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While the exact health risks associated with nanoplastics are currently the focus of intense research, there is no doubt that humans are exposed to nanoplastics and that food could be a major source of exposure. Nanoplastics are released from plastic materials and articles used during food production, processing, storage, preparation, and serving. They are also likely to enter the food chain via contaminated water, air, and soil. However, very limited exposure data for risk assessment exists so far due to the lack of suitable analytical methods. Nanoplastic detection in food poses a great analytical challenge due to the complexity of plastics and food matrices as well as the small size and expectedly low concentration of the plastic particles. Multidetector field flow fractionation has emerged as a valuable analytical technique for nanoparticle separation over the last decades, and the first studies using the technique for analyzing nanoplastics in complex matrices are emerging. In combination with online detectors and offline analysis, multidetector field flow fractionation is a powerful platform for advanced characterization of nanoplastics in food by reducing sample complexity, which otherwise hampers the full potential of most analytical techniques. The focus of this article is to present the current state of the art of multidetector field flow fractionation for nanoplastic analysis and to discuss future trends and needs aiming at the analysis of nanoplastics in food.

The analysis of engineered nanomaterials (ENMs), especially nanoparticles (ENPs) is a fast growing analytical research field. New trends in plasma spectrometry such as direct single particle inductively coupled plasma mass spectrometry (spICPMS) or the coupling of asymmetric flow field flow fractionation to ICPMS (A4F-ICPMS) allow direct analysis of ENPs by getting not only chemical but also size information simultaneously. However, in both techniques dilution of ENP samples is needed or occurs during analysis. The colloidal stability and the agglomeration behavior depend on the ENP-type, coating agent and also on the surrounding media. The stability of charge stabilized ENPs is especially sensitive to changes of pH or ionic strength, sometimes even to dilution. Although the stability of sterically stabilized ENP is typically less affected by the above mentioned factors, agglomeration can still occur in certain environments. Thus, storage, handling and sample preparation is a big challenge in ENP analysis. Kinetic studies of different ENPs, representative for typical nanoparticle types and coatings, point out that the behavior is dependent on various influencing factors pertaining to the chemical environment (pH, ionic strength, dilution). In this study polyvinyl alcohol (Ag@PVA) and citrate (Ag@citrate) stabilized silver nanoparticles, as well as titanium oxide ENPs coated with poly-acrylate (TiO2@PA) have been studied. A simple analytical approach using batch analysis with dynamic light scattering (DLS) is proposed for a fast assessment of samples containing unknown ENP types or structures. Furthermore, unwanted particle-membrane-interactions, which often lead to inappropriate recovery rates in A4F fractionation, are investigated. They are caused by the electrostatic charges carried by different membrane materials and the resulting interaction with the ENP charge. This is critically discussed for membrane materials typical for A4F analysis: polyethersulfone (PES)

The analysis of engineered nanomaterials (ENMs), especially nanoparticles (ENPs) is a fast growing analytical research field. New trends in plasma spectrometry such as direct single particle inductively coupled plasma mass spectrometry (spICPMS) or the coupling of asymmetric flow field flow fractionation to ICPMS (A4F-ICPMS) allow direct analysis of ENPs by getting not only chemical but also size information simultaneously. However, in both techniques dilution of ENP samples is needed or occurs during analysis. The colloidal stability and the agglomeration behavior depend on the ENP-type, coating agent and also on the surrounding media. The stability of charge stabilized ENPs is especially sensitive to changes of pH or ionic strength, sometimes even to dilution. Although the stability of sterically stabilized ENP is typically less affected by the above mentioned factors, agglomeration can still occur in certain environments. Thus, storage, handling and sample preparation is a big challenge in ENP analysis. Kinetic studies of different ENPs, representative for typical nanoparticle types and coatings, point out that the behavior is dependent on various influencing factors pertaining to the chemical environment (pH, ionic strength, dilution). In this study polyvinyl alcohol (Ag@PVA) and citrate (Ag@citrate) stabilized silver nanoparticles, as well as titanium oxide ENPs coated with poly-acrylate (TiO2@PA) have been studied. A simple analytical approach using batch analysis with dynamic light scattering (DLS) is proposed for a fast assessment of samples containing unknown ENP types or structures. Furthermore, unwanted particle-membrane-interactions, which often lead to inappropriate recovery rates in A4F fractionation, are investigated. They are caused by the electrostatic charges carried by different membrane materials and the resulting interaction with the ENP charge. This is critically discussed for membrane materials typical for A4F analysis: polyethersulfone (PES)

