Simulated Body Fluid Medium Research Articles

In Vitro Activity Assays of Sputtered HAp Coatings with SiC Addition in Various Simulated Biological Fluids

Considering the requirements of medical implantable devices, it is pointed out that biomaterials should play a more sophisticated, longer-term role in the customization and optimization of the material–tissue interface in order to ensure the best long-term clinical outcomes. The aim of this contribution was to assess the performance of silicon carbide–hydroxyapatite in various simulated biological fluids (Dulbecco’s modified Eagle’s medium (DMEM), simulated body fluid (SBF), and phosphate buffer solution (PBS)) through immersion assays for 21 days at 37 ± 0.5 °C and to evaluate the electrochemical behavior. The coatings were prepared on Ti6Al4V alloy substrates by magnetron sputtering method using two cathodes made of hydroxyapatite and silicon carbide (SiC). After immersion assays the coating’s surface was analyzed in terms of morphology, chemical and phase composition, and chemical bonds. According to the electrochemical behavior in the media investigated at 37 ± 0.5 °C, SiC addition inhibits the dissolution of the hydroxyapatite in DMEM acellular media. Furthermore, after adding SiC, the slow degradation of hydroxyapatite in PBS and SBF media as well as biomineralization in DMEM were observed.

Effect of hydroxyapatite‐titanium‐MWCNTs composite coating fabricated by electrophoretic deposition on corrosion and cellular behavior of NiTi alloy

In this study, the hydroxyapatite (HA)‐titanium (Ti, 20 wt.%) multiwalled carbon nanotubes (MWCNTs, 1 wt.%) composite coating was applied on the NiTi alloy by using the electrophoretic deposition (EPD) technique. The morphologies and the phase structures of the coatings were investigated by the FESEM and XRD analysis, respectively. The corrosion behaviors of the coated NiTi samples were investigated using the polarization and electrochemical impedance spectroscopy tests in a simulated body fluid (SBF). The amounts of the released Ni ions from the coated NiTi were studied in the SBF. The results of the electrochemical tests revealed the corrosion resistance of the NiTi coated with HA was further improved by the addition of the Ti and MWCNTs to the HA coating. The current density and corrosion resistance of the NiTi alloy changed from 2.52 μA.cm−2 and 24.13 kΩ to 0.91 nA.cm−2 and 5.92 MΩ after coated with the HA‐Ti‐MWCNTs composite coating. Also, the number of nickel ions released from the surface of the NiTi alloy to the SBF medium suppressed from 11.8 to 0.08 μgr.L−1, after coating with HA‐Ti‐MWCNTs. Also, the cellular proliferation in the culture medium consisting of the NiTi alloy coated with the HA‐Ti‐MWCNTs improved significantly (compared with that of the NiTi alloy) as shown no toxicity in the cell culture medium.

Microstructure and corrosion behavior in SBF medium of spark plasma sintered Ti-xZr-20Si-10B (x = 5, 7, 10, 15, 20 at.-%) alloys

This work aims to evaluate the microstructure and corrosion behavior in SBF medium of spark plasma sintered Ti-xZr-20Si-10B (x = 5, 7, 10, 15 and 20 at.-%) alloys. Metastable Ti-Zr-Si-B (at.-%) powders previously prepared ball milling for 600 min were used as starting materials. Spark plasma sintering (SPS) of mechanically alloyed Ti-Zr-Si-B powders was performed under controlled atmosphere at 1100 °C for 12 min using 20 MPa in order to obtain cylindrical bodies with 10 mm diameter. SPS samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry, and corrosion tests. The electrochemical corrosion behavior of these alloys was evaluated in electrolytic solution 1.5 SBF (Simulated Body Fluid) at 36.5 °C and pH 7.4 by means of open circuit potential (OCP) measurements and potentiodynamic polarization tests. SPS process produced dense and homogeneous samples. Despite the short sintering time, the Ti-Zr-Si-B alloys presented near-equilibrium and homogeneous microstructures. Ti6Si2B dissolving between 6.6 and 8.3 at.-% Zr was formed in the quaternary alloys with 5 and 7 at.% Zr, respectively. In detrimental to its formation, the Ti3Si phase was preferentially formed in the SPSed alloys with 10, 15 and 20 at.-% Zr, dissolving between 11.2 and 15.4, 16.9–24, and 20.6–25.3 at.-% Zr, respectively. No transpassive domain was noted in the Ti-15Zr-20Si10B alloy at higher potentials after the passive layer break occurred around the 1.44 V, which presented pits on its corroded surface in SBF medium. SPSed Ti-7Zr-20Si-10B alloy exhibited better corrosion resistance in SBF medium than the Ti pure and Ti-6Al-4V alloy.

