging ligands and seven coordination for Eu.

Photoluminescence of Europium(III) Dithiocarbamate Complexes: Electronic Structure, Charge Transfer and Energy Transfer

For the first time, we observed photoluminescence in Eu(III) dithiocarbamate complexes at room temperature -- more specifically in [Eu(Et(2)NCS(2))(3)phen], [Eu(Et(2)NCS(2))(3)bpy] and the novel [Eu(Ph(2)NCS(2))(3)phen], where phen stands for 1,10-phenanthroline and bpy for 2,2'-bipyridine. Correlations between the electronic structure of the dithiocarbamate ligands on one hand, and covalency, intensity, and ligand field spectroscopic parameters on the other, could be established. Moreover, the relative values of the emission quantum efficiencies obtained for these complexes, as well as their dependence with temperature, could be satisfactorily described by a theoretical methodology recently developed.

Synthesis and spectroscopy of unsymmetric mononuclear lanthanide cryptates. Structure of two europium(III) cryptates co-existing in the same crystal [EuL(OH2)]·[Eu(HL)(NCS)]·9H2O·2MeCN·EtCN·EtOH (H3L = a phenol-bridged N8O3Schiff-base cryptand)

Lanthanide cryptates of a phenol-bridged N8O3 Schiff-base cryptand (H3L) have been synthesized by transmetallation with the sodium cryptate [Na(H2L)], where the cryptand was obtained by a basic template condensation of tris(2-aminoethyl)amine and 2,6-diformyl-4-methoxyphenol. The structure of [EuL(OH2)]·[Eu(HL)(NCS)]·9H2O·2MeCN·EtCN·EtOH showed the coexistence in the same crystal of two kinds of unsymmetric eight-co-ordinate europium(III) cryptates with different second ligands. The Eu–NCS linkage in [Eu(HL)(NCS)] is linear [Eu–NC–S 175(2), NC–S 179(2)° and Eu–N 2.42(1)A].