Browsing by Author "Langlais, Sarah R."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Design of Anisotropically Shaped Plasmonic Nanocrystals from Ultrasmall Sn-Decorated In2O3 Nanoclusters Used as Seed Materials
    (American Chemical Society, 2022-12-07) Davis, Gregory A., Jr.; Prusty, Gyanaranjan; Hati, Sumon; Lee, Jacob T.; Langlais, Sarah R.; Zhan , Xun; Sardar, Rajesh; Chemistry and Chemical Biology, School of Science
    Ultrasmall inorganic nanoclusters (<2.0 nm in diameter) bridge the gap between individual molecules and large nanocrystals (NCs) and provide the critical foundation to design and prepare new solid-state nanomaterials with previously unknown properties and functions. Herein, for the first time, we report the monodispersed colloidal synthesis and successful isolation of metastable, rhombohedral-phase, <2.0 nm indium oxide (In2O3) nanoclusters. Ultrasmall nanocluster formation is controlled by a kinetically driven growth process, as evaluated through the variation of metal-to-passivating ligand concentrations. Although <2.0 nm-diameter In2O3 nanoclusters are synthesized in the presence of tin (Sn) precursors, they do not display typical localized surface plasmon resonance (LSPR) properties, which are commonly observed in Sn-doped In2O3 (Sn:In2O3) NCs. Our Raman and X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy (HRTEM) analyses support the existence of Sn-decorated In2O3 nanoclusters, where Sn complexes reside on the surface of the nanocluster as Z-type ligands, as opposed to the formation of Sn:In2O3 nanoclusters, which behave as wide band gap (∼5.5 eV) nanomaterials. The experimentally determined band gap is in good agreement with the theoretical effective mass calculations. The newly synthesized Sn-decorated, 1.7 nm-diameter In2O3 nanoclusters are further used as reactive monomers for the seeded growth synthesis of bcc-phase, plasmonic Sn:In2O3 NCs via ex situ injection of In precursors without the addition of any Sn precursors. The LSPR peak of Sn:In2O3 NCs, which appear to form nanoflower assemblies, is tunable in the 1800–4000 nm region and possibly even the deep-IR region. In addition to altering the size and assembly of the spherical Sn:In2O3 NCs by introducing different amounts of indium acetylacetonate, injection of indium chloride precursors in the reaction mixture results in the formation of rod-shaped NCs. Surprisingly, Sn-decorated, <1.5 nm-diameter In2O3 nanoclusters do not grow into large plasmonic Sn:In2O3 NCs. Taken together, the results presented here contribute to the fundamental understanding of the surface free energy of ultrasmall metal oxide nanoclusters and further advance the knowledge on the phase transformation and growth of plasmonic NCs.
  • Thumbnail Image
    Item
    β Cell microRNAs Function as Molecular Hubs of Type 1 Diabetes Pathogenesis and as Biomarkers of Diabetes Risk
    (bioRxiv, 2023-06-15) Syed, Farooq; Krishnan, Preethi; Chang, Garrick; Langlais, Sarah R.; Hati, Sumon; Yamada, Kentaro; Lam, Anh K.; Talware, Sayali; Liu, Xiaowen; Sardar, Rajesh; Liu, Jing; Mirmira, Raghavendra G.; Evans-Molina, Carmella; Pediatrics, School of Medicine
    MicroRNAs (miRNAs) are small non-coding RNAs that play a crucial role in modulating gene expression and are enriched in cell-derived extracellular vesicles (EVs). We investigated whether miRNAs from human islets and islet-derived EVs could provide insight into β cell stress pathways activated during type 1 diabetes (T1D) evolution, therefore serving as potential disease biomarkers. We treated human islets from 10 cadaveric donors with IL-1β and IFN-γ to model T1D ex vivo. MicroRNAs were isolated from islets and islet-derived EVs, and small RNA sequencing was performed. We found 20 and 14 differentially expressed (DE) miRNAs in cytokine- versus control-treated islets and EVs, respectively. Interestingly, the miRNAs found in EVs were mostly different from those found in islets. Only two miRNAs, miR-155-5p and miR-146a-5p, were upregulated in both islets and EVs, suggesting selective sorting of miRNAs into EVs. We used machine learning algorithms to rank DE EV-associated miRNAs, and developed custom label-free Localized Surface Plasmon Resonance-based biosensors to measure top ranked EVs in human plasma. Results from this analysis revealed that miR-155, miR-146, miR-30c, and miR-802 were upregulated and miR-124-3p was downregulated in plasma-derived EVs from children with recent-onset T1D. In addition, miR-146 and miR-30c were upregulated in plasma-derived EVs of autoantibody positive (AAb+) children compared to matched non-diabetic controls, while miR-124 was downregulated in both T1D and AAb+ groups. Furthermore, single-molecule fluorescence in situ hybridization confirmed increased expression of the most highly upregulated islet miRNA, miR-155, in pancreatic sections from organ donors with AAb+ and T1D.