Academic literature on the topic 'SBF bioactivity'

In the aim to decrease the degradation rate of magnesium in simulated body fluid, pure magnesium was treated by two different routes, i) by soaking specimens in an HF aqueous solution at 30oC for 30 min and ii) by heating specimens at 345oC for 15 min. The treated samples were immersed in simulated body fluid (SBF) at 37oC for different periods of time. Samples with no treatment were also immersed in SBF. The magnesium released into the SBF, the weight loss of the specimens and the pH of SBF increased with time of immersion in all the cases. The heat treated samples showed a lower degradation rate and lower pH values. A substantial decrease of magnesium concentration in the SBF corresponding to the heat treated samples was also observed. However, the degradation rate of the heat treated samples remains being extremely high. On the other hand, a bonelike apatite layer was observed after only 3 days of immersion in SBF in all the cases. The thickness of this layer increased with time of immersion. Further research needs to be performed to decrease the degradation rate. However, these results indicate that magnesium is a highly potential bioactive material for biomedical applications.

A series of PLGA (poly L-lactide-co-glycolide) based composites modified with gel-derived glasses in the form of foils were obtained by solvent casting procedure. As a modifier, glass particles with different chemical compositions from the CaO–SiO2, CaO–P2O5–SiO2, and Al2O3–SiO2 systems were used. All glasses were synthesized by the sol-gel process. Evaluation of bioactive properties of obtained composites was made on the basis of surface changes occurring during contact with simulated body fluid. The changes of Ca, P and Si ions concentration in SBF after incubation of composites were also measured. The result showed that all composites with bioglasses (CaO–SiO2, CaO–P2O5–SiO2) exhibit formation of calcium phosphates layer after SBF test, however, kinetics of Ca, Si ion release and P uptake from SBF was dependent on bioglass chemical composition. The higher solubility, as well as faster consumption of phosphorus from SBF, was observed for materials from CaO–SiO2 (T1/PLGA, S1/PLGA) compared to composites with respective bioglass particles from the CaO–P2O5–SiO2(T2/PLGA, S2/PLGA). Our results showed that rate of Si and Ca release from the gel-derived glasses and P uptake from SBF are dependent on both: the concentration of respective ions in the materials and the presence of phosphates in their structure. For materials modified with gel-derived glasses from Al2O3–SiO2 system no significant surface changes during contact with SBF were observed, and it seems that their behavior in physiological solution indicate that they are bio-inert materials.

We investigated the electrical polarizability of MgO and B2O3 containing bioactive glass (MBG). The MBG material with good manufacturing properties but low bioactivity was electrically polarized at a high dc field. The electrical polarizability of MBG was evaluated by thermally stimulated depolarization current (TSDC) measurements and immersion in simulated body fluid (SBF). The early precipitation of calcium phosphate on the negatively charged surface of the treated MBG demonstrated the increased bioactivity of the material and confirmed its polarizability. It is suggested that the electrical interactions between the polarized MBG and ions in SBF promoted the formation of the calcium phosphate precipitation. Accordingly, the increased bioactivity of the MBG in SBF is suggested to demonstrate the conversion of MBG into electrovector ceramics by the polarization treatment.

Chitosan-hydroxyapatite composite doped with strontium was synthesised via in situ co-precipitation method. Physicochemical properties of the composite obtained were analysed using X-ray diffraction (XRD), infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX) and Thermogravimetry with differential thermal analysis (DT-TGA). The synthesized composite was subjected to bioactivity studies in simulated body fluid (SBF). The calcium release from the sample in SBF was measured using atomic absorption spectroscopy (AAS). The physicochemical properties and bioactivity of the novel composite was compared with that of hydroxyapatite, strontium doped hydroxyapatite and chitosan hydroxyapatite. The in vitro bioactivity studies of the novel composite showed that it has a higher release of Ca2+ in the SBF compared to the other samples. The novel material was also found to induce more Ca2+ deposition after 28 days of immersion in the SBF. Hence, the novel composite material has the potential to be used as biomaterials for clinical application.