Synthesis and characterization of Zn-Doped hydroxyapatite: scaffold application, antibacterial and bioactivity studies

In this study, the antimicrobial and scaffold of zinc-substituted hydroxyapatite, (Zn-HAp) synthesized via chemical co-precipitation technique was investigated. The structure of the synthesized Zn-HAp was investigated with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Scanning electron microscope (SEM), Energy dispersive X-spectroscopy (EDAX), transmission electron microscope (TEM), Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). Bioactivity study was performed in simulated body fluid (SBF), while the antimicrobial activity was studied using disc diffusion method. The XRD structure revealed that Zn ion incorporation up to 10% led to the second phase hydroxyapatite (HAp) formation, while higher concentration diminished the apatite structure. The presence of phosphate ions, carbonates ions, and hydroxyl groups in the apatite powder was ascertained by the FT-IR evaluation. SEM evaluation showed that the apatite contains fine particles with nearly round shape with interconnected pores and decreasing Ca/P ratio with increasing Zn ion concentration. TEM results showed particulate polycrystalline apatite with crystallite size ranging from 68 nm in pure HAp to 41 nm in 20% Zn-doped HAp indicating a decrease in the crystal size with increasing Zn ion in the samples. The bioactivity study showed spherical deposition around the porous region of the scaffold HAp suggesting the growth of apatite in SBF media after 7 days of incubation, while antibacterial activity studies showed zones of inhibition with an increase in zinc ions concentrations.

Characterization Alloys of the Sn-Zn System Produced by Melt Spinning

The objective of this work was the conformation of ribbons from Sn3Zn alloy and Sn pure, using the melt-spinning fast cooling technique, in order to investigate the applicability as biomaterial. The ribbons were coated with 1% poly-caprolactone (PCL) and subsequent incorporation of silver nanoparticles (NPAg). In the uncoated ribbon was observing a surface roughness due of agglomerate caused by rapid solidification. In the ribbon coated with PCL and NPAg incorporation, it was observed that these compounds adhered to the ribbon. X-ray diffraction analysis showed no ribbons amorphization. The analysis by differential scanning calorimetry, indicated that the Sn3Zn ribbon had a lower melting temperature (198.1°C) than the Sn ribbon (228.7°C). The microhardness of Sn3Zn ribbon was 13.38 HV and Sn ribbon was 11.00 HV, both for the face without contact with the cooling wheel. In the bioactivity assays, performed in simulated body fluid medium, all samples showed apatites formation after four weeks of testing.

