The correlation between the adsorption of adhesive proteins and cell behaviour on hydroxyl-methyl mixed self-assembled monolayers (original) (raw)
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ACS Biomaterials Science & Engineering, 2018
Surface modification plays vital role in regulating protein adsorption and subsequently cell adhesion. In the present work, we prepared nanoscaled modified surfaces using silanization and characterized them using Fourier-transform infrared spectroscopy (FTIR), water contact angle (WCA) and Atomic Force microscopy (AFM). Five different (amine, octyl, mixed, hybrid and COOH) surfaces were prepared based on their functionality and varying wettability and their effect on protein adsorption and initial cell adhesion was investigated. AFM analysis revealed nanoscale roughness on all modified surfaces. Fetal bovine serum (FBS) was used for protein adsorption experiment and effect of FBS was analyzed on initial cell adhesion kinetics (upto 6 h) under three different experimental conditions: (a) with FBS in media, (b) with pre-adsorbed FBS on surfaces and (c) incomplete media, i.e., without FBS. Various cell features such as cell morphology/circularity, cell area and nuclei size were also studied for above stated conditions at different time intervals. The cell adhesion rate as well as cell spreaded area were highest in case of surfaces with pre-adsorbed FBS. We observed higher surface coverage rate by adhering cells on hybrid (rate, 0.073 h-1) and amine (0.072 h-1) surfaces followed by COOH (0.062 h-1) and other surfaces under pre-adsorbed FBS condition. Surface treated with cells in incomplete media exhibited least adhesion rate, poor cell spreading and improper morphology. Furthermore, we found that initial cell adhesion rate and ∆ adhered cells (%) linearly increased with the change in α-helix content of adsorbed FBS on surfaces. Amongst all the modified surfaces and under all three experimental conditions, hybrid surface exhibited excellent properties for supporting cell adhesion and growth and hence can be potentially used as surface modifiers in biomedical applications to design biocompatible surfaces.
Effect of Preadsorbed Proteins on Cell Adhesion to Polymer Surfaces
Journal of Colloid and Interface Science, 1993
Adsorption of three different proteins and adhesion of cells onto various substrates in the presence of serum proteins were studied. Both the maximal protein adsorption and the maximal cell adhesion were observed on surfaces with water contact angle around 70°. Preadsorption of serum albumin prevented cell adhesion to all the substrates, whereas preadsorbed fibronectin (FN) enhanced cell adhesion to all the substrates, independent of their water wettability, except for poly(vinyl alcohol) and acrylamide-grafted films. Competitive adsorption of FN from mixed proteins, ranging from 0.03 to 0.07 p.g/cm2 , markedly influenced cell adhesion in the presence of serum. These results suggest that the effect of the water wettability of surfaces on cell adhesion in the presence of serum should occur through protein layers adsorbed directly to the substrate surfaces. ©1993 Academic Press, inc.
Journal of Biomedical Materials Research Part A, 2009
The adhesion of human leukocytes to nanostructured surfaces with different chemical properties and the effect of protein adsorption were investigated. Self-assembled monolayers (SAMs) prepared with mixtures of methyl- and hydroxyl-terminated alkanethiols in different percentages on gold were used. The surfaces were pre-immersed in distinct protein solutions (human serum albumin, human fibrinogen, and autologous plasma). Adherent leukocytes were analyzed both by light and SEM. SAMs submitted to pre-immersion in plasma presented higher numbers of adherent leukocytes in the pure OH-terminated SAM, whereas methyl-terminated surfaces accounted for the lowest number of adherent cells. We observed a general increase in the number of adherent human leukocytes as the percentage of OH groups on the surface of the SAMs increased for all the pre-immersion conditions investigated. The number of adherent human leukocytes is highly influenced by the pre-immersion conditions used, and this observation is particularly relevant in the case of the methyl-terminated SAMs. The results obtained demonstrate that surface chemistry has a major influence in leukocyte adhesion to biomaterials, and that pre-immersion in protein solutions has a determinant effect in leukocyte adhesion. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Journal of the American Chemical Society, 1998
This paper describes surfaces that promote the ligand-directed binding of cells and resist the cellular deposition of adhesive proteins. These surfaces are based on self-assembled monolayers (SAMs) of alkanethiolates on gold that present mixtures of arginine-glycine-aspartate (RGD), a tripeptide that promotes cell adhesion by binding to cell surface integrin receptors, and oligo(ethyleneglycol) moieties, groups that resist nonbiospecific adsorption of proteins and cells. Surface plasmon resonance (SPR) spectroscopy was used to measure the adsorption of carbonic anhydrase and fibrinogen to mixed SAMs comprising RGD groups ((EG) 6 OGRGD) and tri(ethylene glycol) groups ((EG) 3 OH); SAMs having values of the mole fraction of RGD ( RGD ) e 0.05 adsorbed nearly undetectable levels of carbonic anhydrase or fibrinogen. Bovine capillary endothelial cells attached and spread on SAMs at RGD g 0.00001, with spreading of cells reaching a maximum at RGD g 0.001. These mixed SAMs reduced the deposition of proteins by attached cells relative to both fibronectin adsorbed on SAMs of hexadecanethiolate on gold and RGD peptide coated on glass. After allowing cells to attach for 2 or 4 h to any of these surfaces presenting RGD groups, addition of soluble GRGDSP to the medium contacting the adherent cells rapidly released them from the surfaces. However, if cells were allowed to attach to surfaces for 24 h, only those cells attached to the mixed SAM presenting (EG) 6 OGRGD and (EG) 3 OH groups could be released using the soluble GRGDSP at a rate comparable to cells attached to fibronectin for 2 h. These results demonstrate that RGD alone is sufficient for adhesion and survival of cells over 24 h.
