The Experts below are selected from a list of 66 Experts worldwide ranked by ideXlab platform
Eike Brunner - One of the best experts on this subject based on the ideXlab platform.
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in vivo uptake of gold nanoparticles by the diatom Stephanopyxis turris
Algal Research-Biomass Biofuels and Bioproducts, 2019Co-Authors: Nathalie Pytlik, Susanne Machill, Benjamin Klemmed, Alexander Eychmuller, Eike BrunnerAbstract:Abstract Nanoparticle (NP) implementation in industry has increased during the last years. However, the consequences of NP release to the environment have not been fully understood yet and long-term effects are hardly predictable. Information regarding a possible NP uptake by organisms is urgently needed. Here, we investigate the uptake of presynthesized AuNPs of different diameters by living diatoms. To better understand the influence of NPs on diatoms, cells were monitored in vivo using Surface Enhanced Raman Spectroscopy (SERS). By 3D Raman imaging, AuNPs with diameters ≥50 nm could clearly be localized inside the cells, whereas smaller AuNPs were never detected in the cell interior. This indicates a size-dependent uptake mechanism that comes along with different toxicities. As diatoms present an essential source of the marine food chain, this observation is relevant not only for diatoms themselves but also for higher organisms.
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biological synthesis of gold nanoparticles by the diatom Stephanopyxis turris and in vivo sers analyses
Algal Research-Biomass Biofuels and Bioproducts, 2017Co-Authors: Nathalie Pytlik, Susanne Machill, Janine Kaden, Matthias Finger, Julia Naumann, Stefan Wanke, Eike BrunnerAbstract:Abstract Cultivation of the sea water diatom Stephanopyxis turris (S. turris) in a gold salt containing medium leads to the formation of gold nanoparticles. These biosynthesized nanoparticles were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). According to their diameter, they are classified into two groups with average diameters of around 30 and 10 nm. It is demonstrated that both types of nanoparticles consist exclusively of gold. The location of the gold nanoparticles with respect to the diatom cell was revealed using surface enhanced Raman scattering (SERS). To ensure a reliable observation of SERS spectra in each measured cell, the concentration of the gold solution as well as the incubation time of S. turris in this solution were optimized. 3D Raman imaging of entire S. turris cells was performed to localize SERS spectra of compounds resulting from closely neighbored nanoparticles. Interestingly, intracellular SERS spectra were observed indicating the presence of gold nanoparticles inside S. turris cells. Further investigation shows that the SERS spectra generated by biosynthesized nanoparticles differ significantly from the conventional Raman spectrum of diatoms. While pigments are dominating the resonance enhanced Raman spectrum, SERS spectra exhibit a completely different appearance. Their bands coincide with bands in SERS spectra of various biologically relevant compounds, e.g., hydroxyurea and retinol. The biosynthesized gold nanoparticles therefore have a high potential for prospective in vivo research of algal metabolism and its regulation.
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iron incorporation in biosilica of the marine diatom Stephanopyxis turris dispersed or clustered
Biometals, 2017Co-Authors: Janine Kaden, Susanne Machill, Stephan I Bruckner, Christoph Krafft, Andreas Poppl, Eike BrunnerAbstract:Iron incorporation into diatom biosilica was investigated for the species Stephanopyxis turris. It is known that several “foreign” elements (e.g., germanium, titanium, aluminum, zinc, iron) can be incorporated into the siliceous cell walls of diatoms in addition to silicon dioxide (SiO2). In order to examine the amount and form of iron incorporation, the iron content in the growth medium was varied during cultivation. Fe:Si ratios of isolated cell walls were measured by ICP-OES. SEM studies were performed to examine of a possible influence of excess iron during diatom growth upon cell wall formation. The chemical state of biosilica-attached iron was characterized by a combination of infrared, 29Si MAS NMR, and EPR spectroscopy. For comparison, synthetic silicagels of variable iron content were studied. Our investigations show that iron incorporation in biosilica is limited. More than 95% of biosilica-attached iron is found in the form of iron clusters/nanoparticles. In contrast, iron is preferentially dispersedly incorporated within the silica framework in synthetic silicagels leading to Si–O–Fe bond formation.
