Papers by Marianna Kemell
OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Aug 28, 2006
We present a general approach to prepare metal/aerogel nanocomposites via template directed atomi... more We present a general approach to prepare metal/aerogel nanocomposites via template directed atomic layer deposition (ALD). In particular, we used a Ru ALD process consisting of alternating exposures to bis(cyclopentadienyl)ruthenium (RuCp 2) and air at 350 o C to deposit metallic Ru nanoparticles on the internal surfaces of carbon and silica aerogels. The process does not affect the morphology of the aerogel template and offers excellent control over metal loading by simply adjusting the number of ALD cycles. We also discuss the limitations of our ALD approach, and suggest ways to overcome these.
Proceedings of SPIE, Feb 27, 2015
Slot waveguide based ring resonators filled with atomic layer deposited (ALD) aluminum oxide (Al2... more Slot waveguide based ring resonators filled with atomic layer deposited (ALD) aluminum oxide (Al2O3) were fabricated and characterized. Our results demonstrate that ALD can be used to create slot waveguide ring resonators with relatively high Q-factors, which opens new possibilities for various photonic applications, such as optical sensing and all-optical signal processing.
ACS omega, Jun 27, 2019
Herein, we report an atomic layer deposition (ALD) process for Cu 2 O thin films using copper(II)... more Herein, we report an atomic layer deposition (ALD) process for Cu 2 O thin films using copper(II) acetate [Cu(OAc) 2 ] and water vapor as precursors. This precursor combination enables the deposition of phasepure, polycrystalline, and impurity-free Cu 2 O thin films at temperatures of 180−220°C. The deposition of Cu(I) oxide films from a Cu(II) precursor without the use of a reducing agent is explained by the thermally induced reduction of Cu(OAc) 2 to the volatile copper(I) acetate, CuOAc. In addition to the optimization of ALD process parameters and characterization of film properties, we studied the Cu 2 O films in the fabrication of photoconductor devices. Our proof-of-concept devices show that approximately 20 nm thick Cu 2 O films can be used for photodetection in the visible wavelength range and that the thin film photoconductors exhibit improved device characteristics in comparison to bulk Cu 2 O crystals.
Advanced Materials, Mar 1, 2022
Advanced Materials, Jun 1, 2018
Advanced Materials, Jan 20, 2022
Take-down policy If you believe that this document breaches copyright please contact us providing... more Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Advanced Healthcare Materials
The oral route is highly desirable for colorectal cancer (CRC) treatment because it allows concen... more The oral route is highly desirable for colorectal cancer (CRC) treatment because it allows concentrating the drug in the colon and achieving a localized effect. However, orally administered drugs are often metabolized in the liver, resulting in reduced efficacy and the need for higher doses. Nanoparticle‐based drug delivery systems can be engineered to prevent the diffusion of the drug in the stomach, addressing the release at the target site, and enhancing the efficacy of the delivered drug. Here, an orally administrable galunisertib delivery system is developed with gelatin‐covered diatomite nanoparticles targeting the ligand 1‐cell adhesion molecule (L1‐CAM) on metastatic cells, and further encapsulated in an enteric matrix by microfluidics. The gastro‐resistant polymer protects the nanoparticles from the action of the digestive enzymes and allows for a sustained release of galunisertib at the intestinal pH. The efficacy of antibody–antigen interactions to drive the internalizati...
VTT Technical Research Centre of Finland, 2020
Angewandte Chemie, 2022
Gold is a scarce element in the Earth's crust but indispensable in modern electronic devices.... more Gold is a scarce element in the Earth's crust but indispensable in modern electronic devices. New, sustainable methods of gold recycling are essential to meet the growing eco‐social demand of gold. Here, we describe a simple, inexpensive, and environmentally benign dissolution of gold under mild conditions. Gold dissolves quantitatively in ethanol using 2‐mercaptobenzimidazole as a ligand in the presence of a catalytic amount of iodine. Mechanistically, the dissolution of gold begins when I2 oxidizes Au0 and forms a [AuII2]− species, which undergoes subsequent ligand‐exchange reactions and forms a stable bis‐ligand AuI complex. H2O2 oxidizes free iodide and regenerated I2 returns back to the catalytic cycle. Addition of a reductant to the reaction mixture precipitates gold quantitatively and partially regenerates the ligand. We anticipate our work will open a new pathway to more sustainable metal recycling with the utilization of just catalytic amounts of reagents and green solv...