Particles of calcium phosphate were precipitated by raising the temperature and the pH of simulated body fluid (SBF) named Apatite Nuclei (AN). AN and polyvinylidene fluoride (PVDF) composites thin films with different weight percentages of AN in PVDF were fabricated by solution casting technique, using doctor blade method. In order to assess the bioactivity, the thin films were soaked in simulated body fluid (SBF). It was found that the film containing 30 wt.% of AN in PVDF actively induced hydroxyapatite formation in 3 days soaking period in SBF.

Based on the unique redox property of electrically conductive polymers, Ca2+ was incorporated into polypyrrole (PPy) film that previously doped with polyelectrolyte heparin. Then the apatite-forming ability of the Ca2+-doped PPy was examined by a biomimetic method using stimulated body fluid (SBF), which has ion concentration nearly equal to those of human blood plasma. It was found that the Ca2+-doped PPy successfully formed bonelike apatite deposition on its surface after soaking in SBF for only 3 days, whereas the similar apatite deposition was formed on Ca2+-free PPy after soaking in SBF for 7 days. These indicated that the entrapment of Ca2+ into PPy could accelerate the formation of apatite deposition and the Ca2+-doped PPy was possessed of enhanced bioactivity. It is expected that the Ca2+-doped PPy would be a useful bioactive coating material of metallic medical devices or tissue engineering scaffolds to promote the bone tissue regeneration.

Silicon coatings were prepared by vacuum plasma spraying (VPS) and air plasma spraying (APS) technologies. The samples were hydrothermally treated and then incubated in simulated body fluid (SBF) to evaluate their bioactivity and silicon wafer was used as control sample at the same time. The SBF test showed that a Ca-P layer was formed on the surface of silicon wafer and VPS-Si coating after immersion in SBF for certain time, indicating their improved bioactivity. Whereas no Ca-P layer was found on the surface of APS-Si coating. The results of X-ray photoelectron spectroscopy showed that the Si/O atomic ratio and chemical depth profiles of the silicon oxide films on the surface of silicon wafer, VPS-Si and APS-Si coatings were different. The results indicated that the bioactivity difference of silicon-based material resulted from the different composition of their surface. Hydrothermal treatment maybe a favorable method to improve the bioactivity of silicon-based material having silicon oxide of non-stoichiometric Si/O atomic ratio.

Two common methods have been used to evaluate the in vitro bioactivity of bioceramics for the application of bone repair. One is to evaluate the ability of apatite formation by soaking ceramics in simulated body fluids (SBF); the other method is to evaluate the effect of ceramics on osteogenic differentiation using cell experiments. Both methods have their own drawbacks in evaluating the in vitro bioactivity of bioceramics. In this commentary paper we review the application of both methods in bioactivity of bioceramics and conclude that (i) SBF method is an efficient method to investigate the in vitro bioactivity of silicate-based bioceramics, (ii) cellular bioactivity of bioceramics should be investigated by evaluating their stimulatory ability using standard bioceramics as controls; and (iii) the combination of these two methods to evaluate the in vitro bioactivity of bioceramics can improve the screening efficiency for the selection of bioactive ceramics for bone regeneration.

In this study the fabrication and characterization of a novel sol-gel derived HAp-CaO composite material is investigated. The bioactive behavior of the fabricated composite was assessed by immersion studies in SBF. A brittle and weakly crystalline carbonate hydroxyapatite (HCAp) layer was found to develop few hours after the immersion in SBF confirming high bioactivity. The presence of CaO accelerates the formation of HCAp phase.

Apatite formation in living body is essential condition for artificial materials to exhibit bone-bonding ability, i.e. bioactivity. It has been recently revealed that sulfonic group triggers apatite nucleation in body environment. Organic-inorganic hybrids consisting of organic polymer and the sulfonic group are therefore expected to be useful for novel bone-repairing materials exhibiting flexibility as well as bioactivity. In the present study, organic-inorganic hybrids were prepared from vinylsulfonic acid sodium salt and hydroxyethylmethacrylate (HEMA), a kind of acrylic polymer. Bioactivity of the hybrids was assessed in vitro by examining their acceptance of apatite formation in simulated body fluid (SBF, Kokubo solution). The obtained hybrids showed the apatite deposition after soaking in SBF within 7 d.

