Immersion In SBF Research Articles

A nanotectonics approach to produce hierarchically organized bioactive glass nanoparticles-based macrospheres

Bioactive particles have been widely used in a series of biomedical applications due to their ability to promote bone-bonding and elicit favorable biological responses in therapies associated with the replacement and regeneration of mineralized tissues. In this work hierarchical architectures are prepared by an innovative methodology using SiO(2)-CaO sol-gel based nanoparticles. Inspired by colloidal crystals, spherical aggregates were formed on biomimetic superhydrophobic surfaces using bioactive glass nanoparticles (BG-NPs) able to promote bone regeneration. A highly ordered organization, a common feature of mineralized structures in Nature, was achieved at both nano- and microlevels, being the crystallization degree of the structures controlled by the evaporation rates taking place at room temperature (RT) or at 4 °C. The crystallization degree of the structures influenced the Ca/P ratio of the apatitic film formed at their surface, after 7 days of immersion in SBF. This allows the regulation of bioactive properties and the ability to release potential additives that could be also incorporated in such particles with a high efficiency. Such a versatile method to produce bioactive particles with controlled size and internal structure could open new possibilities in designing new spherical devices for orthopaedic applications, including tissue engineering.

In vitro corrosion behavior of Ti-O film deposited on fluoride-treated Mg–Zn–Y–Nd alloy

In this paper, a new composite coating was fabricated on magnesium alloy by a two-step approach, to improve the corrosion resistance and biocompatibility of Mg–Zn–Y–Nd alloy. First, fluoride conversion layer was synthesized on magnesium alloy surface by immersion treatment in hydrofluoric acid and then, Ti-O film was deposited on the preceding fluoride layer by magnetron sputtering. FE-SEM images revealed a smooth and uniform surface consisting of aggregated nano-particles with average size of 100nm, and a total coating thickness of ∼1.5μm, including an outer Ti-O film of ∼250nm. The surface EDS and XRD data indicated that the composite coating was mainly composed of crystalline magnesium fluoride (MgF2), and non-crystalline Ti-O. Potentiodynamic polarization tests revealed that the composite coated sample have a corrosion potential (Ecorr) of −1.60V and a corrosion current density (Icorr) of 0.17μA/cm2, which improved by 100mV and reduced by two orders of magnitude, compared with the sample only coated by Ti-O. EIS results showed a polarization resistance of 3.98kΩcm2 for the Ti-O coated sample and 0.42kΩcm2 for the composite coated sample, giving an improvement of about 100 times. After 72h immersion in SBF, widespread damage and deep corrosion holes were observed on the Ti-O coated sample surface, while the integrity of composite coating remained well after 7d. In brief, the data suggested that single Ti-O film on degradable magnesium alloys was apt to become failure prematurely in corrosion environment. Ti-O film deposited on fluoride-treated magnesium alloys might potentially meet the requirements for future clinical magnesium alloy stent application.

Investigation on sulphonated PEEK beads for drug delivery, bioactivity and tissue engineering applications

Poly ether ether ketone (PEEK) has wide applications in the field of medicine as a prosthetic material and can be sulphonated using sulphuric acid. This study focuses on the fabrication of water soluble SPEEK beads using infusion pump and the obtained beads were characterised using Fourier Transform Infra Red (FTIR) spectroscopy to confirm the sulphonation, while their surface morphology was studied using scanning electron microscope (SEM). In order to study the bioactivity of the prepared beads, hydroxyapatite was dispersed within them followed by their immersion in SBF. In order to study the drug release kinetics of the beads, they were loaded with amoxicillin in different concentrations. Cytotoxicity studies were performed by MTT method and ALP activity was measured using mouse osteoblast cells (MC3T3-E1). The SEM and FTIR of the prepared beads confirmed the morphology and the sulphonation of the prepared beads. Also, the apatite formation on the SPEEK beads, subsequent to their immersion in SBF, proved that the beads possessed excellent bioactivity. Moreover, the beads developed exhibited low cytotoxicity, implying good biocompatibility and safety. Thus, the results of the study indicated that the novel SPEEK beads could potentially be used as a drug carrying vehicle with low toxicity.

