Cell Adhesion Behavior Research Articles

Investigating the role of surface micro/nano structure in cell adhesion behavior of superhydrophobic polypropylene/nanosilica surfaces

The main aim of the current study was to investigate the effects of different topographical features on the biological performance of polypropylene (PP)/silica coatings. To this end, a novel method including combined use of nanoparticles and non-solvent was used for preparation of superhydrophobic PP coatings. The proposed method led to a much more homogeneous appearance with a better adhesion to the glass substrate. Moreover, a notable reduction was observed in the required contents of nanoparticles (100–20wt% with respect to the polymer) and non-solvent (35.5–9vol%) for achieving superhydrophobicity. Surface composition and morphology of the coatings were also investigated via X-ray photoelectron spectroscopy and scanning electron microscopy. Based on both qualitative and quantitative evaluations, it was found that the superhydrophobic coatings with only nano-scale roughness strongly prevented adhesion and proliferation of 4T1 mouse mammary tumor cells as compared to the superhydrophobic surfaces with micro-scale structure. Such results demonstrate that the cell behavior could be controlled onto the polymer and nanocomposite-based surfaces via tuning the surface micro/nano structure.

Photo-crosslinkable biopolymers targeting stem cell adhesion and proliferation: the case study of gelatin and starch-based IPNs.

The present work focuses on the development of biomaterials that support the adhesion and the proliferation of adipose-tissue derived stem cells. Therefore, gelatin and starch are selected as starting materials. Both hydrogel building blocks are of great interest as they provide a general chemical structure comparable to the protein and the polysaccharide constituting part of the extracellular matrix. Crosslinkable side groups are incorporated on both biopolymers to enable the subsequent chemical crosslinking, thereby ensuring their stability at physiological temperature. An in vitro cellular assay revealed that the hydrogels developed are biocompatible and supported cell adhesion of adipose-tissue derived mesenchymal stem cells. The presence of the starch phase tempered the adhesion resulting in local cell detachment. The results thus indicate that by carefully varying the ratio of the two building blocks, hydrogels can be developed possessing a controllable cell adhesion behavior.

Fabrication of Thermo-Responsive Molecular Layers from Self-Assembling Elastin-Like Oligopeptides Containing Cell-Binding Domain for Tissue Engineering

Novel thermo-responsive elastin-like oligopeptides containing cell-binding epitope (Arg-Gly-Asp-Ser sequence); arginine-glycine-aspartic acid-serine (RGDS)-elastin-like peptides (ELP) and RGDS-deg-ELP; were newly prepared as building blocks of self-assembled molecular layer for artificial extra cellular matrix. A detailed analysis of the conformation of the oligo(ELP)s in water and their self-assembling behavior onto hydrophobic surfaces were performed by using circular dichroism, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy and water contact angle measurements. The experimental results revealed that both oligo(ELP)s self-assembled onto hydrophobic surfaces and formed molecular layers based on their thermo-responsive conformational change from hydrous random coil to dehydrated β-turn structure. Effective cell adhesion and spreading behaviors were observed on these self-assembled oligo(ELP) layers. In addition, attached cells were found to be recovered successfully as a cell-sheet by temperature-induced disassembly of oligo(ELP) layer. This achievement provides an important insight to construct novel oligopeptide-based nano-surfaces for the design of smart artificial extra-cellular matrix.

Self-assembled monolayers of enantiomerically functionalized periodic mesoporous organosilicas and the effect of surface chirality on cell adhesion behaviour

Enantioselective functionalization of fluorescent dye loaded periodic mesoporous organosilicas withd(l)-mannose and the preparation of their self-assembled monolayers are described. Stereoselective interactions of these monolayers with different cell types are demonstrated.

The effect of the physical properties of the substrate on the kinetics of cell adhesion and crawling studied by an axisymmetric diffusion-energy balance coupled model.

