Quantum dots (QDs) are nanocrystalline semiconductor materials that have been tested for biological applications such as cancer therapy, cellular imaging and drug delivery, despite the serious lack of information of their effects on mammalian cells. The present study aimed to evaluate the potential of Si/SiO 2 QDs to induce an inflammatory response in MRC-5 human lung fibroblasts. Cells were exposed to different concentrations of Si/SiO 2 QDs (25-200 lgÁmL À1 ) for 24, 48, 72 and 96 h. The results obtained showed that uptake of QDs was dependent on biocorona formation and the stability of nanoparticles in various biological media (minimum essential medium without or with 10% fetal bovine serum). The cell membrane damage indicated by the increase in lactate dehydrogenase release after exposure to QDs was dose-and time-dependent. The level of lysosomes increased proportionally with the concentration of QDs, whereas an accumulation of autophagosomes was also observed. Cellular morphology was affected, as shown by the disruption of actin filaments. The enhanced release of nitric oxide and the increase in interleukin-6 and interleukin-8 protein expression suggested that nanoparticles triggered an inflammatory response in MRC-5 cells. QDs decreased the protein expression and enzymatic activity of matrix metalloproteinase (MMP)-2 and MMP-9 and also MMP-1 caseinase activity, whereas the protein levels of MMP-1 and tissue inhibitor of metalloproteinase-1 increased. The present study reveals for the first time that silicon-based QDs are able to generate inflammation in lung cells and cause an imbalance in extracellular matrix turnover through a differential regulation of MMPs and tissue inhibitor of metalloproteinase-1 protein expression.
One of the major research interests of nanomedicine is the designing of harmless and biocompatible medical devices. To improve the features of Ti surface, TiO2 based nanotube (TNT) films (50 nm diameter) achieved by anodic oxidation and thermal treatment were grown on titanium and on Ti6Al4V and Ti6Al7Nb alloys. Their in vitro toxicity and biocompatibility were investigated using G292 osteoblast cell line. The LDH release after 24 and 48 h of exposure demonstrated that TNT layers were not cytotoxic. The cell growth on TNT films deposited on titanium and Ti6Al4V was significantly increased compared with Ti6Al7Nb. F-actin staining showed a better organized actin cytoskeleton in osteoblasts grown on these two samples, which provide the best conditions for osteoblast attachment and spreading. Analysis of GSH distribution revealed a higher nuclear level in the samples with TNTs compared with Ti plate without nanotubes, indicating an active proliferation. Thus, nuclear glutathione levels can be used as a useful biomarker for biocompatibility assessment. Our results suggest that the substrate for TNTs can have a significant impact on cell morphology and fate. In conclusion, the TNT/Ti and TNT/Ti6Al4V were toxicity-free and can provide a proper nanostructure for a positive cell response.
The paper proposes a new method for direct measurement of human alkaline phosphatase (ALP) and interleukin-6 and -8 (IL-6, IL-8) content using titania nanotubes (TNT) film as sensitive electrode. Under polarization, the interface characteristics are modified by the specific adhesion of proteins to the electrode surface, as shown by confocal fluorescence microscopy, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) investigations for all 3 biomarkers. These changes can be measured by electrochemical impedance spectroscopy (EIS). A thin and uniform gold plating is beneficial for electrochemical sensitivity toward the investigated biomarkers. This electrode reflects the low levels of human ALP in water and in dilute solutions of human serum (HS) and total protein extract (TPE) by EIS. Good calibrations were obtained for the enzyme activities of 50, 100 and 125 U/L, which go below the detection limit obtained by classical methods. Calibration of IL-6 was performed in the concentration range of 0.165 ÷ 1.645 nM. The paper demonstrates that the annealed and in vacuum gold plated TNT/Ti electrode with 50 nm diameter is a new and credible candidate for a highly stable sensor to be used in the human ALP and IL-6 direct determination.
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