Formation and Biomimetic Deposition of Bone-like Hydroxyapatite on Wollastonite-gypsum Composites

Bone cements are often used for bone repair and fixation. The main objective of formulating a bone cement is to achieve structure and properties similarity to bone. In addition, bioactivity of a bone cement provides a major advantage that helps achieving better binding and interaction with the surrounding tissues. In the current study, gypsum was used as a matrix for a composite that comprises highly crystalline prestine and acid-treated wollastonite (CaSiO3) fibers. Composites made by mixing their powder precursors with deionized water at room temperature, were investigated for their composition using X-ray diffraction (XRD) and Thermogravimetric Analysis (TGA), for their microstructure using Scanning Electron Microscopy (SEM), for their compressive strengths and modulus of elasticity, and for setting time measurements. In addition, cement composites were evaluated for their preliminary bioactivity in a protein-free Simulated Body Fluid (SBF) for up to 14 days. Results show the improvement of mechanical properties and bioactivity of the composites using acid-treated wollastonite fibers. This was attributed to the formation of hydrated silica layer on the surface of the acid-treated fibers which improved the binding with the gypsum matrix and provided nucleating sites for the deposition of bone-like apatite spherolites from SBF media.

Structure and Corrosion of High Voltage Anodic Oxide Coatings on Ti6Al4V Biomaterial

Oxide coatings were produced on Ti-6Al-4V alloy by anodization process using two different aqueous electrolytes. The electrolytes contained calcium and phosphorus in the molar ratios of 5 and 15, respectively. Coatings were obtained by applying 250 and 300 V and were characterized by XRD and TEM. Properties like chemical composition, thickness and surface roughness were obtained. All the coatings contained TiO2 along with calcium and phosphorus. Electrochemical polarization and AC impedance studies were done in Simulated Body Fluid medium. The coating obtained by oxidation at 250 V from the bath maintained at Ca/P ratio of 5 had better corrosion properties. Improvement in corrosion resistance was attributed to the presence of phosphorus in the coatings.

Nanoemulsion synthesis of carbonated hydroxyapatite nanopowders: Effect of variant CO32−/PO43− molar ratios on phase, morphology, and bioactivity

Bone is a composite material containing carbonated hydroxyapatite (CHA) nanocrystallite and protein matrix. Low-temperature synthesis and assessment of the in vitro response of CHA nanopowders were conducted. Samples of CHA nanopowders were considered for their phase system, chemical compound, and reactions in a simulated body fluid (SBF). The crystallite size and phase for the CO32−/PO43− molar ratios of 0.67 and 1.00 were examined through X-ray diffraction (XRD). Chemical distinctiveness was analyzed by Fourier transform infrared (FTIR) spectroscopy. The compositions of the as-synthesized powders were quantified by X-ray fluorescence, and the carbon contents were estimated by carbon hydrogen nitrogen analysis. The morphology and textural properties were examined by field-emission scanning electron microscopy, transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) analysis. In vitro study was conducted in SBF medium, and the pH was intermittently recorded. Then, the dissolution of Ca2+ and PO43− in SBF was quantified by inductively coupled plasma optical emission spectroscopy. The outcomes of XRD and FTIR confirmed that pure single-phase B-type CHA without any secondary phase was formed. CHA.67 showed a crystallite size of (Scherrer) 22.7 nm, particle size by TEM (PTEM) of 24.87, and BET (PSBET) of 26.48 nm. Meanwhile, CHA1.00 achieved a crystallite and particle size of (Scherrer) 4.67, PTEM of 6.50, and PSBET of 13.23 nm. Results indicated that increasing the CO32−/PO43− molar ratio decreases the crystallite size and increases the amount of CO32−. Thus, we concluded that the nanoemulsion-synthesized CHA exhibits a crystallite size and chemistry comparable to those of biological hard tissue.

Effect of Phosphorus and Nickel on Electrochemical Migration of Sn-3Ag-0.7Cu Solder Paste in Simulated Body Fluid

Electrochemical migration (ECM) behaviour of Sn-3Ag-0.7Cu and Sn-3Ag-0.7Cu-0.03P-0.005Ni solder alloys were investigated using simulated body fluid (SBF) solution. In electronic devices, ECM phenomenon potentially leads to incompetence or failure of the whole devices. According to water drop test (WDT), mean-time-to-failure (MTTF) of commercially used Sn-3Ag-0.7Cu solder alloy was prolonged with addition of phosphorus (P) and nickel (Ni) as alloying elements. According to microstructure of each solder paste alloy which was observed using field emission scanning electron microscope (FESEM), dendrite structure in Sn-3Ag-0.7Cu-0.03P-0.005 Ni solder was lesser than in plain the Sn-3Ag-0.7Cu. This phenomenon suggested that presence of P and Ni retarded the growth of dendritic thus improved its corrosion resistance. Therefore, Sn-3Ag-0.7Cu-0.03P-0.005Ni possessed a good corrosion resistance in SBF medium.

