Janus nanoparticles with a poly(L-lactide) face and a polystyrene-based face functionalized with amine or carboxylic acid groups were synthesized via two different approaches. In the first approach, the poly(styrene-co-methacrylic acid) or poly-(styrene-co-2-aminoethyl methacrylate) copolymers were generated in situ in miniemulsion droplets before phase separation between the copolymers and the poly(L-lactide) occurred. In the second approach, the copolymers were prepared before the emulsification step. A solution containing the poly(L-lactide) and one of the copolymers was then emulsified, and the solvent was subsequently removed to induce a phase separation between the polymers, yielding a Janus morphology. The density of functional groups (amine or carboxylic acid) could be varied between 0 and 5 groups per nm 2 . Finally, we demonstrated that one face of the Janus nanoparticle could be selectively employed for a chemical reaction. Indeed, silver nanoparticles could be nucleated selectively on the poly(L-lactide) face.
The function of an organic solar cell relies on making a contact surface between a donor and acceptor material. For an efficient conversion of solar energy, this heterojunction must be...
The oxidation based antimicrobial activity of silver is long known. Microparticles with a particular silver-ruthenium coating and specific physical properties were developed. The coating showed a considerably increased silver ion release rate in comparison to a plain silver coating. Accordingly, an exposure of Escherichia coli and Staphylococcus aureus to these silver-ruthenium coated microparticles resulted in a time and concentration dependent cell killing. Even though contact killing may contribute to this efficacy, rather a release associated diffusion gradient dependent killing was observed. Moreover, cell killing did not involve lysis. The coated microparticles manifested no reduction in antibacterial activity for months. Due to their specific size and density, they sedimented slowly in aqueous solution, showed a low aggregation tendency, and could be recycled easily. Hence, these silver-ruthenium coated microparticles lend themselves to a wide range of antibacterial applications as they combine long-term stability and high efficacy with ease of use.
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