Si-tricalcium phosphate cement: preparation, characterization and bioactivity in SBF

There are evidences considering the effectiveness of Si on enhancing biological properties of calcium phosphates; however, there are not many works relating to the Si-alpha-TCP bone cement. The influence of silicon doping on the properties of Α-TCP cement was analyzed. Si-TCP was obtained by a solid state reaction employing CaCO3, CaHPO4 and CaSiO3 and powder was analyzed by XRD, FTIR, XRF and BET specific area. Cement samples were analyzed for their surface of fracture morphology, mechanical resistance and SBF bioactivity. Cement mechanical resistance was not satisfactory for biomedical application; nonetheless, sample's surface was coated by an apatite layer after immersion in SBF. Notwithstanding, to ensure that silicon is the element responsible for increasing the material's bioactivity it is necessary to evaluate the in vivo performance of the bone cement obtained in this work.

Highly adherent bioactive glass thin films synthetized by magnetron sputtering at low temperature

Thin (380-510 nm) films of a low silica content bioglass with MgO, B(2)O(3), and CaF(2) as additives were deposited at low-temperature (150°C) by radio-frequency magnetron sputtering onto titanium substrates. The influence of sputtering conditions on morphology, structure, composition, bonding strength and in vitro bioactivity of sputtered bioglass films was investigated. Excellent pull-out adherence (~73 MPa) was obtained when using a 0.3 Pa argon sputtering pressure (BG-a). The adherence declined (~46 MPa) upon increasing the working pressure to 0.4 Pa (BG-b) or when using a reactive gas mixture (~50 MPa). The SBF tests clearly demonstrated strong biomineralization features for all bioglass sputtered films. The biomineralization rate increased from BG-a to BG-b, and yet more for BG-c. A well-crystallized calcium hydrogen phosphate-like phase was observed after 3 and 15 days of immersion in SBF in all bioglass layers, which transformed monotonously into hydroxyapatite under prolonged SBF immersion. Alkali and alkali-earth salts (NaCl, KCl and CaCO(3)) were also found at the surface of samples soaked in SBF for 30 days. The study indicated that features such as composition, structure, adherence and bioactivity of bioglass films can be tailored simply by altering the magnetron sputtering working conditions, proving that this less explored technique is a promising alternative for preparing implant-type coatings.

Enhancement of cells proliferation and control of bioactivity of strontium doped glass

Bioactivity and chemical reactivity of bioactive glass offer the ability to bond for soft and hard biological tissues. In this work, synthesis was carried out by using melting and rapid quenching. Strontium was introduced as trace element at different contents in the glass matrix, according to its concentration in the bone matrix. This chemical element presents a high interest in the bone metabolism activity. Investigations were conducted on the surface of biomaterials by using in vitro assay after immersion in SBF. Several physico-chemical methods such as SEM, FTIR, NMR, ICP-OES and MTT test were employed to highlight the effects of the Sr. The in vitro experiments showed that after soaking in SBF, the behaviour of pure glass is different compared to glass doped with Sr. NMR analyses showed in the 29Si MAS-NMR that glass matrix undergoes some changes after in vitro assays particularly the emergence of new components attributed to Q 3(OH). The presence of Sr slowed down the bioactivity of glass after immersion in SBF. The non toxic character of compounds was confirmed. Introduction of Sr at 0.1 wt % induce an enhancement of cells at about 14.3%.

Surface characterization analysis of failed dental implants using scanning electron microscopy

Objective. To investigate the failure of 15 dental implants (Paragon/Zimmer) in relation to their surface quality. Materials and methods. The study comprised of 15 dental implants (7 mm D Advent Implant, 3.9 mm D apex design implant), which were followed from surgery to completion of prosthetic restorations. The implants were placed during a 6-year period from 2003–2009 in non-smoking patients (male; 7, females; 5). There were eight upper and seven lower implants. Surface characterization after immersion in SBF of these failed implants was investigated using SEM and EDS compared to that of an unused implant of the same brand. Results. Results revealed that, following immersion in SBF, the implant surfaces showed new components like Ca+, Na+ and Cl−, but in trace quantities. Conclusions. After SEM observation and EDS analysis, it was concluded that the apatite layer formation could not be verified.

