Silver is commonly used both in ionic form and in nanoparticulate form as a bactericidal agent. This is generally ascribed to a higher toxicity towards prokaryotic cells than towards mammalian cells. Comparative studies with both silver ions (such as silver acetate) and polyvinylpyrrolidone (PVP)stabilized silver nanoparticles (70 nm) showed that the toxic effect of silver occurs in a similar concentration range for Escherichia coli, Staphylococcus aureus, human mesenchymal stem cells (hMSCs), and peripheral blood mononuclear cells (PBMCs), i.e. 0.5 to 5 ppm for silver ions and 12.5 to 50 ppm for silver nanoparticles. For a better comparison, bacteria were cultivated both in Lysogeny broth medium (LB) and in Roswell Park Memorial Institute medium (RPMI)/10% fetal calf serum (FCS) medium, as the state of silver ions and silver nanoparticles may be different due to the presence of salts, and biomolecules like proteins. The effective toxic concentration of silver towards bacteria and human cells is almost the same. Experimental Preparation of silver acetate solutionsSilver acetate (Sigma-Aldrich; ReagentPlus 1 , 99%) was dissolved in ultrapure water, prepared with an ELGA PURELAB Ultra (ELGA Labwater, Germany) instrument.

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Silicate-containing hydroxyapatite-based coatings with different structure and calcium/phosphate ratios were prepared by radio-frequency magnetron sputtering on silicon and titanium substrates, respectively. Scanning electron microscopy, X-ray diffraction and IR spectroscopy were used to investigate the effect of the substrate bias on the properties of the silicate-containing hydroxyapatite-based coatings. The deposition rate, composition, and microstructure of the deposited coatings were all controlled by changing the bias voltage from grounded (0 V) to 250 and 2100 V. The biocompatibility was assessed by cell culture with human osteoblast-like cells (MG-63 cell line), showing a good biocompatibility and cell growth on the substrates.

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The solid components of three toothpastes and a mouth wash which are intended to enhance the remineralization of teeth and occlusion of dentinal tubuli were isolated and analyzed. Samples of the toothpaste BioRepair®, the mouth wash BioRepair®, the toothpaste nanosensitive® hca, and the toothpaste Theramed® S.O.S. Sensitive were characterized by dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray powder diffraction (XRD), atomic absorption spectroscopy (AAS), thermogravimetric analysis (TG), and elemental analysis. All samples contained primary particles in the size range of 30–60 nm, that were all agglomerated in aqueous dispersion to particles in the size range of 200 to 400 nm. BioRepair® contained a zinc‐substituted hydroxyapatite and amorphous silica, nanosensitive®hca contained TiO2 (anatase) and an amorphous Na‐Ca‐Si‐P bioglass, and Theramed® S.O.S. Sensitive contained TiO2 (anatase), amorphous silica and traces of a calcium‐containing phase. The size of the mineral particles was in all cases suitable to fit into dentinal tubuli, especially after breaking up the agglomerated nanoparticles by mechanical forces, e. g. during tooth brushing.

The efficient intracellular delivery of (bio)molecules into living cells remains a challenge in biomedicine. Many biomolecules and synthetic drugs are not able to cross the cell membrane, which is a problem if an intracellular mode of action is desired, for example, with a nuclear receptor. Calcium phosphate nanoparticles can serve as carriers for small and large biomolecules as well as for synthetic compounds. The nanoparticles were prepared and colloidally stabilized with either polyethyleneimine (PEI; cationic nanoparticles) or carboxymethyl cellulose (CMC; anionic nanoparticles) and loaded with defined amounts of the fluorescently labelled proteins HTRA1, HTRA2, and BSA. The nanoparticles were purified by ultracentrifugation and characterized by dynamic light scattering and scanning electron microscopy. Various cell types (HeLa, MG-63, THP-1, and hMSC) were incubated with fluorescently labelled proteins alone or with protein-loaded cationic and anionic nanoparticles. The cellular uptake was followed by light and fluorescence microscopy, confocal laser scanning microscopy (CLSM), and flow cytometry. All proteins were readily transported into the cells by cationic calcium phosphate nanoparticles. Notably, only HTRA1 was able to penetrate the cell membrane of MG-63 cells in dissolved form. However, the application of endocytosis inhibitors revealed that the uptake pathway was different for dissolved HTRA1 and HTRA1-loaded nanoparticles.

In einem von der Landesstiftung Baden–Württemberg geförderten Projekt im Forschungsprogramm “Biomaterialien/Biokompatibilität” wird u. a. der Einsatz der Elektronen–Spin–Resonanz (ESR) zum Nachweis von photokatalytisch erzeugten Radikalen untersucht. Die Licht–induzierte Radikalgenerierung eines Photokatalysators kann in–situ unter UV–A–Bestrahlung im ESR–Spektrometer verfolgt werden. Radikale werden dabei anhand von ihren quantenmechanischen Spin durch Absorptionsmessungen quantitativ in einem Magnetfeld nachgewiesen. Im Rahmen des Projektes werden photokatalytische TiO2–Beschichtungen der Anatas–Kristallmodifikation auf Implantaten für ihre Eignung als antimikrobielle Oberflächenbeschichtungen untersucht. Die erzeugten Radikale können Oberflächenkontaminationen zersetzen. Um ein tieferes Verständnis der Radikalgenerierung zur Erzeugung der antimikrobiellen Wirkung zu erhalten, ist es von Interesse, Radikalspezies und Radikalmengen zu bestimmen. Beides kann mit der ESR auf photokatalytischen TiO2–Oberflächen, abhängig von der Bestrahlungsdosis, untersucht werden. Im folgenden Artikel wird gezeigt, dass die ESR dazu beitragen kann, die Wirksamkeit der photokatalytischen Schichten zu belegen. Zeitaufgelöste Kontaktwinkelmessungen und Elektronenspektroskopie zur chemischen Analyse (ESCA) ergänzen die ESR–Resultate. Ebenso führen die Ergebnisse zu einem erweiterten Verständnis der photokatalytischen Generierung von Radikalen auf Anatas–TiO2–Oberflächen.