Saxer, Sina
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Saxer, Sina
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- PublikationHigh-throughput silica nanoparticle detection for quality control of complex early life nutrition food matrices(American Chemical Society, 2024) Maffeis, Viviana; Otter, Andrea; Düsterloh, André; Kind, Lucy; Palivan, Cornelia; Saxer, Sina [in: ACS Omega]The addition of nanomaterials to improve product properties has become a matter of course for many commodities: e.g., detergents, cosmetics, and food products. While this practice improves product characteristics, the increasing exposure and potential impact of nanomaterials (<100 nm) raise concerns regarding both the human body and the environment. Special attention should be taken for vulnerable individuals such as those who are ill, elder, or newborns. But detecting and quantifying nanoparticles in complex food matrices like early life nutrition (ELN) poses a significant challenge due to the presence of additional particles, emulsion-droplets, or micelles. There is a pressing demand for standardized protocols for nanoparticle quantification and the specification of “nanoparticle-free” formulations. To address this, silica nanoparticles (SiNPs), commonly used as anticaking agents (AA) in processed food, were employed as a model system to establish characterization methods with different levels of accuracy and sensitivity versus speed, sample handling, and automatization. Different acid treatments were applied for sample digestion, followed by size exclusion chromatography. Morphology, size, and number of NPs were measured by transmission electron microscopy, and the amount of Si was determined by microwave plasma atomic emission spectrometry. This successfully enabled distinguishing SiNP content in ELN food formulations with 2–4% AA from AA-free formulations and sorting SiNPs with diameters of 20, 50, and 80 nm. Moreover, the study revealed the significant influence of the ELN matrix on sample preparation, separation, and characterization steps, necessitating method adaptations compared to the reference (SiNP in water). In the future, we expect these methods to be implemented in standard quality control of formulation processes, which demand high-throughput analysis and automated evaluation.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationStabilizing enzymes within polymersomes by coencapsulation of trehalose(American Chemical Society, 22.06.2020) Saxer, Sina; Pieles, Uwe; Dinu, Maria Valentina; Dinu, Ionel Adrian; Meier, Wolfgang; Bruns, Nico; Bruns, Nico [in: Biomacromolecules]Enzymes are essential biocatalysts and very attractive as therapeutics. However, their functionality is strictly related to their stability, which is significantly affected by the environmental changes occurring during their usage or long-term storage. Therefore, maintaining the activity of enzymes is essential when they are exposed to high temperature during usage or when they are stored for extended periods of time. Here, we stabilize and protect enzymes by coencapsulating them with trehalose into polymersomes. The anhydrobiotic disaccharide preserved up to about 81% of the enzyme’s original activity when laccase/trehalose-loaded nanoreactors were kept desiccated for 2 months at room temperature and 75% of its activity when heated at 50 °C for 3 weeks. Moreover, the applicability of laccase/trehalose-loaded nanoreactors as catalysts for bleaching of the textile dyes orange G, toluidine blue O, and indigo was proven. Our results demonstrate the advantages of coencapsulating trehalose within polymersomes to stabilize enzymes in dehydrated state for extended periods of time, preserving their activity even when heated to elevated temperature.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationAmino acid composition of nanofibrillar self-assembling peptide hydrogels affects responses of periodontal tissue cells in vitro(Dove Medical Press, 10/2018) Koch, Franziska; Wolff, Anne; Mathes, Stephanie; Pieles, Uwe; Saxer, Sina; Kreikemeyer, Bernd; Peters, Kirsten [in: Journal of International Nanomedicine]The regeneration of tissue defects at the interface between soft and hard tissue, eg, in the periodontium, poses a challenge due to the divergent tissue requirements. A class of biomaterials that may support the regeneration at the soft-to-hard tissue interface are self-assembling peptides (SAPs), as their physicochemical and mechanical properties can be rationally designed to meet tissue requirements.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationMechanical characteristics of beta sheet-forming peptide hydrogels are dependent on peptide sequence, concentration and buffer composition(Royal Society, 03/2018) Koch, Franziska; König, Finja; Meyer, Nina; Gattlen, Jasmin; Pieles, Uwe; Peters, Kirsten; Kreikemeyer, Bernd; Mathes, Stephanie; Saxer, Sina; Müller, Michael [in: Royal Society Open Science]Self-assembling peptide hydrogels can be modified regarding their biodegradability, their chemical and mechanical properties and their nanofibrillar structure. Thus, self-assembling peptide hydrogels might be suitable scaffolds for regenerative therapies and tissue engineering. Owing to the use of various peptide concentrations and buffer compositions, the self-assembling peptide hydrogels might be influenced regarding their mechanical characteristics. Therefore, the mechanical properties and stability of a set of self-assembling peptide hydrogels, consisting of 11 amino acids, made from four beta sheet self-assembling peptides in various peptide concentrations and buffer compositions were studied. The formed self-assembling peptide hydrogels exhibited stiffnesses ranging from 0.6 to 205 kPa. The hydrogel stiffness was mostly affected by peptide sequence followed by peptide concentration and buffer composition. All self-assembling peptide hydrogels examined provided a nanofibrillar network formation. A maximum self-assembling peptide hydrogel dissolution of 20% was observed for different buffer solutions after 7 days. The stability regarding enzymatic and bacterial digestion showed less degradation in comparison to the self-assembling peptide hydrogel dissolution rate in buffer. The tested set of self-assembling peptide hydrogels were able to form stable scaffolds and provided a broad spectrum of tissue-specific stiffnesses that are suitable for a regenerative therapy.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationPreliminary microstructural investigation of Mg produced by SLM(European Cells and Materials, 2016) Saxer, Sina; Rüegg, Jasmine; Dietschy, Alain; Schumacher, Ralf; de Wild, Michael; Wiese, Björn; Wohlfender, Fabian [in: European Cells and Materials]01A - Beitrag in wissenschaftlicher Zeitschrift