In this paper an analytical approach to study the effect of the substrate physical properties on the kinetics of adhesion and motility behavior of cells is presented. Cell adhesion is mediated by the binding of cell wall receptors and substrate's complementary ligands, and tight adhesion is accomplished by the recruitment of the cell wall binders to the adhesion zone. The binders' movement is modeled as their axisymmetric diffusion in the fluid-like cell membrane. In order to preserve the thermodynamic consistency, the energy balance for the cell-substrate interaction is imposed on the diffusion equation. Solving the axisymmetric diffusion-energy balance coupled equations, it turns out that the physical properties of the substrate (substrate's ligand spacing and stiffness) have considerable effects on the cell adhesion and motility kinetics. For a rigid substrate with uniform distribution of immobile ligands, the maximum ligand spacing which does not interrupt adhesion growth is found to be about 57 nm. It is also found that as a consequence of the reduction in the energy dissipation in the isolated adhesion system, cell adhesion is facilitated by increasing substrate's stiffness. Moreover, the directional movement of cells on a substrate with gradients in mechanical compliance is explored with an extension of the adhesion formulation. It is shown that cells tend to move from soft to stiff regions of the substrate, but their movement is decelerated as the stiffness of the substrate increases. These findings based on the proposed theoretical model are in excellent agreement with the previous experimental observations.

Forces in yeast flocculation.

In the baker's yeast Saccharomyces cerevisiae, cell-cell adhesion ("flocculation") is conferred by a family of lectin-like proteins known as the flocculin (Flo) proteins. Knowledge of the adhesive and mechanical properties of flocculins is important for understanding the mechanisms of yeast adhesion, and may help controlling yeast behaviour in biotechnology. We use single-molecule and single-cell atomic force microscopy (AFM) to explore the nanoscale forces engaged in yeast flocculation, focusing on the role of Flo1 as a prototype of flocculins. Using AFM tips labelled with mannose, we detect single flocculins on Flo1-expressing cells, showing they are widely exposed on the cell surface. When subjected to force, individual Flo1 proteins display two distinct force responses, i.e. weak lectin binding forces and strong unfolding forces reflecting the force-induced extension of hydrophobic tandem repeats. We demonstrate that cell-cell adhesion bonds also involve multiple weak lectin interactions together with strong unfolding forces, both associated with Flo1 molecules. Single-molecule and single-cell data correlate with microscale cell adhesion behaviour, suggesting strongly that Flo1 mechanics is critical for yeast flocculation. These results favour a model in which not only weak lectin-sugar interactions are involved in yeast flocculation but also strong hydrophobic interactions resulting from protein unfolding.

Characteristic cell adhesion behaviors on various derivatives of poly(3-hydroxybutyrate) (PHB) and a block copolymer of poly(3-[RS]-hydroxybutyrate) and poly(oxyethylene)

A high-molecular-weight ABA tri-block copolymer ([RS]-PHB/PEG), consisting of poly(3-[RS]-hydroxybutyrate) ([RS]-PHB: A) and poly(oxyethylene) (polyethylene glycol; PEG: B), was synthesized by ring-opening polymerization of [RS]-β-butyrolactone ([RS]-βBL) in the presence of PEG and 1,3-dichlorotetrabutyldistannoxane (DTD) as the catalyst. By using a series of PHB derivatives including the new block copolymer, cell adhesion was evaluated with 3T3 fibroblast cells. It was found out that the attached cells didn't extend on [RS]-PHB, but extended on [R]-PHB although the numbers of the attached cells were very small on both [RS]-PHB and [R]-PHB. [RS]-PHB/PEG exhibited even poorer cell adhesion than [RS]-PHB because of the increased hydrophilic nature due to the PEG segments. Although the amount of fibronectin adsorbed on the surface of [RS]-PHB was higher than that on the surface of [R]-PHB, the cell adhesion became poorer on the fibronectin-pre-adsorbed [RS]-PHB. These differences in cell adhesion among these PHB derivatives were reasonably attributed to their surface properties related with the accumulation of methyl groups.