Efficacy of Irradiated Bioactive Glass 45S5 on Attenuation of Microbial Growth and Eradication of Biofilm from AISI 316 L Discs: In-vitro Study

Bacterial infection associated with medical implants remains a serious and costly drawback with both temporary and permanent consequences. Recently, some bioactive glasses have been found to show the antibacterial effect when interacting with bacteria. This study assessed the antibacterial activity of the bioactive glass (B.G.) based on 45S5 bioactive glass before and after treatment with gamma irradiation against multi-drug resistant microorganisms commonly involved in osteomyelitis. 45S5 glass which was synthesized by a melting technique with particle size < 45 μm was characterized by optical absorption, optical band gap and Fourier Transform Infrared Spectroscopy (FTIR) before and after exposure to gamma irradiation. From the optical absorption, the optical band gap can be calculated. The antimicrobial activity of 45S5 glass irradiated at 25 and 50 kGy against some pathogenic strains was evaluated. The results revealed that irradiated 45S5 bioactive glass causes a reduction in the number of survivors of the tested strains rather than the non-irradiated one. The microbial counts decreased by increasing the pH. The results also indicated that the colony forming units (cfu) decreased by one log cycle in nutrient broth (NB) medium and three log cycles in simulated body fluid (SBF). Scanning electron microscopy showed cell shrinkage and membrane damage after exposure of the glass to irradiation. So, an alkaline pH and SBF media along with gamma irradiation are considered as the most preferable conditions affecting the antimicrobial activity of the irradiated 45S5 glass and have the ability to eradicate the biofilm produced by P. aeruginosa on AISI 316 L discs which are used in joint replacement.

Effect of Immersion in Simulated Body Fluid on the Mechanical Properties and Biocompatibility of Sintered Fe–Mn-Based Alloys

Fe–Mn-based degradable biomaterials (DBMs) are promising candidates for temporary implants such as cardiovascular stents and bone fixation devices. Identifying their mechanical properties and biocompatibility is essential to determine the feasibility of Fe–Mn-based alloys as DBMs. This study presents the tensile properties of two powder metallurgical processed Fe–Mn-based alloys (Fe–28Mn and Fe–28Mn-3Si, in mass percent) as a function of immersion time in simulated body fluid (SBF). In addition, short-term cytotoxicity testing was performed to evaluate the in vitro biocompatibility of the sintered Fe–Mn-based alloys. The results reveal that an increase in immersion duration deteriorated the tensile properties of both the binary and ternary alloys. The tensile properties of the immersed alloys were severely degraded after being soaked in SBF for ≥45 days. The ion concentration in SBF released from the Fe–28Mn-3Si samples was higher than their Fe–28Mn counterparts after 7 days immersion. The preliminary cytotoxicity testing based on the immersed SBF medium after 7 days immersion suggested that both the Fe–28Mn-3Si and Fe–28Mn alloys presented a good biocompatibility in Murine fibroblast cells.

