Development of HA/Ag-NPs Composite Coating from Green Process for Hip Applications

Are hydroxyapatite-based biomaterials free of genotoxicity? A systematic review

Hydroxyapatite (HA) is a biomaterial widely used in clinical applications and pharmaceuticals. The literature on HA-based materials studies is focused on chemical characterization and biocompatibility. Generally, biocompatibility is analyzed through adhesion, proliferation, and differentiation assays. Fewer studies are looking for genotoxic events. Thus, although HA-based biomaterials are widely used as biomedical devices, there is a lack of literature regarding their genotoxicity. This systematic review was carried out following the PRISMA statement. Specific search strategies were developed and performed in four electronic databases (PubMed, Science Direct, Scopus, and Web of Science). The search used "Hydroxyapatite OR Calcium Hydroxyapatite OR durapatite AND genotoxicity OR genotoxic OR DNA damage" and "Hydroxyapatite OR Calcium Hydroxyapatite OR durapatite AND mutagenicity OR mutagenic OR DNA damage" as keywords and articles published from 2000 to 2022, after removing duplicate studies and apply include and exclusion criteria, 53 articles were identified and submitted to a qualitative descriptive analysis. Most of the assays were in vitro and most of the studies did not show genotoxicity. In fact, a protective effect was observed for hydroxyapatites. Only 20 out of 71 tests performed were positive for genotoxicity. However, no point mutation-related mutagenicity was observed. As the genotoxicity of HA-based biomaterials observed was correlated with its nanostructured forms as needles or rods, it is important to follow their effect in chronic exposure to guarantee safe usage in humans.

A Short Overview of Recent Developments on Antimicrobial Coatings Based on Phytosynthesized Metal Nanoparticles

The phytosynthesis of metallic nanoparticles represents an exciting new area of research, with promising perspectives, gaining in the last decades an increasing importance. Nanotechnology represents an important tool and an efficient option for obtaining particles with controlled morphology and shapes, phytosynthesized nanoparticles (NPs) being a good alternative to remove hazardous reagents. Due to the practical applications of the phytosynthesized nanoparticles, which are mainly associated with their antimicrobial potential, the abundance of scientific literature in this domain is given by researches in the phytosynthesis of metallic nanoparticles (3654 articles) and the evaluation of their antimicrobial properties (2338 papers). The application of phytosynthesized nanoparticles as antimicrobial coatings represented the subject of only 446 works, which lead us to the subject of this review paper. Application of antimicrobial coatings containing phytosynthesized nanoparticles for the development of antimicrobial textiles, other biomedical applications, protection of food (including fruits and vegetables), as well as for other types of applications based on their antimicrobial potential are covered by the present review.

Concurrent biomineralization of silver ions into Ag0 and AgxO by Leptolyngbya strain JSC-1 and the establishment of its axenic culture

Ionic silver is a potential hazard to aquatic life forms because of the increasing usage of silver based materials. The need for developing a sustainable and ecofriendly process to minimize the toxic effects of the free ions burden is now a scientific consensus. Therefore, we report the latest results in cyanobacterium Leptolyngbya JSC-1 investigating the tolerance towards toxic doses of silver, its extracellular biomineralization and silver nano-deposits formation inside the cells, and speculate about potential environmental impacts. In this study, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) analysis reveal the extracellular biomineralization of soluble silver (1-100 μM) into corresponding nanoparticles (50-100 nm in diameter) by JSC-1, while X-ray photoelectron spectroscopy (XPS) examination divulged the presence of both Ag⁺ and Ag⁰ in extracellularly biomineralized silver, depicting a mixture of both Ag_xO and elemental Ag. The scanning transmission electron microscopy (STEM), EDS and elemental mapping visualized the formation of intracellular silver nanoparticles. Moreover, this feature of silver tolerance in JSC-1 was further exploited and a novel protocol was developed for isolation and maintenance of axenic culture of this filamentous cyanobacterium. Consequently, this capability of silver biomineralization by JSC-1, both extra- and intra-cellularly might be useful for modeling the Ag resistance mechanism in cyanobacteria and also might be a sustainable alternative for heavy metals bioremediation in aquatic environments.