Abstract: To study the cytotoxicity and effect on gap junction intracellular communication(GJIC) of SiO2 nanoparticles in HL-7702 cells,and to provide experimental basis for toxicity assessment and the security applications of SiO2 nanoparticles. Methods Transmission electron microscope(TEM) was used to characterize two kinds of SiO2 nanoparticles,verifying their size,dispersion and shape;dynamic light scattering (DLS) method was used to analyze the water dispersion and culture medium dispersion　of the SiO2 nanoparticles;MTT assay was carried out to examine the cytotoxicities of the two sizes SiO2 nanoparticles on the cells;lactate dehydrogenase(LDH) release assay was performed to examine the integrity nano of the cell membrane;Scrape-loading and dye transfer assay was performed to examine the effect of SiO2 nanoparticles on GJIC.Results Based on the result of TEM,two kinds of SiO2 nanoparticles were spherically shaped,uniformly sized and sporadically dispersed;the statistical analysis results showed the diameters of the two nanoparticles were (447.60±20.78) nm and (67.42±5.69) nm,respectively,thus they could be categorized as submicron scale and nano scale.The DLS  method results manifested that the hydration nanoparticle sizes of the two SiO2 nanoparticles were（684.37±18.76） nm，（128.31±7.64） nm in high purity water and （697.02±19.57） nm，（133.74±8.97） nm in RPMI-1640 solution,all the two nanoparticles were well dispersed without aggregation.MTT assay indicated that 24 h after  treatment of SiO2 nanoparticles,the cell viabilities were affected by both the size and the dose of the SiO2 nanoparticles;the higher the dose was,the less viability the cells exhibited.Moreover,the nano scale particles inflicted more damage to the cells.LDH release assay indicated that the SiO2 particles could also damage the cell membrane in a dose-dependent and size-dependent way.Scrape-loading and dye transfer assay indicated that the nano scale particles could cause GJIC inhibition in a dose-dependent way;and when at the same dose,the nanoparticles could cause a more obvious inhibition of GJIC than the submicron particles.Conclusion SiO2 nanoparticles have cytotoxicity on HL-7702 cells,and would cause GJIC inhibition.

Key words: SiO2 nanoparticles, HL-7702 cells, cytotoxicity, gap junction intercellular communication