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Malinovskis, U., Poplausks, R., Erts, D., Ramser, K., Tamulevičius, S., Tamulevičienė, A., . . . Prikulis, J. (2019). High-Density Plasmonic Nanoparticle Arrays Deposited on Nanoporous Anodic Alumina Templates for Optical Sensor Applications. Nanomaterials, 9(4), Article ID 531.
Open this publication in new window or tab >>High-Density Plasmonic Nanoparticle Arrays Deposited on Nanoporous Anodic Alumina Templates for Optical Sensor Applications
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2019 (English)In: Nanomaterials, E-ISSN 2079-4991, Vol. 9, no 4, article id 531Article in journal (Refereed) Published
Abstract [en]

This study demonstrates a new, robust, and accessible deposition technique of metal nanoparticle arrays (NPAs), which uses nanoporous anodic alumina (NAA) as a template for capillary force-assisted convective colloid (40, 60, and 80 nm diameter Au) assembly. The NPA density and nanoparticle size can be independently tuned by the anodization conditions and colloid synthesis protocols. This enables production of non-touching variable-density NPAs with controllable gaps in the 20–60 nm range. The NPA nearest neighbor center distance in the present study was fixed to 100 nm by the choice of anodization protocol. The obtained Au NPAs have the resonant scattering maxima in the visible spectral range, with a refractometric sensitivity, which can be tuned by the variation of the array density. The thickness of the NAA layer in an Aluminum-NAA-NPA multilayer system enables further tuning of the resonance frequency and optimization for use with specific molecules, e.g., to avoid absorption bands. Applicability of the mentioned multilayers for colorimetric refractive index (RI) sensing is demonstrated. Their use as Surface-Enhanced Raman Scattering (SERS) substrates is tested using hemoglobin as a biological probe molecule

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
porous anodic aluminum oxide, colloid deposition, plasmonics, nanoparticle arrays, hemoglobin, SERS
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-73457 (URN)10.3390/nano9040531 (DOI)30987127 (PubMedID)
Note

Validerad;2019;Nivå 2;2019-04-05 (johcin)

Available from: 2019-04-05 Created: 2019-04-05 Last updated: 2019-04-17Bibliographically approved
Krige, A., Sjöblom, M., Ramser, K., Christakopoulos, P. & Rova, U. (2019). On-line Raman spectroscopic study of cytochromes’ redox state of biofilms in microbial fuel cells. Molecules, 24(3), Article ID 646.
Open this publication in new window or tab >>On-line Raman spectroscopic study of cytochromes’ redox state of biofilms in microbial fuel cells
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2019 (English)In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 24, no 3, article id 646Article in journal (Refereed) Published
Abstract [en]

Bio-electrochemical systems such as microbial fuel cells and microbial electrosynthesis cells depend on efficient electron transfer between the microorganisms and the electrodes. Understanding the mechanisms and dynamics of the electron transfer is important in order to design more efficient reactors, as well as modifying microorganisms for enhanced electricity production. Geobacter are well known for their ability to form thick biofilms and transfer electrons to the surfaces of electrodes. Currently, there are not many “on-line” systems for monitoring the activity of the biofilm and the electron transfer process without harming the biofilm. Raman microscopy was shown to be capable of providing biochemical information, i.e., the redox state of C-type cytochromes, which is integral to external electron transfer, without harming the biofilm. In the current study, a custom 3D printed flow-through cuvette was used in order to analyze the oxidation state of the C-type cytochromes of suspended cultures of three Geobacter sulfurreducens strains (PCA, KN400 and ∆pilA). It was found that the oxidation state is a good indicator of the metabolic state of the cells. Furthermore, an anaerobic fluidic system enabling in situ Raman measurements was designed and applied successfully to monitor and characterize G. sulfurreducens biofilms during electricity generation, for both a wild strain, PCA, and a mutant, ∆S. The cytochrome redox state, monitored by the Raman peak areas, could be modulated by applying different poise voltages to the electrodes. This also correlated with the modulation of current transferred from the cytochromes to the electrode. The Raman peak area changed in a predictable and reversible manner, indicating that the system could be used for analyzing the oxidation state of the proteins responsible for the electron transfer process and the kinetics thereof in-situ. 

