Folic acid-conjugated core/shell ZnS:Mn/ZnS quantum dots as targeted probes for two photon fluorescence imaging of cancer cells.

This work presents a novel approach to producing water soluble manganese-doped core/shell ZnS/ZnS quantum dots (ZnS:Mn/ZnS). The Mn-doped ZnS core was prepared through a nucleation doping strategy and a ZnS shell was grown on ZnS:Mn d-dots by decomposition of Zn(2+)-3-mercaptopropionic acid (MPA) complexes at 100 °C. It was found that the Mn2+(4)T1→6A1 fluorescence emission at ∼590 nm significantly increased after growth of the shell when the Mn2+ doping content was 4.0 at.%. A photoluminescence quantum yield of ∼22% was obtained for core/shell nanocrystals. The nanoparticles were structurally and compositionally characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and dynamic light scattering. The surface MPA molecules favor the dispersion of ZnS:Mn/ZnS QDs in aqueous media and make possible conjugation with targeting folic acid molecules. The folate receptor-mediated delivery of folic acid-conjugated ZnS:Mn/ZnS QDs was demonstrated using confocal microscopy with biphotonic excitation. Bare and folate-conjugated QDs exhibit only weak cytotoxicity towards folate receptor-positive T47D cancer cells and MCF-7 cells, used as a reference, at high concentrations (mmolar range) after 72h incubation.

Geszke M ，Murias M ，Balan L ，Medjahdi G ，Korczynski J ，Moritz M ，Lulek J ，Schneider R ... -  《-》

Synthesis and characterization of ZnS:Mn/ZnS core/shell nanoparticles for tumor targeting and imaging in vivo.

Yu Z ，Ma X ，Yu B ，Pan Y ，Liu Z ... -  《-》

Facile synthesis of high-quality water-soluble N-acetyl-L-cysteine-capped Zn(1-x)Cd(x)Se/ZnS core/shell quantum dots emitting in the violet-green spectral range.

In this paper, we report a new facile method to synthesize water-soluble Zn(1-x)Cd(x)Se and core/shell Zn(1-x)Cd(x)Se/ZnS quantum dots (QDs) emitting in the violet-green spectral range, using N-acetyl-L-cysteine (NAC) as a stabilizer. The influence of various experimental variables, including the precursor Zn/Cd/Se/NAC molar ratios, the pH of original solution and the refluxing time on optical properties were explored systematically. The obtained aqueous Zn(1-x)Cd(x)Se QDs exhibit a tunable photoluminescence (PL) emission (from approximately 415 nm to 506 nm) and a favorable narrow PL bandwidth (FWHM: 27-38 nm). After coating with a ZnS shell, the PL emission intensity of the formed core/shell Zn(1-x)Cd(x)Se/ZnS QDs is greatly increased (PL quantum yield (QY): approximately 30%). These resulting Zn(1-x)Cd(x)Se and core/shell Zn(1-x)Cd(x)Se/ZnS QDs were further characterized by transmission electron microscopy (TEM), energy disperse spectroscopy (EDS) and X-ray diffraction (XRD). In addition, the cytotoxicity and the fluorescence imaging of Zn(1-x)Cd(x)Se/ZnS QDs to MCF-7 cells were preliminarily investigated. The experimental results show that the as-prepared violet-green-emitting Zn(1-x)Cd(x)Se/ZnS QDs have low cytotoxicity, which makes them an ideal inorganic fluorescent probe for biolabeling and cell imaging.

Cao J ，Xue B ，Li H ，Deng D ，Gu Y ... -  《-》

Aqueous synthesis of highly luminescent glutathione-capped Mn²⁺-doped ZnS quantum dots.

In this paper, an aqueous-based route has been developed to prepare highly luminescent glutathione (GSH)-capped Mn-doped ZnS quantum dots (QDs). The dots obtained have an average diameter of 4.3 nm and exhibit the Mn(2+)-related orange luminescence with very low surface defect density. The highest photoluminescence was observed for a Mn(2+) to Zn(2+) molar ratio of 3%. Consecutive overcoating of the Mn:ZnS@GSH QDs by a ZnS shell was done, and the core/shell structured QDs exhibit a PL quantum yield of 23%. Transmission electron microscopy, X-ray powder diffraction, electron spin resonance, X-ray photoelectron spectroscopy, UV-visible spectroscopy and spectrofluorometry have been used to characterize the crystal structure, the doping status, and the optical properties of the doped-QDs. Our systematic investigation shows that Mn:ZnS/ZnS@GSH QDs are highly promising fluorescent labels in biological applications.

Kolmykov O ，Coulon J ，Lalevée J ，Alem H ，Medjahdi G ，Schneider R ... -  《-》

Folic acid targeted Mn:ZnS quantum dots for theranostic applications of cancer cell imaging and therapy.

Bwatanglang IB ，Mohammad F ，Yusof NA ，Abdullah J ，Hussein MZ ，Alitheen NB ，Abu N ... -  《-》