In vitro and in vivo studies of BMP-2-loaded PCL-gelatin-BCP electrospun scaffolds.

To confirm the effect of recombinant human bone morphogenetic protein-2 (BMP-2) for bone regeneration, BMP-2-loaded polycaprolactone (PCL)-gelatin (Gel)-biphasic calcium phosphate (BCP) fibrous scaffolds were fabricated using the electrospinning method. The electrospinning process to incorporate BCP nanoparticles into the PCL-Gel scaffolds yielded an extracellular matrix-like microstructure that was a hybrid system composed of nano- and micro-sized fibers. BMP-2 was homogeneously loaded on the PCL-Gel-BCP scaffolds for enhanced induction of bone growth. BMP-2 was initially released at high levels, and then showed sustained release behavior for 31 days. Compared with the PCL-Gel-BCP scaffold, the BMP-2-loaded PCL-Gel-BCP scaffold showed improved cell proliferation and cell adhesion behavior. Both scaffold types were implanted in rat skull defects for 4 and 8 weeks to evaluate the biological response under physiological conditions. Remarkable bone regeneration was observed in the BMP-2/PCL-Gel-BCP group. These results suggest that BMP-2-loaded PCL-Gel-BCP scaffolds should be considered for potential bone tissue engineering applications.

Analysis of cellular adhesion on superhydrophobic and superhydrophilic vertically aligned carbon nanotube scaffolds.

We analyzed GFP cells after 24h cultivated on superhydrophilic vertically aligned carbon nanotube scaffolds. We produced two different densities of VACNT scaffolds on Ti using Ni or Fe catalysts. A simple and fast oxygen plasma treatment promoted the superhydrophilicity of them. We used five different substrates, such as: as-grown VACNT produced using Ni as catalyst (Ni), as-grown VACNT produced using Fe as catalyst (Fe), VACNT-O produced using Ni as catalyst (NiO), VACNT-O produced using Fe as catalyst (FeO) and Ti (control). The 4',6-diamidino-2-phenylindole reagent nuclei stained the adherent cells cultivated on five different analyzed scaffolds. We used fluorescence microscopy for image collect, ImageJ® to count adhered cell and GraphPad Prism 5® for statistical analysis. We demonstrated in crescent order: Fe, Ni, NiO, FeO and Ti scaffolds that had an improved cellular adhesion. Oxygen treatment associated to high VACNT density (group FeO) presented significantly superior cell adhesion up to 24h. However, they do not show significant differences compared with Ti substrates (control). We demonstrated that all the analyzed substrates were nontoxic. Also, we proposed that the density and hydrophilicity influenced the cell adhesion behavior.

Fabrication of biopolymers reinforced TNT/HA coatings on Ti: Evaluation of its Corrosion resistance and Biocompatibility

Titania nanotube (TNT) arrays were fabricated on Ti alloy by rapid breakdown anodization (RBA) method and chitosan (CS) - polyvinylpyrrolidone (PVP) biopolymers were codeposited on TNT followed by subsequent electrodeposition of hydroxyapatite (HA, Ca10(PO4)6(OH)2,). The coatings were characterized by FE-SEM, EDX, XRD and AT-FTIR techniques. The mechanical, anticorrosion properties and biocompatibility of the coatings were evaluated. SEM analysis shows that among all coatings, the TNT/CS-PVP/HA coating possesses homogeneous surface and the incorporation of PVP into CS resulted in better morphology. The tentative mechanism for the deposition of CS-PVP biopolymers on TNT was proposed. Studies on the mechanical properties indicate that the addition of PVP into CS increase the hardness and adhesion strength of the coatings and the deposition of HA on TNT/CS-PVP coating further increase the mechanical strength. Similarly TNT/CS-PVP/HA coating shows good corrosion resistance, better fibroblast cell adhesion and low cytotoxicity behaviour than TNT and TNT/CS-PVP coatings.

