Analysis of Structural, Optical, and Magnetic Properties of (Fe,Co) Co-Doped ZnO Nanoparticles Synthesized under UV Light

In this report, we discuss the preparation of undoped and (Fe,Co) co-doped ZnO nanocomposites via an ultrasonicated probe, which were both under UV irradiation for 12 h and annealed at 400 °C for four hours in ambient air. Here, we investigated the different concentration of dopant transition metals (ZnO-Fe1-x-Cox) (x = 0.03, 0.05, and 0.07). X-ray diffraction (XRD) analyses confirmed the nanophase, crystallinity, good uniformity, and around 28 nm core sizes of all of the (ZnO-Fe1-x-Cox) as-synthesized composites with different rates. The optical properties of ZnO doped with a high percent of Fe nanoparticles displayed an increase in absorption in the UV region and a slight decrease in the energy band gap to 3.13 eV. Magnetic measurements revealed that doping enhanced the ferromagnetism of ZnO. Recent studies which aimed to improve the optical and magnetic properties of metal oxides, the most important of which being zinc oxide, have allowed their applications to diversify and multiply in the medical, industrial, and electronic fields

The spectrum of mosaic mutations in megalencephaly and other growth disorders by ultra-deep targeted next-generation sequencing (NGS)

Thesis (Master's)--University of Washington, 2021This is a retrospective study aimed at analyzing genetic variants and levels of mosaicism identified in a cohort of patients clinically tested for brain and body overgrowth phenotypes between 2014 and 2019 through the Megaplex multi-gene panel offered at the University of Washington. We analyzed the megaplex data to further characterize the molecular basis of overgrowth phenotypes and to optimize future interpretation and analysis of this panel. In this study, we examined samples from 180 clinical patients diagnosed with brain and body overgrowth disorders. An additional 33 samples were collected from parents to determine the inheritance of compelling variants. The panel consisted of 37 genes known to be associated with brain and body overgrowth disorders. DNA was extracted from peripheral blood in 169 (53.8%) of the samples, 69 (22.8%) in skin fibroblast, 68 (21.8%) in tissue, 3 (0.9%) in saliva, 2 (0.6%) in cell-free DNA (cfDNA), and 2 (0.6%) in unknown samples. Capture-based Next-Generation sequencing (NGS) was performed using custom-designed SureSelect probe libraries and analyzed using short read sequencing on Illumina HiSeq 2000 or MiSeq sequencers. Identified mutations were confirmed and analyzed using a custom in-house bioinformatics pipeline. Of the 213 individuals tested, 128 (41.0%) had pathogenic and likely pathogenic mutations. Most of these variants were in PIK3CA (N =49, 38%) and PTEN 17 (13.3%). There were no pathogenic or likely pathogenic mutations reported in 161 cases (51.6%). In this study, variants of uncertain significance were reported in 23 (7.4%) of cases. Ultra-deep NGS can efficiently identity mosaic mutations in megalencephaly and overgrowth disorders including detecting low levels of mosaicism, compared to Sanger sequencing and standard-depth NGS testing. Detecting mosaic mutations using deep NGS testing improves the clinical yield and provides a better understating of the spectrum of mosaic mutations underlying these phenotypes

On the Absorption and Photoluminescence Properties of Pure ZnSe and Co-Doped ZnSe:Eu3+/Yb3+ Crystals

Co-doped Zinc selenide (ZnSe) is a promising material because of a high photoluminescence efficiency and wide spectral range emission in the visible region. In this work, ZnSe and Eu3+/Yb3+ co-doped ZnSe crystals were grown by the chemical vapour transport method. Photoluminescence and optical measurements revealed the effect of trivalent rare earth Eu3+/Yb3+ ions on the emission of new lines with enhancement intensity. In the photoluminescence spectrum, some sharp and intense lines were observed that allow for the possibility of covering a broad emission range. Moreover, the optical measurement showed a lower bandgap compared to that of pure ZnSe bulk crystal. This material is suitable for developing optoelectronic devices, which can emit light in the visible and near infrared range with an improved emission efficiency and wide tunability

On the Absorption and Photoluminescence Properties of Pure ZnSe and Co-Doped ZnSe:Eu³⁺/Yb³⁺ Crystals

Co-doped Zinc selenide (ZnSe) is a promising material because of a high photoluminescence efficiency and wide spectral range emission in the visible region. In this work, ZnSe and Eu3+/Yb3+ co-doped ZnSe crystals were grown by the chemical vapour transport method. Photoluminescence and optical measurements revealed the effect of trivalent rare earth Eu3+/Yb3+ ions on the emission of new lines with enhancement intensity. In the photoluminescence spectrum, some sharp and intense lines were observed that allow for the possibility of covering a broad emission range. Moreover, the optical measurement showed a lower bandgap compared to that of pure ZnSe bulk crystal. This material is suitable for developing optoelectronic devices, which can emit light in the visible and near infrared range with an improved emission efficiency and wide tunability

Assessing the Heat Generation and Self-Heating Mechanism of Superparamagnetic Fe₃O₄ Nanoparticles for Magnetic Hyperthermia Application: The Effects of Concentration, Frequency, and Magnetic Field