Dizertační práce se zabývala syntézou a studiem kompozitních materiálů pro potenciální lékařské využití. Teoretická část je zaměřena na biomateriály, zejména na kompozity složené z polyvinylalkoholu a hydroxyapatitu(PVA/HA). Byly připraveny kompozitní membrány složené z polyvinylalkoholu s různým hmotnostním zastoupením hydroxyapatitu - 0%, 10%, 20%, 30%, 40% a 50%. Hydroxyapatit (HA) byl připraven srážecí metodou z hydrogenfosforečnanu amonného a tetrahydrátu dusičnanu vápenatého ve vodném alkalickém prostředí. Vzniklá suspenze se smísila s roztokem polyvinylalkoholu, který byl připraven rozpuštěním ve vodě o teplotě 85° C. Jednotlivé směsi byly odlity do formy a sušeny po dobu 7 dní při teplotě 30 ° C, vzniklé 0,5 mm tenké membrány byly analyzovány ATR-FTIR spektroskopií k identifikaci funkčních skupin v kompozitu, dále byla provedena XRD analýza. Zkouška tahem a TGA měření byly realizovány k určení vlivu HA na mechanické vlastnosti, respektive změnu tepelné odolnosti kompozitů ve srovnání s čistým PVA. Byla provedena zkouška bioaktivity v simulovaném krevním roztoku (SBF) po dobu 2h, 7 a 28 dnů. SEM byla použita k charakterizaci povrchové mikrostruktury biocompositních membrán před a po ponoření do SBF. Na povrchu testovaných membrán vznikla vrstva apatitu, která je charakteristická pro bioaktivní materiály. Bylo zjištěno, že s rostoucím množstvím HA částic docházelo ke vzniku aglomerátů v kompozitu, které vznikly mimo jiné jako důsledek růstu krystalů HA během sušení membrán. Bioaktivita rostla s delším působením SBF na vzorky.

Se sintetizaron nanocompuestos híbridos en bloque de poli(etil metacrilato-co-hidroxietil acrilato) 70/30 wt%/sílice, P(EMA-co-HEA)/SiO2, con distintas proporciones de sílice hasta el 30 wt%. El procedimiento de síntesis consistió en la copolimerización de los monómeros orgánicos durante la polimerización sol-gel simultánea de tetraetoxisilano, TEOS como precursor de sílice. El TEOS se hidroliza eficientemente y condensa dando lugar a sílice, y presenta una distribución homogénea en forma de agregados inconexos de nanopartículas de sílice elementales en los híbridos con bajos contenidos de sílice (<10 wt%) o redes continuas interpenetradas con la red orgánica tras la coalescencia de los agregados de sílice (>10 wt%). La red polimérica orgánica se forma en los poros producidos en el interior de las nanopartículas elementales de sílice, y también en los poros formados entre los agregados de nanopartículas. Los nanohíbridos con contenidos de sílice intermedios (10-20 wt%) exhibieron las propiedades más equilibradas e interesantes: i) refuerzo mecánico de la matriz orgánica conseguida gracias a redes de sílice continuas e interpenetradas, ii) buena capacidad de hinchado debida a la expansión de la red orgánica no impedida todavía por un esqueleto de sílice rígido, y a un número alto de grupos silanol terminales hidrófilos (concentraciones inorgánicas en los alrededores de la coalescencia), y iii) mayor reactividad superficial debido a un contenido relativo bastante elevado de grupos polares silanol terminales disponibles en las superficies. La 'bioactividad' o capacidad de los materiales en bloque de formar hidroxiapatita (HAp) sobre sus superficies fue estudiada in vitro sumergiéndolos en fluido biológico simulado (simulated body fluid, SBF). La formación de la capa de HAp viene controlada por el mecanismo y el tiempo de inducción a la nucleación de la misma, que dependen a su vez de la estructura de la sílice.
Vallés Lluch, A. (2008). P(EMA-co-HEA)/SiO2 hybrid nanocomposites for guided dentin tissue regeneration: structure, characterization and bioactivity [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/3795
Palancia

