Examinando por Autor "Chen, Kaiwen"

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    Microbial green synthesis of luminescent terbium sulfide nanoparticles using E. Coli: a rare earth element detoxification mechanism
    (BioMed Central Ltd, 2024-12) León, Juan José; Oetiker, Nía; Torres, Nicolás; Bruna, Nicolás; Oskolkov, Evgenii; Lei, Pedro; Kuzmin, Andrey; Chen, Kaiwen; Andreadis, Stelios; Pfeifer, Blaine A.; Swihart, Mark T.; Prasad, Paras N. b
    Background: Rare-earth sulfide nanoparticles (NPs) could harness the optical and magnetic features of rare-earth ions for applications in nanotechnology. However, reports of their synthesis are scarce and typically require high temperatures and long synthesis times. Results: Here we present a biosynthesis of terbium sulfide (TbS) NPs using microorganisms, identifying conditions that allow Escherichia coli to extracellularly produce TbS NPs in aqueous media at 37 °C by controlling cellular sulfur metabolism to produce a high concentration of sulfide ions. Electron microscopy revealed ultrasmall spherical NPs with a mean diameter of 4.1 ± 1.3 nm. Electron diffraction indicated a high degree of crystallinity, while elemental mapping confirmed colocalization of terbium and sulfur. The NPs exhibit characteristic absorbance and luminescence of terbium, with downshifting quantum yield (QY) reaching 28.3% and an emission lifetime of ~ 2 ms. Conclusions: This high QY and long emission lifetime is unusual in a neat rare-earth compound; it is typically associated with rare-earth ions doped into another crystalline lattice to avoid non-radiative cross relaxation. This suggests a reduced role of nonradiative processes in these terbium-based NPs. This is, to our knowledge, the first report revealing the advantage of biosynthesis over chemical synthesis for Rare Earth Element (REE) based NPs, opening routes to new REE-based nanocrystals. © The Author(s) 2024.
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    Unlocking nature’s brilliance: using Antarctic extremophile Shewanella baltica to biosynthesize lanthanide-containing nanoparticles with optical up-conversion
    (BioMed Central Ltd, 2024-12) Oetiker, Nia; León, Juan José; Swihart, Mark; Chen, Kaiwen; Pfeifer, Blaine A.; Dutta, Avisek; Pliss, Artem; Kuzmin, Andrey N.
    Both lanthanide-containing and fluorine-containing nanomaterials present challenging targets for microbial biosynthesis because these elements are toxic to most bacteria. Here, we overcome these challenges by using an Antarctic Shewanella baltica strain that tolerates these elements and report the first biosynthesis of lanthanide-doped fluoride nanoparticles (NPs) from them. NaYF4 NPs doped with Er3+/Yb3+ are prototypical lanthanide-based upconverting nanoparticles (UCNPs) with upconverted luminescence at visible wavelengths under infrared excitation. However, their synthesis employs high precursor concentrations, organic solvents, and elevated temperatures. Microbial biosynthesis offers a greener alternative but has not been explored for these materials. Here, we harness an extremophile S. baltica strain to biosynthesize UCNPs at room temperature, based upon its high tolerance for fluoride and lanthanide ions and the observation that tolerance of lanthanides increased in the presence of fluoride. Our biosynthesis produces electron-dense nanostructures composed of Na, Y, F, Yb, and Er in the bacterial periplasm, adhered to the outer cell membrane, and dispersed extracellularly, which exhibited up-converted emission under 980 nm excitation. This suggests that extracellular or periplasmic mineralization of lanthanides as fluorides protects the bacteria from lanthanide toxicity. Subsequent heating both enhanced upconverted emission from UCNPs and allowed observation of their crystallinity in transmission electron microscopy (TEM). This work establishes the first biosynthesis of NaYF4:Yb: Er UCNPs, advancing both nanotechnology and biotechnology. Graphical Abstract: (Figure presented.) © The Author(s) 2024.