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

Integrating silver compounds and nanoparticles into ceria nanocontainers for antimicrobial applications

Silver compounds and nanoparticles (NPs) are gaining increasing interest in medical applications, specifically in the treatment and prevention of biomaterial-related infections. However, the silver release from these materials, resulting in a limited antimicrobial activity, is often difficult to control. In this paper, ceria nanocontainers were synthesized by a template-assisted method and were then used to encapsulate silver nitrate (AgNO₃/CeO₂ nanocontainers). Over the first 30 days, a significant level of silver was released, as determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). A novel type of ceria container containing silver NPs (AgNP/CeO₂ containers) was also developed using two different template removal methods. The presence of AgNPs was confirmed both on the surface and in the interior of the ceria containers by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Upon removal of the template by calcination, the silver was released over a period exceeding three months (>90 days). However, when the template was removed by dissolution, the silver release was shortened to ≤14 days. The antimicrobial activity of the silver-containing CeO₂ containers was observed and the minimum bactericidal concentration (MBC) was determined using the broth dilution method. Investigation on human cells, using a model epithelial barrier cell type (A549 cells), highlighted that all three samples induced a heightened cytotoxicity leading to cell death when exposed to all containers in their raw form. This was attributed to the surface roughness of the CeO₂ nanocontainers and the kinetics of the silver release from the AgNO₃/CeO₂ and AgNP/CeO₂ nanocontainers. In conclusion, despite the need for further emphasis on their biocompatibility, the concept of the AgNP/CeO₂ nanocontainers offers a potentially alternative long-term antibactericidal strategy for implant materials

Synthesis, characterization, antibacterial activity and cytotoxicity of hollow /TiO₂-coated CeO₂ nanocontainers encapsulating silver nanoparticles for controlled silver release

Biomaterials as implants are being applied more extensively in medicine due to their on-going development and associated improvements, and the increase in human life expectancy. Nonetheless, biomaterial-related infections, as well as propagating bacterial resistance, remain significant issues. Therefore, there is a growing interest for silver-based drugs because of their efficient and broad-range antimicrobial activity and low toxicity to humans. Most newly-developed silver-based drugs have an extremely fast silver-ion release, increasing adverse biological impact to the surrounding tissue and achieving only short-term antimicrobial activity. Nanoencapsulation of these drugs is hypothesized as beneficial for controlling silver release, and thus is the aim of the present study. Initially, an amorphous or crystalline (anatase) titania (TiO₂) coating was synthesized around silver nanoparticle-containing (AgNP) ceria (CeO₂) nanocontainers using a sonication method forming AgNP/CeO₂/TiO₂ nanocontainers. These nanocontainers were characterized by high-resolution transmission electron microscopy, scanning electron microscopy, powder X-ray diffraction, gas sorption experiments and energy-dispersive X-ray spectroscopy. Silver release, monitored by using inductively coupled plasma optical emission spectroscopy, showed that these containers prevented silver release in water at neutral pH, and released the silver in concentrated nitric acid solution (pH = 1.1). The AgNP/CeO₂/TiO₂ nanocontainers showed an antibacterial activity against E. coli, however a concentration-dependent cytotoxicity towards a model epithelial barrier cell type (A549 cells) was observed. These nanocontainers offer the concept of potentially controlling silver delivery for the prevention of implant-associated infections

Jeunes autochtones et protection de la jeunesse : leur point de vue sur leur prise en charge

The overrepresentation of Aboriginal youth in child welfare services in Canada is a concerning reality. However, less is known of their experiences of child welfare services from their own perspective. This study explores Aboriginal youth’s thoughts of child welfare services in Val-d’Or, Quebec. The article is based on data from a research project on judicialization of poverty with urban Aboriginal youth who had an experience with child welfare system. The study is based on a symbolic interactionism perspective that takes into account how Aboriginal youth make meaning of child welfare intervention. The study finds that Aboriginal youth view child welfare intervention as a way to protect them from their difficult environmental circumstances associated with poverty. It concludes that issues associated with living in poverty need to be consider when addressing overrepresentation of Aboriginal youth in child welfare system