During recent years, numerous studies have shown the ability of dietary fiber toprotect the colon from disease and to improve intestinal health. Beneficial healtheffects, such as the lowering of blood cholesterol levels and a reduction in the risk of coronary heart disease, are often directly related to cereal β-glucan, one of the major components of dietary fiber found in oat and barley. No definitive theory on the mechanisms of β-glucan during human digestion has yet been established, although it has been suggested that its solution and aggregation behavior, as well as its ability to form viscous slurries in the gut, are important and have the biggest impact.The aim of the first part of this work was to develop an extraction method formixed-linkage β-glucan from oat and barley, in which the effects of extraction on its structure were minimized, and to improve current knowledge concerning the solution and aggregation behavior of β-glucan found in food products.Relatively high purities were obtained with the extraction method developed. β-Glucan was characterized using asymmetric flow field-flow fractionation (AF4) incombination with UV, multiangle light scattering (MALS), differential refractiveindex (dRI) and fluorescence detectors to obtain information on molecular size,molar mass distribution and conformation. The β-glucan analyzed contained high molar masses and large sizes. Cryo-transmission electron microscopy (cryo-TEM) showed the presence of highly aggregated structures in a widely distributed and loose arrangement in both oat and barley β-glucan, whereas barley β-glucan also showed surprisingly well-defined and dense aggregates. No proteins were found to be covalently bound to the β-glucan. However, as potential proteinaceous moieties in the extracts might affect the solution behavior of β-glucan, a study was carried out to investigate the relation between β-glucan and proteins. Aggregation patterns were found suggesting that electrostatic interactions pla

Nanoparticles (NPs) adsorb proteins when in the biological matrix, and the resulted protein corona could affect NP-cell interactions. The corona has a dynamic nature with the adsorbed proteins constantly exchanging with the free proteins in the matrix at various rates. The rapidly exchanging proteins compose the soft corona, which responds more dynamically to environment changes than the hard corona established by the ones with slow exchange rates. In the present study, the corona formed on the superparamagnetic iron oxide NPs (SPIONs) in human serum was studied by flow field-flow fractionation and ultracentrifugation, which rapidly differentiated the corona proteins based on their exchange rates. By varying the surface hydrophobicity of the SPIONs with a core size around 10 nm, we found out that, the more hydrophobic surface ligand attracted proteins with higher surface hydrophobicity and formed a more dynamic corona with a larger portion of the involved proteins with fast exchange rates. Increasing the core diameter of the SPIONs but keeping the surface ligand the same could also result in a more dynamic corona. A brief investigation of the effect on the cellular uptake of SPIONs using one selected corona protein, transferrin, was conducted. The result showed that, only the stably bound transferrin could significantly enhance cellular uptake, while transferrin bound in a dynamic nature had negligible impact. Our study has led to a better understanding of the relationship between the particle properties and the dynamic nature of the corona, which can help with design of nanomaterials with higher biocompatibility and higher efficacy in biosystems for biomedical applications.

Nanoparticles (NPs) adsorb proteins when in the biological matrix, and the resulted protein corona could affect NP-cell interactions. The corona has a dynamic nature with the adsorbed proteins constantly exchanging with the free proteins in the matrix at various rates. The rapidly exchanging proteins compose the soft corona, which responds more dynamically to environment changes than the hard corona established by the ones with slow exchange rates. In the present study, the corona formed on the superparamagnetic iron oxide NPs (SPIONs) in human serum was studied by flow field-flow fractionation and ultracentrifugation, which rapidly differentiated the corona proteins based on their exchange rates. By varying the surface hydrophobicity of the SPIONs with a core size around 10 nm, we found out that, the more hydrophobic surface ligand attracted proteins with higher surface hydrophobicity and formed a more dynamic corona with a larger portion of the involved proteins with fast exchange rates. Increasing the core diameter of the SPIONs but keeping the surface ligand the same could also result in a more dynamic corona. A brief investigation of the effect on the cellular uptake of SPIONs using one selected corona protein, transferrin, was conducted. The result showed that, only the stably bound transferrin could significantly enhance cellular uptake, while transferrin bound in a dynamic nature had negligible impact. Our study has led to a better understanding of the relationship between the particle properties and the dynamic nature of the corona, which can help with design of nanomaterials with higher biocompatibility and higher efficacy in biosystems for biomedical applications.