L'acide fluorosilicique (FSA) est la principale eau usée générée par la fabrication d'acide phosphorique en Tunisie. Actuellement, Une énorme quantité de cet acide est générée comme sous-produit de l'industrie des engrais phosphatés. En plus des pertes économiques, le rejet de cette industrie dans la mer, entraine également un véritable danger dans le cadre écologique pour le domaine marin. Par conséquent, notre attention s'est portée sur le développement d'un procédé de traitement par extraction de la silice de ces déchets fluorés, qui peut être utilisée dans plusieurs applications intéressantes comme la synthèse de biomatériaux. En effet, cette étude se concentre sur la récupération du fluor dans l'industrie des engrais phosphatés, la majeure partie de cette récupération étant basée sur la FSA. En fait, cette étude se concentre sur la récupération du fluor dans l'industrie des engrais phosphatés, la majeure partie de cette récupération étant basée sur la FSA. Le processus implique la réaction de FSA et d'hydroxyde de sodium pour générer la suspension aqueuse alcaline. Les particules de silice extraites ont une largeur moyenne de particule de 50 à 60 nm et une longueur à l'échelle microscopique. La seconde partie de ce travail de recherche porte sur la synthèse de verres bioactifs à partir de cette silice extraite pour une utilisation comme biomatériau osseux. Ils sont synthétisés par la méthode de fusion dans le système SiO₂-CaO-Na₂O-P₂O₅. L'ingénierie tissulaire est apparue comme une approche alternative pour créer du tissu osseux en cultivant des cellules sur des échafaudages 3D. Cette étude a pour objectif de synthétiser un composite verre / chitosane (BG-CH) en utilisant le procédé New Salt Leaching Using Powder (SLUP) afin de contrôler le taux de porosité puis la réactivité chimique du produit final. Le processus SLUP consiste à créer de cavités avec les tailles de pores souhaitées. Ce processus est basé sur la dissolution des particules de NaCl utilisées pour cela. Cela est dû à sa grande solubilité dans les milieux aqueux. Il ne nécessite pas de traitement thermique. Ce travail est basée sur l’élaboration, la caractérisation physico-chimique et l’évaluation biologique de bioverre pure et associé au chitosane. Une gamme de scaffolds avec différentes teneurs en verre bioactif / chitosane a été synthétisée. Différents tailles des particules du NaCl ont été utilisés dans le but d'optimiser le réseau de pores. Les résultats obtenus montrent que la surface spécifique et le volume des pores augmentent avec l'augmentation de la teneur en chitosane et en porogène (NaCl). Les mêmes observations pour le volume des pores ont été enregistrées. Les scaffolds obtenus avaient une porosité élevée (90%) avec une forte connectivité entre pores. Les images MEB ont révélé une forte dépendance des tailles et des formes des pores de rapports sel / composite
Fluorosilicic Acid (FSA) is the main wastewater generated by the phosphoric acid manufacture in Tunisia. Currently, this effluent is wildly discharged into the sea, which is an ever more serious environmental stake for phosphoric acid production plants. Therefore, our attention has been focused on developing a treatment process by extracting silica from this fluorine waste, which can be used in several interesting applications such as the synthesis of biomaterials. In fact, this study focuses on fluorine recovery in the phosphate fertilizer industry, with most of this recovery based on FSA. To model and optimize the process conditions, response surface methodology and a full factorial design were employed in the extraction of silica from FSA. The process involves the reaction of FSA and sodium hydroxide to generate the alkaline aqueous slurry. Extracted silica particles were found to have an average particle width of 50-60 nm and length in the micronic scale. The second part of this research work focuses on synthesis of bioactive glasses based on this extracted silica for use as bone biomaterial. They are synthesized by the melting method in the system SiO₂-CaO-Na₂O-P₂O₅. Tissue engineering has emerged as an alternative approach to create bone tissue by growing cells on 3D scaffolding. The aim of this study was to synthesize a composite glass/chitosan (BG-CH) by using New Salt Leaching Using Powder (SLUP) process in order to control the porosity rate and then the chemical reactivity of the final product. SLUP process consists on the cavities creation with desired pore sizes. This process is based on the washing out the NaCl particles used for that. It is due to its high solubility in aqueous media. It does not require heat treatment. This work focuses on the elaboration, physicochemical and chemical reactivity studies of pure bioactive glass and bioactive glass associated with chitosan. A range of composite scaffolds with different bioactive glass/Chitosan contents has been synthesized. NaCl with a distinct range size was used with the aim of optimizing the pore network. Obtained results show that the specific surface area and pores volume increase with increasing of chitosan and porogen content. The same observations for pores volume were registered. The obtained scaffolds had high porosity (90%) with good pore connectivity. SEM images revealed strong dependence of sizes and shapes of pores on the salt/composite ratios