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
Cytochrome-C, Geobacter sulfurreducens, Microbial fuel cell, Omc, Raman spectroscopy
National Category
Bioprocess Technology Applied Mechanics
Research subject
Biochemical Process Engineering; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-73003 (URN)10.3390/molecules24030646 (DOI)000458934000270 ()30759821 (PubMedID)2-s2.0-85061525740 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-26 (svasva)

Available from: 2019-02-26 Created: 2019-02-26 Last updated: 2019-02-27Bibliographically approved
Knoepp, F., Wahl, J., Andersson, A. G., Borg, J., Weissmann, N. & Ramser, K. (2018). Development of a Gas-Tight Microfluidic System for Raman Sensing of Single Pulmonary Arterial Smooth Muscle Cells Under Normoxic/Hypoxic Conditions. Sensors, 10, Article ID 3238.
Open this publication in new window or tab >>Development of a Gas-Tight Microfluidic System for Raman Sensing of Single Pulmonary Arterial Smooth Muscle Cells Under Normoxic/Hypoxic Conditions
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2018 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 10, article id 3238Article in journal (Refereed) Published
Abstract [en]

Acute hypoxia changes the redox-state of pulmonary arterial smooth muscle cells (PASMCs). This might influence the activity of redox-sensitive voltage-gated K⁺-channels (Kv-channels) whose inhibition initiates hypoxic pulmonary vasoconstriction (HPV). However, the molecular mechanism of how hypoxia-or the subsequent change in the cellular redox-state-inhibits Kv-channels remains elusive. For this purpose, a new multifunctional gas-tight microfluidic system was developed enabling simultaneous single-cell Raman spectroscopic studies (to sense the redox-state under normoxic/hypoxic conditions) and patch-clamp experiments (to study the Kv-channel activity). The performance of the system was tested by optically recording the O₂-content and taking Raman spectra on murine PASMCs under normoxic/hypoxic conditions or in the presence of H₂O₂. Oxygen sensing showed that hypoxic levels in the gas-tight microfluidic system were achieved faster, more stable and significantly lower compared to a conventional open system (1.6 ± 0.2%, respectively 6.7 ± 0.7%, n = 6, p < 0.001). Raman spectra revealed that the redistribution of biomarkers (cytochromes, FeS, myoglobin and NADH) under hypoxic/normoxic conditions were improved in the gas-tight microfluidic system (p-values from 0.00% to 16.30%) compared to the open system (p-value from 0.01% to 98.42%). In conclusion, the new redox sensor holds promise for future experiments that may elucidate the role of Kv-channels during HPV.

Keywords
Raman spectroscopy, hypoxia, microfluidic system, redox reactions on single cell level
National Category
Applied Mechanics Fluid Mechanics and Acoustics
Research subject
Experimental Mechanics; Fluid Mechanics
Identifiers
urn:nbn:se:ltu:diva-71090 (URN)10.3390/s18103238 (DOI)000448661500066 ()30261634 (PubMedID)2-s2.0-85054841733 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-10-03 (svasva)

Available from: 2018-10-03 Created: 2018-10-03 Last updated: 2018-11-29Bibliographically approved
Phounglamcheik, A., Wang, L., Romar, H., Broström, M., Ramser, K., Skreiberg, Ø. & Umeki, K. (2018). Effects of pyrolysis oil recycling and reaction gas atmosphere on the physical properties and reactivity of charcoal from wood. In: : . Paper presented at 22nd International Symposium on Analytical and Applied Pyrolysis, Kyoto, Japan, 3-8 June 2018.
Open this publication in new window or tab >>Effects of pyrolysis oil recycling and reaction gas atmosphere on the physical properties and reactivity of charcoal from wood
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2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Bioenergy Renewable Bioenergy Research Energy Engineering
Research subject
Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-70428 (URN)
Conference
22nd International Symposium on Analytical and Applied Pyrolysis, Kyoto, Japan, 3-8 June 2018
Available from: 2018-08-15 Created: 2018-08-15 Last updated: 2018-08-16Bibliographically approved
Amer, E., Gren, P., Ramser, K. & Sjödahl, M. (2018). Measurement of selective species concentration using spectroscopic holography. In: M. Kujawińska ; L. R. Jaroszewicz (Ed.), Speckle 2018: VII International Conference on Speckle Metrology. Paper presented at Speckle 2018: VII International Conference On Speckle Metrology 9-12 September 2018 Janów Podlaski, Poland. SPIE - International Society for Optical Engineering, 10834, Article ID 108340P.
Open this publication in new window or tab >>Measurement of selective species concentration using spectroscopic holography
2018 (English)In: Speckle 2018: VII International Conference on Speckle Metrology / [ed] M. Kujawińska ; L. R. Jaroszewicz, SPIE - International Society for Optical Engineering, 2018, Vol. 10834, article id 108340PConference paper, Published paper (Refereed)
Abstract [en]