Magnetite nanoparticles (MNPs) exhibit favorable heating responses under magnetic excitation, which makes them particularly suited for various hyperthermia applications. Herein, we report the detailed self-heating mechanisms of MNPs prepared via the Ko-precipitation Hydrolytic Basic (KHB) methodology. The as-prepared MNPs were fully characterized using various spectroscopic techniques including transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). MNPs exhibited stable 15 nm quasi-spherical small-sized particles, pure crystalline cubic Fe3O4 phases, high saturation magnetizations (Ms = ~40 emu·g−1), and superparamagnetic behavior. In response to alternating magnetic fields (AMFs), these MNPs displayed excellent self-heating efficiencies with distinctive heating responses, even when minimal doses of MNPs were used. Heating efficacies and specific absorption rate (SAR) values as functions of concentration, frequency, and amplitude were systematically investigated. Remarkably, within only a few minutes, MNPs (2.5 mg/mL) showed a rapid dissipation of heat energy, giving a maximum intrinsic loss power (ILP) of 4.29 nHm2/kg and a SAR of 261 W/g. Hyperthermia temperatures were rapidly reached in as early as 3 min and could rise up to 80 °C. In addition, Rietveld refinement, Langevin, and linear response theory (LRT) models were studied to further assess the magnetic and heating mechanisms. The LRT model was used to determine the Néel relaxation time (τR = 5.41 × 10−7 s), which was compared to the Brownian relation time value (τB = 11 × 10−7 s), showing that both mechanisms are responsible for heat dissipated by the MNPs. Finally, the cytotoxicity assay was conducted on aqueous dispersions of MNPs, indicating their biocompatibility and low toxicity. Our results strongly suggest that the as-prepared Fe3O4 MNPs are promising vehicles for potential magnetically triggered biomedical hyperthermia applications

A Continuously Tunable Full-Color Emission Nitrogen-Doped Carbon Dots and for Ultrasensitive and Highly Selective Detection of Ascorbic Acid

Nitrogen-doped carbon dots exhibiting excitation-dependent full-color emissions (F-NCDs) were prepared via the one-step hydrothermal method with citric acid and phenylenediamine. Specifically, the emission wavelength of the F-NCDs tuned from 452 nm to 602 nm due to the introduction of new energy levels by C=O and C=N functional groups. We exploited its stability in illumination, ionic strength, and pH, as well as its specificity, sensitivity, especially in ascorbic acid (AA) detection. F-NCDs could measure the AA concentration in the linear ranges of 0~0.1 and 0.1~1 mmol/L with the detection limit (LOD, S/N = 3) as low as 2.6 nmol/L. Additionally, we successfully detected AA in bovine serum with our F-NCDs and obtained the result within 1 min. Because of full-color emission features, we believe our F-NCDs have a great potential in fluorescent sensor detection

Preparation and characterization of various PVPylated divalent metal-doped ferrite nanoparticles for magnetic hyperthermia

There is an incessant demand to keep improving on the heating responses of polymeric magnetic nanoparticles (MNPs) under magnetic excitation, particularly in the pursuit for them to be utilized for clinical hyperthermia applications. Herein, we report the fabrication of a panel of PVP-capped divalent metal-doped MFe2O4 (M ≅ Co, Ni, Zn, Mg, and Sn) MNPs prepared via the Ko-precipitation Hydrolytic Basic (KHB) methodology and assess their magneto-thermal abilities. The physiochemical, structural, morphological, compositional, and magnetic properties of the doped ferrites were fully characterized using various techniques mainly TEM, XRD, EDX, FTIR, and VSM. The obtained doped MNPs exhibited stabilized quasi-spherical sized particles (10–17 nm), pure well-crystallized cubic spinel phases, and high saturation magnetizations (Ms = 26–81 emu g−1). In response to a clinically-safe alternating magnetic field (AMF) (f = 332.8 kHz and H = 170 Oe), distinctive heating responses of these doped ferrites were attained. Hyperthermia temperatures of 42 °C can be reached very fast in only ∼5 min, with heating temperatures slowly increasing to reach up to 55 °C. The highest heating performance was observed for PVP-NiFe2O4 and the lowest for PVP-Sn-doped NPs (SAR values: PVP-NiFe2O4 > PVP-CoFe2O4 > PVP-ZnFe2O4 > PVP-MgFe2O4 > PVP-SnFe2O4). This trend was found to be directly correlated to their observed magnetic saturation and anisotropy. Heating efficiencies and specific SAR values as functions of concentration, frequency, and amplitude were also systematically investigated. Finally, cytotoxicity assay was conducted on aqueous dispersions of the doped ferrite NPs, proving their biocompatibility and safety profiles. The PVPylated metal-doped ferrite NPs prepared here, particularly Ni- and Co-doped ferrites, are promising vehicles for potential combined magnetically-triggered biomedical hyperthermia applications

Performance Improvement of Graded Bandgap Solar Cell via Optimization of Energy Levels Alignment in Si Quantum Dot, TiO₂ Nanoparticles, and Porous Si

Charge carriers’ generation from zinc includes silicon quantum dots (ZnSiQDs) layer sandwiched in-between porous silicon (PSi) and titania nanoparticles (TiO2NPs) layer-based solar cell is an efficient way to improve the cell’s performance. In this view, ZnSiQDs layer with various QDs sizes have been inserted, separating the PSi and TiO2NPs layers to achieve some graded bandgap quantum dot solar cells (GBQDSCs). In this process, ZnSiQDs of mean diameter 1.22 nm is first prepared via the top-down method. Next, ZnSiQDs have been re-grown using the bottom-up approach to get various mean diameters of 2.1, 2.7 and 7.4 nm. TiO2NPs of mean diameter in the range of 3.2 to 33.94 nm have been achieved via thermal annealing. The influence of different ZnSiQDs sizes on the designed GBGQDSCs performance has been determined. The proposed cell attains a short circuit current of 40 mA/cm2 and an efficiency of 4.9%. It has been shown that the cell performance enhances by optimizing the energy levels alignment in the PSi, ZnSiQDs, TiO2NPs layers