To explore the toxicity and biological activity of cobalt nanoparticles (CoNPs) on osteoclasts, and to analyze the relationship between cobalt nanoparticles and osteolysis.

From November 2014 to July 2015, RAW264.7 cell was induced to osteoclastlike cell by LPS. Different concentrations of cobalt nanoparticles and cobalt chloride were added, and the cell morphology was observed under a microscope. 24 h after induction on RAW264.7, cells were grouped in- to cobalt nanoparticles group (10, 20, 50, 100 μmol/L), cobalt chloride group (10, 20, 50, 100 mol/L) and control group. MTT assessment and Q-PCR were performed at 2 h, 4 h, 8 h, 24 h, 48 h post-treatment.

With the increase of concentration (10, 20, 50, 100 μmol/L) and the action time (2 h, 4 h, 8 h, 24 h, 48 h), the inhibition rate of cobalt nanoparticles and cobalt chloride on osteoclast like cells was significantly increased, and the inhibition rate of cobalt nanoparticles was higher. With different concentrations (10, 20, 50, 100 μmol/L) of CoNPs and cobalt chloride, the relative expression of CAII, Cat K gene mRNA expression decreased compared with the control group, when the concentration of CoNPs was in the range of 10-50 μmol/L, the relative expression of CAII and Cat K was increased, which was reduced in cobalt chloride group.

Different concentrations of cobalt nanoparticles and cobalt chloride can inhibit the proliferation and differentiation of osteoclasts, and cobalt nanoparticles is more pronounced, when the concentration of cobalt nanoparticles was 10-50 μmol/L, the relative expression of osteoclasts CAII, Cat K increaseed, which was suppressed at the same concentration of cobalt chloride.

Osteoclasts; Cobalt; Toxic actions