Metabolically stable cellular adhesion to inert surfaces

The structure of D-amino acid hexapeptides that promote cellular adhesion was determined by screening D-amino acid hexapeptide libraries synthesized on otherwise inert beaded PEGA resin. These new adhesion molecules provide a completely stable cellular environment and facilitate the maintenance of a monolayer of cells on beads for extended periods. The presence of the peptides promotes spreading of the cells on the bead surface. Not surprisingly, the molecules contained a significant number of arginines and/or lysines. However, the exact structure of each peptide is quite important for the degree of adhesion observed, and a motif with three or four basic amino acids spaced within amino acids of intermediate polarity clearly prevailed, for example, k-l/r-h-r-i/v-r-a; this maintains a polar/hydrophobic balance.     

Phosphorylated gelatin to enhance cell adhesion to titanium

Phosphorylated gelatin was prepared for surface modification of titanium to enhance cell attachment. The modified gelatin was synthesized by coupling gelatin with phosphonobutyric acid with water‐soluble carbodiimide. Circular dichroism revealed no significant change in the gelatin as a result of phosphorylation. The binding behavior of phosphorylated gelatin on the titanium surface was observed by quartz crystal microbalance. The modified titanium surface was analyzed by measuring the water contact angle. Enhancement of the attachment of osteoblast cells MC‐3T3L1 was observed on the phosphorylated‐gelatin‐modified titanium. Phosphorylation of gelatin was effective for preparation of a cell‐adhesive titanium surface. © 2013 Society of Chemical Industry     

Wettability and osteoblastic cell adhesion on ultrapolished commercially pure titanium surfaces: the role of the oxidation and pollution states

The oxidation state of the surfaces of titanium-based biomaterials strongly depends on their previous history. This factor affects the titanium wettability and it probably conditions the success of the implanted biomaterials. However, the separate role of the pollution and oxidation states of metallic titanium surfaces remains still controversial. To elucidate this, it is required to standardize the initial surface state of titanium in terms of roughness and surface chemistry, and then, to monitor its wettability after the corresponding treatment. In this work, we studied finely polished surfaces of commercially pure titanium (cpTi) which were subjected to cleaning surface treatments. X-Photoelectron spectroscopy was used to characterize the surface chemistry and the oxide film thickness. The contact angle hysteresis in underwater conditions was measured with the growing/shrinking captive bubble method, which allowed for mimicking the real conditions of implantable devices. The water wettability of smooth cpTi surfaces was stabilized with weak thermal oxidation (230?°C, 30?min). The osteoblastic cell response of the stabilized and non-stabilized cpTi surfaces was analyzed. Although the oxidation and pollution states were also stabilized and normalized, no correlation was observed between the stable response in wettability of titanium and its cell adhesion.     

Peeling model for cell adhesion on electrospun polymer nanofibres

Need for controlled drug delivery has gained immense attention over the conventional dosage forms due to improved therapeutic efficacy and reduced toxicity by controlled delivery. Recently, electrospun fibres have gained wide attention particularly for drug delivery systems, tissue engineering and vascular grafts for biomedical application. In the present work, the feasibility of producing fibrous composite of polylactic acid (PLA) and hydroxyapatite with silver nitrate using electrospinning technique was explored to understand the antibacterial property of the dressing. These non-woven fibres were post processed and heat treated with UV radiations. Such heat treatment is known to reduce the ionic silver to silver nanoparticles and also improve the crystalline properties of hydroxyapatite and PLA. Antimicrobial tests show that these fibres have maintained antibacterial properties against Staphylococcos aureus. It was noticed that there was no discolouration in the wound mat. To test the biocompatibility of these fabrics, the electrospun mats were cultured with fibroblasts. The results indicated that the cells attached and proliferated as continuous layers and maintained a healthy morphology. Once the biomaterial is implanted, no control is possible either over the biomaterial characteristics or the healing process. At this point the modelling process takes over. The present study is extended to a mathematical model for a primary step in tissue regeneration–cell adhesion, using a ‘one-dimensional peeling model’.     