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analytical studies on the incorporation of aluminium in the cell walls of the marine diatom Stephanopyxis turris
Biometals, 2013Co-Authors: Susanne Machill, Rene Hedrich, Lydia Kohler, Susanne Ueberlein, Marco Kunaschk, Silvia Paasch, Renate Schulze, Eike BrunnerAbstract:The eukaryotic diatoms are unicellular algae. They are well known for their filigree micro- and nanostructured cell walls which mainly consist of amorphous silica as well as various organic compounds. However, diatoms are also known to incorporate certain amounts of aluminium into their cell walls. Unexpectedly, enhanced Al concentrations in the Southern Yellow Sea were found to be correlated with a diatom spring bloom. Therefore, we have analyzed the influence of strongly enhanced Al concentrations in the culture medium upon the growth behaviour of the diatom Stephanopyxis turris (S. turris). The uptake and incorporation of Al into the cell walls was monitored. It turned out that S. turris survives aluminium concentrations up to 105.5 μM (2.85 mg/l) in the culture medium. Under the applied conditions, this corresponds to an Al/Si ratio of 1:1. These large amounts of Al had to be offered in the form of bis–tris-chelates in order to prevent uncontrolled precipitation. Under these conditions, the Al/Si ratio in the cell walls could be increased up to about 1:15 as determined by ICP-OES, the highest amount of aluminium found in diatom cell walls yet. Structural characterization of the biosilica by ATR-FTIR and solid-state 27Al NMR spectroscopy revealed that an amorphous aluminosilicate phase is formed where the aluminium exists as four- and sixfold-coordinated species.
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biomineralization in diatoms phosphorylated saccharides are part of Stephanopyxis turris biosilica
Carbohydrate Research, 2013Co-Authors: Rene Hedrich, Susanne Machill, Eike BrunnerAbstract:Diatoms—unicellular algae with silicified cell walls—have become model organisms for investigations of biomineralization processes. Numerous studies suggest the importance of biosilica-associated or even embedded biomolecules for the biosilica formation. Such molecules are peptides, polyamines, and even saccharides. However, the role of the latter class of biomolecules is only poorly understood yet. Therefore, we investigated the saccharide composition of the biosilica-associated organic material of the diatom Stephanopyxis turris. This species exhibits a considerably high saccharide content in its siliceous cell walls. Gas chromatography-mass spectrometry analysis revealed that mannose-6-phosphate is strongly associated to the cell walls. This phosphorylated saccharide has not yet been found in diatom biosilica. In vitro studies on the polyallylamine-induced silica precipitation were carried out in the presence of mannose-6-phosphate. Compared to inorganic phosphate, mannose-6-phosphate significantly influenced the precipitation behavior of this model system suggesting a possible contribution of mannose-6-phosphate to the biomineralization process of Stephanopyxis turris.
Susanne Machill - One of the best experts on this subject based on the ideXlab platform.
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in vivo uptake of gold nanoparticles by the diatom Stephanopyxis turris
Algal Research-Biomass Biofuels and Bioproducts, 2019Co-Authors: Nathalie Pytlik, Susanne Machill, Benjamin Klemmed, Alexander Eychmuller, Eike BrunnerAbstract:Abstract Nanoparticle (NP) implementation in industry has increased during the last years. However, the consequences of NP release to the environment have not been fully understood yet and long-term effects are hardly predictable. Information regarding a possible NP uptake by organisms is urgently needed. Here, we investigate the uptake of presynthesized AuNPs of different diameters by living diatoms. To better understand the influence of NPs on diatoms, cells were monitored in vivo using Surface Enhanced Raman Spectroscopy (SERS). By 3D Raman imaging, AuNPs with diameters ≥50 nm could clearly be localized inside the cells, whereas smaller AuNPs were never detected in the cell interior. This indicates a size-dependent uptake mechanism that comes along with different toxicities. As diatoms present an essential source of the marine food chain, this observation is relevant not only for diatoms themselves but also for higher organisms.