Based on an international workshop (Gothenburg, 14-16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research on iron biogeochemistry. The major scientific findings of the past decade are structured into sections on natural and artificial iron fertilization, iron inputs into coastal and estuarine systems, colloidal iron and organic matter, and biological processes. Potential effects of global climate change, particularly ocean acidification, on iron biogeochemistry are discussed. The findings are synthesized into recommendations for future research areas.

Based on an international workshop (Gothenburg, 14-16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research on iron biogeochemistry. The major scientific findings of the past decade are structured into sections on natural and artificial iron fertilization, iron inputs into coastal and estuarine systems, colloidal iron and organic matter, and biological processes. Potential effects of global climate change, particularly ocean acidification, on iron biogeochemistry are discussed. The findings are synthesized into recommendations for future research areas.

Relationships between trace metals and nanoparticles were investigated using analytical transmission electron microscopy (aTEM) and asymmetric flow field flow fractionation (aFlFFF) coupled to both multi-angle laser light scattering (MALLS) and high resolution-inductively coupled plasma mass spectroscopy (HR-ICPMS). Riverbed sediment samples were taken from the Clark Fork River in Montana, USA where a large-scale dam removal project has released reservoir sediment contaminated with toxic trace metals (namely Pb, Zn, Cu and As) which accumulated from one and a half centuries of mining activities upstream. An aqueous extraction method was used to attempt to separate the nanoparticles from the bulk sediment. After analysis of initial results, it was found that low density clays were being selected for in this process and made up a major portion of the particles within the extracts. However, it was also realized that the metals of interest were associated almost exclusively with nano-sized Fe and Ti oxides. In order to more fully examine these relationships, a density separation method, using sodium polytungstate (2.8g/cm3), was developed to separate these higher density oxides from the lower density clays. The heavy fraction was then subjected to an aqueous extraction routine to extract the nanoparticulate fraction. FFF results indicated a smaller size distribution and more ideal fractionation with this method. The aFlFFF-HR-ICPMS profiles for Fe and Ti also matched strongly with the data for the trace metals. The majority of particles analyzed with the TEM were nano-sized Fe and Ti oxides (most commonly goethite, ferrihydrite and brookite), which typically had trace metals associated with them. In many cases, it was aggregates of these nano oxides that were found hosting trace metals. Nanoparticles and aggregates are known to behave differently than their bulk mineral phases or constituent particles, respectively. Nanoparticles are also capable of extended transport i

Based on an international workshop (Gothenburg, 14-16 May 2008), this review article aims to combine interdisciplinary knowledge from coastal and open ocean research on iron biogeochemistry. The major scientific findings of the past decade are structured into sections on natural and artificial iron fertilization, iron inputs into coastal and estuarine systems, colloidal iron and organic matter, and biological processes. Potential effects of global climate change, particularly ocean acidification, on iron biogeochemistry are discussed. The findings are synthesized into recommendations for future research areas.

