High potential of Mn-doped ZnS nanoparticles with different dopant concentrations as novel MRI contrast agents: synthesis and in vitro relaxivity studies
Abstract:Over several decades, metal-doped quantum dots (QDs) with core-shell structure have been studied as dual probes: fluorescence and magnetic resonance imaging (MRI) probes (Dixit et al., Mater Lett 63(30):2669-2671). However, metal-doped nanoparticles, in which the majority of metal ions are close to the surface, can affect their efficacy as MRI contrast agents (CAs). In this context, herein the high potential of synthesized Mn-doped ZnS QDs via polyol method as imaging probe is demonstrated. The mean diameters… Show more
“…This is observed because the emissions at these positions are not related to Ag. The blue emission at 421 nm corresponds to sulfur vacancy in the lattice sites [30]. The second peak at 483 nm could be ascribed as the recombination effect of sulfur vacancy and related electron trap [31].…”
Silver (Ag)-doped (0, 5, 10 and 15%) ZnS nanoparticles are synthesized by microwave-assisted chemical route using polyvinylpyrrolidone (PVP). We study the compositional, structural, optical and luminescence properties by energy-dispersive analysis of X-rays (EDAX), transmission electron microscopy (TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy and photoluminescence (PL) spectroscopy, respectively. Synthesized Ag-doped ZnS nanoparticles do not possess any impurity as seen from EDAX spectra. TEM images show particles to be in spherical shape with agglomeration, and corresponding selected area electron diffraction (SAED) pattern showed that they are polycrystalline in nature. Allowed LO and TO modes corresponding to cubic phase for all the samples are observed in Raman spectra. FTIR spectroscopy is used to study the interaction between PVP and as-synthesized nanoparticles. Blue shift can be seen in pure and Ag-doped ZnS nanoparticles compared to bulk ZnS as seen from absorption spectra. Green emission is observed in PL spectra due to Ag doping without showing any quenching behavior.
“…This is observed because the emissions at these positions are not related to Ag. The blue emission at 421 nm corresponds to sulfur vacancy in the lattice sites [30]. The second peak at 483 nm could be ascribed as the recombination effect of sulfur vacancy and related electron trap [31].…”
Silver (Ag)-doped (0, 5, 10 and 15%) ZnS nanoparticles are synthesized by microwave-assisted chemical route using polyvinylpyrrolidone (PVP). We study the compositional, structural, optical and luminescence properties by energy-dispersive analysis of X-rays (EDAX), transmission electron microscopy (TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy and photoluminescence (PL) spectroscopy, respectively. Synthesized Ag-doped ZnS nanoparticles do not possess any impurity as seen from EDAX spectra. TEM images show particles to be in spherical shape with agglomeration, and corresponding selected area electron diffraction (SAED) pattern showed that they are polycrystalline in nature. Allowed LO and TO modes corresponding to cubic phase for all the samples are observed in Raman spectra. FTIR spectroscopy is used to study the interaction between PVP and as-synthesized nanoparticles. Blue shift can be seen in pure and Ag-doped ZnS nanoparticles compared to bulk ZnS as seen from absorption spectra. Green emission is observed in PL spectra due to Ag doping without showing any quenching behavior.
“…Dual-mode probes combining light-emitting QDs or Ln-UCNPs with MRI contrast agents have been developed using multiple approaches, including core-shell nanostructures [127], chelate conjugation [128,129], and Gd 3+ or Mn 2+ co-doping [130,131]. Hu et al developed a dual-modality nanoprobe based on Ag 2 S QDs, which emits in the second biological window and conjugated with the Gd-DOTA MRI contrast agent [132].…”
“…Specifically, the presence of SPIONs shortens the transverse relaxation time of surrounding water protons, leading to a decrease of the MRI signal (negative contrast agents). Normally, NPs biomedical applications require a high hydrophilic character together with the possibility of their conjugation with biological species [18,28]. Additionally, the colloidal stability of SPIONs may constrain their applications in MRI.…”
In this work a one-pot synthesis of water soluble glutathione capped magnetite nanoparticles is reported. The magnetic characterization of the samples shows the expected superparamagnetic behavior, but a wide range of blocking temperatures is found, since the size and interparticle interactions are very sensitive to preparation conditions. These properties are correlated with the glutathione-iron ratio and oxidant dose, in order to optimize the aqueous colloidal stability and magnetic properties of the superparamagnetic iron oxide nanoparticles for Magnetic Resonance Imaging applications. The efficiency of the glutathione coated nanoparticles as contrast agent is then evaluated by means of the determination of the relaxation times T1 and T2 in 1 H Nuclear Magnetic Resonance experiments. Moreover, the influence of the thickness of the glutathione capping layer on the colloidal stability and, thus, on relaxation times has been studied. Finally, the relaxitivity of the sample that shows the best performance has been determined. Graphic abstract A novel one-pot synthesis for "in situ" functionalized hydrophilic magnetite nanoparticles at atmospheric pressure and a temperature lower than 200 °C for Magnetic Resonance Imaging applications is reported. Their properties are analyzed in terms of the synthesis process: glutathione-iron ratio and oxidant dose.
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