The adhesion of animal cells to surfaces: The measurement of critical surface shear stress permitting attachment or causing detachment

The ‘LH Fowler Cell Adhesion Measurement Module’ was successfully adapted to permit the determination of the critical shear forces involved in both the attachment to and the detachment from glass and plastic surfaces, by mammalian fibroblasts. Variations in the sensitivity of different cell types to critical shear forces were observed, although generally the critical shear forces permitting attachment were in the order of 1000-times less than those causing detachment. Finally alterations to culture conditions indicated that the sensitivity of cell attachment to shear forces is strongly affected outside of optimal conditions.     

Modeling cell adhesion to a substrate with gradient in ligand density

Surface density profile of bioadhesive ligands greatly influences spreading and migration of cells on substrates. A 1D peeling model is developed to predict the equilibrium adhesion strength and peeling tension of a cell membrane, adhered on a substrate with linearly increasing density of ligands. Cell membrane is modeled as a linear elastic shell subjected to a tensile force applied at the free extremity and adhesive traction due to specific receptor‐ligand interactions with the substrate. Membrane peeling tension increased with gradient slope and reached an asymptotic limit independent of gradient slope but proportional to receptor‐ligand interaction energy. Peeling tension from substrates with negative gradient slope, at the rear edge of adhesion zone, was considerably lower than the tension from substrates with positive gradient slope at the leading edge, indicating that detachment is more likely to be initiated at the rear edge. This prediction leads to a possible mechanism for experimentally observed haptotactic locomotion of motile cells toward the direction of higher ligand density. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

The effects of thermoresponsive microgel density on cell adhesion,proliferation, and detachment

In recent years, poly(N-isopropylacrylamide)-based microgels have been emerged as a new thermoresponsive coating for cell/cell sheet harvesting, yet few work reports their effect on cell attachment, morphology, activity, and proliferation in details. In this work, poly(N-isopropylacrylamide-co-styrene) (pNIPAAmSt) microgel was selected as the model to study its density on NIH3T3 cell adhesion, morphology, activity, and detachment. Results showed that 0.5 wt % pNIPAAmSt microgel density leads to more cells adhesion, higher cell activity yet lower cell proliferation. Moreover, cell adhesion location can be well controlled either by manipulating the sub-cellular scale distances between microgels or by fabricating large scale surface patterns of the microgels on higher microgel density. By temperature stimuli, similar ratio cells detached from the microgel density surface from 0.5 to 1.5 wt %. The results in this article are worthy for the application of thermoresponsive microgels in cell regulation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48773.     

Oligosaccharide mimics containing galactose and fucose specifically label tumour cell surfaces and inhibit cell adhesion to fibronectin

With the aim of establishing a versatile and easy synthesis of branched saccharides for biological applications, we used molecular-dynamics simulations to model Lewis(y) to two classes of di- or triantennary saccharide mimetics. One set of mimetics was based on 1,3,5-tris(hydroxymethyl)cyclohexane (TMC) as the core, the other on furan, and both were derivatised with galactose and/or fucose. The TMC-based saccharides were biotinylated, while the furan disaccharides were treated with maleimide-activated biotin in a Diels-Alder fashion to yield oxazatricyclodecanes (OTDs). These were then assayed as cell-surface labels in human colon (SW480 and CaCo-2), liver (PLC), Glia (U333 CG 343) and ovary (SKOV-3) tumour cell lines. Discrete staining patterns were observed in all cells, usually at one or two poles of the cells, particularly with the asymmetric 3-beta-L-fucopyranosyloxymethyl-4-beta-D-galactopyranosyloxymethyl-OTD. Normal SV40-transformed fibroblasts (SV80) showed no staining. Adhesion of the highly metastatic mouse melanoma line B16 F10 to fibronectin was inhibited by 80 % by the TMC-digalactoside and by 30 % by 3,4-bis-(beta-D-galactopyranosyloxymethyl)furan. None of the saccharide mimetics inhibited the adhesion of the less metastatic B16 F1 line. Migration of B16 F10 cells through Matrigel was greatly inhibited by the TMC-digalactoside and weakly inhibited by the TMC-trigalactoside. The saccharide mimetics that had shown the best structural agreements with the terminal saccharides of Lewis(y) in the molecular dynamics simulation were also the most biologically potent compounds; this underlines the predictive nature of molecular dynamics simulations. The use of the non-saccharide cores enabled us to adapt spacer lengths and terminal saccharides to optimise the structures to bind more avidly to cell-surface lectins.     