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biological synthesis of gold nanoparticles by the diatom Stephanopyxis turris and in vivo sers analyses
Algal Research-Biomass Biofuels and Bioproducts, 2017Co-Authors: Nathalie Pytlik, Susanne Machill, Janine Kaden, Matthias Finger, Julia Naumann, Stefan Wanke, Eike BrunnerAbstract:Abstract Cultivation of the sea water diatom Stephanopyxis turris (S. turris) in a gold salt containing medium leads to the formation of gold nanoparticles. These biosynthesized nanoparticles were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). According to their diameter, they are classified into two groups with average diameters of around 30 and 10 nm. It is demonstrated that both types of nanoparticles consist exclusively of gold. The location of the gold nanoparticles with respect to the diatom cell was revealed using surface enhanced Raman scattering (SERS). To ensure a reliable observation of SERS spectra in each measured cell, the concentration of the gold solution as well as the incubation time of S. turris in this solution were optimized. 3D Raman imaging of entire S. turris cells was performed to localize SERS spectra of compounds resulting from closely neighbored nanoparticles. Interestingly, intracellular SERS spectra were observed indicating the presence of gold nanoparticles inside S. turris cells. Further investigation shows that the SERS spectra generated by biosynthesized nanoparticles differ significantly from the conventional Raman spectrum of diatoms. While pigments are dominating the resonance enhanced Raman spectrum, SERS spectra exhibit a completely different appearance. Their bands coincide with bands in SERS spectra of various biologically relevant compounds, e.g., hydroxyurea and retinol. The biosynthesized gold nanoparticles therefore have a high potential for prospective in vivo research of algal metabolism and its regulation.
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iron incorporation in biosilica of the marine diatom Stephanopyxis turris dispersed or clustered
Biometals, 2017Co-Authors: Janine Kaden, Susanne Machill, Stephan I Bruckner, Christoph Krafft, Andreas Poppl, Eike BrunnerAbstract:Iron incorporation into diatom biosilica was investigated for the species Stephanopyxis turris. It is known that several “foreign” elements (e.g., germanium, titanium, aluminum, zinc, iron) can be incorporated into the siliceous cell walls of diatoms in addition to silicon dioxide (SiO2). In order to examine the amount and form of iron incorporation, the iron content in the growth medium was varied during cultivation. Fe:Si ratios of isolated cell walls were measured by ICP-OES. SEM studies were performed to examine of a possible influence of excess iron during diatom growth upon cell wall formation. The chemical state of biosilica-attached iron was characterized by a combination of infrared, 29Si MAS NMR, and EPR spectroscopy. For comparison, synthetic silicagels of variable iron content were studied. Our investigations show that iron incorporation in biosilica is limited. More than 95% of biosilica-attached iron is found in the form of iron clusters/nanoparticles. In contrast, iron is preferentially dispersedly incorporated within the silica framework in synthetic silicagels leading to Si–O–Fe bond formation.
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analytical studies on the incorporation of aluminium in the cell walls of the marine diatom Stephanopyxis turris
Biometals, 2013Co-Authors: Susanne Machill, Rene Hedrich, Lydia Kohler, Susanne Ueberlein, Marco Kunaschk, Silvia Paasch, Renate Schulze, Eike BrunnerAbstract:The eukaryotic diatoms are unicellular algae. They are well known for their filigree micro- and nanostructured cell walls which mainly consist of amorphous silica as well as various organic compounds. However, diatoms are also known to incorporate certain amounts of aluminium into their cell walls. Unexpectedly, enhanced Al concentrations in the Southern Yellow Sea were found to be correlated with a diatom spring bloom. Therefore, we have analyzed the influence of strongly enhanced Al concentrations in the culture medium upon the growth behaviour of the diatom Stephanopyxis turris (S. turris). The uptake and incorporation of Al into the cell walls was monitored. It turned out that S. turris survives aluminium concentrations up to 105.5 μM (2.85 mg/l) in the culture medium. Under the applied conditions, this corresponds to an Al/Si ratio of 1:1. These large amounts of Al had to be offered in the form of bis–tris-chelates in order to prevent uncontrolled precipitation. Under these conditions, the Al/Si ratio in the cell walls could be increased up to about 1:15 as determined by ICP-OES, the highest amount of aluminium found in diatom cell walls yet. Structural characterization of the biosilica by ATR-FTIR and solid-state 27Al NMR spectroscopy revealed that an amorphous aluminosilicate phase is formed where the aluminium exists as four- and sixfold-coordinated species.
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biomineralization in diatoms phosphorylated saccharides are part of Stephanopyxis turris biosilica
Carbohydrate Research, 2013Co-Authors: Rene Hedrich, Susanne Machill, Eike BrunnerAbstract:Diatoms—unicellular algae with silicified cell walls—have become model organisms for investigations of biomineralization processes. Numerous studies suggest the importance of biosilica-associated or even embedded biomolecules for the biosilica formation. Such molecules are peptides, polyamines, and even saccharides. However, the role of the latter class of biomolecules is only poorly understood yet. Therefore, we investigated the saccharide composition of the biosilica-associated organic material of the diatom Stephanopyxis turris. This species exhibits a considerably high saccharide content in its siliceous cell walls. Gas chromatography-mass spectrometry analysis revealed that mannose-6-phosphate is strongly associated to the cell walls. This phosphorylated saccharide has not yet been found in diatom biosilica. In vitro studies on the polyallylamine-induced silica precipitation were carried out in the presence of mannose-6-phosphate. Compared to inorganic phosphate, mannose-6-phosphate significantly influenced the precipitation behavior of this model system suggesting a possible contribution of mannose-6-phosphate to the biomineralization process of Stephanopyxis turris.
