Papers by Keyword: Protein Adsorption

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Authors: Marcia S. Sader, Elena Mavropoulos, Ana Paula Moreira Duarte, Moema Hausen, Andrea Machado Costa, Jessica Dornelas, Marcelo N. Tanaka, Gloria A. Soares, Alexandre Rossi
Abstract: The influence of surface chemistry, roughness and hidrophilicity on the protein adhesion onto the biomaterial modulates the cell attachment, proliferation and differentiation. β-TCP is a synthetic bone substitute with bioactive, osteoconductive properties. Insulin is a polypeptide hormone that acts as a growth-stimulating factor for some cells types in culture. Few studies have been discussing this hormone role in bone remodeling and cells metabolism in vitro. The aim of this work was to evaluate the cell responses when insulin is adsorbed on β-TCP commercial discs surfaces. FTIR detected the characteristics bands of insulin adsorbed on sintered powder surface. The insulin adsorption on discs surface increase its wettability and favored growth and differentiation of the pre-osteoblastics cells. Although no addition of differentiation factors was present, it was observed deposits of extracellular matrix and collagen at 7 days in culture. The increase on affinity and cellular activity to the adsorbed insulin β-TCP substract was remarkable. It was quite clear that the insulin presents a role on activate and speed up the bone cells response while adhered to β-TCP substract. However, the insulin application on bone grafts for clinical purposes must be considered after detailed studies on animal models, which are required to fully evaluate the safe use of hormone containing grafts in clinical trials.
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Authors: Naznin Sultana, Min Wang
Abstract: Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) was used to make composite scaffolds for bone tissue engineering in our previous studies. To control the degradation rate and process of composite scaffolds, PHBV was blended with poly(L-lactic acid) (PLLA), which has a much higher degradation rate than PHBV, and PHBV/PLLA blends were used as polymer matrices for composite scaffolds. Composite scaffolds based on these blends and containing nano-sized hydroxyapatite (nHA) were fabricated using an emulsion freezing / freeze-drying technique. Non-porous films of PHBV/PLLA blends were prepared using the solvent casting method. In vitro degradation tests of non-porous PHBV/PLLA blends and porous composite scaffolds were conducted by immersing samples in phosphate buffered saline (PBS) for various periods of time. It was found that the composition of polymer blends affected water uptake of films and scaffolds. For PHBV/PLLA-based scaffolds, the incorporated nHA particles also significantly increased water uptake within the initial immersion time. Both PHBV/PLLA blends and composite scaffolds underwent rapid weight losses within the first few weeks. The degradation of composite scaffolds arose from the dissolution of nHA particles and degradation of the PLLA component of polymer blends. Composite scaffolds exhibited enhanced adsorption of bovine serum albumin (BSA), a model protein, in the current study.
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Authors: Ludwig J. Gauckler, Kurosch Rezwan
Abstract: Protein adsorption onto metal oxide surfaces is an essential aspect of the cascade of biological reactions taking place at all interfaces between implanted materials and the biological environment. The types and amounts of adsorbed proteins mediate subsequent adhesion, proliferation and differentiation of cells. Protein adsorption to surfaces of metal oxides and their kinetics are important in the formation and growth of seashells, one of the toughest natural ceramics, in modern bio-analytical devices as well as in bone and teeth implant technology. This paper describes results obtained in a feasibility study of how to use metal-oxide particles to obtain biosensors with a high turnover. The most important features of proteins are outlined describing them as purpose-built "polymers" from amino acids with specific conformations. Some key aspects of Metaloxide (MeO) surfaces in water and the influence of electrostatic and hydrophobic interaction on protein adsorption are reported. Results concerning the interaction between different proteins and MeO surfaces in water are discussed in detail. Examples of purely electrostatic interactions of proteins with MeO surfaces as well as the influence of hydrophobic interaction are elucidated. An outlook of the implications of the new insights on natural and synthetic materials will be given concerning bio-compatibility, bio-mineralization and self assembly of materials.
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Authors: Motohiro Tagaya, Toshiyuki Ikoma, Taro Takemura, Mitsuhiro Okuda, Nobutaka Hanagata, Tomohiko Yoshioka, Dinko Chakarov, B. Kasemo, M. Tanaka
Abstract: The adsorption of multiple proteins derived from fetal bovine serum (FBS) in phosphate buffer saline (PBS) and alpha minimum essential (aMEM) was in situ analyzed with a quartz crystal microbalance with dissipation technique on gold, titanium and HAp sensors. The adsorption behaviors of FBS proteins were varied depending on the sensors. The DD/Df value of the HAp sensor were clearly different in PBS and aMEM, and others were not changed. The viscoelastic properties of the protein films adsorbed on the HAp sensor in PBS were flexible in comparison with those on the gold and titanium sensors. The D-f plots incidated that the proteins adsorbed on HAp in PBS would lead to competitive adsorption and conformational change and those in aMEM could form a monolayer. The adsorption behavior on the HAp in carbonate buffer saline was found to be similar to that in aMEM. These differential adsorption behaviors on the HAp surface were attributed to the pre-adsorptive ion, such PO43- or CO32- in the solvent.