Bovine Serum Albumin Adsorption onto Hydroxyapatite and Biphasic Calcium Phosphate Ceramic Granules

Calcium phosphate ceramics are one of the most studied biomaterials for bone substitution and regeneration. Bioactivity is one of the most important properties for these materials and it can be evaluated by adsorption of proteins and by hydroxyapatite formation on the surface in simulated body fluid (SBF). The aim of this work was to evaluate the bioactivity of ceramic granules with various hydroxyapatite (HAp) and beta tricalcium phosphate (β-TCP) ratios by adsorption of bovine serum albumin (BSA) in SBF and phosphate saline buffer (PBS) solution. The highest adsorption capacity in both solutions was observed for biphasic calcium phosphate sample with HAp/β-TCP ratio 50/50 but the lowest – for sample 10/90. The adsorption capacity of all samples was more than 2 times higher in SBF media than in PBS. The possibility of hydroxyapatite formation was evaluated by changes of Ca2+ concentration in SBF. After 5 days of incubation at 37oC all samples showed a decrease in Ca2+ concentration.

Accelerated synthesis of biomimetic nano hydroxyapatite using simulated body fluid

The aim of this study was to synthesize and characterize nano hydroxyapatite (nHAp) in a shorter duration than what conventionally occurs today (over 24 h) through a novel biomimetic approach. Despite the fact that nHAp has a wide range of medical applications and mimics the inorganic phase of natural bone tissue, nHAp synthesis protocols have not been optimized for quick precipitation times to obtain biomimetic nHAp in simulated body fluid (SBF). To overcome these issues, the synthesis of “bone-like” carbonated nHAp was carried out here with optimized concentrations of calcium chloride and disodium phosphate in SBF medium using a non-stoichiometric chemical composition via a biomineralization method. The results suggest that the presently prepared nHAp was “bone-like” B-type carbonated nHAp in nature with traces of Na, Mg, K and Cl. Physicochemical characterization confirmed the formation of nHAp in rod shapes with dimensions of 27 × 7 nm. The optimized shortest incubation time for nHAp synthesis was 3 h. Therefore, the most important finding of the present study was the elucidation that nHAp can be synthesized biomimetically after just 3 h. This can be used as a biomaterial for bone tissue engineering and other biomedical applications.

Preparation of bone-implants by coating hydroxyapatite nanoparticles on self-formed titanium dioxide thin-layers on titanium metal surfaces

Preparation of hydroxyapatite coated custom-made metallic bone-implants is very important for the replacement of injured bones of the body. Furthermore, these bone-implants are more stable under the corrosive environment of the body and biocompatible than bone-implants made up of pure metals and metal alloys. Herein, we describe a novel, simple and low-cost technique to prepare biocompatible hydroxyapatite coated titanium metal (TiM) implants through growth of self-formed TiO2 thin-layer (SFTL) on TiM via a heat treatment process. SFTL acts as a surface binder of HA nanoparticles in order to produce HA coated implants. Colloidal HA nanorods prepared by a novel surfactant-assisted synthesis method, have been coated on SFTL via atomized spray pyrolysis (ASP) technique. The corrosion behavior of the bare and surface-modified TiM (SMTiM) in a simulated body fluid (SBF) medium is also studied. The highest corrosion rate is found to be for the bare TiM plate, but the corrosion rate has been reduced with the heat-treatment of TiM due to the formation of SFTL. The lowest corrosion rate is recorded for the implant prepared by heat treatment of TiM at 700°C. The HA-coating further assists in the passivation of the TiM in the SBF medium. Both SMTiM and HA coated SMTiM are noncytotoxic against osteoblast-like (HOS) cells and are in high-bioactivity. The overall production process of bone-implant described in this paper is in high economic value.

In vitro bioactivity and drug release kinetics studies of mesoporous silica-biopolymer composites

Targeted drug delivery systems become highly significant in certain diseases where the required dosage of drug cannot be delivered due to poor blood circulation in the targeted hard tissues. The present study reports a simple method of preparing mesoporous silica (SBA-15)/Biopolymer composite and loading an antibiotic in the silica scaffold which may find applications in bone drug delivery system. The SBA-15 was prepared under different conditions and analyzed for its texture and structural properties. The as prepared silica was characterized by low angle X-ray diffraction and BET surface area measurement which shows mesoporosity associated with hexagonally organized channels, a narrow pore size distribution and a large surface area. Chitin and Chitosan were the biopolymers used in the preparation of composites and bioactivity of the composites was investigated in the SBF medium. Ciprofloxacin was used as a model drug molecule in the drug delivery studies as its molecular size is suitable for inclusion within the mesopores of the SBA-15 material. The in vitro drug release was investigated in the simulated body fluid medium. The mesoporous silica’s were found to be highly bioactive and found to possess sustained drug delivery kinetics.