Sami Alsabeb - One of the best experts on this subject based on the ideXlab platform.
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phytoplankton abundance in relation to the quality of the coastal water arabian gulf saudi arabia
The Egyptian Journal of Aquatic Research, 2017Co-Authors: Mostafa Abdel Mohsen El Gammal, Mohammed Nageeb, Sami AlsabebAbstract:Abstract Phytoplankton abundance in relation to some physicochemical characters of the costal water of Arabian Gulf (Saudi Arabia) was studied for one year. The sampling program included 15 locations in Dammam, Saihat, Al-Qatif, Al-Awamia and Safwa. Water samples were analyzed monthly for these parameters; temperature, pH, salinity, dissolved oxygen, nitrite, nitrate, ammonia, carbon dioxide, total chloride, reactive orthophosphate and total phosphorus and alkalinity, also phytoplankton communities were identified and Chlorophyll a was estimated. The results showed that, the high phytoplankton density attaining the maximum (190.3 × 104/m3) during May and June, and the minimum (10.4 × 104/m3) during November and December. Forty Five species belonging to 5 phytoplankton groups were recorded. Bacillariophyceae was the first dominant group forming 48% of the total phytoplankton communities (23 species). The dominant species of Bacillariophyceae were Pleurosigma strigosum, Pleurosigma elongatum, Lyrella clavata, Rhizosolenia shrubsolei, Cylindrotheca closterium, Nitzschia panduriform, Nitzschia longissimia, Amphora sp and Stephanopyxis. Dinophyceae was the second dominant group and formed 31% of the total phytoplankton communities (10 species); the dominant species were Ceratium fusus, Heterosigma sp, Ceratium furca, Prorocentrum triestium, Protoperidinium sp, Gyrodinium spirale, Noctiluca scintillans and Scrippsiella trochoidea. Cyanophyceae formed 13% (5 species) where Nostoc sp, Oscillatoria and Merismopedia sp were the dominant species. Chlorophyceae had 8% (6 species); Scendesmus sp., Chlorella sp., Chlamydomonas sp., Dunaliella salina and Nannochloropsis sp were the dominant species. The Euglinophyceae was rare only one species (Euglina sp). The relationship was positive between the phytoplankton, chlorophyll a and carbon dioxide while negative amongst dissolved oxygen and total nitrogen. This research indicated that the relation between water quality and phytoplankton organisms at the coast of Arabian Gulf (Saudi Arabia) was extremely overlapping and interdependent; any changes in the one component may significantly affect those of the other components.
Nathalie Pytlik - One of the best experts on this subject based on the ideXlab platform.
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in vivo uptake of gold nanoparticles by the diatom Stephanopyxis turris
Algal Research-Biomass Biofuels and Bioproducts, 2019Co-Authors: Nathalie Pytlik, Susanne Machill, Benjamin Klemmed, Alexander Eychmuller, Eike BrunnerAbstract:Abstract Nanoparticle (NP) implementation in industry has increased during the last years. However, the consequences of NP release to the environment have not been fully understood yet and long-term effects are hardly predictable. Information regarding a possible NP uptake by organisms is urgently needed. Here, we investigate the uptake of presynthesized AuNPs of different diameters by living diatoms. To better understand the influence of NPs on diatoms, cells were monitored in vivo using Surface Enhanced Raman Spectroscopy (SERS). By 3D Raman imaging, AuNPs with diameters ≥50 nm could clearly be localized inside the cells, whereas smaller AuNPs were never detected in the cell interior. This indicates a size-dependent uptake mechanism that comes along with different toxicities. As diatoms present an essential source of the marine food chain, this observation is relevant not only for diatoms themselves but also for higher organisms.
