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Currently, the apatite-forming ability evaluation of a biomaterial employs Kokubo's simulated body fluid (SBF) as a testing medium. As the conventional SBF simulates only the ionic composition and pH of human serum (HS), this study aimed to compare the apatite formation in SBF and HS on the sol-gel-derived bioglass (BG) 83S2 and commercial 45S5 as well as to verify the influence of preincubation of BG in both fluids on cytocompatibility towards human fetal osteoblast cell line hFOB 1.19. The apatite formation in HS was hindered, regardless of the type of used BG. Relatively higher apatite-forming ability was noticed for BG83S2. In direct contact test, both BGs were cytocompatible towards osteoblasts, regardless of the type of used fluid. In the case of extracts; however, only the extract obtained from BG83S2 preincubated in HS did not show the cytotoxic effect. The evaluation of apatite-forming ability in SBF appears to be a fast screening method for comparing the apatite-forming ability of various bioglasses. Nonetheless, SBF is unable to precisely imitate the morphology and crystallinity of apatite observed during the assay in HS, as well as it does not mimic the changes in profiles of osteogenic ions. [Display omitted] [ABSTRACT FROM AUTHOR]

The development and characterization of bioactive surfaces based on chitosan-polyethylene glycol coatings modified with hydroxyapatite on Ti6Al4V alloy were conducted to enhance bioactivity. Characterization techniques such as scanning electron microscopy, X-ray diffraction, infrared spectroscopy, atomic absorption spectroscopy, and electrochemical impedance spectroscopy were used to evaluate coating properties, apatite formation after immersion in simulated body fluid, and electrochemical stability. Results demonstrated apatite deposition due to the bioactivity of the polymer-ceramic composite, with calcium accumulation observed on the substrate surface after 5 days of immersion. Electrochemical impedance spectroscopy revealed a highly capacitive layer in the 50:50 chitosanpolyethylene glycol coating with 0.05% w/v hydroxyapatite, indicating increased interaction with the biological medium while preserving the protective resistive properties of the Ti6Al4V alloy. These findings suggest that this coating composition is a promising material for bone tissue regeneration applications. [ABSTRACT FROM AUTHOR]

Laser-welding is a promising technique for welding NiTi shape memory alloys with acceptable tensile strength and comparable corrosion performance for biomedical applications. The microstructural characteristics and localized corrosion behavior of NiTi alloys in a simulated body fluid (SBF) environment are evaluated. A microstructural examination indicated the presence of fine and equiaxed grains with a B2 austenite phase in the base metal (BM), while the weld metal (WM) had a coarse dendritic microstructure with intermetallic precipitates including Ti2Ni and Ni4Ti3. The hardness decreased from the BM to the WM, and the average hardness for the BM was 352 ± 5 HV, while it ranged between 275 and 307 HV and 265 and 287 HV for the HAZ and WM, respectively. Uni-axial tensile tests revealed a substantial decrease in the tensile strength of NiTi WM (481 ± 19 MPa), with a reduced joint efficiency of 34%. The localized corrosion performance of NiTi BM was superior to the WM, with electrochemical test responses indicating a pitting potential and low corrosion rate in SBF environments. The corrosion rate of the NiTi BM and WM was 0.048 ± 0.0018 mils per year (mpy) and 0.41 ± 0.019 mpy, respectively. During welding, NiTi's strength and biocompatibility properties changed due to the alteration in microstructure and formation of intermetallic phases as a result of Ti enrichment. The performance and safety of welded medical devices may be impacted during welding, and it is essential to preserve the biocompatibility of NiTi components for biomedical applications. [ABSTRACT FROM AUTHOR]

Bioresponsive ceramics, a new concept in ceramic biomaterials, respond to biological molecules or environments, as exemplified by salts composed of calcium ions and phosphate esters (SCPEs). SCPEs have been shown to form apatite in simulated body fluid (SBF) containing alkaline phosphatase (ALP). Thus, surface modification with SCPEs is expected to improve the apatite-forming ability of a material. In this study, we modified the surface of α-tricalcium phosphate (α-TCP) using methyl, butyl, or dodecyl phosphate to form SCPEs and investigated their apatite formation in SBF and SBF containing ALP. Although apatite did not form on the surface of the unmodified α-TCP in SBF, apatite formation was observed following surface modification with methyl or butyl phosphate. When ALP was present in SBF, apatite formation was especially remarkable on α-TCP modified with butyl phosphate. These SCPEs accelerated apatite formation by releasing calcium ions through dissolution and supplying inorganic phosphate ions, with the latter process only occurring in SBF containing ALP. Notably, no apatite formation occurred on α-TCP modified with dodecyl phosphate, likely because of the low solubility of the resulting calcium dodecyl phosphate/calcium phosphate composites. This new method of using SCPEs is anticipated to contribute to the development of novel ceramic biomaterials. [ABSTRACT FROM AUTHOR]