Mammalian Cell Behavior on Hydrophobic Substrates: Influence of Surface Properties
Colloids and Interfaces, 2019
The influence of different surface properties holding to a modification of the substrate towards hydrophobic or superhydrophobic behavior was reviewed in this paper. Cell adhesion, their communication, and proliferation can be strongly manipulated, acting on interfacial relationship involving stiffness, surface charge, surface chemistry, roughness, or wettability. All these features can play mutual roles in determining the final properties of biomedical applications ranging from fabrics to cell biology devices. The focus of this work is the mammalian cell viability in contact with moderate to highly water repellent coatings or materials and also in combination with hydrophilic areas for more specific application. Few case studies illustrate a range of examples in which these surface properties and design can be fruitfully matched to the specific aim.
Journal of Biomedical Materials Research, 2003
Integrin-mediated cell adhesion to proteins adsorbed onto synthetic surfaces anchors cells and triggers signals that direct cell function. In the case of fibronectin (Fn), adsorption onto substrates of varying properties alters its conformation/structure and its ability to support cell adhesion. In the present study, self-assembled monolayers (SAMs) of alkanethiols on gold were used as model surfaces to investigate the effects of surface chemistry on Fn adsorption, integrin binding, and cell adhesion. SAMs presenting terminal CH 3 , OH, COOH, and NH 2 functionalities modulated adsorbed Fn conformation as determined through differences in the binding affinities of monoclonal antibodies raised against the central cell-binding domain (OH Ͼ COOH ϭ NH 2 Ͼ CH 3 ). Binding of ␣ 5  1 integrin to adsorbed Fn was controlled by SAM surface chemistry in a manner consistent with antibody binding (OH Ͼ COOH ϭ NH 2 Ͼ CH 3 ), whereas ␣ V integrin binding followed the trend:
2006
The ability of fibronectin (Fn) to mediate cell adhesion through binding to a 5 b 1 integrins is dependent on the conditions of its adsorption to the surface. Using a model system of alkylsilane SAMs with different functional groups (X ¼ OH, COOH, NH 2 and CH 3 ) and an erythroleukemia cell line expressing a single integrin (a 5 b 1 ), the effect of surface properties on the cellular adhesion with adsorbed Fn layers was investigated. 125 I-labeled Fn, a modified biochemical cross-linking/extraction technique and a spinning disc apparatus were combined to quantify the Fn adsorption, integrin binding and adhesion strength, respectively. This methodology allows for a binding equilibrium analysis that more closely reflects cellular adhesion found in stable tissue constructs in vivo. Differences in detachment strength and integrin binding were explained in terms of changes in the adhesion constant (c, related to affinity) and binding efficiency of the adsorbed Fn for the a 5 b 1 integrins (CH 3 ENH 2 oCOOHEOH) and the resulting average bond strength. Fn interacted more strongly with a 5 b 1 integrins when adsorbed on COOH vs. OH surfaces suggesting that negative charge may be a critical component of inducing efficient cellular adhesion. As evident by the low c values, Fn adsorbed on NH 2 and CH 3 surfaces interacted inefficiently with a 5 b 1 integrins and also possessed significant non-specific components to adhesion. Lastly, comparison of cellular adhesion to Fn adsorbed onto smooth and rough surfaces showed that nano-scale roughness altered cellular adhesion by increasing the surface density of adsorbed Fn. r
Chemistry of Materials, 2005
A series of copolymers of N-isopropylacrylamide (NIPAM) and the more hydrophobic comonomer N-tert-butylacrylamide (NTBAM), with increasing NTBAM content (i.e., increasing hydrophobicity) were prepared. The adhesion of human epithelial cells on polymer films prepared from copolymers of NIPAM: NTBAM was observed to increase with increasing polymer hydrophobicity. However, in the absence of serum, cell adhesion to the different surfaces was statistically indistinguishable. Thus, it appears that the copolymer films differentially support cell adhesion due to selective adsorption of proteins from the physiological environment (the serum). Using contact angle measurements, molecular simulations, and Raman spectroscopy to characterize the different surfaces, we show evidence that the different behavior of cells on the films of increasing hydrophobicity is actually due to the different chemical properties of the surfaces with increasing content of NTBAM in the copolymers. As the NTBAM content is increased, the number of NH residues at the surface decreases, due to the additional steric hindrance of the bulkier NTBAM group, which results in decreased hydrogen bonding and thus decreased adsorption of proteins such as albumin. However, in some cases, the adsorption is driven by hydrophobic interactions, and proteins such as fibronectin were found to adsorb more to the films with a higher content of NTBAM. There appears, thus, to be a direct correlation between surface composition, i.e., the functional groups exposed at the surface, and protein binding and subsequent cell adhesion.
The effect of non-specific interactions on cellular adhesion using model surfaces
2005
The contribution of non-specific interactions between cells and model functional surfaces was measured using a spinning disc apparatus. These model functional surfaces were created using self-assembled monolayers (SAM) of alkylsilanes terminated with epoxide, carboxyl (COOH), amine (NH 2 ), and methyl (CH 3 ) groups. These SAMs were characterized using ellipsometry, atomic force microscopy, contact angle goniometry, and X-ray photoelectron spectroscopy to confirm the presence of well-formed monolayers of expected physicochemical characteristics. All substrates also demonstrated excellent stability under prolonged exposure (up to 18 h) to aqueous conditions. The adhesion strength of K100 erythroleukemia cells to the functional substrates followed the trend: CH 3 o COOH E epoxide { NH 2 . The NH 2 SAM surface exhibited nearly an order of magnitude greater adhesion strength than the other SAMs and this non-specific effect exceeded the adhesion measured when RGD tri-peptides were also immobilized on the surface. These findings illustrate the importance of substrate selection in quantitative studies of peptidemediated cellular adhesion. r