Corrosion Behavior of a Novel Hybrid Co/UHMWPE Composite Biocoating with Potential Application as a Biomaterial

In the present paper we report the acquisition of a composite coating based on cobalt and ultra high molecular weight polyethylene (Co/UHMWPE) as a novel hybrid biocoating with potential application as a biomaterial, using the electrochemical deposition technique at room temperature. Three different concentrations of UHMWPE, namely 20 gL-1, 30 gL-1 and 50 gL-1, were used in a cobalt sulphate bath. The corrosion behaviour of the Co/UHMWPE hybrid biocoating was studied in comparison with pure cobalt coating at different exposure times in Hanks’ solution as simulated body fluid (SBF), using the electrochemical impedance spectroscopy method. The polarisation resistance of the Co/UHMWPE hybrid biocoating increased during immersion time in the SBF medium in comparison to the pure cobalt coating. An easy way to prepare Co/UHMWPE hybrid biocoatings was identified: namely, by properly incorporating UHMWPE microparticles into a Co matrix using electrocodeposition from a cobalt electrolyte plating bath with increasing corrosion resistance in a solution simulating body fluid.

Silicon carbide whiskers reinforced akermanite scaffolds for tissue engineering

The poor mechanical properties of akermanite (AKM), especially fracture toughness, limits its applications in bone tissue engineering, although it possesses favorable biological performance. In this research, silicon carbide whiskers (SiCw) are added in order to reinforce AKM scaffolds with controllable porous structures fabricated by selective laser sintering (SLS). The mechanical properties, microstructure and toughening mechanisms are analyzed. The results indicate that the compressive strength and fracture toughness increases with increasing SiCw from 5 to 20 wt.%, and then decreases when more SiCw are incorporated. The strengthening and toughening mechanisms are attributed to interface debonding, whisker fracture and whisker pull-out, and the main fracture mode becomes transgranular fracture. Moreover, the phase composition of SiCw remains constant, confirmed by X-ray diffraction (XRD) analysis. The bioactivity and degradation behaviour of the scaffolds were evaluated by soaking them in simulated body fluid (SBF). The results show that the composite scaffolds with 20 wt.% SiCw exhibits good apatite-mineralization ability and a moderate degradation rate in SBF medium. Moreover, scanning electron microscopy (SEM) analysis, MTT assay and alizarin red staining of human bone marrow stromal cells (hBMSCs) seeded scaffolds confirm the stem cell attachment, viability, proliferation and differentiation on the scaffolds. Thus, the overall study proves that SiCw reinforced AKM scaffolds have the potential to be used in bone tissue engineering.

Preparation and in vitro evaluation of strontium-doped calcium silicate/gypsum bioactive bone cement

