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  1. Article: Origin of the pH Dependence of Emission of Aqueous Dihydrolipoic Acid-Capped PbS Quantum Dots

    Schwabacher, James C / Kodaimati, Mohamad S / Weiss, Emily A

    Journal of physical chemistry. 2019 June 24, v. 123, no. 28

    2019  

    Abstract: This paper describes the mechanism behind the pH response of the photoluminescence (PL) of aqueous dihydrolipoic acid (DHLA)-capped PbS quantum dots (QDs). The PL spectra of ensembles of PbS-DHLA QDs bathochromically shift by up to 95 meV as the pH value ...

    Abstract This paper describes the mechanism behind the pH response of the photoluminescence (PL) of aqueous dihydrolipoic acid (DHLA)-capped PbS quantum dots (QDs). The PL spectra of ensembles of PbS-DHLA QDs bathochromically shift by up to 95 meV as the pH value decreases from 12 to 5. The results of optical spectroscopy and dynamic light scattering experiments, along with the results of a phenomenological model for exciton hopping among QDs, suggest that bathochromic shifts can be entirely accounted for by Förster-type energy transfer (EnT) among QDs as they aggregate with decreasing pH. The magnitude of the PL shift is strongly correlated with the full width at half maximum (fwhm) of the ensemble’s PL in its most disaggregated state (i.e., the polydispersity of the sample directly after phase transfer into basic water). Extrapolation of these data to a hypothetically completely monodisperse sample of QDs yields a PL fwhm of an ensemble of single DHLA-capped PbS QDs in water of 130 meV. This work shows that the PL linewidth before aggregation, which is controlled by the phase transfer procedure, is an excellent predictor of the pH response of the emission spectra of the QDs.
    Keywords energy transfer ; light scattering ; models ; pH ; photoluminescence ; physical chemistry ; quantum dots ; spectroscopy
    Language English
    Dates of publication 2019-0624
    Size p. 17574-17579.
    Publishing place American Chemical Society
    Document type Article
    ISSN 1932-7455
    DOI 10.1021/acs.jpcc.9b03619
    Database NAL-Catalogue (AGRICOLA)

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  2. Article: Small Surfactant Concentration Differences Influence Adsorption of Human Serum Albumin on Polystyrene Nanoparticles

    Winzen, Svenja / Schwabacher James C / Müller Julius / Landfester Katharina / Mohr Kristin

    Biomacromolecules. 2016 Nov. 14, v. 17, no. 11

    2016  

    Abstract: Surfactants, even in miniscule amounts, are often used for the synthesis and especially the stabilization of nanomaterials, which is essential for in vivo applications. In this study, we show that the interaction between nanoparticles and proteins ... ...

    Abstract Surfactants, even in miniscule amounts, are often used for the synthesis and especially the stabilization of nanomaterials, which is essential for in vivo applications. In this study, we show that the interaction between nanoparticles and proteins strongly depends on the type of stabilizing surfactants and their (small) concentration changes. The reaction between human serum albumin and polystyrene nanoparticles stabilized by an ionic or nonionic surfactantsodium dodecyl sulfate or Lutensol AT50, respectivelywas monitored using isothermal titration calorimetry. It was found that the amount of surfactant molecules on the surface significantly determines the protein binding affinity and adsorption stoichiometry, which is important for all nanomaterials coming into contact with biological components such as blood plasma proteins. Thus after synthesizing nanomaterials for in vivo applications as drug delivery agents, it is crucial to perform a detailed analysis of the obtained surface chemistry that accounts for the presence of minimal amounts of stabilizing agents.
    Keywords adsorption ; binding capacity ; blood plasma ; calorimetry ; chemical elements ; drugs ; human serum albumin ; nanoparticles ; polystyrenes ; stoichiometry ; sulfates ; surfactants ; titration
    Language English
    Dates of publication 2016-1114
    Size p. 3845-3851.
    Publishing place American Chemical Society
    Document type Article
    ISSN 1526-4602
    DOI 10.1021%2Facs.biomac.6b01503
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Properties of quantum dots coupled to plasmons and optical cavities.

    Westmoreland, Dana E / McClelland, Kevin P / Perez, Kaitlyn A / Schwabacher, James C / Zhang, Zhengyi / Weiss, Emily A

    The Journal of chemical physics

    2019  Volume 151, Issue 21, Page(s) 210901

    Abstract: Quantum electrodynamics is rapidly finding a set of new applications in thresholdless lasing, photochemistry, and quantum entanglement due to the development of sophisticated patterning techniques to couple nanoscale photonic emitters with photonic and ... ...