Simulated body fluid (SBF) and artificial saliva (AS) are used in biomedical and dental research to mimic the physiological conditions of the human body. In this study, the biomimetic precipitation of double-doped amorphous calcium phosphate in SBF and AS are compared by thermodynamic modelling of chemical equilibrium in the SBF/AS-CaCl2-MgCl2-ZnCl2-K2HPO4-H2O and SBF/AS-CaCl2-MgCl2-ZnCl2-K2HPO4-Glycine/Valine-H2O systems. The saturation indices (SIs) of possible precipitate solid phases at pH 6.5, close to pH of AS, pH 7.5, close to pH of SBF, and pH 8.5, chosen by us based on our previous experimental data, were calculated. The results show possible precipitation of the same salts with almost equal SIs in the two biomimetic environments at the studied pHs. A decrease in the saturation indices of magnesium and zinc phosphates in the presence of glycine is a prerequisite for reducing their concentrations in the precipitates. Experimental studies confirmed the thermodynamic predictions. Only X-ray amorphous calcium phosphate with incorporated Mg (5.86–8.85 mol%) and Zn (0.71–2.84 mol%) was obtained in the experimental studies, irrespective of biomimetic media and synthesis route. Solid-state nuclear magnetic resonance (NMR) analysis showed that the synthesis route affects the degree of structural disorder of the precipitates. The lowest concentration of dopant ions was obtained in the presence of glycine. Further, the behaviour of the selected amorphous phase in artificial saliva was studied. The dynamic of Ca2+, Mg2+, and Zn2+ ions between the solid and liquid phases was monitored. Both direct excitation 31P NMR spectra and 1H-31P CP-MAS spectra proved the increase in the nanocrystalline hydroxyapatite phase upon increasing the incubation time in AS, which is more pronounced in samples with lower additives. The effect of the initial concentration of doped ions on the solid phase transformation was assessed by solid-state NMR. [ABSTRACT FROM AUTHOR]

In this work, SnO2:TiO2 nano composite with silver dopant have been prepared by chemical route method at preparation temperature 100 ℃, with 6% Ag ratio. Titanium chloride (TiCl3) has been used as the precursors of TiO2 and tin chloride (SnCl2) were taken as the precursors of SnO2 in the laboratory. The prepared samples were described by FESEM, X-Ray diffraction and uv-visible spectrophotometer. Results show that compared to pure SnO2 and pure TiO2,SnO2:TiO2 nano composite calcined 400℃ shows a large surface area. The average crystalline size was estimated from XRD analysis by using Debye-Scherrer’s formula and the result shows that the crystalline size increases from (27.78) nm to (29.2354)nm after adding Ag. Bio activity application of the prepared composite has been tested after immersion SnO2:TiO2 nano composite in the simulated body fluid SBF, the morphology and particle size of the prepared immersed samples have been estimated after 20 days by FESEM images. [ABSTRACT FROM AUTHOR]

The goal of the current work is to analyse the Zn scaffold porosity effects on its corrosion behavior. Organized porous network structure (OPNS) zinc samples with varying porosity were manufactured by a newly developed rapid tooling approach that combined 3D printing and microwave sintering. The outcomes of the OPNS Zn samples were also compared to the dense zinc sample. For the corrosion analysis, porous and dense zinc samples electrochemical corrosion testing were conducted in SBF electrolyte at 37 °C. The zinc samples morphological study was accessed by scanning electron microscopy (SEM). It was confirmed by the findings of the morphological study that the Zn samples contained randomly distributed micropores and designed or organized macropores. The zinc sample corrosion behavior in SBF was analyzed by potentiodynamic (PD) polarisation and electrochemical impedance spectroscopy (EIS) curves. In addition, an electrical equivalent circuit (EEC) model was developed using the EIS experimental data to establish an understanding of the corrosion behavior of Zn samples. Overall corrosion testing results demonstrate that the diffusion mechanism had an impact on the corrosion mechanism of Zn samples and diffusion mechanism during electrochemical reaction supported by the porosity of the sample. The Zn samples corrosion rate was found to be minimum for the dense sample (0.14 mm y−1), while it was maximum for the highest porosity OPNS Zn sample (0.66 mm y−1). The present study corrosion rate of Zn samples was comparable with the required value for bone implants. [ABSTRACT FROM AUTHOR]