Abstract 2091: Metastatic oral cancer cell adhesion to vascular and lymphatic endothelial cells is sialyl Lewis A/X-dependent

Abstract Background: The vast majority of mortalities from cancer, including oral cancer, are due to metastatic disease. Previous studies have shown that sialylated cell surface glycoconjugates mediate the extravasation of circulating tumor cells from several different tumor types. The aim of this study was to investigate whether metastatic oral squamous cell carcinoma (OSCC) cells overexpress and employ sialyl Lewis A/X (sLeA/X) to adhere to E-selectin on endothelial cells. Materials and methods: Twenty-one matched-pairs of primary and nodal metastatic OSCC tissue sections were evaluated immunohistochemically using anti-sLeA (clone KM231) and anti-sLeX (clone KM93) monoclonal antibodies (mAbs). q-PCR was performed to measure relative transcript expression of a panel of glycogens potentially involved in sLeA/X synthesis in OSCC cells. sLeA/X cell surface expression was assessed by flow cytometry and fluorescence immunocytochemistry. sLeA/X involvement in OSCC cell adhesion behavior was evaluated using static and flow adhesion assays employing recombinant E-selectin (rE-selectin) and TNF-α-stimulated human dermal microvascular endothelial cells (HuDMEC) or human lymphatic endothelial cells (HLEC), respectively. Several approaches to prevent OSCC cell binding to rE-selectin or HuDMEC were tested including the use of anti-sLeA/X mAbs, neuraminidase, fucosidase, IELLQAR®, chondroitin sulfate, swainsonine and FUT3 siRNA. Results: Immunohistochemistry analysis showed sLeA/X to be mainly expressed by well- to moderately-differentiated OSCC. sLeA/X expression on primary OSCC correlates with lymph node metastasis but not tumor differentiation status. The metastatic OSCC cells, TR146, displayed higher sLeA/X expression than the non-metastatic OSCC cells, SCC4 and Cal27, and this was at least partially related to up-regulated gene expression of fucosyltransferase III. Knocking down FUT3 expression in TR146 cells reduced sLeX but not sLeA levels. TR146 cells adhered to rE-selectin and TNF-α-stimulated HuDMEC/HLEC in significantly greater numbers than SCC4 cells. Attachment of TR146 cells to rE-selectin was significantly reduced following incubation with anti-sLeA/X mAbs, neuraminidase and FUT3 siRNA. Treatment of TR146 cells with neuraminidase also caused a significant decrease in cell adhesion to HuDMEC under hydrodynamic flow conditions. Conclusions: Elevated levels of sLeX in metastatic OSCC cells results from increased FUT3 expression. Metastatic OSCC cell binding to HuDMEC/HLEC is sLeA/X-mediated and may be a target for anti-metastasis therapy. Citation Format: Ahmed Alkishi, Syed Ali Khurram, Martin Thornhill, Craig Murdoch. Metastatic oral cancer cell adhesion to vascular and lymphatic endothelial cells is sialyl Lewis A/X-dependent. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2091. doi:10.1158/1538-7445.AM2014-2091

Effect of surface topography and bioactive properties on early adhesion and growth behavior of mouse preosteoblast MC3T3-E1 cells.

