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Sökning: WFRF:(Fritzsche Joachim) > Chalmers tekniska högskola

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1.
  • Fritzsche, Joachim, 1977, et al. (författare)
  • Single Particle Nanoplasmonic Sensing in Individual Nanofluidic Channels
  • 2016
  • Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 16:12, s. 7857-7864
  • Tidskriftsartikel (refereegranskat)abstract
    • Nanoplasmonics allows label-free optical sensing and spectroscopy at the single nanoparticle level by exploiting plasmonic excitations in metal nanoparticles. Nanofluidics offers exclusive possibilities for applying and controlling fluid flow and mass transport at the nanoscale and toward nanosized objects. Here, we combine these two concepts in a single device, by integrating single particle nanoplasmonic sensing with nanofluidics using advanced nanofabrication. The developed devices enable on-chip referenced parallel single particle nanoplasmonic sensing inside multiple individual nanofluidic channels with dimensions down to the 100 nm range. Beyond detailed discussion of the nanofabrication, general device characterization, and parallelized single particle plasmonic readout concepts, we demonstrate device function on two examples: (i) in situ measurements of local buffer concentrations inside a nanofluidic channel; (ii) real time binding kinetics of alkanethiol molecules to a single plasmonic nanonatenna sensor in a single nanochannel. Our concept thus provides a powerful solution for controlling mass transport to and from individual (plasmonic) nanoparticles, which in a long-term perspective offers unique opportunities for label-free detection of analyte molecules at low concentrations and for fundamental studies of fluids in extreme confinement.
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2.
  • Fritzsche, Michael, et al. (författare)
  • A Highly UV-transparent Fused Silica Biochip for Sensitive Hepatotoxicity Testing by Autofluorescence
  • 2014
  • Ingår i: Biochip Journal. - : Springer Science and Business Media LLC. - 2092-7843 .- 1976-0280. ; 8:2, s. 115-121
  • Tidskriftsartikel (refereegranskat)abstract
    • Fabrication and application of a non-fluorescent and UV-transparent microfluidic biochip in fused silica that allows sensitive autofluorescence detection are described. The biochip is particularly useful in cell-based assays where the most informative autofluorescence signals from the cells reside in the ultraviolet spectral range and where plastic labware materials commonly used in cell culture work severely disturb such measurements. In this study the fused silica biochip was used for measuring intrinsic autofluorescence from liver cells in order to assess hepatotoxic effects of drugs. The assessment assay was carried out with the human liver cell line HepG2 under perfusion conditions in the microfluidics of the biochip. The autofluorescence from the.liver cells exposed to quinidine was readily recorded without background disturbance and correlated well with reference toxicity data.
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3.
  • Albinsson, David, 1990, et al. (författare)
  • Operando detection of single nanoparticle activity dynamics inside a model pore catalyst material
  • 2020
  • Ingår i: Science advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 6:25
  • Tidskriftsartikel (refereegranskat)abstract
    • Nanoconfinement in porous catalysts may induce reactant concentration gradients inside the pores due to local conversion. This leads to inefficient active material use since parts of the catalyst may be trapped in an inactive state. Experimentally, these effects remain unstudied due to material complexity and required high spatial resolution. Here, we have nanofabricated quasi-two-dimensional mimics of porous catalysts, which combine the traits of nanofluidics with single particle plasmonics and online mass spectrometry readout. Enabled by single particle resolution at operando conditions during CO oxidation over a Cu model catalyst, we directly visualize reactant concentration gradient formation due to conversion on single Cu nanoparticles inside the “model pore” and how it dynamically controls oxidation state-and, thus, activity-of particles downstream. Our results provide a general framework for single particle catalysis in the gas phase and highlight the importance of single particle approaches for the understanding of complex catalyst materials.
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4.
  • Albinsson, David, 1990, et al. (författare)
  • Shedding light on CO oxidation surface chemistry on single Pt catalyst nanoparticles inside a nanofluidic model pore
  • 2021
  • Ingår i: ACS Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 11:4, s. 2021-2033
  • Tidskriftsartikel (refereegranskat)abstract
    • Investigating a catalyst under relevant application conditions is experimentally challenging and parameters like reaction conditions in terms of temperature, pressure, and reactant mixing ratios, as well as catalyst design, may significantly impact the obtained experimental results. For Pt catalysts widely used for the oxidation of carbon monoxide, there is keen debate on the oxidation state of the surface at high temperatures and at/above atmospheric pressure, as well as on the most active surface state under these conditions. Here, we employ a nanoreactor in combination with single-particle plasmonic nanospectroscopy to investigate individual Pt catalyst nanoparticles localized inside a nanofluidic model pore during carbon monoxide oxidation at 2 bar in the 450-550 K temperature range. As a main finding, we demonstrate that our single-particle measurements effectively resolve a kinetic phase transition during the reaction and that each individual particle has a unique response. Based on spatially resolved measurements, we furthermore observe how reactant concentration gradients formed due to conversion inside the model pore give rise to position-dependent kinetic phase transitions of the individual particles. Finally, employing extensive electrodynamics simulations, we unravel the surface chemistry of the individual Pt nanoparticles as a function of reactant composition and find strongly temperature-dependent Pt-oxide formation and oxygen spillover to the SiO2 support as the main processes. These results therefore support the existence of a Pt surface oxide in the regime of high catalyst activity and demonstrate the possibility to use plasmonic nanospectroscopy in combination with nanofluidics as a tool for in situ studies of individual catalyst particles.