The development and characterization of bioactive surfaces based on chitosan-polyethylene glycol coatings modified with hydroxyapatite on Ti6Al4V alloy were conducted to enhance bioactivity. Characterization techniques such as scanning electron microscopy, X-ray diffraction, infrared spectroscopy, atomic absorption spectroscopy, and electrochemical impedance spectroscopy were used to evaluate coating properties, apatite formation after immersion in simulated body fluid, and electrochemical stability. Results demonstrated apatite deposition due to the bioactivity of the polymer-ceramic composite, with calcium accumulation observed on the substrate surface after 5 days of immersion. Electrochemical impedance spectroscopy revealed a highly capacitive layer in the 50:50 chitosan-polyethylene glycol coating with 0.05% w/v hydroxyapatite, indicating increased interaction with the biological medium while preserving the protective resistive properties of the Ti6Al4V alloy. These findings suggest that this coating composition is a promising material for bone tissue regeneration applications.

Due to the excellent biocompatibility of Zn, Ag, and Ca, these elements were chosen for the development of a Mg–Zn–Ag–Ca alloy system for biomedical applications. This study studied the effect of Ca on the microstructure and corrosion behavior of as-cast Mg–Zn-0.5Ag-xCa alloy. The composition and microstructure of the alloys were analyzed using metallographic microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The alloys were immersed in Hank's solution for weight loss experiments to analyze the corrosion rate and micro-corrosion morphology of alloys with different Ca contents. It was observed that with the increase of Ca content, grain refinement and the amount of the second phase increased. Corrosion tests in Hank's solution demonstrated that a minor addition of Ca could reduce the corrosion rate, but the rate increased sharply once the Ca content exceeded 1.0 wt%. Considering corrosion performance, the optimal range of Ca concentration was determined to be 1.0 wt% to 1.5 wt%.

Zr-50Ti alloys are promising biomaterials due to their excellent mechanical properties and low magnetic susceptibility. However, Zr-50Ti alloys do not inherently bond well with bone. This study aims to enhance the bioactivity and bonding strength of Zr-50Ti alloys for orthopedic implant materials. Initially, the surface of Zr-50Ti alloys was treated with a sulfuric acid solution to create a microporous structure, increasing surface roughness and area. Subsequently, low crystalline calcium phosphate (L-CaP) precipitation was controlled by adding Mg2+ and/or CO32− ions in modified simulated body fluid (m-SBF). The treated Zr-50Ti alloys were then subjected to cold isostatic pressing to force m-SBF into the micropores, followed by incubation to allow L-CaP formation. The apatite-forming process was tested in simulated body fluid (SBF). The results demonstrated that the incorporation of Mg2+ and/or CO32− ions enabled the L-CaP to cover the entire surface of Zr-50Ti alloys within only one day. After short-term soaking in SBF, the L-CaP layer, modulated by Mg2+ and/or CO32− ions, formed a uniform hydroxyapatite (HA) coating on the surface of the Zr-50Ti alloys, showing potential for optimized bone integration. After soaking in SBF for 14 days, the bonding strength between the apatite layer and alloy has the potential to meet the orthopedic application requirement of 22 MPa. This study demonstrates an effective method to enhance the bioactivity and bonding strength of Zr-50Ti alloys for orthopedic applications. [ABSTRACT FROM AUTHOR]

