2020-06-22, Saxer, Sina, Pieles, Uwe, Dinu, Maria Valentina, Dinu, Ionel Adrian, Meier, Wolfgang, Bruns, Nico, Bruns, Nico

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.

2016-06-30, Grether, Yasmin, Waser, Marcus, Pieles, Uwe, Köser, Joachim

Plasma-etching represents a facile approach to nanostructure polymer surfaces. Here we report on the antibacterial properties of plasma-structured polycarbonate (PC)surfaces. PC foils were structured with O2 plasma and incubated with E.coli. Metabolic activity of adhered live bacteria was quantified with resazurin metabolic indicator. Different incubation times under shaking/resting conditions diminished metabolic activity on structured versus unstructured PC, indicating reduced bacterial adhesion on structured surfaces. Furthermore chemical surface modifications increased metabolic activity on structured compared to unstructured surfaces. Further research on other polymers will be done to analyse the generality of these observations.

2015-08, Braissant, Olivier, Chavanne, Philippe, de Wild, Michael, Pieles, Uwe, Stevanovic, Sabrina, Schumacher, Ralf, Straumann, Lukas, Wirz, Dieter, Gruner, Philipp, Bachmann, Alexander, Bonkat, Gernot

Biomaterials with antimicrobial properties are now commonly used in different clinical specialties including orthopedics, endodontic, and traumatology. As a result, assessing the antimicrobial effect of coatings applied on implants is of critical importance. In this study, we demonstrate that isothermal microcalorimetry (IMC) can be used for monitoring bacterial growth and biofilm formation at the surface of such coatings and for determining their antimicrobial effects. The antibacterial effects of silver doped hydroxyapatite (HA) and calcium hydroxide coatings on Staphylococcus epidermidis were determined with a minimal workload. Using the Gompertz growth model we determined biofilm growth rates close to those values reported in the literature. Furthermore, we were able to estimate the reduction in the bacterial inocula originally applied at the surface of the coatings. Therefore, in addition to monitoring the antimicrobial effect of silver doped HA and calcium hydroxide coatings, we also demonstrate that IMC might be a valuable tool for assessing such antimicrobial properties of implant coatings at a minimal workload.

2018-10, Koch, Franziska, Wolff, Anne, Mathes, Stephanie, Pieles, Uwe, Saxer, Sina, Kreikemeyer, Bernd, Peters, Kirsten

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.

2016-02-25, Köser, Joachim, Pieles, Uwe, Meier, Pascal, Widmer, A.

2015, Rimmer, Natalie, Burgio, Floriana, Rohner, Adrian, Chavanne, Philippe, Zimmermann, Simon, Gruner, Philipp, Schumacher, Ralf, de Wild, Michael, Papadimitropoulos, Adam, Martin, Yvan, Hugot Beaufils, Marina, Pieles, Uwe

2018-03, Koch, Franziska, König, Finja, Meyer, Nina, Gattlen, Jasmin, Pieles, Uwe, Peters, Kirsten, Kreikemeyer, Bernd, Mathes, Stephanie, Saxer, Sina, Müller, Michael

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.

2016, Köser, Joachim, Pieles, Uwe