汽车用阻尼材料及其与车身的粘接

对汽车阻尼材料与车身结构粘接进行测试,分析了稳定粘接的条件、材料的组成对粘接效果的影响及粘接与阻尼性能的关系。     

Phenolic extracts from grape stems inhibit Listeria monocytogenes motility and adhesion to food contact surfaces

This study evaluated the effect of grape stems extracts on motility, surface energy and adhesion of L. monocytogenes to stainless steel and polypropylene surfaces. Stem extracts from Red Globe grapes showed a higher content of total phenolics than Carignan stems. Moreover, both extracts reduced adhesion of Listeria to stainless steel (0.77–2.22 log CFU cm^?2) and polypropylene (0.71–2.38 log CFU cm^?2) and completely inhibited bacterial motility at 4.5 and 5 mg mL^?1 of Red Globe and Carignan extracts, respectively. Similarly, both extracts affected the surface energy of bacteria and modified the adhesion potential of L. monocytogenes to both surfaces. Otherwise, caffeic, ferulic and gallic acids, catechin and rutin, presented in both extracts, reduced adhesion of L. monocytogenes to stainless steel (0.39–2.04 log CFU cm^?2) at 10 mM. In conclusion, Red Globe and Carignan grape stem extracts inhibited adhesion of L. monocytogenes to stainless steel and polypropylene surfaces by inhibiting motility and modifying its adhesion potential.     

Novel RGD lipopeptides for the targeting of liposomes to integrin-expressing endothelial and melanoma cells

RGD peptides targeting alphav-integrins are promising ligands for the generation of vascular targeting agents. We isolated from phage display RGD motif libraries novel high-affinity cyclic RGD peptides by selection on either endothelial or melanoma cells. Although the starting sequences contained only two cysteine residues flanking the RGD motif, several of the isolated peptides possessed four cysteine residues. A high-affinity peptide (RGD10) constrained by only one disulfide bond was used to generate novel lipopeptides composed of a lipid anchor, a short flexible spacer and the peptide ligand conjugated to the spacer end. Incorporation of RGD10 lipopeptides into liposomes resulted in specific and efficient binding of the liposomes to integrin-expressing cells. In vivo experiments applying doxorubicin-loaded RGD10 liposomes in a C26 colon carcinoma mouse model demonstrated improved efficacy compared with free doxorubicin and untargeted liposomes.     

Collagen‐based new biomedicial films: Synthesis,property, and cell adhesion

Grafted‐collagen films with poly(methyl methacrylate), poly(butyl methacrylate), and poly(styrene) were prepared by photoirradiation of the collagen films in the presence of respective monomers. Cell adhesion onto the films was investigated, and the amount of cells adhered onto every grafted films was almost the same as that onto the collagen film crosslinked with glutaraldehyde. Because the swollen grafted films are stronger than the collagen film, they are expected to be good biomedical materials. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2433–2438, 2001     

Modification of poly(tetrafluoroethylene) and copper foil surfaces by graft polymerization for adhesion improvement