In this work, hybrid reinforced epoxy biopolymer composites were developed using natural hydroxyapatite and zinc oxide (nHAp/ZnO). The epoxy was reinforced with varying addition of nHAp and ZnO in the steps of 3, 5 and 7 wt. % respectively using stir casting molding process. The developed composites were immersed in simulated body fluid (SBF) at 37oC to determine their bioactivity. Microstructure evaluation using scanning electron microscopy was also used to assess the morphology of the developed composites before and after in vitro test, respectively. The microstructure evaluation in vitro showed good deposition of white-like layers on the surface indicating good bioactivity reaction with the SBF and affirm that the developed biopolymers will react well with living tissue when used in vivo. However, hybrid sample BP5HB showed better apatite-like layer deposition. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) has become desirable for biomedical applications, particularly implantable devices. However, the degradation of PLA in biological environments under mechanical stress remains incompletely understood and requires further investigation. This study compared the plain fatigue (PF) and the biodegraded fatigue (BDF) behavior of 3D-printed PLA. For this purpose, two sets of standard fatigue specimens were additively manufactured by the fused filament fabrication (FFF) method. One set was used for plain fatigue testing, and the other was immersed for 330 days in simulated body fluid (SBF). After immersion, the samples were dried and weighed before fatigue testing. The fully reversed rotary bending fatigue tests were conducted on both sets of specimens, and the stress-lifetime (S-N) curves were obtained. Additionally, the fatigue properties of PF and BDF specimens were evaluated. Moreover, the fracture behaviors of the materials were studied using field emission scanning electron microscopy (FESEM). The outcomes implied that the weight of the samples extended during the immersion period, primarily due to water absorption by the PLA. However, after drying, the final weights did not change compared to the weights before immersion. The SBF immersion significantly reduced the fatigue performance of the biodegraded samples comparing the PF result.

This research focuses on the enhancement of the tribological behavior of commercial pure titanium (Cp-Ti) in a simulated body fluid (SBF) via surface reinforcement by titanium borides. The protective boride coatings were formed through the pack cementation process at two different temperatures (950 and 1050 °C) to create diverse hard compositions of TiB and TiB–TiB2 in the coating, with hardness of 1032 and 1291 Hv, respectively. The roughness and wettability of top surfaces were evaluated before the tribology studies due to their impacts on the tribology behavior. Box-Behnken design (BBD) was applied to investigate the effects of the wear parameters in dry and SBF environments. The duration of the wear tests was 53, 35, and 26 min for low, medium, and high speed. It was found that the abrasion wear type was dominant at the beginning of sliding, and then changed to the plastic deformation in the dry conditions, while there is no sign of the abrasion and adhesion wear features at the surface of the reinforced samples abraded in the SBF solution. Results confirmed a high coincidence between BBD predictions and actual findings. The released debris from the coatings was also investigated to find origins. Results showed that majority of the debris in the SBF solution belonged to the calcium phosphate particles demonstrating the bioactivity of the TiB–TiB2 coatings. According to findings, hard TiB–TiB2 coatings could significantly improve the tribological behavior of the Ti implants, which could in turn result in expanding the biological application of Cp-Ti.

In this research, the pure fatigue behaviors of AM60 magnesium alloy with polylactic acid (PLA) coating (PF-AM60-PLA) and the corrosion fatigue behaviors of magnesium alloy with PLA coating (CF-AM60-PLA) were evaluated. Polymer coating was made by fused deposition modeling (FDM) with a 3D printer and attached to standard fatigue test specimens with glue. Then, after 27 days of immersion in the simulated body fluid (SBF), the high-cycle bending fatigue test was performed on samples. Due to corrosion, the weight of the specimens was reduced by an average of 35%. The corrosion rate decreased in the first 7 days and then increased. PF samples with a coating had an average 49% increase in fatigue lifetime. Regarding the CF samples, despite the use of a 10-times stronger solution, the fatigue lifetime of these samples decreased by only 35%. The field-emission scanning electron microscopy (FESEM) results also showed cleavage plates and striations. In addition, the separation of the glue from the coating and Mg was observed. Corrosion products, in addition to microcracks and holes, were seen on the fracture surface of CF specimens, which caused the stress concentration and the crack initiation. Holes caused by the release of gases were also observed in polymer coatings, which were fabricated by 3D printing. [ABSTRACT FROM AUTHOR]

A self-sealing coating was prepared on the surface of basic magnesium alloy material (BM) by micro-arc oxidation (MAO) technique. The corrosion behavior of BM and MAO samples in a simulated body fluid (SBF) at different flow rates (0, 0.5, and 1.5 ml/s) was studied by immersion test. The electrochemical impedance spectrum (EIS) of the samples was measured at 0, 2, 12, 16 and 24 h during the immersion process to analyze the evolution of the electrochemical corrosion resistance. The corrosion morphology and element composition of the samples were characterized by scanning electron microscopy (SEM) and energy-dispersive spectrometer (EDS). The results showed that the corrosion resistance of BM and MAO samples gradually decreases with increasing flow rate. At higher flow rates, the MAO coating is more effective in improving the corrosion resistance of magnesium alloys. Based on the experimental results, the corrosion mechanism of BM and MAO samples at different flow rates was clarified. [ABSTRACT FROM AUTHOR]