The effects of bioactive properties and surface topography of biomaterials on the adhesion and spreading properties of mouse preosteoblast MC3T3-E1 cells was investigated by preparation of different surfaces. Poly lactic-co-glycolic acid (PLGA) electrospun fibers (ES) were produced as a porous rough surface. In our study, coverslips were used as a substrate for the immobilization of 3,4-dihydroxyphenylalanine (DOPA) and collagen type I (COL I) in the preparation of bioactive surfaces. In addition, COL I was immobilized onto porous electrospun fibers surfaces (E-COL) to investigate the combined effects of bioactive molecules and topography. Untreated coverslips were used as controls. Early adhesion and growth behavior of MC3T3-E1 cells cultured on the different surfaces were studied at 6, 12, and 24 h. Evaluation of cell adhesion and morphological changes showed that the all the surfaces were favorable for promoting the adhesion and spreading of cells. CCK-8 assays and flow cytometry revealed that both topography and bioactive properties were favorable for cell growth. Analysis of β1, α1, α2, α5, α10 and α11 integrin expression levels by immunofluorescence, real-time RT-PCR, and Western blot and indicated that surface topography plays an important role in the early stage of cell adhesion. However, the influence of topography and bioactive properties of surfaces on integrins is variable. Compared with any of the topographic or bioactive properties in isolation, the combined effect of both types of properties provided an advantage for the growth and spreading of MC3T3-E1 cells. This study provides a new insight into the functions and effects of topographic and bioactive modifications of surfaces at the interface between cells and biomaterials for tissue engineering.

Synthesis of a novel bioactive glass using the ultrasonic energy assisted hydrothermal method and their biocompatibility evaluation

Abstract

Bioactivation of Plane and Patterned PDMS Thin Films by Wettability Engineering

This study shows how surface properties of polydimethylsiloxane (PDMS) thin films, such as wettability and cellular adhesive behavior, can be influenced by surface modification and patterning, to improve the suitability of such modified PDMS for biomedical applications. For that purpose, different types of PDMS (i.e., soft (S-) and hard (H-) PDMS) and differently patterned surfaces were prepared by a commercially available tool which is originally used to produce patterned PDMS stamps for substrate conformal imprint lithography. To increase surface wettability and cellular adhesive behavior, PDMS surfaces were modified by O2, Ar/O2, Ar, and forming gas (N2/H2) plasma treatment. It is shown that, especially, plasma treatment using N2/H2 is a promising method to modify PDMS surfaces towards enhanced wettability. Such modified PDMS surfaces exhibit water contact angle values (WCA) of nearly 0° and demonstrate enhanced attachment of melanoma cells. Differences between as-prepared and plasma-treated S- and H-PDMS can be observed, where H-PDMS shows smaller WCA than S-PDMS. Even plasma-treated PDMS surfaces, however, exhibit only temporary hydrophilicity, due to hydrophobic recovery. To overcome this problem, plasma-treated PDMS films were stored in ethanol and water, where low and constant WCAs for several months could be achieved. Finally, the influence of surface topography of different patterned PDMS thin films on the adhesion behavior of melanoma cells was investigated. It can be concluded that chemical as well as structural modifications of PDMS enable to gradually control the adhesive properties of cells on their surfaces. This has a high technological impact since regulated and topologically stable adhesion and repulsion of cells by their scaffolds has high potency for in vitro as well as in vivo applications.

An in situ synthesis of mesoporous SBA-16/hydroxyapatite for ciprofloxacin release: in vitro stability and cytocompatibility studies.

The present work developed a biomaterial (HA/SBA-16) based on the growth of calcium phosphate (HA) particles within an organized silica structure (SBA-16) to evaluate its application as a drug delivery system. The samples were charged with ciprofloxacin as a model drug and in vitro release assays were carried out. The samples were characterized by elemental analysis (CHN), Fourier transform infrared spectroscopy, nitrogen adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), small angle X-ray scattering (SAXS) and X-ray diffraction. The results obtained by TEM, SEM and SAXS reveal a well-defined cubic arrangement of a uniform spherical mesoporous structure, an intrinsic characteristic of these materials, which indicated that SBA-16 and HA/SBA-16 could potentially encapsulate bioactive molecules by means of ordered mesopores. It was found that both surface interaction and pore volume affect the rate and amount of ciprofloxacin released from the mesoporous materials. In vitro assays were performed to evaluate the adhesion, viability, and growth behavior of human adipose tissue-derived stem cells (hADSC) on SBA-16 and HA/SBA-16 nanocomposites to verify their potential as a scaffold for application in bone-tissue engineering using MTT assay and alkaline phosphatase activity tests. The results showed that the materials are promising systems for bone repair, providing a good environment for the adhesion and proliferation of rat mesenchymal stem cells and hADSC in vitro.

