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Johnson, C. Magnus
Publikasjoner (7 av 7) Visa alla publikasjoner
Zhao, W. & Johnson, C. M. (2019). Nano Infrared Microscopy: Obtaining Chemical Information on the Nanoscale in Corrosion Studies. Journal of the Electrochemical Society, 166(11), C3456-C3460
Åpne denne publikasjonen i ny fane eller vindu >>Nano Infrared Microscopy: Obtaining Chemical Information on the Nanoscale in Corrosion Studies
2019 (engelsk)Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, nr 11, s. C3456-C3460Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

In this perspective article, the novel technique "nano infrared microscopy" is introduced as a valuable tool in the field of corrosion science to obtain chemical information with a spatial resolution of around 10 nm. Accordingly, the resolution is well below the diffraction limit, in contrast to conventional vibrational microscopy techniques. Thus, studies of corrosion initiation, localized corrosion, and thin protective films can be performed in greater detail than before. There are a few different types of nano infrared microscopes, but they all have in common that they are based on a combination of infrared (IR) spectroscopy and atomic force microscopy (AFM). In this article the theory of the different techniques is discussed, and some results are highlighted to show the ability of the technique in the field of corrosion science. Future possibilities of the technique in studies of corrosion and degradation of materials are also discussed. 

sted, utgiver, år, opplag, sider
ELECTROCHEMICAL SOC INC, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-255434 (URN)10.1149/2.0531911jes (DOI)000473483700001 ()
Merknad

QC 20190820

Tilgjengelig fra: 2019-08-20 Laget: 2019-08-20 Sist oppdatert: 2019-08-20bibliografisk kontrollert
Niga, P., Hansson-Mille, P. M., Swerin, A., Claesson, P. M., Schoelkopf, J., Gane, P. A. C., . . . Johnson, C. M. (2019). Propofol adsorption at the air/water interface: a combined vibrational sum frequency spectroscopy, nuclear magnetic resonance and neutron reflectometry study. Soft Matter, 15(1), 38-46
Åpne denne publikasjonen i ny fane eller vindu >>Propofol adsorption at the air/water interface: a combined vibrational sum frequency spectroscopy, nuclear magnetic resonance and neutron reflectometry study
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2019 (engelsk)Inngår i: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 15, nr 1, s. 38-46Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Propofol is an amphiphilic small molecule that strongly influences the function of cell membranes, yet data regarding interfacial properties of propofol remain scarce. Here we consider propofol adsorption at the air/water interface as elucidated by means of vibrational sum frequency spectroscopy (VSFS), neutron reflectometry (NR), and surface tensiometry. VSFS data show that propofol adsorbed at the air/ water interface interacts with water strongly in terms of hydrogen bonding and weakly in the proximity of the hydrocarbon parts of the molecule. In the concentration range studied there is almost no change in the orientation adopted at the interface. Data from NR show that propofol forms a dense monolayer with a thickness of 8.4 angstrom and a limiting area per molecule of 40 angstrom(2), close to the value extracted from surface tensiometry. The possibility that islands or multilayers of propofol form at the air/water interface is therefore excluded as long as the solubility limit is not exceeded. Additionally, measurements of the 1H NMR chemical shifts demonstrate that propofol does not form dimers or multimers in bulk water up to the solubility limit.

sted, utgiver, år, opplag, sider
ROYAL SOC CHEMISTRY, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-241311 (URN)10.1039/c8sm01677a (DOI)000454838800015 ()30516226 (PubMedID)2-s2.0-85058894693 (Scopus ID)
Merknad

QC 20190125

Tilgjengelig fra: 2019-01-25 Laget: 2019-01-25 Sist oppdatert: 2019-04-09bibliografisk kontrollert
Kaestner, B., Johnson, C. M., Hermann, P., Kruskopf, M., Pierz, K., Hoehl, A., . . . Ulm, G. (2018). Infrared Nanospectroscopy of Phospholipid and Surfactin Monolayer Domains. ACS OMEGA, 3(4), 4141-4147
Åpne denne publikasjonen i ny fane eller vindu >>Infrared Nanospectroscopy of Phospholipid and Surfactin Monolayer Domains
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2018 (engelsk)Inngår i: ACS OMEGA, ISSN 2470-1343, Vol. 3, nr 4, s. 4141-4147Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

