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In this work we study the interaction of two types of metallic silver nanoparticles, obtained by the polyol process (IQ–USP) and the electrolytic method (Khemia®), in smooth muscle cells. An extensive characterization work was carried out, describing the physico-chemical nature of these nanoparticles. Optical absorption measurements showed that nanoparticles exhibit smooth bands around 400 nm, the blue region of the electromagnetic spectrum, due to the resonance of the surface plasmons, evidencing the tendency to aggregate with time. Transmission electron microscopy was performed to obtain images of the nanoparticles in micrographs. Histograms were constructed to determine the size of NPs and the index of polydispersity. EDS spectra were obtained for the chemical characterization of the samples. X-ray diffraction patterns were obtained for the AgNPs.The diffraction peaks have been indexed and showed a single crystal layer of silver, with cubic structure and oxidation state, Ag 0. By means of these diffractograms, the network parameter and the interplanar distance of the diffraction planes were calculated. Using the Scherrer equation and a Gaussian fit of the Ag peaks shown in the X-ray diffractograms, it was possible to obtain the crystallite size for IQ–USP nanoparticles. DLS experiments showed monomodal number distribution for Khemia® AgNPs and, for washed IQ–USP AgNPs, bimodal distribution, estimating the number and size distribution. The results showed that the dominant distribution is always for smaller rays, suggesting smaller particles that aggregate with time and form larger dimensions. SAXS results showed that the samples provide good scattering intensity. Using the theoretical models, the average radius of the distribution, polydispersity and radius of gyration were calculated. The data revealed that the IQ–USP nanoparticles have a larger radius than the Khemia® and did not show aggregation. In contrast, Khemia® AgNPs showed higher aggregation, with 72% relative polydispersity. For IQ–USP AgNPs, SAXS analyzes provided particle size comparable to TEM and quite different from DLS. SAXS measurements for Khemia® AgNPs show differences with TEM and DLS measurements. It was evident the effect of the aggregation that has influences from the sample preparation until the time of performing the measurements. Cytotoxicity tests and morphological analysis studies by fluorescence microscopy evidenced the cytotoxic characteristics of each nanoparticle. The results presented by the morphological analysis performed with fluorescence microscopy agree with the cytotoxicity tests. IQ–USP nanoparticles showed high toxicity up to the concentration of 9.37 μg/m`, where the cells are presented with nuclear fragmentation. At lower concentrations, the IQ–USP AgNPs exhibited morphological characteristics comparable to the control group. In addition, Khemia® AgNPs show high toxicity up to the concentration of 1.37 μg/m`, with IC50 in the range of 1.3 to 6.7 μg/m`. It was possible to observe that higher concentrations induce nuclear fragmentation, triggering processes such as apoptosis and necrosis. Experiments using the OMTC technique demonstrated that different concentrations of silver nanoparticles can modify cell stiffness. This is evidenced when we compare the control group with the other groups, with the different concentrations of NPs. For higher concentrations of nanoparticles, there was an increase in viscoelasticity. The two types of nanoparticles studied showed changes in mechanical properties, but Khemia® AgNPs showed a greater increase in viscoelasticity at different concentrations. This change in viscoelasticity was explained to be due to the increased availability of calcium, released by apoptotic cells, which is used in the myosin-actin complex to generate muscle contraction.

Mecanismos de ação de nanopartículas de prata no comportamento de propriedades mecânicas celulares