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5.
  • Albinsson, David, 1990, et al. (författare)
  • Single Particle Nanoplasmonic Sensing in Individual Nanofluidic Channels
  • 2017
  • Ingår i: The 8th International Conference on Surface Plasmon Photonics (SPP8).
  • Konferensbidrag (refereegranskat)abstract
    • By combining the precise mass transport control of nanofluidics with the single particle sensing abilities of nanoplasmonics we demonstrate real time single particle parallel readout of multiple nanofluidic channels from the same chip using plasmonic nanospectroscopy.The exceptional label-free sensitivity of individual plasmonic nanoparticles combined with dark-field scattering spectroscopy has proven to be a powerful tool in catalysis[1], materials science[2], and gas sensing[3], as well as to detect single molecular binding events[4]. However, despite the proven sensitivity of single particle plasmonic nanosensors, the detection of ultralow concentrations of specific analyte molecules is limited by the fact that they usually are free to diffuse away from the sensing surface, which gives rise to unpractical detection times on the order of days.As a first step to alleviate this limitation, we present an integrated nanoplasmonic-nanofluidic platform comprised of nanochannels integrated with a single plasmonic nanoantenna sensor, schematically presented in Fig 1. The dimensions of the nanofluidic system are chosen such that the entire volume of analyte solution is forced to pass the plasmonic sensor within the decay length of the near field, in order to significantly enhance the probability of direct interaction of the sensor surface with analyte in the channel. The developed devices enable on-chip referenced parallel single particle nanoplasmonic sensing inside multiple individual nanofluidic channels with dimensions down to the 100 nm range. Beyond detailed discussion of the nanofabrication, general device characterization, and parallelized single particle plasmonic readout concepts, we present the device function on two examples: (i) in situ measurements of local buffer concentrations inside a nanofluidic channel; (ii) real time binding kinetics of alkanethiol molecules to a single plasmonic nanoantenna sensor in a single nanochannel.
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6.
  • Alekseeva, Svetlana, 1987, et al. (författare)
  • Grain-growth mediated hydrogen sorption kinetics and compensation effect in single Pd nanoparticles
  • 2021
  • Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 12:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Grains constitute the building blocks of polycrystalline materials and their boundaries determine bulk physical properties like electrical conductivity, diffusivity and ductility. However, the structure and evolution of grains in nanostructured materials and the role of grain boundaries in reaction or phase transformation kinetics are poorly understood, despite likely importance in catalysis, batteries and hydrogen energy technology applications. Here we report an investigation of the kinetics of (de)hydriding phase transformations in individual Pd nanoparticles. We find dramatic evolution of single particle grain morphology upon cyclic exposure to hydrogen, which we identify as the reason for the observed rapidly slowing sorption kinetics, and as the origin of the observed kinetic compensation effect. These results shed light on the impact of grain growth on kinetic processes occurring inside nanoparticles, and provide mechanistic insight in the observed kinetic compensation effect. Grains are the building blocks of crystalline solids. Here the authors show how hydrogen-sorption induced grain-growth in Pd nanoparticles slows down the hydrogen sorption kinetics and constitutes the physical origin of corresponding kinetic compensation.
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7.
  • Alizadehheidari, Mohammadreza, 1987, et al. (författare)
  • Nanoconfined Circular and Linear DNA: Equilibrium Conformations and Unfolding Kinetics
  • 2015
  • Ingår i: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 48:3, s. 871-878
  • Tidskriftsartikel (refereegranskat)abstract
    • Studies of circular DNA confined to nanofluidic channels are relevant both from a fundamental polymer-physics perspective and due to the importance of circular DNA molecules in vivo. We here observe the unfolding of confined DNA from the circular to linear configuration as a light-induced double-strand break occurs, characterize the dynamics, and compare the equilibrium conformational statistics of linear and circular configurations. This is important because it allows us to determine to what extent existing statistical theories describe the extension of confined circular DNA. We find that the ratio of the extensions of confined linear and circular DNA configurations increases as the buffer concentration decreases. The experimental results fall between theoretical predictions for the extended de Gennes regime at weaker confinement and the Odijk regime at stronger confinement. We show that it is possible to directly distinguish between circular and linear DNA molecules by measuring the emission intensity from the DNA. Finally, we determine the rate of unfolding and show that this rate is larger for more confined DNA, possibly reflecting the corresponding larger difference in entropy between the circular and linear configurations.
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8.
  • Alizadehheidari, Mohammadreza, 1987, et al. (författare)
  • Nanoconfined circular DNA
  • 2014
  • Ingår i: 18th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2014. - 9780979806476 ; , s. 1353-1355
  • Konferensbidrag (refereegranskat)abstract
    • Studies of nanoconfined circular DNA are of interest both from a biological as well as a fundamental polymer physics perspective. We here present the use of nanofluidic channels as a tool for comparing statics and dynamics of the linear and circular configuration of the same DNA molecule.
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9.
  • Alizadehheidari, Mohammadreza, 1987, et al. (författare)
  • Nanoconfined Circular DNA
  • 2014
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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10.
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