A main challenge in understanding the structure of a cell membrane and its interactions with drugs is the ability to chemically study the different molecular species on the nanoscale. We have achieved this for a model system consisting of mixed monolayers (MLs) of the biologically relevant phospholipid 1,2-distearoyl-sn-glycero-phosphatidylcholine and the antibiotic surfactin. By employing nano-infrared (IR) microscopy and spectroscopy in combination with atomic force microscopy imaging, it was possible to identify and chemically detect domain formation of the two constituents as well as to obtain IR spectra of these species with a spatial resolution on the nanoscale. A novel method to enhance the near-field imaging contrast of organic MLs by plasmon interferometry is proposed and demonstrated. In this technique, the organic layer is deposited on gold and ML graphene substrates, the latter of which supports propagating surface plasmons. Plasmon reflections arising from changes in the dielectric environment provided by the organic layer lead to an additional contrast mechanism. Using this approach, the interfacial region between surfactin and the phospholipid has been mapped and a transition region is identified.

sted, utgiver, år, opplag, sider
American Chemical Society (ACS), 2018
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-227230 (URN)10.1021/acsomega.7b01931 (DOI)000430200300057 ()2-s2.0-85045388569 (Scopus ID)
Merknad

QC 20180514

Tilgjengelig fra: 2018-05-14 Laget: 2018-05-14 Sist oppdatert: 2018-05-14bibliografisk kontrollert
Niga, P., Hansson-Mille, P. M., Swerin, A., Claesson, P. M., Schoelkopf, J., Gane, P. A., . . . Johnson, C. M. (2018). Interactions between model cell membranes and the neuroactive drug propofol. Journal of Colloid and Interface Science, 526, 230-243
Åpne denne publikasjonen i ny fane eller vindu >>Interactions between model cell membranes and the neuroactive drug propofol
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2018 (engelsk)Inngår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 526, s. 230-243Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Vibrational sum frequency spectroscopy (VSFS) complemented by surface pressure isotherm and neutron reflectometry (NR) experiments were employed to investigate the interactions between propofol, a small amphiphilic molecule that currently is the most common general anaesthetic drug, and phospholipid monolayers. A series of biologically relevant saturated phospholipids of varying chain length from C18 to C14 were spread on either pure water or propofol (2,6-bis(1-methylethyl)phenol) solution in a Langmuir trough, and the change in the molecular structure of the film, induced by the interaction with propofol, was studied with respect to the surface pressure. The results from the surface pressure isotherm experiments revealed that propofol, as long as it remains at the interface, enhances the fluidity of the phospholipid monolayer. The VSF spectra demonstrate that for each phospholipid the amount of propofol in the monolayer region decreases with increasing surface pressure. Such squeeze out is in contrast to the enhanced interactions that can be exhibited by more complex amphiphilic molecules such as peptides. At surface pressures of 22–25 mN m−1, which are relevant for biological cell membranes, most of the propofol has been expelled from the monolayer, especially in the case of the C16 and C18 phospholipids that adopt a liquid condensed phase packing of its alkyl tails. At lower surface pressures of 5 mN m−1, the effect of propofol on the structure of the alkyl tails is enhanced when the phospholipids are present in a liquid expanded phase. Specifically, for the C16 phospholipid, NR data reveal that propofol is located exclusively in the head group region, which is rationalized in the context of previous studies. The results imply a non-homogeneous distribution of propofol in the plane of real cell membranes, which is an inference that requires urgent testing and may help to explain why such low concentration of the drug are required to induce general anaesthesia.

sted, utgiver, år, opplag, sider
Academic Press, 2018
Emneord
Langmuir trough, Model membrane, Neutron reflectometry, Phospholipid monolayers, Propofol, Small amphiphilic drug, Surface pressure isotherm, Vibrational sum frequency spectroscopy
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-228699 (URN)10.1016/j.jcis.2018.03.052 (DOI)000436900400025 ()2-s2.0-85046641029 (Scopus ID)
Merknad