Development and characterization of a novel bioresorbable and bioactive biomaterial based on polyvinyl acetate, calcium carbonate and coralline hydroxyapatite

Coralina® HAP-200 (coralline hydroxyapatite obtained by hydrothermal treatment of marine corals) and POVIAC® (polymeric matrix based on PVAc), commercial trade marks were mixed with a natural product from the Cuban sea costs, i.e. calcium carbonate from Porites Porites coral, to obtain a novel bioactive composite with potential use as bone restoration material. The samples were characterized by physical-chemical (FTIR, XRD, SEM, EDS) and mechanical studies. It was shown that there is no chemical interaction between the inorganic filler and the polymer matrix, each conserving the original properties of the raw materials. The studied formulation had a compressive strength similar to that reported for trabecular bone. Scanning electron microscopy examination revealed that the addition of CaCO3 induces a change on the morphologic structure of the composite obtained after 30 days of SBF immersion. These composites generate novel biomaterials capable of promoting the deposition of a new phase, a Ca-P layer due to the bioactivity of a Ca2+ precursors.

Structure and apatite induction of a microarc-oxidized coating on a biomedical titanium alloy

An oxide coating with nanostructure was prepared by micro-arc oxidation (MAO) on a biomedical Ti–24Nb–4Zr–7.9Sn alloy. Chemical composition of the coating mainly includes O, Ti, Nb, Ca, P, Na, Zr and Sn, where the ratio of Ca/P is about 1.6. Ti, Nb, Zr and Sn participate in the oxidation to form TO 2, Nb 2O 5, ZrO 2 and SnO 2 nanocrystals, while Ca, P and Na are present in the form of amorphous phases. After alkali treatment, the surface of the MAO coating becomes rough, and Na concentration increases remarkably while P disappears basically. The alkali treated coating shows better apatite forming ability than the untreated one, as evidenced by apatite formation after SBF immersion for 7 days. The improvement of apatite forming ability of the modified coating is attributed to the formation of a sodium titanate layer and numbers of submicron-scale network flakes. The enhancement of the surface wettability of the alkali treated coating also plays an important role in promoting the apatite forming ability.

Silver ion-exchanged sodium titanate and resulting effect on antibacterial efficacy

Surface modification with silver ion is an effective way to reduce infections. In the present work, the effect of silver ion-exchanged sodium titanate on the titanium has characterized by thin film X-ray diffraction analysis (TF-XRD) and high resolution scanning electron microscopy (HR-SEM). Antibacterial activity of silver ion-exchanged sodium titanate on titanium was assessed by the plate-counting method using against Staphylococcus aureus. The results show that silver ion-exchanged samples improve the antibacterial activity depends on NaOH concentration in electrolyte while the titanium oxide layer shows a significant decline. It is also found that the apatite-forming ability of silver ion-exchanged samples was showed after 7 days by immersion in SBF. In conclusion, silver ion-exchange method to the sodium-titanate is favorable to increase the antibacterial activity of titanium surfaces as well as apatite-forming ability.

Effect of the content of hydroxyapatite nanoparticles on the properties and bioactivity of poly(l-lactide) – Hybrid membranes

Poly(l-lactide)/hydroxyapatite, PLLA/HA, composite membranes for bone regeneration with different concentrations of nanoparticles have been prepared and their physicochemical properties and bioactivity have been determined. Hydroxyapatite nanoparticles act as nucleating agent of the poly(l-lactide) crystals, as detected by DSC, and as reinforcing filler, as proven by the monotonous increase of the elastic modulus of the microporous membranes with increasing nano-filler content. The bioactivity, which regards to the use of these materials in bone regeneration, was tested by immersing the samples in a simulated body fluid, SBF. A faster deposition of a biomimetic apatite layer was observed as increases the content of hydroxyapatite nanoparticles, thus membranes with a 15% (w/w) of hydroxyapatite particles (relative to PLLA weight) present a homogeneous layer of hydroxyapatite on the surface of their pores after 7days of immersion in SBF. An especial emphasis has been made on the influence of a plasma treatment on the bioactivity of the membranes. With this aim, the membranes were submitted to a plasma treatment previously to their immersion in a simulated body fluid. It has been observed that the surface of a PLLA membrane after 21days of immersion in SBF is still not completely covered by hydroxyapatite whereas the same sample treated with plasma show a smooth layer of biomimetic hydroxyapatite. The increase of bioactivity achieved with this treatment was less important in high hydroxyapatite content composites.

Biomimetic apatite coating on magnetite particles

Apatite-coated magnetite particles have been prepared using a novel biomimetic method. This method consisted of immersing magnetite particles in simulated body fluids (SBF, 1.5 SBF) along with disk-shaped sintered wollastonite. Different routes were followed: 7 days of immersion in SBF or 1.5 SBF and 7 or 28 days using a re-immersion method. The magnetic properties were evaluated both before and after the biomimetic process. A bone-like apatite layer was formed on all the samples tested and not a significant change was observed on their original magnetic behavior. These bioactive and superparamagnetic particles may be potential materials for bone cancer treatment.