Spectroscopic holography refers to techniques in which the detected hologram contains information about specific species in the medium under study. In general, at least two lasers are required with wavelengths chosen carefully to fit the interaction process utilized. In this process, energy from the shorter wavelength laser beam is transferred to the longer wavelength coherently through the process of stimulated emission. Two interaction mechanisms are considered; Stimulated Laser Induced Fluorescence (LIF) and Stimulated Raman Scattering (SRS), which both are species specific with the ability of coherent interaction. In this paper, the fundamental properties of spectroscopic holography is presented and demonstrated with a few idealized experiments. These validation experiments are performed in a gas chamber in which different gases may be blended and the gas pressure changed between 1-12 bars. In addition, two examples of applications are presented. In the first set of experiments, LIF holography is used to image light absorption and laser heating in a dye simultaneously. The second set of experiments is performed in a ow of methane gas. It is demonstrated that the combination of holographic phase measurements and SRS gain images may be used for calibration. This calibration may further be used to measure absolute concentration in a burning flame.

Place, publisher, year, edition, pages
SPIE - International Society for Optical Engineering, 2018
Series
Proceedings of SPIE - the International Society for Optical Engineering, ISSN 0277-786X ; 10834
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-72430 (URN)10.1117/12.2319386 (DOI)000455052600021 ()2-s2.0-85058412906 (Scopus ID)9781510622975 (ISBN)
Conference
Speckle 2018: VII International Conference On Speckle Metrology 9-12 September 2018 Janów Podlaski, Poland
Available from: 2019-01-03 Created: 2019-01-03 Last updated: 2019-01-28Bibliographically approved
Knoepp, F., Ramser, K. & Weissmann, N. (2017). Hypoxia alters the redox state and inhibits K+-currents in mouse pulmonary arterial smooth muscle cells. Paper presented at 96th Annual Meeting of the German Physiological Society, Greifswald, Germany, 16–18 March 2017. Acta Physiologica, 219(S711), 139
Open this publication in new window or tab >>Hypoxia alters the redox state and inhibits K+-currents in mouse pulmonary arterial smooth muscle cells
2017 (English)In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 219, no S711, p. 139-Article in journal, Meeting abstract (Refereed) Published
Place, publisher, year, edition, pages
John Wiley & Sons, 2017
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-63043 (URN)10.1111/apha.12870 (DOI)000395770300273 ()
Conference
96th Annual Meeting of the German Physiological Society, Greifswald, Germany, 16–18 March 2017
Note

Special Issue: Abstracts of the 96th Annual Meeting of the German Physiological Society, 16–18 March 2017, Greifswald, Germany

Available from: 2017-04-18 Created: 2017-04-18 Last updated: 2018-10-03Bibliographically approved
Lindahl, O. A., Ramser, K., Bäcklund, T., Ljungberg, B. & Bergh, A. (2017). Prostate cancer detection ex vivo combining Raman spectroscopy and tactile resonance technology. In: Hannu Eskola, Outi Väisänen, Jari Viik, Jari Hyttinen (Ed.), EMBEC & NBC 2017: Joint Conference of the European Medical and Biological Engineering Conference (EMBEC) and the Nordic-Baltic Conference on Biomedical Engineering and Medical Physics (NBC), Tampere, Finland, June 2017. Paper presented at Joint Conference of the European Medical and Biological Engineering Conference (EMBEC) and the Nordic-Baltic Conference on Biomedical Engineering and Medical Physics (NBC), Tampere, Finland, 11-15 June 2017 (pp. 193-196). Singapore: Springer
Open this publication in new window or tab >>Prostate cancer detection ex vivo combining Raman spectroscopy and tactile resonance technology
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2017 (English)In: EMBEC & NBC 2017: Joint Conference of the European Medical and Biological Engineering Conference (EMBEC) and the Nordic-Baltic Conference on Biomedical Engineering and Medical Physics (NBC), Tampere, Finland, June 2017 / [ed] Hannu Eskola, Outi Väisänen, Jari Viik, Jari Hyttinen, Singapore: Springer, 2017, p. 193-196Conference paper, Published paper (Refereed)
Abstract [en]