Frontiers in Microbiology, 2019
The uptake of nickel [Ni(II)] by Paenibacillus sp., Methylobacterium sp., Paraburkholderia sp., a... more The uptake of nickel [Ni(II)] by Paenibacillus sp., Methylobacterium sp., Paraburkholderia sp., and Pseudomonas sp. strains isolated from a boreal bog was studied using batch experiments. All strains removed Ni(II) from the solution and the uptake efficiency was affected by the nutrient source, incubation temperature, time, and pH. As highest Ni uptake (with a maximum K d of 1890 L/kg DW) was recorded for the Pseudomonas sp. strains, these bacteria were used in the following protein expression (SDS-PAGE and MALDI-TOFF), transmission electron microscopy (TEM) and EDS experiments. In addition, Freundlich and Langmuir sorption isotherms were determined. In the Ni(II) treated cells, dense crystalline intra-cellular accumulations were observed in TEM examinations, which were identified as Ni accumulations using EDS. SDS-PAGE and MALDI-TOFF spectra of Ni(II) treated cells showed several changes in the protein profiles, which can indicate active accumulation of Ni in these bacteria. Concurrently, we observed Ni(II) uptake to follow Freundlich and Langmuir isotherms, suggesting straight cellular biosorption in addition to the intra-cellular accumulation. The role of cellular (cell membrane and cell wall) functional groups involved in Ni(II) binding were therefore studied using Fourier transformation infrared spectroscopy. These analyses supported the potential role of the alcoholic hydroxyl, carboxyl and amine groups in Ni(II) binding in these bacteria, therefore suggesting two different Ni(II) uptake mechanisms; (i) intra-cellular accumulation [possibly connected to detoxification of Ni(II)], and (ii) straight biosorption on cell membrane/wall functional groups.
An automated on-line isolation and fractionation system including controlling software was develo... more An automated on-line isolation and fractionation system including controlling software was developed for selected nanosized biomacromolecules from human plasma by on-line coupled immunoaffinity chromatography-asymmetric flow field-flow fractionation (IAC-AsFlFFF). The on-line system was versatile, only different monoclonal antibodies, anti-apolipoprotein B-100, anti-CD9, or anti-CD61, were immobilized on monolithic disk columns for isolation of lipoproteins and extracellular vesicles (EVs). The platelet-derived CD61-positive EVs and CD9-positive EVs, isolated by IAC, were further fractionated by AsFlFFF to their sizebased subpopulations (e.g., exomeres and exosomes) for further analysis. Field-emission scanning electron microscopy elucidated the morphology of the subpopulations, and 20 free amino acids and glucose in EV subpopulations were identified and quantified in the ng/mL range using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). The study revealed that there were significant differences between EV origin and size-based subpopulations. The on-line coupled IAC-AsFlFFF system was successfully programmed for reliable execution of 10 sequential isolation and fractionation cycles (37−80 min per cycle) with minimal operator involvement, minimal sample losses, and contamination. The relative standard deviations (RSD) between the cycles for human plasma samples were 0.84−6.6%.
Advanced Functional Materials, 2020
A biomaterial system incorporating nanocellulose, poly(glycerol sebacate), and polypyrrole is int... more A biomaterial system incorporating nanocellulose, poly(glycerol sebacate), and polypyrrole is introduced for the treatment of myocardial infarction. Direct ink writing of the multicomponent aqueous suspensions allows multifunctional lattice structures that not only feature elasticity and electrical conductivity but enable cell growth. They are proposed as cardiac patches given their biocompatibility with H9c2 cardiomyoblasts, which attach extensively at the microstructural level, and induce their proliferation for 28 days. Two model drugs (3i‐1000 and curcumin) are investigated for their integration in the patches, either by loading in the precursor suspension used for extrusion or by direct impregnation of the as‐obtained, dry lattice. In studies of drug release conducted for five months, a slow in vitro degradation of the cardiac patches is observed, which prevents drug burst release and indicates their suitability for long‐term therapy. The combination of biocompatibility, biodeg...
