In this study, the possible cellular effects of tin dioxide (SnO2) nanoparticles, together with its bulk form, on mouse dermal fibroblasts (DFs) were revealed using in vitro assays. Particle characterizations were carried out with AFM, Braun–Emmet–Teller, and DLS analyses. | Turkish Journal of Biology Research Article Turk J Biol (2018) 42: 435-446 © TÜBİTAK doi: Comparative evaluation of nano and bulk tin dioxide cytotoxicity on dermal fibroblasts by real-time impedance-based and conventional methods 1,2 , Şükran ŞEKER * Tissue Engineering, Biomaterials and Nanobiotechnology Laboratory, Faculty of Science, Ankara University, Ankara, Turkey 2 Ankara University, Stem Cell Institute, Ankara, Turkey 1 Received: Accepted/Published Online: Final Version: Abstract: In this study, the possible cellular effects of tin dioxide (SnO2) nanoparticles, together with its bulk form, on mouse dermal fibroblasts (DFs) were revealed using in vitro assays. Particle characterizations were carried out with AFM, Braun–Emmet–Teller, and DLS analyses. The cells were treated with nano and bulk SnO2 at concentrations of , 1, 10, 50, and 100 μg/mL for 6, 24, and 48 h. At the end of the exposure periods, the morphology, viability, particle uptake, and membrane leakage statuses of the cells were evaluated. Furthermore, real-time monitoring of cell responses was performed by using an impedance-based label-free system. Findings showed that at concentrations of –10 μg/mL, cells had similar doubling time to that of control cells ( ± h), while the doubling time of cells exposed to 100 μg/mL of nano and bulk SnO2 increased slightly (P ˃ ) to ± h and ± h, respectively. The results indicated that DFs exhibited a similar toxicity response to nano and bulk SnO2; thus, 50 and 100 μg/mL of nano and bulk SnO2 had mild toxic effects on DFs. In conclusion, this study provides information and insight necessary for the safe use of SnO2 in medical and consumer products. Key words: Tin oxide nanoparticles, dermal fibroblasts, cytotoxicity, real-time impedance measurement, cell index, nanoparticle aggregation, lactate dehydrogenase, MTT 1. .