    Abstract Quantum electrodynamics is rapidly finding a set of new applications in thresholdless lasing, photochemistry, and quantum entanglement due to the development of sophisticated patterning techniques to couple nanoscale photonic emitters with photonic and plasmonic cavities. Colloidal and epitaxial semiconductor nanocrystals or quantum dots (QDs) are promising candidates for emitters within these architectures but are dramatically less explored in this role than are molecular emitters. This perspective reviews the basic physics of emitter-cavity coupling in the weak-to-strong coupling regimes, describes common architectures for these systems, and lists possible applications (in particular, photochemistry), with a focus on the advantages and issues associated with using QDs as the emitters.
    MeSH term(s) Optical Devices ; Photochemical Processes ; Quantum Dots/chemistry
    Language English
    Publishing date 2019-12-10
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 3113-6
    ISSN 1089-7690 ; 0021-9606
    ISSN (online) 1089-7690
    ISSN 0021-9606
    DOI 10.1063/1.5124392
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

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  4. Article ; Online: Small Surfactant Concentration Differences Influence Adsorption of Human Serum Albumin on Polystyrene Nanoparticles.

    Winzen, Svenja / Schwabacher, James C / Müller, Julius / Landfester, Katharina / Mohr, Kristin

    Biomacromolecules

    2016  Volume 17, Issue 11, Page(s) 3845–3851

    Abstract: Surfactants, even in miniscule amounts, are often used for the synthesis and especially the stabilization of nanomaterials, which is essential for in vivo applications. In this study, we show that the interaction between nanoparticles and proteins ... ...

    Abstract Surfactants, even in miniscule amounts, are often used for the synthesis and especially the stabilization of nanomaterials, which is essential for in vivo applications. In this study, we show that the interaction between nanoparticles and proteins strongly depends on the type of stabilizing surfactants and their (small) concentration changes. The reaction between human serum albumin and polystyrene nanoparticles stabilized by an ionic or nonionic surfactant-sodium dodecyl sulfate or Lutensol AT50, respectively-was monitored using isothermal titration calorimetry. It was found that the amount of surfactant molecules on the surface significantly determines the protein binding affinity and adsorption stoichiometry, which is important for all nanomaterials coming into contact with biological components such as blood plasma proteins. Thus after synthesizing nanomaterials for in vivo applications as drug delivery agents, it is crucial to perform a detailed analysis of the obtained surface chemistry that accounts for the presence of minimal amounts of stabilizing agents.
    MeSH term(s) Adsorption ; Calorimetry ; Drug Delivery Systems ; Humans ; Nanoparticles/chemistry ; Nanoparticles/therapeutic use ; Particle Size ; Polystyrenes/chemistry ; Polystyrenes/therapeutic use ; Protein Binding ; Serum Albumin/chemistry ; Serum Albumin/therapeutic use ; Sodium Dodecyl Sulfate/chemistry ; Sodium Dodecyl Sulfate/therapeutic use ; Surface-Active Agents/chemistry ; Surface-Active Agents/therapeutic use
    Chemical Substances Polystyrenes ; Serum Albumin ; Surface-Active Agents ; Sodium Dodecyl Sulfate (368GB5141J)
    Language English
    Publishing date 2016-11-14
    Publishing country United States
    Document type Journal Article
    ISSN 1526-4602
    ISSN (online) 1526-4602
    DOI 10.1021/acs.biomac.6b01503
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Polyvinyl alcohol-montmorillonite composites for water purification: Analysis of clay mineral cation exchange and composite particle synthesis.

    Brown, Karlena / Mendoza, Mary / Tinsley, Tamanika / Bee-DiGregorio, Madeleine Y / Bible, Michael / Brooks, Jerin L / Colorado, Melvin / Esenther, Jacob / Farag, Andrew / Gill, Rachel / Kalivas, Eleni N / Lara, Raquel / Lutz, Alex / Nazaire, Jasmine / Rasines Mazo, Alicia / Rodriguez, Rebeca S / Schwabacher, James C / Zestos, Alexander G / Hartings, Matthew R /
    Fox, Douglas M

    Polyhedron

    2021  Volume 205

    Abstract: Municipal and residential water purification rely heavily on activated carbon (AC), but regeneration of AC is costly and cannot be performed at the point-of-use. Clay minerals (CMs) comprise a class of naturally abundant materials with known capacities ... ...