Ultrastructural evaluation of in vitro mineralized calcium phosphate phase on surface phosphorylated poly(hydroxy ethyl methacrylate-co-methyl methacrylate)

The in vitro functionality of surface phosphorylated poly(hydroxy ethyl methacrylate-co-methyl methacrylate), poly(HEMA-co-MMA) to induce bioinspired mineralization of calcium phosphate phase is evaluated. The primary nucleation of calcium phosphate on the surface phosphorylated copolymer occurs within 3 days of immersion when immersed in 1.5x simulated body fluid and the degree of mineralization is proportional to the hydroxy ethyl methacrylate content in the copolymer. The calcium phosphate phase is identified as hydroxyapatite by X-Ray diffraction analysis. The transmission electron microscopic evaluation combined with selected area diffraction pattern and energy dispersive analysis exemplified that the primary nuclei of amorphous calcium phosphate transforms to crystalline needle like calcium rich apatite, within a period of 3 days immersion in simulated body fluid. The atomic force microscopic results corroborate the c-axis growth of the crystals within 3 days immersion in SBF.

In vitro bioactivity and crystallization behavior of bioactive glass in the system SiO2-CaO-Al2O3-P2O5-Na2O-MgO-CaF2

AbstractIn this study, bioactivity of glass in the system SiO2-CaO-Al2O3-P2O5-Na2O-MgO-CaF2 was investigated. For this purpose, a glass sample was prepared by the traditional melting method. Crystallization behavior of bioactive glass was also investigated using differential thermal analyses. The Avrami constant of bioactive glass sample calculated according to the Ozawa equation was 3.72 ± 0.4, which indicates bulk crystallization. Using the Matusita-Sakka and the Kissinger equations, activation energy of crystal growth was determined as (394 ± 17) kJ mol−1 and (373 ± 12) kJ mol−1, respectively. These results indicate that the crystallization activation energy data of bioactive glass obtained in this study are accurate and reliable. Bioactivity of the resultant glass sample was analyzed by immersion in simulated body fluid. Scanning electron microscopy, thin film X-ray diffraction, ultraviolet spectroscopy and inductively coupled plasma techniques were used to monitor changes in the glass surface and the simulated body fluid composition. The results revealed that a hydroxyapatite layer was formed on the glass surface after 21 days of immersion in SBF. Formation of the hydroxyapatite layer confirmed the bioactivity of the glass in the system SiO2-CaO-Al2O3-P2O5-Na2O-MgO-CaF2. In addition, physical and mechanical properties of the sample were measured to determine changes in the properties with the immersion time. The results show that bioactive glass maintained its strength during the immersion in a simulated body fluid solution.

The composite films of gradient TiO 2-based/nano-scale hydrophilic sodium titanate: Biomimetic apatite induction and cell response

Chemical treatment was performed to modify the surfaces of the TiO 2-based (TOB) film containing P for improving its bioactivity. The apatite-forming ability of the chemically treated TOB (C-TOB) film was enhanced due to the formation of hydroxyl-functionalized surface during the SBF immersion process. However, further heat treatment of the C-TOB films formed crystalline sodium titanate, showing poor ability to release Na + ions, which does not facilitate the formation of hydroxyl-functionalized surface, thus lowering the apatite-forming ability. Firstly, amorphous Ca- and P-containing precipitates formed during the SBF immersion process, eventually transformed to crystalline biomimetic apatite, exhibiting a porous structure on two-scales of micron and nanometer levels. The preliminary cell experiment showed that the C-TOB film has good biocompatibility.

Structure, cell response and biomimetic apatite induction of gradient TiO 2-based/nano-scale hydrophilic amorphous titanium oxide containing Ca composite coatings before and after crystallization

Chemical treatment was used to modify the surface of microarc oxidized (MAO) coating containing Ca and P. And the chemically treated MAO (C-MAO) coating was further heat-treated at 400–800 °C. The average roughness of the MAO and C-MAO coatings is about 250 nm; further heat treatment improved the roughness of the C-MAO coating. The chemical and heat treatment enhanced the wetting ability of the MAO coating. During SBF immersion, amorphous Ca- and P-containing precipitate (Ca–P) appeared firstly, eventually transforming to crystalline apatites. At the same time, the apatite firstly formed at the concave region on the surface, and then spreads on the whole surface. The induced biomimetic apatite possessed a porous structure on two-scales of micron and nanometer levels. In the interlayer and outlayer of the C-MAO coating, the elements of Ca, P and Ti showed a gradient distribution. In the apatite layer, Ti disappeared basically, and the concentrations of Ca and P did not change obviously. In this work, continuous MG63 cell layer was observed on the surface of the C-MAO coating, which can provide good environment for the cell proliferation.