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biological synthesis of gold nanoparticles by the diatom Stephanopyxis turris and in vivo sers analyses
Algal Research-Biomass Biofuels and Bioproducts, 2017Co-Authors: Nathalie Pytlik, Susanne Machill, Janine Kaden, Matthias Finger, Julia Naumann, Stefan Wanke, Eike BrunnerAbstract:Abstract Cultivation of the sea water diatom Stephanopyxis turris (S. turris) in a gold salt containing medium leads to the formation of gold nanoparticles. These biosynthesized nanoparticles were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). According to their diameter, they are classified into two groups with average diameters of around 30 and 10 nm. It is demonstrated that both types of nanoparticles consist exclusively of gold. The location of the gold nanoparticles with respect to the diatom cell was revealed using surface enhanced Raman scattering (SERS). To ensure a reliable observation of SERS spectra in each measured cell, the concentration of the gold solution as well as the incubation time of S. turris in this solution were optimized. 3D Raman imaging of entire S. turris cells was performed to localize SERS spectra of compounds resulting from closely neighbored nanoparticles. Interestingly, intracellular SERS spectra were observed indicating the presence of gold nanoparticles inside S. turris cells. Further investigation shows that the SERS spectra generated by biosynthesized nanoparticles differ significantly from the conventional Raman spectrum of diatoms. While pigments are dominating the resonance enhanced Raman spectrum, SERS spectra exhibit a completely different appearance. Their bands coincide with bands in SERS spectra of various biologically relevant compounds, e.g., hydroxyurea and retinol. The biosynthesized gold nanoparticles therefore have a high potential for prospective in vivo research of algal metabolism and its regulation.
Janine Kaden - One of the best experts on this subject based on the ideXlab platform.
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biological synthesis of gold nanoparticles by the diatom Stephanopyxis turris and in vivo sers analyses
Algal Research-Biomass Biofuels and Bioproducts, 2017Co-Authors: Nathalie Pytlik, Susanne Machill, Janine Kaden, Matthias Finger, Julia Naumann, Stefan Wanke, Eike BrunnerAbstract:Abstract Cultivation of the sea water diatom Stephanopyxis turris (S. turris) in a gold salt containing medium leads to the formation of gold nanoparticles. These biosynthesized nanoparticles were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). According to their diameter, they are classified into two groups with average diameters of around 30 and 10 nm. It is demonstrated that both types of nanoparticles consist exclusively of gold. The location of the gold nanoparticles with respect to the diatom cell was revealed using surface enhanced Raman scattering (SERS). To ensure a reliable observation of SERS spectra in each measured cell, the concentration of the gold solution as well as the incubation time of S. turris in this solution were optimized. 3D Raman imaging of entire S. turris cells was performed to localize SERS spectra of compounds resulting from closely neighbored nanoparticles. Interestingly, intracellular SERS spectra were observed indicating the presence of gold nanoparticles inside S. turris cells. Further investigation shows that the SERS spectra generated by biosynthesized nanoparticles differ significantly from the conventional Raman spectrum of diatoms. While pigments are dominating the resonance enhanced Raman spectrum, SERS spectra exhibit a completely different appearance. Their bands coincide with bands in SERS spectra of various biologically relevant compounds, e.g., hydroxyurea and retinol. The biosynthesized gold nanoparticles therefore have a high potential for prospective in vivo research of algal metabolism and its regulation.
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iron incorporation in biosilica of the marine diatom Stephanopyxis turris dispersed or clustered
Biometals, 2017Co-Authors: Janine Kaden, Susanne Machill, Stephan I Bruckner, Christoph Krafft, Andreas Poppl, Eike BrunnerAbstract:Iron incorporation into diatom biosilica was investigated for the species Stephanopyxis turris. It is known that several “foreign” elements (e.g., germanium, titanium, aluminum, zinc, iron) can be incorporated into the siliceous cell walls of diatoms in addition to silicon dioxide (SiO2). In order to examine the amount and form of iron incorporation, the iron content in the growth medium was varied during cultivation. Fe:Si ratios of isolated cell walls were measured by ICP-OES. SEM studies were performed to examine of a possible influence of excess iron during diatom growth upon cell wall formation. The chemical state of biosilica-attached iron was characterized by a combination of infrared, 29Si MAS NMR, and EPR spectroscopy. For comparison, synthetic silicagels of variable iron content were studied. Our investigations show that iron incorporation in biosilica is limited. More than 95% of biosilica-attached iron is found in the form of iron clusters/nanoparticles. In contrast, iron is preferentially dispersedly incorporated within the silica framework in synthetic silicagels leading to Si–O–Fe bond formation.