most suitable to study time
Ed the rate of their agglomeration.most suitable to study time dependent stability and changes in PC formation on the differently functionalized SiO2 NPs. DLS data showed that all of the examined NPs were stable at concentration of 1?012 NPs mL-1 in DMEM supplemented with 10 FBS for at least 5-dichloro-N-(2-(isopropylsulfonyl)phenyl)pyrimidin-4-amine Ethyl 2 weeks (Figure 3). After 48 h of incubation in the protein solution the particle sizes seemed to slightly rise. The zeta potential values also became more negative. In this case, it would suggest a higher stability of the nanosystem. TEM 4-((2-Hydroxyethyl)(methyl)amino)benzaldehyde images of plain SiO2 NPs after different incubation times are shown in Figure 4. A protein layer surrounded the NPs was observed after 10 min. After 48 h the NPs size increased to 60 nm, and after 2 weeks to 80 nm. Since no NPs aggregation/sedimentation was detected during this time, this suggested that more than a single layer of proteins was immobilized onto the NPs surface, providing an effective protection against NP-NP interactions leading to PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/23410069 aggregation. It is worth noting, that a multilayer of proteins implies protein denaturation [53]. This kind of denaturation is rarely observed and is related to a specific surface charge and hydrophobicity. It has already been shown by Vroman, in 1962, that adsorption of blood serum proteins onto an inorganic surface was time dependent [54]. Vroman assumed that the proteins with the highest mobility attached firstly, and later were replaced by less mobile biomolecules that had a higher affinity to the surface, in a process that took several hours. Thus, the kinetics of serum protein adsorption onto differently functionalized SiO2 NPs were additionally investigated in our work. The majority of in vitro and in vivo tests concerning NPs are performedIzak-Nau et al. Particle and Fibre Toxicology 2013, 10:56 http://www.particleandfibretoxicology.com/content/10/1/Page 5 ofFigure 3 Time 4-Bromopicolinaldehyde dependent silica nanoparticles stability in biological medium. DMEM + 10 FBS; NPs concentration of 1×1012 NPs mL-1; DLS (left panel), zeta potential (right PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/13867361 panel).using bovine serum, mainly because of its availability and traditional use in many assays, as well as for economic reasons. Since the proteins of bovine serum differ from human proteins, the PC formation and its composition may differ as well. To study differences in proteins associations in different serum, FBS and human serum were applied. SDS-PAGE results indicated that formation of the hard PC took much longer than it was described in the literature before (Figure 5). Previous publications [34,40] have shown that the hard PC was formed after 1 h after NPs incubation in biological medium. In our case, there were still some changes in the hard PC observed even after 24 h. Some slight changes in the proteins adsorption/ desorption were even visible after one week. Based on a visual evaluation of the SDS-PAGE gels, the total amounts of adsorbed protein changed not only with time but theextent of protein adsorption/desorption was also functionalization dependent. This might be one of the factors leading to diverse intracellular responses and toxicological outcomes [55]. The amount of proteins was additionally estimated by ImageJ software (Figure 6). Figure 5 and Figure 6 show that the NPs which attracted the highest amount of FBS proteins were the plain SiO2 and the SiO2_NH2. In the case of the plain SiO2 NPs, after 72 h incubation time and onwards, there were no significant changes in the PC composition. It is worth noting that, in th.