A correlation study of protein adsorption and cell behaviors on substrates with different densities of PEG chains

The adsorption of proteins, in particular fibronectin (Fn), was studied on poly(ethylene glycol) (PEG, 5kDa)-grafted surfaces, and was correlated with the adhesion behaviors of smooth muscle cells (SMCs). The PEG molecules were covalently grafted on aldehyde-activated substrates with different densities of amino groups. The thickness of PEG layer increased nearly 10 fold in a hydrated state, reaching to 27nm on the surface of highest PEG chain density with a brush configuration. On the lower PEG-grafted surfaces, however, the PEG molecules adopted a mushroom configuration. The adsorption of Fn without and with the competition of bovine serum albumin (BSA) and serum was studied by using ellipsometry, fluorescence microscopy and radio-labeling techniques. The adsorption amount of Fn in serum decreased initially with increased PEG chain density until 0.12chains/nm2 PEG, and then slightly increased on the 0.29chains/nm2 PEG. A series of protein preadsorption experiments were carried out under different conditions before SMCs culture in vitro. Compared with those substrates without Fn preadsorption, the cell adhesion and spreading were significantly enhanced on all the PEG surfaces preadsorbed with Fn and serum, although they overall decreased along with the increase of PEG grafting density. The adhesion force of Fn decreased monotonously with the increase of PEG grafting density, which was in accordance with the cell adhesion force. The correlation between the PEG-grafted surfaces, Fn adsorption, and cellular behaviors is finally suggested.

Hydrophobization of silk fibroin nanofibrous membranes by fluorocarbon plasma treatment to modulate cell adhesion and proliferation behavior

Saturated fluorocarbon (CF4) immobilized silk fibroin (SF) nanofibrous membranes were prepared and characterized for biomedical applications. Biocompatible barrier membranes that provide both hydrophobic and hydrophilic surface properties on each side are critical to prohibit soft tissue invasion into localized bone defect. As a barrier membrane, SF nanofibrous mat was fabricated by electrospinning method, and then subsequently modified with water vapor treatment for insolubilization in water and CF4 gas plasma treatment for surface hydrophobization. Morphology of SF nanofibrous mats were observed by scanning electron microscopy. Conformational change of insolubilized SF nanofibers was confirmed by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and 13C nuclear magnetic resonance (NMR) spectroscopy. Immobilized fluorine atoms on CF4 plasma treated SF nanofibrous membranes were detected using electron spectroscopy for chemical analysis (ESCA). Water contact angle of the SF nanofiber membrane surface was analyzed by varying plasma input power and time. Insolubilized SF nanofibrous membrane maintained nonwoven mat structure without deformation after water immersion. SF nanofibrous membranes showed significant increment of water contact angle from 99.7° to 141.2° by CF4 gas plasma treatment. Fibroblasts on plasma untreated SF nanofibrous membranes were well attached and spread than a control tissue culture polystyrene dish. Fibroblasts on the CF4 gas plasma treated SF nanofibrous membrane showed significantly lower proliferation behavior than plasma untreated SF nanofibrous membranes. Fluorocarbon immobilized SF nanofibrous barrier membrane will be useful for biomedical applications such as a guided bone regeneration. Open image in new window

