Dose-dependent cytotoxicity evaluation of graphite nanoparticles for diamond-like carbon film application on artificial joints

Abstract

While a diamond-like carbon (DLC)-coated joint prosthesis represents the implant of choice for total hip replacement in patients, it also leads to concern due to the cytotoxicity of wear debris in the form of graphite nanoparticles (GNs), ultimately limiting its clinical use. In this study, the cytotoxicity of various GN doses was evaluated. Mouse macrophages and osteoblasts were incubated with GNs (<30 nm diameter), followed by evaluation of cytotoxicity by means of assessing inflammatory cytokines, results of alkaline phosphatase assays, and related signaling protein expression. Cytotoxicity evaluation showed that cell viability decreased in a dose-dependent manner (10-100 μg ml), and steeply declined at GNs concentrations greater than 30 μg ml. Noticeable cytotoxicity was observed as the GN dose exceeded this threshold due to upregulated receptor of activator of nuclear factor kB-ligand expression and downregulated osteoprotegerin expression. Meanwhile, activated macrophage morphology was observed as a result of the intense inflammatory response caused by the high doses of GNs (>30 μg ml), as observed by the increased release of TNF-α and IL-6. The results suggest that GNs had a significant dose-dependent cytotoxicity in vitro, with a lethal dose of 30 μg ml leading to dramatic increases in cytotoxicity. Our GN cytotoxicity evaluation indicates a safe level for wear debris-related arthropathy and could propel the clinical application of DLC-coated total hip prostheses.

Mg(OH)2 nanoparticles enhance the antibacterial activities of macrophages by activating the reactive oxygen species

“…32 Liao et al found that the cell viabilities decreased in a dose-dependent manner (10-100 μg/ml) and steeply declined at concentrations greater than 30 μg/ml for graphite nanoparticles. 33 In the current study, the results of the MTT and LDH assays conducted on RAW264.7 cells suggested that Mg(OH) 2 NPs at their MICs (4.4 μg/ml) had no significant effect on the biological activity of macrophages. E. coli cells were found to be more vulnerable to Mg(OH) 2 NPs.…”

“…Hussain et al showed that Fe 3 O 4 , Al, MoO 3 , and TiO 2 nanoparticles had no measurable effects at lower doses (10–50 μg/ml), while significant effects were observed at higher levels (100–250 μg/ml) 32 . Liao et al found that the cell viabilities decreased in a dose‐dependent manner (10–100 μg/ml) and steeply declined at concentrations greater than 30 μg/ml for graphite nanoparticles 33 . In the current study, the results of the MTT and LDH assays conducted on RAW264.7 cells suggested that Mg(OH) 2 NPs at their MICs (4.4 μg/ml) had no significant effect on the biological activity of macrophages.…”

The Effect of Coating Density on Functional Properties of SiNx Coated Implants

“…Nanocrystalline diamond (NCD) has shown good results after millions of cycles in wear simulators [3,15,16,17]. DLC is a coating with high hardness and a low coefficient of friction due to self-lubricating characteristics that has been found to give a reduced metal ion release, but there is a concern of cytotoxicity due to release of graphite nanoparticles [3,18,19,20,21,22]. While ZrN is already in use in knee implants, with an estimated service life between 20–25 years [23,24], there is a lack of coatings showing consistently good results in hip joint replacements, which have a more challenging wear pattern.…”

New alternate bearing surfaces in total hip arthroplasty: A review of the current literature

“…Cell viability of both mouse osteoblasts and macrophages were affected in a dosedependent manner from these debris, but when graphite nanoparticles exceeded 30 mg/mL, cell cytotoxicity was dramatically increased. 39 The few clinical applications of DLC have been marked by failure, with inferior survivorship in comparison to aluminum oxide heads at 8.5 years and coating delamination likely due to in vivo dissolution of a silicon-containing substrate-adhesion layer. 40 Further study of multilayer DLC with focus on substantiating substrate adhesion is necessary before more clinical trials are justified.…”