The combination of two or more bioactive components with different biodegradability could cooperatively improve the physicochemical and biological performances of the biomaterials. Here we explore the use of α-calcium sulfate hemihydrate (α-CSH) and calcium silicate with and without strontium doping (Sr-CSi, CSi) to fabricate new bioactive cements with appropriate biodegradability as bone implants. The cements were fabricated by adding different amounts (0–35 wt%) of Sr-CSi (or CSi) into the α-CSH-based pastes at a liquid-to-solid ratio of 0.4. The addition of Sr-CSi into α-CSH cements not only led to a pH rise in the immersion medium, but also changed the surface reactivity of cements, making them more bioactive and therefore promoting apatite mineralization in simulated body fluid (SBF). The impact of additives on long-term in vitro degradation was evaluated by soaking the cements in Tris buffer, SBF, and α-minimal essential medium (α-MEM) for a period of five weeks. An addition of 20% Sr-CSi to α-CSH cement retarded the weight loss of the samples to 36% (in Tris buffer), 43% (in SBF) and 54% (in α-MEM) as compared with the pure α-CSH cement. However, the addition of CSi resulted in a slightly faster degradation in comparison with Sr-CSi in these media. Finally, the in vitro cell-ion dissolution products interaction study using human fetal osteoblast cells demonstrated that the addition of Sr-CSi improved cell viability and proliferation. These results indicate that tailorable bioactivity and biodegradation behavior can be achieved in gypsum cement by adding Sr-CSi, and such biocements will be of benefit for enhancing bone defect repair.

Growth and electrochemical stability of self-organized TiO2nanotubes on Ti-2 grade and orthopedic Ti6Al4V alloy for biomedical application

Titanium and its alloys are biomaterials used in endosseous implants, due to desirable mechanical properties, high corrosion resistance and biocompatibility. Using electrochemical anodization technique these materials can be recovered with self-organized TiO2 nanotubes layer resulting in increased specific surface area and probable bioactivity improvement. This research aimed determine potentiostatic anodization parameters to obtain self-organized TiO2nanotubes layer with reproducibility and ideal diameters for probable bioactive response on Ti - 2 grade (ASTM F67) and Ti6Al4V (ASTM F136) orthopedic alloy and evaluation the electrochemical stability behavior in simulated body fluid media. The self-organized nanotubes layer were obtained by potentiostatic electrochemical method in electrolyte containing fluoride ions, H3PO4/HF for Ti 2 grade and H3PO4/NH4F for Ti6Al4V alloy, the applied potentials were 15 V, 20 V and 25 V for 30, 60 and 90 minutes, for both materials. For morphologic characterization were employed scanning electron microscopy SEM and the Image J software for nanodiameter measurements. The nanoestructure electrochemical stability was evaluated by open circuit potential after immersion for 15, 30 and 60 days in artificial blood plasma, into an electrochemical cell, using SCE (saturated calomel electrode) as reference electrode, in PBS ((phosphate buffered saline) solution electrolyte for 90 minutes. The ideal anodization parameters were 15 V and 20 V for 1 hour and a reproducible, uniform and homogeneous self-organized nanotubes layer were obtained with ideal diameters that probably improve the implant superficial bioactivity with 80 and 120 nm respectively, according to the literature. Open-circuit potentials from metal/oxide system obtained on both materials are stable with potentials in range of -0.031 V to -0,183 V indicating good stability of nanoestructures in simulated body fluid. Nanotubes layer as a superficial treatment is viable with high reproducibility, low cost and electrochemical stability in simulated body fluid media.

Synthesis and processability into textile structures of radiopaque, biodegradable polyesters and poly(ester‐urethanes)

Radiopaque biodegradable polymers have been synthesized by ring‐opening polymerization of l/dl‐lactide and caprolactone with the iodine‐containing starter molecule 2,2‐bis(hydroxymethyl)propane‐1,3‐diyl bis(2,3,5‐triiodobenzoate) followed by chain elongation with a diacid chloride or diisocyanates. The resulting polyesters and poly(ester‐urethanes) exhibited a radiopacity of 60−124% relative to an aluminium sample of the same thickness. The polymers were processed into monofilament fibres by melt‐spinning and into fibre meshes by electrospinning. All polymers were biodegradable in simulated body fluid medium under in vitro conditions and showed an excellent in vitro cytocompatibility even after several months of hydrolytic degradation. A current drawback is the relatively low tensile strength of the polymer monofilaments, which needs to be improved for applications as textile structures. Nevertheless, the new radiopaque and biodegradable polymers are promising candidates in fields of application where radiopacity of implants is an important parameter.