| Biomaterials such as nanobiomaterials and tissue regeneration materials have been widely applied in drug/gene delivery and tissue repair system. Upon contacting with biological systems, biomaterials surfaces will specifically or nonspecifically adsorb a variety of proteins, which further regulate the behaviors of cells via the "protein-materials" complexes. Therefore, it is of great challenge to study the interactions between biomedical surfaces and serum proteins, and the cell behaviors, and also explain how the adsorbed proteins influence the cell behaviors such as cell adhesion and cellular uptake.In this work, the serum proteins adsorption and cells behavior induced by different physical and chemical properties of nanobiomaterials and tissue regeneration materials, and the relationship of them were studied. It was revealed by the surface properties of the material to control the protein adsorption, thereby affecting mechanism of subsequent cell behaviors.Firstly, the binding kinetics of human fibrinogen (Fg) to negatively charged 11-mercaptoundecanoic acid-functionalized gold nanoparticles (AuNPs) ranging from 5.6 nm to 64.5 nm were examined. The Fg was adsorbed through a side-on configuration on the smaller (5.6 nm and 14.2 nm) AuNPs. It also retained the native conformation. By contrast, the Fg adopts the end-on configuration and loses most of the secondary structure on the 64.5 nm AuNPs. In the presence of excess Fg, only the 64.5 nm AuNPs showed severe aggregation.The role of alkyl length on AuNPs in mediating serum protein adsorption and the subsequent cellular uptake by A549 cells was studied. The AuNPs (5 nm) were modified with carboxylic alkyl thiols of different chain length (3MA,11 MA and 16MA), cells took up higher amount of MA-AuNPs with longer ligands (11MA-AuNPs and 16MA-AuNPs), which showed better dispersity in cytoplasm too. Whereas the total amount of adsorbed serum proteins had no significant difference, the relative amounts of adhesion mediators (fibronectin (Fn), fibrinogen (Fg), vitronectin (Vn) and laminin (Ln)) especially Vn which can specifically interact with cells, increased significantly with the alkyl length increasing. Therefore, the cytoplasmic distribution and cellular uptake of MA-AuNPs with different alkyl ligands are controlled by the "MA-AuNPs-protein" complex consisting of different amounts of adhesion mediators especially Vn, but not the bare MA-AuNPs and the total amount of adsorbed proteins. Taking into account all the results, the protein adsorption and its role in linking alkyl length on AuNPs to cellular uptake are figured out.The chiral properties of nanoparticles and the effects of serum concentration on protein adsorption and cell endocytosis were investigated. Monolayers of 2-mercaptoacetyl-L(D)-valine (L(D)-MAV) and poly(acryloyl-L(D)-valine) (L(D)-PAV) chiral molecules were formed on gold nanoparticles (AuNPs) surface. When AuNPs were incubated in cell culture medium with 10% fetal bovine serum (10% FBS/DMEM), the internalized amount of L-PAV-AuNPs and D-PAV-AuNPs by HepG2 and A549 cells was chirality dependent. However the cellular uptake of L-MAV-AuNPs and D-MAV-AuNPs which had less optical activity was chirality independent. As the concentration of FBS was up to 50%, the internalized amount of L-PAV-AuNPs and D-PAV-AuNPs was decreased and had no significant difference. As a result, this study reveals the molecular chirality on AuNPs as a direct regulator of cellular uptake, but the effect of chirality on cellular uptake can be ignored when NPs are incubated in the complex biological systems, especially in which they are applied (e.g. blood).To study the effect of tissue regenerative materials on protein adsorption and cell adhesion and migration, adsorption of Fn on salt-treated multilayers was characterized. Poly(sodium 4-styrenesulfonate) (PSS)/poly(diallydimethyl ammonium chloride) (PDADMAC) multilayers were treated with 1 M,3 M and 5 M NaCl solutions (Multilayer-1M, Multilayer-3M and Multilayer-5M). For Multilayer-1M, the original structure and properties of the multilayers are mostly retained, with a PDADMAC dominated, positively surface charged and a larger swelling ratio. The hardly swollen Multilayer-3M film, by contrast, has a PSS dominated and negatively charged surface. For the Mulatilayer-5M, PSS becomes abundant and the swelling ratio is pretty high. The amounts of adsorbed Fn increased linearly along with the increase of thickness o Multilayer-1M and 5M, but was independent on the thickness of Multilayer-3M. These results reveal that Fn molecules penetrated into Multilayer-1M and Multilayer-5M, whereas they adsorbed on the top surface of Multilayer-3M. The normalized relative activity of RGD in the adsorbed Fn molecules was highest on Multilayer-3M, which was supported by the larger content of random coils in the adsorbed Fn molecules. The interplay between the surface chemistry and swelling properties of the salt-treated multilayers, protein adsorption, and cell adhesion strength determines the cell mobility. When the adhesion force of human vascular smooth muscle cells (VSMCs), which is mediated by the adsorbed Fn and its relative activity, is appropriate, such as on Multilayer-5M, the cells will have the highest mobility. In contrast, the cell mobility is quite low on Multilayer-3M with high RGD activity, which causes cell adhesion that was too strong and a difficulty with rear end release of the cells. All these results suggest that the adsorption manner of Fn, its conformation, and activity contribute heavily to the responses of VSMCs to the salt-treated multilayers in terms of cell adhesion, spreading, and migration. |
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