Exposure effects of endotoxin-free titanium-based wear particles to human osteoblasts

Titanium-based materials are widely employed by the biomedical industry in orthopedic and dental implants. However, when placed into the human body, these materials are highly susceptible to degradation processes, such as corrosion, wear, and tribocorrosion. As a consequence, metallic ions or particles (debris) may be released, and although several studies have been conducted in recent years to better understand the effects of their exposure to living cells, a consensual opinion has not yet been obtained. In this work, we produced metallic based wear particles by tribological tests carried out on Ti-6Al-4V and Ti-15Zr-15Mo alloys. They were posteriorly physicochemically characterized according to their crystal structure, size, morphology, and chemical composition and compared to Ti-6Al-4V commercially available particles. Finally, adsorbed endotoxins were removed (by applying a specific thermal treatment) and endotoxin-free particles were used in cell experiments to evaluate effects of their exposure to human osteoblasts (MG-63 and HOb), namely cell viability/metabolism, proinflammatory cytokine production (IL-6 and PGE2), and susceptibility to internalization processes. Our results indicate that tribologically-obtained wear particles exhibit fundamental differences in terms of size (smaller) and morphology (irregular shapes and rough surfaces) when compared to the commercial ones. Consequently, both Ti-6Al-4V and Ti-15Zr-15Mo particles were able to induce more pronounced effects on cell viability (decrease) and cytokine production (increase) than did Ti-6Al-4V commercial particles. Furthermore, both types of wear particles penetrated osteoblast membranes and were internalized by the cells. Influences on cytokine production by endotoxins were also demonstrated.This work was supported by Fundacao de Amparo a Pesquisa do Estado de Sao Paulo - FAPESP (2015/50280-5 and 2017/24300-4), Fundacao para a Ciencia e Tecnologia - FCT (UID/EEA/04436/2013), Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - CAPES (Finance Code 0001), FCT/CAPES Joint Research Project (99999.008666/2014-08), FCT COMPETE 2020 (POCI-01-0145-FEDER-006941 and POCI-01-0145-FEDER-007265) and M-ERA-NET (0001/2015)

Speciation of Silver Nanoparticles and Silver(I) by Reversed-Phase Liquid Chromatography Coupled to ICPMS

The tremendous increase in the use of engineered nanoparticles in daily life has raised concerns about their impact on the environment and in biological systems. Among them, silver-containing material is of high industrial interest and of manifold use in consumer products, mainly because of their antimicrobial activity. Therefore, analytical methods are urgently needed for the reliable determination of Ag nanoparticles and their corresponding Ag­(I) species. In this study, we present the development of coupling reversed-phase high-performance liquid chromatography (HPLC) to inductively coupled plasma-mass spectrometry (ICPMS) for the speciation of engineered Ag-containing nanoparticles and Ag­(I) species. The method has been designed for the separation/detection of all investigated silver species in a single chromatographic run. For this purpose, the addition of thiosulfate to the mobile phase has been used to elute Ag­(I) species from the column without degradation of the other species. The analytical figures of merit show repeatable results for the recoveries (>80%) of both, the Ag nanoparticles and Ag­(I) species. The obtained detection limits are in the medium ng·L^–1 range and therefore allow the trace analysis of the sought analytes in real samples. However, the matrix (e.g., fetal bovine serum) showed an impact on the retention behavior of the Ag nanoparticles, so that for size determinations the use of gold nanoparticles as internal size standard is suggested. Finally, the analysis of textile products exemplarily demonstrates the applicability to the analysis of real samples. Besides silver-containing nanoparticles, Ag­(I) species can be identified as one of the major species in the extraction solution from sports socks. However, extraction conditions will be the subject of further investigations in the future in order to obtain reliable quantitative data