Předkládaná disertační práce se zabývá charakterizací, zpracováním a gelací rozpustného kolagenu. Literární rešerše shrnuje postavení kolagenu na trhu s transplantáty, jeho aplikace a jednotlivé typy kolagenu. Detailně jsou rozebrány jednotlivé metody charakterizace rozpustného kolagenu a způsoby jeho gelace. Experimentální část je rozdělena na dvě podkapitoly. První podkapitola experimentální části se zabývá rozpouštěním a gelací rozpustného kolagenu v natlakované CO2 atmosféře. Proti jiným podobným metodám, metoda pracuje na poměrně nízkém tlaku (do 0.9MPa) a je bezpečná z pohledu denaturace kolagenu neboť funguje za nízké teploty blízké 0°C. Tímto způsobem mohou být průhledné gely, obsahující velmi tenká vlákna kolagenu, vytvořeny mnohem rychleji než za použití konvenčních metod. Rychlost gelace a transparentnost dává konceptu potenciál v oblasti oftalmologie a měla by přinést podstatné výhody pro injektovatelné produkty, vytváření mikro kuliček a 3D tisk. Druhá část popisuje unikátní charakterizaci rozpustného kolagenu v nativním stavu pomocí metody průtokové frakcionace s víceúhlovým rozptylem světla (AF4-MALS). Získaná molekulová hmotnost (při nejvyšší detekované koncentraci) odpovídá předpovězené hmotnosti a nativní i denaturovaný kolagen lze snadno rozeznat v konformačním grafu. Tato nová metoda poskytuje konzistentní a stabilní výsledky ve srovnání s ostatními zavedenými metodami. Metoda může být použita pro optimalizaci kvality výtěžků během výroby rozpustného kolagenu, nebo pro citlivou detekci denaturace během zpracování kolagenu., Proposed thesis deals with the characterization, processing and gelling of soluble collagen. A literature review summarizes position of collagen at the transplant market, explains its application and describes different types of collagen. Various methods of characterization of soluble collagen are analysed in detail and different ways of its gelation are thoroughly discussed. The experimental part is divided into two sections. The first section of experimental part deals with the dissolution and gelation of soluble collagen in pressurized CO2 atmosphere. Compared to the other similar methods, our method operates in a relatively low pressure (up to 0.9MPa) and and low temperatures (close to 0°C) that does not denature soluble collagen (works at low temperatures). This method can be used for fast formation of transparent gels containing very thin fibers. Speed of gelation and transparency of gels give a new potential to the concept of ophthalmology and should bring significant benefits to injectable products, creating microspheres and 3D printing. The second section describes the unique characterization of soluble collagen in native state by Asymmetric Flow Field Flow Fractionation - Multi Angle Light Scattering (AF4-MALS) method. The obtained molar mass perfectly fits the expected molar mass. Native and denatured collagen can readily be identified on the conformational graph. This new method provides stable and consistent results in comparison with other established methods. AF4-MALS method can be used either to optimize yields and purification during the production of soluble collagen or for sensitive detection of collagen denaturation during processing.

Předkládaná disertační práce se zabývá charakterizací, zpracováním a gelací rozpustného kolagenu. Literární rešerše shrnuje postavení kolagenu na trhu s transplantáty, jeho aplikace a jednotlivé typy kolagenu. Detailně jsou rozebrány jednotlivé metody charakterizace rozpustného kolagenu a způsoby jeho gelace. Experimentální část je rozdělena na dvě podkapitoly. První podkapitola experimentální části se zabývá rozpouštěním a gelací rozpustného kolagenu v natlakované CO2 atmosféře. Proti jiným podobným metodám, metoda pracuje na poměrně nízkém tlaku (do 0.9MPa) a je bezpečná z pohledu denaturace kolagenu neboť funguje za nízké teploty blízké 0°C. Tímto způsobem mohou být průhledné gely, obsahující velmi tenká vlákna kolagenu, vytvořeny mnohem rychleji než za použití konvenčních metod. Rychlost gelace a transparentnost dává konceptu potenciál v oblasti oftalmologie a měla by přinést podstatné výhody pro injektovatelné produkty, vytváření mikro kuliček a 3D tisk. Druhá část popisuje unikátní charakterizaci rozpustného kolagenu v nativním stavu pomocí metody průtokové frakcionace s víceúhlovým rozptylem světla (AF4-MALS). Získaná molekulová hmotnost (při nejvyšší detekované koncentraci) odpovídá předpovězené hmotnosti a nativní i denaturovaný kolagen lze snadno rozeznat v konformačním grafu. Tato nová metoda poskytuje konzistentní a stabilní výsledky ve srovnání s ostatními zavedenými metodami. Metoda může být použita pro optimalizaci kvality výtěžků během výroby rozpustného kolagenu, nebo pro citlivou detekci denaturace během zpracování kolagenu., Proposed thesis deals with the characterization, processing and gelling of soluble collagen. A literature review summarizes position of collagen at the transplant market, explains its application and describes different types of collagen. Various methods of characterization of soluble collagen are analysed in detail and different ways of its gelation are thoroughly discussed. The experimental part is divided into two sections. The first section of experimental part deals with the dissolution and gelation of soluble collagen in pressurized CO2 atmosphere. Compared to the other similar methods, our method operates in a relatively low pressure (up to 0.9MPa) and and low temperatures (close to 0°C) that does not denature soluble collagen (works at low temperatures). This method can be used for fast formation of transparent gels containing very thin fibers. Speed of gelation and transparency of gels give a new potential to the concept of ophthalmology and should bring significant benefits to injectable products, creating microspheres and 3D printing. The second section describes the unique characterization of soluble collagen in native state by Asymmetric Flow Field Flow Fractionation - Multi Angle Light Scattering (AF4-MALS) method. The obtained molar mass perfectly fits the expected molar mass. Native and denatured collagen can readily be identified on the conformational graph. This new method provides stable and consistent results in comparison with other established methods. AF4-MALS method can be used either to optimize yields and purification during the production of soluble collagen or for sensitive detection of collagen denaturation during processing.

