Papers by Keyword: Protein Adsorption

Abstract: The surface structure of Hydroxyapatite (HAp) particles during hydrothermal synthesis and their protein adsorption behavior was investigated. The HAp particles were prepared by mixing calcium acetate solution and diammonium hydrogen phosphate solution by hydrothermal synthesis. When the temperature of mixture were heated up to 120°C, 150°C and 180°C, the HAp particles were collected during hydrothermal synthesis. The adsorption properties of proteins onto HAp were studied using three types of proteins: bovine serum albumin (BSA), myoglobin (MGB) and lysozyme (LSZ). Surface analysis by BET revealed that their pore volumes were decreased by increasing synthesis temperature. The adsorbed amount of BSA and LSZ per unit milligrams showed no obvious difference in all of the HAp particles prepared with synthesis temperature. In contrast, the amount of MGB adsorbed onto HAp particles synthesized at 120°C, 150°, and 180°C shows the decreasing with an increasing synthesis temperature. This result suggests that the adsorbed amount of MGB was decreased by decreasing pore volume of HAp particles.

Abstract: Protein adsorption is considered to have a strong influence on the biological reactions of bone-substituting materials. However, the osteoconductivity of protein adsorbed Ti surface is not completely clear. In this study, we produced the protein adsorbed Ti implants using hydro-processing. The hydrothermal treatment in the distilled water gave the super-hydrophilic Ti surface and they had much protein adsorbability. Fibronectin or albumin was picked up as a protein, which was cell adhesive protein and not cell adhesive, respectively. And also, the content of the adsorbed protein was evaluated by FT-IR (ATR) analysis. The water contact angle influenced the amount of the adsorption of the protein and the osteoconductivity of the samples were evaluated by in vivo testing.

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.

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.

Abstract: Gelatin methacrylate (GelMA) hydrogel comprised of modified natural extracellular matrix (ECM) components, making it a potentially attractive material for surface modification. In this paper, we hypothesize that establishing a GelMA hydrogel coating on titanium surface will accelerate osseointegration. Titanium substrates were silanized with 3-Aminopropyltriethoxysilane (APTES), which was treated by alkali-heated treatment firstly. The GelMA hydrogel coating was constructed on the silanized titanium surface by in situ photopolymerization under UV illumination. Adsorption of bovine serum albumin (BSA) onto modifed titanium surfaces was investigated. The results showed that GelMA-coated titanium adsorbed greater amount of protein than other Ti surfaces. The differences in protein adsorption behavior could result in very different initial cellular behavior on GelMA-coated titanium implant surfaces.

Abstract: Hydroxyapatite Ca₁₀(PO₄)₆(OH)₂ (HAP) is widely applied in a biomaterial because of its excellent biocompatibility and bioactivity. However, all properties of HAP, especially the adsorption properties can be tailored by modifying the composition with ionic substitutions. Among many cations that can substitute for calcium in the structure of HAP, strontium is a kind of essential trace elements in human body. It has been known as one of the cationic substitute for calcium in the HAP lattice. The strontium-substituted hydroxyapatite (Sr-HAP) is formed when strontium is doped in HAP structure. The bioactivity, biocompatibility, and adsorption properties are improved when the original lattice of HAP is destroyed. In this study, we focus on synthesis of strontium-substituted HAP nanocrystals in ultrasonic field which is a mild and simple synthesis method. The Sr-HAP with different Sr contents was synthesized. The effects of reaction temperature, sintering temperature and reaction time on protein adsorption of Sr-HAP were studied. In addition, the crystalline phase, chemical compound, surface area and morphology were characterized by XRD, FTIR, TEM and BET. The results indicate that the original lattice of HAP was destroyed and the structure of HAP doped with strontium formed. Sr-HAP with smaller crystal size, larger specific surface area and homogeneous distribution was prepared. Especially, it has great adsorption to target protein, bovine serum albumin (BSA).

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.

Abstract: In total hip replacement, once the stem–cement interface debonds under physiological loading, pseudo-synovial fluid would be pumped into this interface serving as the lubricant. In the present study, a tribological test was performed using stainless steel 316L and bone cement lubricated by 25% calf serum. The results demonstrated that the mean friction coefficient was 0.35 and slight scratches were observed on the stainless steel 316L surface. The thickness of physically adsorbed proteins was calculated as more than 10 µm, which protected the stem surface from fretting wear.

Abstract: Fibrinogen adsorption onto surface-attached poly(methacrylic acid) monolayers and poly(methacrylic acid)/polyethyleneimine bilayers has been investigated. The adsorbed amount of fibrinogen was found to be dependant on the charge sign of the topmost layer because of electrostatic interactions.

Abstract: This study is concerned with multilayered protein adsorption on carbonate apatite (CAp) that is measured with a quartz crystal microbalance (QCM) technique. A carbonate apatite-deposited QCM sensor was prepared by electrophoretic deposition (EPD). On the CAp-deposited QCM sensor, fibrinogen adsorption followed by thrombin adsorption was investigated. The adsorption of fibrinogen on CAp led to a clear decrease in the resonance frequency of the sensor, which means that fibrinogen adsorbed on the CAp-deposited QCM sensor. The adsorbed amount of fibrinogen was larger on CAp than on a pristine sensor (Au). Although successive thrombin adsorption occurred on fibrinogen adlayers on both CAp and Au, the adsorbed amount and its conformation were different depending on the surface.