Prostate cancer is the most common cancer for men in the western world. The most prevalent curative treatment is radical prostatectomy. However, prostate surgery can give unwanted side effects and there is a need for an instrument that can provide decision support to the surgeon during surgery on the presence of cancer cells in the surgical margin. A dual-modality probe, combining Raman spectroscopy and tactile resonance technology, has been used for detecting cancer in fresh human prostate tissue. The tactile resonance modality measures the tissue stiffness and Raman spectroscopy depicts the molecular content in tissue, both related to cancer. After ethical approval, the study investigated the potential of the dual-modality probe by testing its ability to differentiate between normal and cancerous prostate tissue ex vivo. It also investigated the minimal amount of measurement points needed to securely detect cancer on the surface of prostate tissue. Measurements on three prostate tissue slices show that the tactile resonance modality measuring stiffness was able to detect differences between normal and cancerous tissue on a significant level of 90%, but the sample size was too low to draw any firm conclusions. It was also suggested from the study results that the high wavenumber region in the Raman spectrum can give valuable information about cancer in prostate tissue. A number of 24 measurement points were enough for detecting cancer in prostate slices in this study. It can be suggested from this study that combining these two sensor modalities is promising for accurate detection of prostate cancer that is needed during prostate surgery, but more measurements including more prostates must be performed before the full value of the study result can be established.

Place, publisher, year, edition, pages
Singapore: Springer, 2017
Series
IFMBE Proceedings ; 65
National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-64064 (URN)10.1007/978-981-10-5122-7_49 (DOI)000449778900049 ()2-s2.0-85021733002 (Scopus ID)
Conference
Joint Conference of the European Medical and Biological Engineering Conference (EMBEC) and the Nordic-Baltic Conference on Biomedical Engineering and Medical Physics (NBC), Tampere, Finland, 11-15 June 2017
Available from: 2017-06-15 Created: 2017-06-15 Last updated: 2018-12-03Bibliographically approved
Erjavec, N., Pinato, G. & Ramser, K. (2016). Raman spectroscopy as a tool for detecting mitochondrial fitness (ed.). Journal of Raman Spectroscopy, 47(8), 933-939
Open this publication in new window or tab >>Raman spectroscopy as a tool for detecting mitochondrial fitness
2016 (English)In: Journal of Raman Spectroscopy, ISSN 0377-0486, E-ISSN 1097-4555, Vol. 47, no 8, p. 933-939Article in journal (Refereed) Published
Abstract [en]

Raman spectroscopy allows the molecular chemical analysis of whole living cells by comparing them to known Raman signatures of specific vibrational bonds. In this work we used Raman spectroscopy to differentiate between wild type yeast cells and mutants characterized by increased or reduced mitochondrial fragmentation. To associate mitochondrial fragmentation with biochemical markers, we performed Linear Discriminant Analysis (LDA) of whole cell Raman spectra (~50–100 cells/spectrum). We show that the long-lived, less fragmented mutants fall into a significantly distant cluster from the wild type and short-lived, more fragmented mutants. Clustering depends on respiratory growth and coincides with that of membrane phospholipids and some respiratory chain components. Spectral clustering is supported by enzymatic activity measurements of OXPHOS Complexes. In addition, we find that NAD(P)H autofluorescence also correlates with mitochondrial fragmentation, representing another likely aging biomarker, besides phospholipids and OXPHOS components. In summary, we demonstrate that Raman spectroscopy has the potential to become a powerful tool for differentiating healthy from unhealthy aged tissues, as well as for the prognostic evaluation of mitochondrial function and fitness.

National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-7725 (URN)10.1002/jrs.4930 (DOI)000380949500009 ()2-s2.0-84964334439 (Scopus ID)624a7da3-d98b-4a00-a755-02ee20e082cf (Local ID)624a7da3-d98b-4a00-a755-02ee20e082cf (Archive number)624a7da3-d98b-4a00-a755-02ee20e082cf (OAI)
Note

Validerad; 2016; Nivå 2; 20160419 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Alrifaiy, A., Borg, J., Lindahl, O. & Ramser, K. (2015). A lab-on-a-chip for hypoxic patch clamp measurements combined with optical tweezers and spectroscopy: first investigations of single biological cells (ed.). Paper presented at . Biomedical engineering online, 14, Article ID 36.
Open this publication in new window or tab >>A lab-on-a-chip for hypoxic patch clamp measurements combined with optical tweezers and spectroscopy: first investigations of single biological cells
2015 (English)In: Biomedical engineering online, ISSN 1475-925X, E-ISSN 1475-925X, Vol. 14, article id 36Article in journal (Refereed) Published
Abstract [en]