Sol-Gel Hydroxyapatite-CaO Composites: Fabrication and Bioactivity Studies

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.

Influence of Mixing Liquid on the Properties of Calcium Aluminate Cement

The effect of using Na2HPO4 solution as mixing liquid in the physicochemical and mechanical properties of calcium aluminate cement (CAC), with a view to a possible reinforcement additive of conventional α-TCP-based CPC was studied. The results showed that the degree of the hydration reaction of CaAl2O4 (CA) increased when Na2HPO4 solution was used as mixing liquid. The porosity of cement was also lower (37.9 ± 1.3 %) than for H2O (33.2 ± 3.6 %). The values of compressive strength for cements prepared with both mixing liquids were lower than 3 MPa due to the excessive L/P ratio employed and large porosity. After immersion in SBF, only the Al(OH)3 hydrate is observed and no other crystalline hydrated calcium aluminate nor calcium phosphate was formed in any of the cements. Both cements released Ca ions to, and removed P ions from SBF, being this effect more remarkable when Na2HPO4 was used. As for other CAC, no Al was released to the SBF and no potential toxicity due to this ion should be expected.

Early stage reactivity and in vitro behavior of silica-based bioactive glasses and glass-ceramics

The surface reactivity of different sets of glasses and glass-ceramics belonging to the SiO(2)-P(2)O(5)-CaO-MgO-K(2)O-Na(2)O system have been investigated. The attention was focused on the role of their composition on the bioactivity kinetics, in terms of pH modifications, silica-gel formation and its evolution toward hydroxycarbonatoapatite, after different times of soaking in simulated body fluid. Glasses and glass ceramics have been characterized by thermal analysis, SEM-EDS observations and phase analysis (XRD). XPS measurements have been carried out on the most representative set of sample in order to evaluate the evolution of the surface species during the growth of silica-gel and hydroxycarbonatoapatite. The response of murine fibroblast 3T3 to the material before and after a conditioning pre-treatment (immersion in SBF) has been investigated on the same set of samples in order to point out the role of the bioactivity mechanism on cell viability. The main differences among the various glasses have been related to the modifier oxides ratio and to the MgO content, which seems to have an influence on the glass stability, both in terms of thermal properties and surface reactivity. The surface characterization and in vitro tests revealed few variations in the reactivity of the different glasses and glass-ceramics in their pristine form. On the contrary, the different surface properties before and after the pre-treatment in SBF seem to play a role on the biocompatibility of both glass and glass-ceramics, due to the different ion release and hydrophilicity of the surfaces, affecting both cell viability and protein adsorption.

In vitro degradation of poly-l-d-lactic acid (PLDLA) pellets and powder used as synthetic alloplasts for bone grafting

The objective of this study was to evaluate the in vitro degradation of pellet and powder forms of a poly-L-D-lactic acid material used to produce plates and screws for orthopedic, oral, and maxillofacial applications. In order to produce the powder form the as-received pellets were milled in a cryogenic chamber. Particles size distribution (PSD) histograms were developed for both forms. The materials were then characterized by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA) before and after immersion in simulated body fluid for 30, 60, and 90 days. SEM showed that for both forms material degradation started after 30 days of immersion in SBF and evolved until 90 days. Degradation started at the amorphous zones of the polymer and exposed of deeper crystalline layers. The pellet and powder samples PSD showed polydispersed patterns with mean diameters of 673.98 microm and 259.55 microm. Thermal onset degradation temperatures were 365.64 degrees C and 360.30 degrees C, and of 363.49 degrees C and 359.83 degrees C before immersion and after 90 days in SBF for the pellet and powder forms, respectively. The Tg's of the pellets and the powder were approximately 61.5 degrees C and 66 degrees C, and their respective endothermic peaks were observed at approximately 125 degrees C and 120 degrees C. The specific heat (c) was approximately 8.5 J/g and 6.2 J/g for the pellet and powder material, respectively. According to the results obtained, cryogenic milling resulted in particle plastic deformation, and alterations in glass transition temperature, melting temperature, and specific heat of the material.