The present work exploits Ti sheets and TiO 2 nanotube (TNT) layers and their surface modifications for the proliferation of different cells. Ti sheets with a native oxide layer, Ti sheets with a crystalline thermal oxide layer, and two kinds of TNT layers (prepared via electrochemical anodization) with a defined inner diameter of 12 and 15 nm were used as substrates. A part of the Ti sheets and the TNT layers was additionally coated by thin TiO 2 coatings using atomic layer deposition (ALD). An increase in cell growth of WI-38 fibroblasts (>50%), MG-63 osteoblasts (>30%), and SH-SY5Y neuroblasts (>30%) was observed for all materials coated by five cycles ALD compared to their uncoated counterparts. The additional ALD TiO 2 coatings changed the surface composition of all materials but preserved their original structure and protected them from unwanted crystallization and shape changes. The presented approach of mild surface modification by ALD has a significant effect on the materials' biocompatibility and is promising toward application in implant materials.

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Cadmium is a heavy metal causing toxicity especially in kidney cells. The toxicity is linked also with enhanced oxidative stress leading to cell death. On the other hand, our recent experiments have shown that an increase of total intracellular dehydrogenases activity can also occur in kidney cells before declining until cell death. The aim of the present study, therefore, was to evaluate this transient enhancement in cell viability after cadmium treatment. The human kidney HK-2 cell line was treated with CdCl2 at concentrations 0-200 µM for 2-24 h and intracellular dehydrogenase activity was tested. In addition, we measured reactive oxygen species (ROS) production, glutathione levels, mitochondrial membrane potential, and C-Jun-N-terminal kinase (JNK) activation. We found that significantly increased dehydrogenase activity could occur in cells treated with 25, 100, and 200 µM CdCl2. Moreover, the results showed an increase in ROS production linked with JNK activation following the enhancement of dehydrogenase activity. Other tests detected no relationship with the increased in intracellular dehydrogenase activity. Hence, the transient increase in dehydrogenase activity in HK-2 cells preceded the enhancement of ROS production and our finding provides new evidence in cadmium kidney toxicity.

Purpose Titanium dioxide nanoparticles, 25 nm in size of crystallites (TiO 2 P25), are among the most produced nanomaterials worldwide. The broad use of TiO 2 P25 in material science has implied a request to evaluate their biological effects, especially in the lungs. Hence, the pulmonary A549 cell line has been used to estimate the effects of TiO 2 P25. However, the reports have provided dissimilar results on caused toxicity. Surprisingly, the physicochemical factors influencing TiO 2 P25 action in biological models have not been evaluated in most reports. Thus, the objective of the present study is to characterize the preparation of TiO 2 P25 for biological testing in A549 cells and to evaluate their biological effects. Methods We determined the size and crystallinity of TiO 2 P25. We used four techniques for TiO 2 P25 dispersion. We estimated the colloid stability of TiO 2 P25 in distilled water, isotonic NaCl solution, and cell culture medium. We applied the optimal dispersion conditions for testing the biological effects of TiO 2 P25 (0–100 µg.mL −1 ) in A549 cells using biochemical assays (dehydrogenase activity, glutathione levels) and microscopy. Results We found that the use of fetal bovine serum in culture medium is essential to maintain sufficient colloid stability of dispersed TiO 2 P25. Under these conditions, TiO 2 P25 were unable to induce a significant impairment of A549 cells according to the results of biochemical and microscopy evaluations. When the defined parameters for the use of TiO 2 P25 in A549 cells were met, similar results on the biological effects of TiO 2 P25 were obtained in two independent cell laboratories. Conclusion We optimized the experimental conditions of TiO 2 P25 preparation for toxicity testing in A549 cells. The results presented here on TiO 2 P25-induced cellular effects are reproducible. Therefore, our results can be helpful for other researchers using TiO 2 P25 as a reference material.

At present, nuclear condensation and fragmentation have been estimated also using Hoechst probes in fluorescence microscopy and flow cytometry. However, none of the methods used the Hoechst probes for quantitative spectrofluorometric assessment. Therefore, the aim of the present study was to develop a spectrofluorometric assay for detection of nuclear condensation and fragmentation in the intact cells. We used human hepatoma HepG2 and renal HK-2 cells cultured in 96-well plates treated with potent apoptotic inducers (i.e. cisplatin, staurosporine, camptothecin) for 6–48 h. Afterwards, the cells were incubated with Hoechst 33258 (2 µg/mL) and the increase of fluorescence after binding of the dye to DNA was measured. The developed spectrofluorometric assay was capable to detect nuclear changes caused by all tested apoptotic inducers. Then, we compared the outcomes of the spectrofluorometric assay with other methods detecting cell impairment and apoptosis (i.e. WST-1 and glutathione tests, TUNEL, DNA ladder, caspase activity, PARP-1 and JNKs expressions). We found that our developed spectrofluorometric assay provided results of the same sensitivity as the TUNEL assay but with the advantages of being fast processing, low-cost and a high throughput. Because nuclear condensation and fragmentation can be typical markers of cell death, especially in apoptosis, we suppose that the spectrofluorometric assay could become a routinely used method for characterizing cell death processes.