Effect of blasting treatment and Fn coating on MG63 adhesion and differentiation on titanium: a gene expression study using real-time RT-PCR.

Biomaterial surface properties, via alterations in the adsorbed protein layer, and the presence of specific functional groups can influence integrin binding specificity, thereby modulating cell adhesion and differentiation processes. The adsorption of fibronectin, a protein directly involved in osteoblast adhesion to the extracellular matrix, has been related to different physical and chemical properties of biomaterial surfaces. This study used blasting particles of different sizes and chemical compositions to evaluate the response of MG63 osteoblast-like cells on smooth and blasted titanium surfaces, with and without fibronectin coatings, by means of real-time reverse transcription-polymerase chain reaction (qRT-PCR) assays. This response included (a) expression of the a5, av and a3 integrin subunits, which can bind to fibronectin through the RGD binding site, and (b) expression of alkaline phosphatase (ALP) and osteocalcin (OC) as cell-differentiation markers. ALP activity and synthesis of OC were also tested. Cells on SiC-blasted Ti surfaces expressed higher amounts of the a5 mRNA gene than cells on Al2O3-blasted Ti surfaces. This may be related to the fact that SiC-blasted surfaces adsorbed higher amounts of fibronectin due to their higher surface free energy and therefore provided a higher number of specific cell-binding sites. Fn-coated Tisurfaces decreased a5 mRNA gene expression, by favoring the formation of other integrins involved in adhesion over a5b1. The changes in a5 mRNA expression induced by the presence of fibronectin coatings may moreover influence the osteoblast differentiation pathway, as fibronectin coatings on Ti surfaces also decreased both ALP mRNA expression and ALP activity after 14 and 21 days of cell culture.Peer ReviewedPostprint (published version

Modélisation de l’effet de la rugosité sur l’adhésion d’ostéoblastes : application au titane

International audienceAn implant lifetime partly depends on the quality of the osseointegration. It has been established that osseointegration is influenced by treatments performed to shape and obtain the implants, throughout mechanical properties which can be modified in a given depth, as well as chemical and topographical properties. In order to predict the effect of a surface treatment on cellular behavior, a model has been elaborated to simulate cellular attachment on different titanium surfaces. This model is based on the space occupation of spherical cells randomly distributed on topographical profiles. The simulated design is then compared to in-vitro experiments with MG63 osteoblastical cells. The number of cells per square millimeter is calculated in each case; comparisons between experimental and theoretical results demonstrate the feasibility of reaching such parameter by modelling. Future developments of the model will allow to study cellular spreading, mechanical constraints, scale-dependent topographical parameters and surface chemical properties.La durée de vie des implants est en partie dépendante de la qualité de l’ostéointégration. Or il a été reconnu que l’ostéointégration est influencée par les traitements de mise en forme et d’obtention des implants, au travers des propriétés mécaniques, qui peuvent être modifiées sur une certaine profondeur, des propriétés chimiques et topographiques. Afin d’anticiper l’effet d’un traitement de surface sur le comportement cellulaire, un modèle a été mis au point simulant l’adhésion cellulaire sur différentes surfaces de titane. Ce modèle est basé sur l’encombrement géométrique de cellules sphériques distribuées aléatoirement sur des profils topographiques. La modélisation est ensuite comparée à des tests réalisés in vitro avec les cellules ostéoblastiques MG63. Le nombre de cellules par mm2 est calculé dans chacun des cas et la confrontation entre les résultats expérimentaux et théoriques montre qu’il est possible d’estimer correctement ce paramètre par la modélisation. Les prochains développements du modèle introduiront les notions d’étalement cellulaire, de contraintes mécaniques, de paramètres topographiques échelle-dépendants et de propriétés chimiques de la surface

Atomic force microscopy characterization of polyethylene terephthalate grafting with poly(styrene sulfonate)

Polyethylene terephthalate (PET) is widely used to elaborate biomaterials and medical devices in particular for long-term implant applications but tuning their surface properties remains challenging. We investigate surface functionalization by grafting poly(sodium 4-styrene sulfonate, PNaSS) with the aim of enhancing protein adhesion and cellular activity. Elucidating the topography and molecular level organization of the modified surfaces is important for understanding and predicting biological activity. In this work, we explore several grafting methods including thermal grafting, thermal grafting in the presence of Mohr\u27s salt, and UV activation. We characterize the different surfaces obtained using atomic force microscopy (AFM), contact angle (CA), and X-ray photoelectron spectroscopy (XPS). We observe an increase in the percentage of sulfur atoms (XPS) that correlates with changes in (CA), and we identify by AFM characteristic features, which we interpret as patches of polymers on the PET surfaces. This work demonstrates tuning of biomaterials surface by functionalization and illustrates the capability of atomic force microscopy to provide insights into the spatial organization of the grafted polymer