Some basic questions on mechanosensing in cell–substrate interaction

Cells constantly probe their surrounding microenvironment by pushing and pulling on the extracellular matrix (ECM). While it is widely accepted that cell induced traction forces at the cell–matrix interface play essential roles in cell signaling, cell migration and tissue morphogenesis, a number of puzzling questions remain with respect to mechanosensing in cell–substrate interactions. Here we show that these open questions can be addressed by modeling the cell–substrate system as a pre-strained elastic disk attached to an elastic substrate via molecular bonds at the interface. Based on this model, we establish analytical and numerical solutions for the displacement and stress fields in both cell and substrate, as well as traction forces at the cell–substrate interface. We show that the cell traction generally increases with distance away from the cell center and that the traction-distance relationship changes from linear on soft substrates to exponential on stiff substrates. These results indicate that cell adhesion and migration behaviors can be regulated by cell shape and substrate stiffness. Our analysis also reveals that the cell traction increases linearly with substrate stiffness on soft substrates but then levels off to a constant value on stiff substrates. This biphasic behavior in the dependence of cell traction on substrate stiffness immediately sheds light on an existing debate on whether cells sense mechanical force or deformation when interacting with their surroundings. Finally, it is shown that the cell induced deformation field decays exponentially with distance away from the cell. The characteristic length of this decay is comparable to the cell size and provides a quantitative measure of how far cells feel into the ECM.

Effect of the distribution of adsorbed proteins on cellular adhesion behaviors using surfaces of nanoscale phase-reversed amphiphilic block copolymers

In order to create suitable biocompatible materials for various tissue engineering applications, it is important to be able to understand protein adsorption and cell adhesion behaviors on the material’s surfaces. It is known that the nanoscale distribution of adsorbed proteins affects cell adhesion behaviors. However, how nanoscale structures affect cell adhesion behaviors is still unclear. Therefore, in this study, we investigate the effect of the distribution of adsorbed proteins by the phase reversal of amphiphilic block copolymers composed of protein-non-adsorptive poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and protein-adsorptive poly(3-methacryloyloxy propyltris(trimethylsilyloxy) silane) (PMPTSSi) on cell adhesion behaviors. The nanodomain structures of phase-separated block copolymers were successfully confirmed using transmission electron microscopy and atomic force microscopy. Surfaces that had PMPC dot-like domains (23±4nm) and ones that had PMPTSSi dot-like domains (25±6nm) were made. From protein adsorption and L929 cell adhesion measurements, it was found that even on surfaces with equal quantities of protein adsorption, the number of cells on surfaces with PMPC dot-like domains was larger than those with PMPTSSi dot-like domains. This suggests that the simple phase-reversal of the distribution of adsorbed proteins can be used to affect cell adhesion behaviors for designing biomaterial surfaces for tissue engineering applications.

Osteoselection supported by phase separated polymer blend films

The instability of implants after placement inside the body is one of the main obstacles to clinically succeed in periodontal and orthopedic applications. Adherence of fibroblasts instead of osteoblasts to implant surfaces usually results in formation of scar tissue and loss of the implant. Thus, selective bioadhesivity of osteoblasts is a desired characteristic for implant materials. In this study, we developed osteoselective and biofriendly polymeric thin films fabricated with a simple phase separation method using either homopolymers or various blends of homopolymers and copolymers. As adhesive and proliferative features of cells are highly dependent on the physicochemical properties of the surfaces, substrates with distinct chemical heterogeneity, wettability, and surface topography were developed and assessed for their osteoselective characteristics. Surface characterizations of the fabricated polymer thin films were performed with optical microscopy and SEM, their wettabilities were determined by contact angle measurements, and their surface roughness was measured by profilometry. Long-term adhesion behaviors of cells to polymer thin films were determined by F-actin staining of Saos-2 osteoblasts, and human gingival fibroblasts, HGFs, and their morphologies were observed by SEM imaging. The biocompatibility of the surfaces was also examined through cell viability assay. Our results showed that heterogeneous polypropylene polyethylene/polystyrene surfaces can govern Saos-2 and HGF attachment and organization. Selective adhesion of Saos-2 osteoblasts and inhibited adhesion of HGF cells were achieved on micro-structured and hydrophobic surfaces. This work paves the way for better control of cellular behaviors for adjustment of cell material interactions.