L’expérience des jeunes autochtones pris en charge par la protection de la jeunesse : entre déracinement et émancipation

Cet article vise à partager le point de vue de jeunes autochtones quant à leur vécu de prise en charge par la protection de la jeunesse et aux effets de cette prise en charge. L’article s’appuie sur les données recueillies dans le cadre d’une recherche plus large sur la judiciarisation et la défense des droits des personnes en situation de pauvreté. Les résultats font ressortir trois types d’expérience de prise en charge impliquant un placement des jeunes autochtones : les résistants qui vivent le placement comme un déracinement ; les résilients qui vivent le placement comme une émancipation ; les résignés qui vivent le placement comme un détachement. Ces résultats montrent que les liens des jeunes autochtones avec leur milieu d’origine pendant le placement influencent grandement leur façon de vivre la prise en charge par la protection de la jeunesse, les effets de cette prise en charge ainsi que le regard qu’ils portent sur cette expérience. L’article propose des pistes d’intervention visant à améliorer le bien-être des jeunes autochtones pris en charge par la protection de la jeunesse.This article aims to share the point of view of young Aboriginals about their experience of youth protection and the effects of this care. The article draws on data collected as part of broader research on the judiciarization and advocacy of people living in poverty. The results highlight three types of care experience involving placement of Aboriginal youth: « Resistants » who experience placement as uprooting; « Resilients » who live the placement as an emancipation; the « Resigned » who live the placement as a detachment. These results show that the relationship of Aboriginal youth with their home environment during placement greatly influences how they experience youth care, the effects of caregiving and the way they look at it. This article proposes ways to improve the well-being of Aboriginal youth in care of youth protection

Embedding CeO2 nanocontainers in a TiO2 coating on glass surfaces

Various strategies are being developed for the prevention of implant-related infections. One of them is the encapsulation of antimicrobial drugs in inorganic containers that can be released at the site of the implant. However, the attachment of such containers onto implant surfaces may be a challenge. In this study, it is demonstrated that CeO2 nanocontainers can be added to a TiO2 coating on glass surfaces. The structure, crystal phase and surface properties of the nanocontainers were characterized by transmission electron microscopy, scanning electron microscopy (SEM), powder X-ray diffraction, infrared spectroscopy, Raman spectroscopy and a zetasizer. The coatings were analyzed by SEM and energy-dispersive X-ray spectroscopy to determine their homogeneity and ensure CeO2 encapsulation. The coatings were stable in air over prolonged time periods (> 6 months) and therefore hold promise for pursuing in biomedical applications

Antibacterial properties of the pituitary adenylate cyclase-activating polypeptide: A new human antimicrobial peptide.

The Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP), a polycationic, amphiphilic and helical neuropeptide, is well known for its neuroprotective actions and cell penetrating properties. In the present study, we evaluated the potent antibacterial property of PACAP38 and related analogs against various bacterial strains. Interestingly, PACAP38 and related analogs can inhibit the growth of various bacteria including Escherichia coli (JM109), Bacillus subtilis (PY79), and the pathogenic Burkholderia cenocepacia (J2315). Investigation of the mechanism of action suggested that a PACAP metabolite, identified as PACAP(9-38), might indeed be responsible for the observed PACAP38 antibacterial action. Surprisingly, PACAP(9-38), which does not induce haemolysis, exhibits an increased specificity toward Burkholderia cenocepacia J2315 compared to other tested bacteria. Finally, the predisposition of PACAP(9-38) to adopt a π-helix conformation rather than an α-helical conformation like PACAP38 could explain this gain in specificity. Overall, this study has revealed a new function for PACAP38 and related derivatives that can be added to its pleiotropic biological activities. This innovative study could therefore pave the way toward the development of new therapeutic agents against multiresistant bacteria, and more specifically the Burkholderia cenocepacia complex