We tested the effects of nanomaterials (NM) carbon black (CB), graphene oxide (GO), titanium dioxide (TiO2), and titanium dioxide coated with polyvinylpyrrolidone (PVP TiO2) on human cell lines. The NM tested were added either in their pure forms, or previously coated with bovine serum albumine (BSA). Upon entering the biological medium, the surface of each NM is covered with proteins that form protein corona. Protein corona reduces the binding of NM to cell membranes and consequently reduces the uptake of NM into cells. The effect of NM was tested on HUVEC and THP-1 cells. Mycoplasma was not present in cell cultures. Effects of carbon and metal NM differed. We found that NM interfere with spectrophotometric and spectrofluorimetric tests. MTT assay and uptake of neutral red dye assay proved to be suitable for testing CB and GO cytotoxicity, while MTT assay is suitable for testing the effects of TiO2 and TiO2 PVP. The remaining tests affected the final results. The impact of one type NM did not have a similar effect on different types of cells. THP-1 cells were more resistant to the effect of NM in comparison with the HUVEC cells. BSA had an effect on HUVEC cells, while different concentrations of BSA did not cause any changes to the THP-1 cells. Carbon NM with BSA corona reduced cytotoxic effects on HUVEC cells. CB, GO, TiO2 and TiO2 PVP had an effect on HUVEC cells. CB also had an effect on THP-1 cells. GO, TiO2 and TiO2 PVP didn’t have any effect on THP-1 cells, because they did not show any cytotoxic effects. Use of BSA-coated NM still decreased cell viability.