Different real‐time degradation scenarios of functionalized poly(ε‐caprolactone) for biomedical applications

International audienceAnterior cruciate ligament (ACL) ruptures are a much‐commented injury as it can end the season or even career of professional athletes. However, the recovery of a patient from the general population is no less painful during the long period required by current treatments. Artificial ligaments could improve this healing, yet, orthopedic surgeons are still cautious about permanent ACL implants. Therefore, combining biodegradation and bioactivity could be a key feature for the popularization of these devices. This study aim at evaluating the real‐time degradation of poly(ε‐caprolactone) (PCL) grafted with the bioactive polymer sodium polystyrene sulfonate in different scenarios. PCL physical–chemical properties were evaluated before and after degradation. In addition, in vitro experiments were realized to confirm the long term influence of the grafting on cell response. Altogether, we were able to show different degradations scenarios, enabling to study the impact of degradation environment on degradation mode and rate of functionalized PCL

Atomic force microscopy characterization of polyethylene terephthalate grafting with poly(styrene sulfonate)

International audiencePolyethylene terephthalate (PET) is widely used to elaborate biomaterials and medical devices in particular for long-term implant applications but tuning their surface properties remains challenging. We investigate surface functionalization by grafting poly(sodium 4styrene sulfonate, PNaSS) with the aim of enhancing protein adhesion and cellular activity. 2 Elucidating the topography and molecular level organization of the modified surfaces is important for understanding and predicting biological activity. In this work, we explore several grafting methods including thermal grafting, thermal grafting in the presence of Mohr's salt, and UV activation. We characterize the different surfaces obtained using atomic force microscopy (AFM), contact angle (CA), and X-ray photoelectron spectroscopy (XPS). We observe an increase in the percentage of sulfur atoms (XPS) that correlates with changes in (CA), and we identify by AFM characteristic features, which we interpret as patches of polymers on the PET surfaces. This work demonstrates tuning of biomaterials surface by functionalization and illustrates the capability of atomic force microscopy to provide insights into the spatial organization of the grafted polymer

A bioactive polymer grafted on titanium oxide layer obtained by electrochemical oxidation. Improvement of cell response

1 - ArticleThe anchorage failure of titanium implants in human body is mainly due to biointegration problem. The proposed solution is to graft a bioactive polymer at the surface of the implant in order to improve and control the interactions with the living system. In this paper, we describe the grafting of poly sodium styrene sulfonate on titanium surface by using a silanization reaction. The key point is to increase the TiOH content at the surface of the implant which can react with methoxy silane groups of 3-methacryloxypropyltrimethoxysilane (MPS). Two procedures were used: chemical oxidation and electrochemical oxidation. The last oxidation procedure was carried out in two different electrolytes: oxalic acid and methanol. These different oxidation methods allow controlling the roughness and the depth of the oxide layer. The methacryloyl group of MPS grafted at the titanium surface by silanization reaction is copolymerized with sodium styrene sulfonate using a thermal initiator able to produce radicals by heating. Colorimetric method, ATR-FTIR, XPS techniques and contact angle measurements were applied to characterize the surfaces. MG63 osteoblastic cell response was studied on polished, oxidized and grafted titanium samples. Cell adhesion, Alkaline Phosphatase activity and calcium nodules formation were significantly enhanced on grafted titanium surfaces compared to un-modified surfaces

Increasing the bioactivity of elastomeric poly(epsilon-caprolactone) scaffolds for use in tissue engineering

1- articleInternational audienceBACKGROUND: Biodegradable polymers used in tissue engineering applications, such as poly(ε-caprolactone) (PCL), are hydrophobic leading to a lack of favorable cell signalization and finally to a poor cell adhesion, proliferation and differentiation. To overcome this problem, scaffolds undergo generally a surface modification. OBJECTIVE: Our laboratory has demonstrated that the grafting of poly(sodium styrene sulfonate) (pNaSS) onto titanium or poly(ethylene terephthalate) surfaces, leads to a more specific protein adsorption and a better control of cell proliferation. The objective of this work is to develop, through a straightforward way, bioactive elastomeric PCL scaffolds by grafting pNaSS. METHODS: Porous elastomeric PCL scaffolds were developed using a particulate-leaching process. pNaSS was grafted into the scaffold by a "grafting from" technique. In vitro tests were carried out to assess cell adhesion and protein expression. RESULTS: pNaSS was grafted homogeneously onto PCL scaffolds without degrading the biodegradable polymer or the porous structure. The in vitro studies have shown that pNaSS grafted onto PCL improves the cell response with a better expression of collagen, fibronectin and integrin α1. CONCLUSIONS: The grafting of pNaSS onto biomaterial surfaces is a versatile method that can provide a new generation of biodegradable scaffolds which could be "biointegrable"