Bioactive glass ceramics (BGCs) have been used in orthopedic and dentistry due to having better osteoconductive and osteostimulative properties. This study aimed to evaluate and compare the drug release properties of two different BGCs; 45S5 and S53P4. The BGCs were composed with four phases of SiO2 – CaO – Na2O – P2O5 system, synthesized by sol–gel method using dual templates; a block-copolymer as mesoporous templates and polymer colloidal crystals as macroporous templates, called three-dimensionally ordered macroporous-mesoporous bioactive glass ceramics (3DOM-MBGCs). In vitro bioactivity test performed by soaking the 3DOM-MBGCs in simulated body fluid (SBF) at 37°C. The results indicated that, the 45S5 have the ability to grow hydroxyapatite-like layer on the surfaces faster than S53P4. Gentamicin drug was used to examine in vitro drug release properties in phosphate buffer solution (PBS). The amount of drug release was quantified through UV/Vis spectroscopy by using o-phthaldialdehyde reagent. S53P4 showed high drug loading content. The outcome of drug release in PBS showed that both S53P4 and 45S5 exhibited a slowly continuous gentamicin release. The resultant drug release profiles were fitted to the Peppas-Korsmeyer model to establish the predominant drug release mechanisms, which revealed that the kinetics of drug release from the glasses mostly dominated by Fickian diffusion mechanism.

Achieving optimal mechanical strength of scaffolds is the key issue in bone tissue engineering. We describe a biomimetic route for design of composites of polymers (polyacrylic acid (PAAc) and polycaprolactone (PCL)) and hydroxyapatite (HAP). The mineral polymer interfaces have a significant role on mechanical behavior as well as bioactivity of the composite systems. We have used a combination of experimental (photoacoustic infrared spectroscopy) as well as modeling (molecular dynamics) techniques to evaluate the nature of interfaces in the composites. Porous composite scaffolds of in situ HAP with PCL are made. Our simulation studies indicate calcium bridging between COO− of PAAc and surface calcium of HAP as well as hydrogen bonding. These results are also supported by infrared spectroscopic studies. PAAc modified surfaces of in situ HAP influence the microstructure and mechanical response of porous composites. Significant differences are present in the mechanical response of in situ and ex situ composite scaffolds. In addition, the growth and mechanism of apatite growth in the in situ and ex situ composites is different. Bioactivity is measured by soaking composite scaffolds in simulated body fluid (SBF). Apatite growth in ex situ composites is primarily by heterogeneous nucleation and that in in situ is primarily by homogeneous nucleation. We also observe that apatite grown on in situ HAP/PCL composites from SBF exhibits higher elastic modulus and hardness. Thus, by influencing the interfacial behavior in bone biomaterials both mechanical response and bioactivity of the composite systems may be modified. The present study gives insight into the interfacial mechanisms responsible for mechanical response as well as bioactivity in biomaterials.