    Abstract Municipal and residential water purification rely heavily on activated carbon (AC), but regeneration of AC is costly and cannot be performed at the point-of-use. Clay minerals (CMs) comprise a class of naturally abundant materials with known capacities for analyte adsorbance. However, the gel-forming properties of CMs in aqueous suspension pose problems for these materials being used in water-purification. In this study, we have taken three main steps to optimize the use of CMs in these applications. First, we produced several variants of montmorillonite CMs to evaluate the effect of interstitial cation hydrophobicity on the ability of the CM to uptake chargecarrying organic pollutants. These variants include CMs with the following cations: sodium, hexyl(triphenyl) phosphonium, hexyadecyl(triphenyl)phosphonium, and hexyl(tributyl)phosphonium. Second, we synthesized polymer-clay mineral composite films composed of polyvinyl alcohol (PVA), crosslinked in the presence of a CM variant. These films were evaluated for their ability to uptake malachite green (MG). Finally, we developed a one-pot synthetic method for the generation of polymer-clay particles for use in a continuous column process. We synthesized polymer-clay mineral particles using the highest performing CM (based on the film experiments) and evaluated the equilibrium capacity and kinetics of MG uptake from solution.
    Language English
    Publishing date 2021-05-29
    Publishing country England
    Document type Journal Article
    ZDB-ID 2000326-2
    ISSN 0277-5387
    ISSN 0277-5387
    DOI 10.1016/j.poly.2021.115297
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Protein-templated gold nanoparticle synthesis: protein organization, controlled gold sequestration, and unexpected reaction products.

    Hart, Cassidy / Abuladel, Nouf / Bee, Madeleine / Kreider, Megan C / CVitan, Alexander C / Esson, Moira M / Farag, Andrew / Ibeh, Trisha / Kalivas, Eleni N / Larco, Daniel-Mario / Walker Long, Andrew / Lymperopoulos, Loukas / Mendel, Zachary / Miles, Nancy / Zareba, Carly M / Schwabacher, James C / Slucher, Helen / Vinals, Javier / Heddleston, John M /
    Li, Wenyue / Fox, Douglas M / Hartings, Matthew R

    Dalton transactions (Cambridge, England : 2003)

    2017  Volume 46, Issue 47, Page(s) 16465–16473

    Abstract: Emerging applications that exploit the properties of nanoparticles for biotechnology require that the nanoparticles be biocompatible or support biological recognition. These types of particles can be produced through syntheses that involve biologically ... ...

    Abstract Emerging applications that exploit the properties of nanoparticles for biotechnology require that the nanoparticles be biocompatible or support biological recognition. These types of particles can be produced through syntheses that involve biologically relevant molecules (proteins or natural extracts, for example). Many of the protocols that rely on these molecules are performed without a clear understanding of the mechanism by which the materials are produced. We have investigated a previously described reaction in which gold nanoparticles are produced from the reaction of chloroauric acid and proteins in solution. We find that modifications to the starting conditions can alter the product from the expected solution-suspended colloids to a product where colloids are formed within a solid, fibrous protein structure. We have interrogated this synthesis, exploiting the change in products to better understand this reaction. We have evaluated the kinetics and products for 7 different proteins over a range of concentrations and temperatures. The key factor that controls the synthetic outcome (colloid or fiber) is the concentration of the protein relative to the gold concentration. We find that the observed fibrous structures are more likely to form at low protein concentrations and when hydrophilic proteins are used. An analysis of the reaction kinetics shows that AuNP formation occurs faster at lower protein (fiber-forming) concentrations than at higher protein (colloid-forming) concentrations. These results contradict traditional expectations for reaction kinetics and protein-fiber formation and are instructive of the manner in which proteins template gold nanoparticle production.
    MeSH term(s) Animals ; Chemistry Techniques, Synthetic ; Gold/chemistry ; Kinetics ; Metal Nanoparticles/chemistry ; Nanotechnology/methods ; Proteins/chemistry
    Chemical Substances Proteins ; Gold (7440-57-5)
    Language English
    Publishing date 2017-12-21
    Publishing country England
    Document type Journal Article
    ZDB-ID 1472887-4
    ISSN 1477-9234 ; 1364-5447 ; 0300-9246 ; 1477-9226
    ISSN (online) 1477-9234 ; 1364-5447
    ISSN 0300-9246 ; 1477-9226
    DOI 10.1039/c7dt03275g
    Database MEDical Literature Analysis and Retrieval System OnLINE

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