ACS Omega, 2020
The kraft lignin's low molecular weight and too high hydroxyl content hinder its application in b... more The kraft lignin's low molecular weight and too high hydroxyl content hinder its application in bio-based carbon fibers. In this study, we were able to polymerize kraft lignin and reduce the amount of hydroxyl groups by incubating it with the white-rot fungus Obba rivulosa. Enzymatic radical oxidation reactions were hypothesized to induce condensation of lignin, which increased the amount of aromatic rings connected by carbon− carbon bonds. This modification is assumed to be beneficial when aiming for graphite materials such as carbon fibers. Furthermore, the ratio of remaining aliphatic hydroxyls to phenolic hydroxyls was increased, making the structure more favorable for carbon fiber production. When the modified lignin was mixed together with cellulose, the mixture could be spun into intact precursor fibers by using dry-jet wet spinning. The modified lignin leaked less to the spin bath compared with the unmodified lignin starting material, making the recycling of spin-bath solvents easier. The stronger incorporation of modified lignin in the precursor fibers was confirmed by composition analysis, thermogravimetry, and mechanical testing. This work shows how white-rot fungal treatment can be used to modify the structure of lignin to be more favorable for the production of bio-based fiber materials.
Chemical Communications, 2020
A liquid organic hydrogen carrier (LOHC) is an interesting concept for hydrogen storage. Pt suppo... more A liquid organic hydrogen carrier (LOHC) is an interesting concept for hydrogen storage. Pt supported on a rutile-anatase form of titania was found to be an active catalyst system for dehydrogenation of perhydrogenated dibenzyl toluene.
Nanotechnology, 2020
Amorphous SiO2-Nb2O5 nanolaminates and mixture films were grown by atomic layer deposition. The f... more Amorphous SiO2-Nb2O5 nanolaminates and mixture films were grown by atomic layer deposition. The films were grown at 300 o C from Nb(OC2H5)5, Si2(NHC2H5)6, and O3 to thicknesses ranging from 13 to 130 nm. The niobium to silicon atomic ratio was varied in the range of 0.11-7.20. After optimizing the composition, resistive switching properties could be observed in the form of characteristic current-voltage behavior. Switching parameters in the conventional regime were well defined only in a SiO2:Nb2O5 mixture at certain, optimized, composition with Nb:Si atomic ratio of 0.13, whereas low-reading voltage measurements allowed recording memory effects in a wider composition range.
Chemistry – A European Journal, 2019
HNO3‐oxidized carbon nanotubes catalyze oxidative dehydrogenative (ODH) carbon–carbon bond format... more HNO3‐oxidized carbon nanotubes catalyze oxidative dehydrogenative (ODH) carbon–carbon bond formation between electron‐rich (hetero)aryls with O2 as a terminal oxidant. The recyclable carbocatalytic method provides a convenient and an operationally easy synthetic protocol for accessing various benzofused homodimers, biaryls, triphenylenes, and related benzofused heteroaryls that are highly useful frameworks for material chemistry applications. Carbonyls/quinones are the catalytically active site of the carbocatalyst as indicated by model compounds and titration experiments. Further investigations of the reaction mechanism with a combination of experimental and DFT methods support the competing nature of acid‐catalyzed and radical cationic ODHs, and indicate that both mechanisms operate with the current material.
Ceramics International, 2018
In the present work, ZnO thin films were irradiated with 700 keV Au + ions at different fluence (... more In the present work, ZnO thin films were irradiated with 700 keV Au + ions at different fluence (1 × 10 13 , 1 × 10 14 , 2 × 10 14 , 5 × 10 14 ions/cm 2). The structural, morphological, optical and electrical properties of pristine and irradiated ZnO thin films were characterized by X-ray 2 diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), scanning electron microscope (SEM), spectroscopy ellipsometry (SE) and four point probe technique respectively. XRD results showed that the crystallite size decreased from pristine value at the fluence 1 × 10 13 ions/cm 2 , with further increase of ion fluence the crystallite size also increased due to which the crystallinity of thin films improved. SEM micrographs showed acicular structures appeared on the ZnO thin film surface at high fluence of 5 × 10 14 ions/cm 2. FTIR showed absorption band splitting due to the growth of ZnO nanostructures. The optical study revealed that the optical band gap of ZnO thin films changed from 3.08 eV (pristine) to 2.94 eV at the high fluence (5 × 10 14 ions/cm 2). The electrical resistivity of ZnO thin film decreases with increasing ion fluence. All the results can be attributed to localized heating effect by ions irradiation of thin films and well correlated with each other.
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Papers by Marianna Kemell