Ag Nanoencapsulation for Antimicrobial Applications.

Biomaterial-related infections remain a significant challenge in medicine. Antimicrobial materials on the basis of Ag nanoparticles represent a promising solution for this issue. Therefore several Ag-containing nanocontainers and nanorattles have been synthesized and characterized that exhibit remarkable control over the release of Ag+ as antimicrobial active species. Their biological evaluation against prokaryotic as well as eukaryotic cells reveals that they fulfill the prerequisites for applications as antimicrobial implant coatings.

Antimicrobial silver-filled silica nanorattles with low immunotoxicity in dendritic cells.

The progression in the use of orthopedic implants has led to an increase in the absolute number of implant infections, triggering a search for more effective antibacterial coatings. Nanorattles have recently gained interest in biomedical applications such as drug delivery, as encapsulation of the cargo inside the hollow structure provides a physical protection from the surrounding environment. Here, silver-containing silica nanorattles (Ag@SiO2) were evaluated for their antimicrobial potential and for their impact on cells of the immune system. We show that Ag@SiO2 nanorattles exhibited a clear antibacterial effect against Escherichia coli as well as Staphylococcus aureus found in post-operative infections. Immunotoxicological analyses showed that the particles were taken up through an active phagocytic process by dendritic cells of the immune system and did not affect their viability nor induce unwanted immunological effects. Silver-containing silica nanorattles thus fulfill several prerequisites for an antibacterial coating on surgical implants.

Nanorattles or yolk-shell nanoparticles--what are they, how are they made, and what are they good for?

The development of nanotechnology has led to the design of cutting-edge nanomaterials with increasing levels of complexity. Although "traditional" solid, uniform nanoparticles are still the most frequently reported structures, new generations of nanoparticles have been constantly emerging over the last several decades. The outcome of this nano-art extends beyond nanomaterials with alternative compositions and/or morphologies. The current state-of-the-art allows for the design of nanostructures composed of different building blocks that exhibit diverse properties. Furthermore, those properties can be a reflection of either individual features, which are characteristic of a particular building block alone, and/or synergistic effects resulting from interactions between building blocks. Therefore, the unique structures as well as the outstanding properties of nanorattles have attracted increasing attention for possible biomedical and industrial applications. Although these nanoparticles resemble core-shell particles, they have a distinctive feature, which is a presence of a void that provides a homogenous environment for the encapsulated core. In this Review, we give a comprehensive insight into the fabrication of nanorattles. A special emphasis is put on the choice of building blocks as well as the choice of preparation method, because those two aspects further influence properties and thus possible future applications, which will also be discussed.