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Authors: Maria Bousnaki, Petros Koidis
Abstract: When used as an implanted material, titanium (Ti) surface controls the subsequent biological reactions and leads to tissue integration. Cells interactions with the surface, through a protein layer that is being formed from the moment Ti surface comes in contact with blood and its components, and indeed this protein layer formation, are regulated by surface properties such as topography, chemistry, charge and surface energy. Currently, the implementation of nanotechnology, in an attempt to support mimicking the natural features of extracellular matrix, has provided novel approaches for understanding and translating surface mechanisms whose modification and tailoring are expected to lead to enhanced cell activity and improved integration. Despite the fact that there has been extensive research on this subject, the sequence of interactions that take place instantly after the exposure of the implanted material into the biologic microenvironment are not well documented and need further investigation as well as the optimization of characteristics of Ti surface. This review, including theoretical and experimental studies, summarizes some of the latest advances on the Ti surface concerning modifications on surface properties and how these modifications affect biomolecular reactions and also attempts to present the initial adsorption mechanism of water and protein molecules to the surface.
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Authors: Reshmi Dey, Pranjali Nanda, Arunachalam Thirugnanam
Abstract: The aim of the present investigation is to enhance in-vitro bioactivity and protein adsorption of porous titanium with 3D interconnected pores by various chemical treatments (alkali, dual acid, citric acid and fluoride treatments). The untreated and treated samples were characterized using X-ray powder diffraction (XRD), optical microscopy and scanning electron microscopy (SEM). The protein adsorption study was carried out with Bradford’s reagent using Bovine Serum Albumin (BSA). The optical microscopy reveals that untreated Ti sample exhibited 41.36% surface porosity. The in-vitro bioactivity of the treated and untreated Ti sample was evaluated by immersing them in simulated body fluid (SBF) for different time intervals. The immersed samples were characterized using XRD and SEM to confirm the growth and morphology of apatite. It was observed that apatite deposition of fluoride treated sample was denser than other treated samples for the same period immersed in SBF. All the surface treated samples showed good protein adsorption. The alkali treated sample showed maximum protein adsorption amongst other chemically treated samples which may be due to enhanced micro-roughness and strong electrostatic affinity between the protein and the surface. The enhanced in vitro bioactivity in the surface treated porous titanium indicates that the healing time of the bone and implant in patients can be reduced with good osseointegration.
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Authors: Barbara Nebe, Frank Luethen, Regina Lange, Ulrich Beck
Abstract: The contact of a cell on the biomaterial’s surface is mediated by its adhesion components. The topography of titanium surfaces influences these adhesion components of osteoblasts, e.g. the integrins, the adapter proteins and the actin cytoskeleton. In our current experiments we were interested in why osteoblasts were strongly aligned to the grooves of a structured pure titanium surface (grade 2). The titanium was characterized by EIS to get insights in the electro-chemically active surface. We used MG-63 human bone cells, cultured in DMEM with 10% FCS at 37°C. For protein adsorption the titanium discs were incubated for 24h with complete medium containing soluble fibronectin at 37°C. Interestingly, only in the grooves cells adhered and were aligned and this is not dependent on the gravitation. The cell adhesion seems to depend on the protein adsorption of fibronectin which we could find to be adsorbed exclusively in the valleys. We speculate that there are local differences in electro-chemical characteristics of this structured titanium surface.
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Authors: Toru Tonegawa, Toshiyuki Ikoma, Tomohiko Yoshioka, Guo Ping Chen, Nobutaka Hanagata, M. Tanaka
Abstract: The adsorption properties of metal ions containing hydroxyapatite (Ca10(PO4)6(OH)2, HAp) were elucidated for the development of protein drug carrier. As-prepared metal ion containing HAp nanocrystal showed plate-like morphology with 10-20nm in length and 5-10nm in width. The metal ion containing HAp microparticles had higher specific surface area than the HAp microparticle. The adsorption amount per unit area of HAp showed higher than those of metal ion containing HAp. The adsorption behavior followed the Langmuir curves for each protein, indicating the monolayer adsorption. The loaded amount of proteins could be one of the most important properties for the application of drug delivery carrier.
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Authors: Satoshi Nagai, Kanji Tsuru, Satoshi Hayakawa, Akiyoshi Osaka
Abstract: The structural change of bovine serum albumin (BSA) was analyzed by means of ultraviolet (UV) and circular dichroism (CD) spectroscopy due to in contact with ceramics powders such as Al2O3, SiO2, TiO2, ZrO2, hydroxyapatite and b-tricalcium phosphate. The absorbance of the UV spectra increased for the BSA solution in contact with TiO2, ZrO2 and Al2O3, that is, the BSA solution clouded. This indicated the aggregation of BSA after contact with those ceramics powders. The CD spectroscopy showed that the ordered secondary structure of BSA was diminished on contact with TiO2 and ZrO2. We discussed the protein adsorption property of ceramics on the basis of the magnitude of the interaction forces between proteins and the bioceramics.
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Authors: Zong Bin Liu, Bei Zhang, Brian Yu Fung Pow, Mo Yang, Arthur Fuk Tak Mak
Abstract: This paper introduces a new method of surface modification by self-assembled monolayer (SAM) and polymer monolayer grafting. Since most of the glass surfaces lack the reactive functional group, an activation process with 3-(trimethoxysilyl)propyl methacrylate(TPM) is used in our experiment to generate the vinyl reactive sites on the substrate surface for further graft polymerization. The TPM saline layer acts as the “anchor” part to link the functional part onto the surface of substrate. The paper summarizes the surface modifications by the polymerizations of PEGMA, AA(Acrylic acid) and NVP(Nitrogen-vinyl-2-pyrrolidone) respectively and their applications for protein adsorption and cell adhesion through a series of measurements. In previous research, AA and NVP had also been adopted for surface treatment and had achieved good results. The substrate can be glass, alumina, silicon, metals or stainless steel. We choose glass as our substrate during the experiment.
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