Předkládaná disertační práce se zabývá charakterizací, zpracováním a gelací rozpustného kolagenu. Literární rešerše shrnuje postavení kolagenu na trhu s transplantáty, jeho aplikace a jednotlivé typy kolagenu. Detailně jsou rozebrány jednotlivé metody charakterizace rozpustného kolagenu a způsoby jeho gelace. Experimentální část je rozdělena na dvě podkapitoly. První podkapitola experimentální části se zabývá rozpouštěním a gelací rozpustného kolagenu v natlakované CO2 atmosféře. Proti jiným podobným metodám, metoda pracuje na poměrně nízkém tlaku (do 0.9MPa) a je bezpečná z pohledu denaturace kolagenu neboť funguje za nízké teploty blízké 0°C. Tímto způsobem mohou být průhledné gely, obsahující velmi tenká vlákna kolagenu, vytvořeny mnohem rychleji než za použití konvenčních metod. Rychlost gelace a transparentnost dává konceptu potenciál v oblasti oftalmologie a měla by přinést podstatné výhody pro injektovatelné produkty, vytváření mikro kuliček a 3D tisk. Druhá část popisuje unikátní charakterizaci rozpustného kolagenu v nativním stavu pomocí metody průtokové frakcionace s víceúhlovým rozptylem světla (AF4-MALS). Získaná molekulová hmotnost (při nejvyšší detekované koncentraci) odpovídá předpovězené hmotnosti a nativní i denaturovaný kolagen lze snadno rozeznat v konformačním grafu. Tato nová metoda poskytuje konzistentní a stabilní výsledky ve srovnání s ostatními zavedenými metodami. Metoda může být použita pro optimalizaci kvality výtěžků během výroby rozpustného kolagenu, nebo pro citlivou detekci denaturace během zpracování kolagenu., Proposed thesis deals with the characterization, processing and gelling of soluble collagen. A literature review summarizes position of collagen at the transplant market, explains its application and describes different types of collagen. Various methods of characterization of soluble collagen are analysed in detail and different ways of its gelation are thoroughly discussed. The experimental part is divided into two sections. The first section of experimental part deals with the dissolution and gelation of soluble collagen in pressurized CO2 atmosphere. Compared to the other similar methods, our method operates in a relatively low pressure (up to 0.9MPa) and and low temperatures (close to 0°C) that does not denature soluble collagen (works at low temperatures). This method can be used for fast formation of transparent gels containing very thin fibers. Speed of gelation and transparency of gels give a new potential to the concept of ophthalmology and should bring significant benefits to injectable products, creating microspheres and 3D printing. The second section describes the unique characterization of soluble collagen in native state by Asymmetric Flow Field Flow Fractionation - Multi Angle Light Scattering (AF4-MALS) method. The obtained molar mass perfectly fits the expected molar mass. Native and denatured collagen can readily be identified on the conformational graph. This new method provides stable and consistent results in comparison with other established methods. AF4-MALS method can be used either to optimize yields and purification during the production of soluble collagen or for sensitive detection of collagen denaturation during processing.