The response and the reaction of the brain system to hypoxia is a vital research subject that requires special instrumentation. With this research subject in focus, a new multifunctional lab-on-a-chip (LOC) system with control over the oxygen content for studies on biological cells was developed. The chip was designed to incorporate the patch clamp technique, optical tweezers and absorption spectroscopy. The performance of the LOC was tested by a series of experiments. The oxygen content within the channels of the LOC was monitored by an oxygen sensor and verified by simultaneously studying the oxygenation state of chicken red blood cells (RBCs) with absorption spectra. The chicken RBCs were manipulated optically and steered in three dimensions towards a patch-clamp micropipette in a closed microfluidic channel. The oxygen level within the channels could be changed from a normoxic value of 18% O 2 to an anoxic value of 0.0-0.5% O 2. A time series of 3 experiments were performed, showing that the spectral transfer from the oxygenated to the deoxygenated state occurred after about 227 ± 1 s and a fully developed deoxygenated spectrum was observed after 298 ± 1 s, a mean value of 3 experiments. The tightness of the chamber to oxygen diffusion was verified by stopping the flow into the channel system while continuously recording absorption spectra showing an unchanged deoxygenated state during 5400 ± 2 s. A transfer of the oxygenated absorption spectra was achieved after 426 ± 1 s when exposing the cell to normoxic buffer. This showed the long time viability of the investigated cells. Successful patching and sealing were established on a trapped RBC and the whole-cell access (Ra) and membrane (Rm) resistances were measured to be 5.033 ± 0.412 M Ω and 889.7 ± 1.74 M Ω respectively.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering Applied Mechanics
Research subject
Industrial Electronics; Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-15236 (URN)10.1186/s12938-015-0024-6 (DOI)000353330300001 ()25907197 (PubMedID)2-s2.0-84928337538 (Scopus ID)ebc3778e-f4fc-49c8-a1c0-bf991c7677d6 (Local ID)ebc3778e-f4fc-49c8-a1c0-bf991c7677d6 (Archive number)ebc3778e-f4fc-49c8-a1c0-bf991c7677d6 (OAI)
Note
Validerad; 2015; Nivå 2; 20150428 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Nyberg, M., Jalkanen, V., Ramser, K., Ljungberg, B., Bergh, A. & Lindahl, O. (2015). Dual-modality probe intended for prostate cancer detection combining Raman spectroscopy and tactile resonance technology—discrimination of normal human prostate tissues ex vivo (ed.). Paper presented at . Journal of Medical Engineering & Technology, 39(3), 198-207
Open this publication in new window or tab >>Dual-modality probe intended for prostate cancer detection combining Raman spectroscopy and tactile resonance technology—discrimination of normal human prostate tissues ex vivo
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2015 (English)In: Journal of Medical Engineering & Technology, ISSN 0309-1902, E-ISSN 1464-522X, Vol. 39, no 3, p. 198-207Article in journal (Refereed) Published
Abstract [en]

Prostate cancer is the most common cancer for men in the western world. For the first time, a dual-modality probe, combining Raman spectroscopy and tactile resonance technology, has been used for assessment of fresh human prostate tissue. The study investigates the potential of the dual-modality probe by testing its ability to differentiate prostate tissue types ex vivo. Measurements on four prostates show that the tactile resonance modality was able to discriminate soft epithelial tissue and stiff stroma (p < 0.05). The Raman spectra exhibited a strong fluorescent background at the current experimental settings. However, stroma could be discerned from epithelia by integrating the value of the spectral background. Combining both parameters by a stepwise analysis resulted in 100% sensitivity and 91% specificity. Although no cancer tissue was analysed, the results are promising for further development of the instrument and method for discriminating prostate tissues and cancer

National Category
Applied Mechanics
Research subject
Experimental Mechanics
Identifiers
urn:nbn:se:ltu:diva-16285 (URN)10.3109/03091902.2015.1021430 (DOI)25762203 (PubMedID)2-s2.0-84926353218 (Scopus ID)fe957028-5257-40a6-a492-377ef3d2879a (Local ID)fe957028-5257-40a6-a492-377ef3d2879a (Archive number)fe957028-5257-40a6-a492-377ef3d2879a (OAI)
Note
Validerad; 2015; Nivå 2; 20150316 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-3268-1691

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