Thermal graft polymerization-induced lamination of surface-modified copper foil to surface-modified poly(tetrafluoroethylene) (PTFE) film was achieved in the presence of an epoxy resin adhesive and glycidyl methacrylate (GMA) monomer, or in the presence of GMA and hexamethylenediamine (HEDA). The copper foil surfaces were pretreated with an organosilane coupling agent (SCA), such as (3-mercaptopropyl)trimethoxysiane, 3-(trimethoxysilyl)propyl methacrylate, or N¹-[3-(trimethoxysilyl)propyl]diethylene-triamine. The silanized copper foils were subjected to brief Ar plasma treatment and subsequently to UV-induced graft polymerization with GMA (the Cu-SCA-g-GMA surface). Surface modification of PTFE film included Ar plasma treatment alone, or Ar plasma pretreatment followed by UV-induced graft polymerization with GMA (the GMA-g-PTFE surface). The modified surfaces and interfaces were characterized by X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. The Cu-SCA-g-GMA/epoxy resin-GMA/PTFE or Cu-SCA-g-GMA/GMA–HEDA/GMA-g-PTFE laminates exhibited T-peel adhesion strengths in excess of 9 N/cm and the joints delaminated by cohesive failure inside the bulk of the PTFE film. The strong adhesion in these Cu foil-PTFE laminates is attributable to the fact that the GMA chains are covalently tethered on both the PTFE and the silanized Cu surfaces, as well the fact that these grafted GMA chains are covalently incorporated into the highly crosslinked network structure of the adhesive at the interphase.     

Influence of surface pretreatment and electrocoating parameters on the adhesion of cathodic electrocoat to the Al alloy surfaces

Adhesion of cathodic electrocoat films to the aluminum alloys 2024-T3 bare and Alclad 2024-T3 with different pretreatments and with different cathodic electrocoat process parameters was investigated. The pretreatments studied were acetone wipe and alkaline cleaning. The cathodic electrocoat process parameters studied include variation of cathodic electrocoating voltage and time. Adhesion performance was evaluated by measuring the delamination time and percent delamination of the electrocoat from the alloy surface by placing the small specimen of the sample in the N-methyl pyrrolidinone (NMP) solution at 60°C until the film lifts off or for 2 h whichever comes first. NMP times for electrodeposited film delamination from alkaline cleaned surfaces were found to be higher than the acetone wiped and or those of as-supplied metal surfaces. There was not much effect of acetone cleaning of these alloy surfaces on the adhesion performance of the cathodic electrocoat. The voltage–current (of cathodic electrocoating process) relationships for alkaline cleaned surfaces were also found to be significantly different from the other two types of surfaces. The NMP times of cathodic electrocoat delamination at lower cathodic electrocoating voltage and lower electrocoating times were higher than those at higher cathodic electrocoating voltage and electrocoating times for alkaline cleaned 2024 bare surfaces. Electrocoat thickness developed on the surfaces during the electrodeposition process increased with increasing electrodeposition voltage and time as anticipated.     

Engineering of Bio-Adhesive Ligand Containing Recombinant RGD and PHSRN Fibronectin Cell-Binding Domains in Fusion with a Colored Multi Affinity Tag: Simple Approach for Fragment Study from Expression to Adsorption

Engineering of biomimetic motives have emerged as promising approaches to improving cells’ binding properties of biomaterials for tissue engineering and regenerative medicine. In this study, a bio-adhesive ligand including cell-binding domains of human fibronectin (FN) was engineered using recombinant protein technology, a major extracellular matrix (ECM) protein that interacts with a variety of integrins cell-surface’s receptors and other ECM proteins through specific binding domains. 9th and 10th fibronectin type III repeat containing Arginine-Glycine-Aspartic acid (RGD) and Pro-His-Ser-Arg-Asn (PHSRN) synergic site (FNIII9-10) were expressed in fusion with a Colored Multi Affinity Tag (CMAT) to develop a simplified production and characterization process. A recombinant fragment was produced in the bacterial system using E. coli with high yield purified protein by double affinity chromatography. Bio-adhesive surfaces were developed by passive coating of produced fragment onto non adhesive surfaces model. The recombinant fusion protein (CMAT-FNIII9/10) demonstrated an accurate monitoring capability during expression purification and adsorption assay. Finally, biological activity of recombinant FNIII9/10 was validated by cellular adhesion assay. Binding to α5β1 integrins were successfully validated using a produced fragment as a ligand. These results are robust supports to the rational development of bioactivation strategies for biomedical and biotechnological applications.