QC 20180529

Tilgjengelig fra: 2018-05-29 Laget: 2018-05-29 Sist oppdatert: 2018-07-18bibliografisk kontrollert
Besharat, Z., Alvarez-Asencio, R., Tian, H., Yu, S., Johnson, C. M., Gothelid, M. & Rutland, M. W. (2017). In-situ evaluation of dye adsorption on TiO2 using QCM. EPJ Photovoltaics, 8, Article ID 80401.
Åpne denne publikasjonen i ny fane eller vindu >>In-situ evaluation of dye adsorption on TiO2 using QCM
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2017 (engelsk)Inngår i: EPJ Photovoltaics, ISSN 2105-0716, Vol. 8, artikkel-id 80401Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

We measured the adsorption characteristics of two organic dyes; triphenylamine-cyanoacrylic acid (TPA-C) and phenoxazine (MP13), on TiO2, directly in a solution based on quartz crystal microbalance (QCM). Monitoring the adsorbed amount as a function of dye concentration and during rinsing allows determination of the equilibrium constant and distinction between chemisorbed and physisorbed dye. The measured equilibrium constants are 0.8 mM(-1) for TPA-C and 2.4 mM(-1) for MP13. X-ray photoelectron spectroscopy was used to compare dried chemisorbed layers of TPA-C prepared in solution with TPA-C layers prepared via vacuum sublimation; the two preparation methods render similar spectra except a small contribution of water residues (OH) on the solution prepared samples. Quantitative Nanomechanical Mapping Atomic Force Microscopy (QNM-AFM) shows that physisorbed TPA-C layers are easily removed by scanning the tip across the surface. Although not obvious in height images, adhesion images clearly demonstrate removal of the dye.

sted, utgiver, år, opplag, sider
EDP Sciences, 2017
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-248715 (URN)10.1051/epjpv/2017002 (DOI)000396159700001 ()2-s2.0-85061784497 (Scopus ID)
Merknad

QC 20190514

Tilgjengelig fra: 2019-04-10 Laget: 2019-04-10 Sist oppdatert: 2019-10-09bibliografisk kontrollert
Liljeblad, J. F. .., Rutland, M. W., Bulone, V. & Johnson, C. M. (2010). Stability and structure of phospholipid monolayers probed by vibrational sum frequency spectroscopy (VSFS). Abstracts of Papers of the American Chemical Society, 239
Åpne denne publikasjonen i ny fane eller vindu >>Stability and structure of phospholipid monolayers probed by vibrational sum frequency spectroscopy (VSFS)
2010 (engelsk)Inngår i: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 239Artikkel i tidsskrift, Meeting abstract (Annet vitenskapelig) Published
sted, utgiver, år, opplag, sider
KTH Stockholm, Royal Inst Technol, Dept Surface & Corros Sci, Stockholm, Sweden. KTH Stockholm, Royal Inst Technol, Dept Glycosci, Stockholm, Sweden.: AMER CHEMICAL SOC, 2010
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-243271 (URN)000208189304298 ()2-s2.0-77952778434 (Scopus ID)
Merknad

QC 20190904

Tilgjengelig fra: 2019-09-04 Laget: 2019-09-04 Sist oppdatert: 2019-11-29bibliografisk kontrollert
Tyrode, E., Johnson, C. M., Claesson, P. M. & Rutland, M. W. (2006). COLL 153-Molecular ordering at the liquid/air interface and hydration of surfactants. Abstract of Papers of the American Chemical Society, 232
Åpne denne publikasjonen i ny fane eller vindu >>COLL 153-Molecular ordering at the liquid/air interface and hydration of surfactants
2006 (engelsk)Inngår i: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 232Artikkel i tidsskrift, Meeting abstract (Annet vitenskapelig) Published
sted, utgiver, år, opplag, sider
AMER CHEMICAL SOC, 2006
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-242404 (URN)000207781603145 ()
Merknad

QC 20190212

Tilgjengelig fra: 2019-02-12 Laget: 2019-02-12 Sist oppdatert: 2019-02-12bibliografisk kontrollert
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