Thiol-Poly(Sodium Styrene Sulfonate) (PolyNaSS-SH) Gold Complexes: From a Chemical Design to a One-Step Synthesis of Hybrid Gold Nanoparticles and Their Interaction with Human Proteins

International audienceThis study highlights recent advances in the synthesis of nanoconjugates based on gold (Au(III)) complex with a bioactive polymer bearing sulfonate groups called thiol-poly(sodium styrene sulfonate) (PolyNaSS-SH) with various molecular weights (5, 10, and 35 kDa). The three nanomaterials differ substantially in shape and structure. In particular, for PolyNaSS-SH of 35 kDa, we obtained a characteristic core−shell flower shape after chelation of the Au(III) ions and successively reduction with sodium borohydride (NaBH 4). The mechanism of formation of the hybrid nanoparticles (PolyNaSS-SH@AuNPs (35 kDa) and their interactions between plasmatic proteins (human serum albumin (HSA), collagen I (Col 1), and fibronectin (Fn)) were deeply studied from a chemical and physical point of view by using several analytical techniques such as Raman spectroscopy, UV−visible, transmission electron microscopy (TEM), 1 H NMR, and X-ray photoelectron spectroscopy (XPS)

Double functionalization for the design of innovative craniofacial prostheses

International audienceTitanium (Ti) is the most commonly used material for cranial prostheses. However, this material does not exhibit the same mechanical properties as the bone. Incorporating polymers onto Ti by combining both their properties is a solution to overcome this issue. Thus, sandwich materials made of two Ti skin sheets and a poly(methyl methacrylate) (PMMA) core are promising structures to design biomedical prostheses. The "grafting to" and "grafting from" procedures to functionalize the Ti/PMMA interface are described in this paper as two strategies for chemically connecting PMMA chains on Ti surfaces. The advantage of the first approach is the capacity to control the architecture of the grafted PMMA on Ti. Moreover, a method for selectively grafting a bioactive polymer such as poly(sodium styrene sulfonate) (PNaSS) on one side of the Ti and PMMA on the other side is developed. This contribution presents efficient ways of functionalizing Ti for biomedical applications

Effect of blasting treatment and Fn coating on MG63 adhesion and differentiation on titanium: A gene expression study using real-time RT-PCR

Biomaterial surface properties, via alterations in the adsorbed protein layer, and the presence of specific functional groups can influence integrin binding specificity, thereby modulating cell adhesion and differentiation processes. The adsorption of fibronectin, a protein directly involved in osteoblast adhesion to the extracellular matrix, has been related to different physical and chemical properties of biomaterial surfaces. This study used blasting particles of different sizes and chemical compositions to evaluate the response of MG63 osteoblast-like cells on smooth and blasted titanium surfaces, with and without fibronectin coatings, by means of real-time reverse transcription-polymerase chain reaction (qRT-PCR) assays. This response included (a) expression of the a5, av and a3 integrin subunits, which can bind to fibronectin through the RGD binding site, and (b) expression of alkaline phosphatase (ALP) and osteocalcin (OC) as cell-differentiation markers. ALP activity and synthesis of OC were also tested. Cells on SiC-blasted Ti surfaces expressed higher amounts of the a5 mRNA gene than cells on Al2O3-blasted Ti surfaces. This may be related to the fact that SiC-blasted surfaces adsorbed higher amounts of fibronectin due to their higher surface free energy and therefore provided a higher number of specific cell-binding sites. Fn-coated Ti surfaces decreased a5 mRNA gene expression, by favoring the formation of other integrins involved in adhesion over a5b1. The changes in a5 mRNA expression induced by the presence of fibronectin coatings may moreover influence the osteoblast differentiation pathway, as fibronectin coatings on Ti surfaces also decreased both ALP mRNA expression and ALP activity after 14 and 21 days of cell culture.Postprint (published version