In this study, we applied argon plasma treatment to titanium surfaces with nanostructures deposited by concentrated alkali treatment and investigated the effects on the surface of the material and the tissue surrounding an implant site. The results showed that the treatment with argon plasma removed carbon contaminants and increased the surface energy of the material while the nanoscale network structure deposited on the titanium surface remained in place. Reactive oxygen species reduced the oxidative stress of bone marrow cells on the treated titanium surface, creating a favorable environment for cell proliferation. Good results were observed in vitro evaluations using rat bone marrow cells. The group treated with argon plasma exhibited the highest apatite formation in experiments using simulated body fluids. The results of in vivo evaluation using rat femurs revealed that the treatment improved the amount of new bone formation around an implant. Thus, the results demonstrate that argon plasma treatment enhances the ability of nanostructured titanium surfaces to induce hard tissue differentiation and supports new bone formation around an implant site. [ABSTRACT FROM AUTHOR]

Present study deals with the corrosion behavior of a harmonic structured Cantor alloy (FeCrMnNiCo) in freely aerated Hank's simulated body fluid. Harmonic structure featuring distinguished core regions containing clusters of coarse grains and shell regions containing a continuous network of fine grains is attained by powder metallurgical route. X-ray diffraction confirmed FCC structure both in the core and shell regions. Corrosion tests were carried out on the harmonic structured Cantor alloy and compared with its conventional counterpart and harmonic structured 316L stainless steel, a well-known biomaterial. The corrosion resistance of the harmonic structured Cantor alloy is found to be better than the conventional one and comparable to the harmonic structured 316L stainless steel. During corrosion, enrichment of Cr at the shell regions of the harmonic structured Cantor alloy allows early passivation, leading to its enhanced corrosion resistance. [ABSTRACT FROM AUTHOR]

Simulated body fluid (SBF) is widely utilized in preclinical research for estimating the mineralization efficacy of biomaterials. Therefore, it is of great significance to construct an efficient and stable SBF mineralization system. The conventional SBF solutions cannot maintain a stable pH value and are prone to precipitate homogeneous calcium salts at the early stages of the biomimetic process because of the release of gaseous CO2. In this study, a simple but efficient five times SBF buffered by 5 % CO2 was developed and demonstrated to achieve excellent mineralized microstructure on a type of polymer-aligned nanofibrous scaffolds, which is strikingly similar to the natural human bone tissue. Scanning electron microscopy and energy-dispersive X-ray examinations indicated the growth of heterogeneous apatite with a high-calcium-to-phosphate ratio on the aligned nanofibers under 5 times SBF buffered by 5 % CO2. Moreover, X-ray diffraction spectroscopy and Fourier transform infrared analyses yielded peaks associated with carbonated hydroxyapatite with less prominent crystallization. In addition, the biomineralized aligned polycaprolactone nanofibers demonstrated excellent cell attachment, alignment, and proliferation characteristics in vitro. Overall, the results of this study showed that 5 × SBFs buffered by 5 % CO2 partial pressure are attractive alternatives for the efficient biomineralization of scaffolds in bone tissue engineering, and could be used as a model for the prediction of the bone-bonding bioactivity of biomaterials.

Magnesium has a special place in biomedical applications due to its biocompatibility and biodegradability properties. The high corrosion rate of magnesium in the body environment requires the use of a biocompatible coating such as calcium phosphate. In this paper, the effect of microstructure and crystalline texture of AZ31 magnesium alloy substrate on the morphology of calcium phosphate coating and the corrosion behavior of the material was investigated. The results imply that apatite crystals can form and grow on the surfaces of the biomimetic coating after soaking in simulated body fluid (SBF). The corrosion behavior of the material was investigated using an electrochemical polarization test in SBF solution for 3 days. The results showed that changes in the microstructure and crystalline texture of the substrate changed the coating morphology so that the growth of calcium phosphate changed from a rod-shaped with a diameter of 100–150 nm to a blade-shaped with a thickness of 20–50 nm. An increase in the corrosion resistance of the coated specimens with the corrosion rate of 0.65 mm/year was obtained compared to the uncoated specimen with the corrosion rate of 2.62 mm/year.

Ximing Peng,1,* Xin Liu,2,* Yanqing Yang,1,* Mingwei Yu,1 Zhiwei Sun,1 Xiangru Chen,1 Keqiang Hu,1 Jing Yang,1 Shaotang Xiong,2 Bin Wang,2 Liya Ma,3 Zhenxing Wang,4 Hanxiao Cheng,5,* Chuchao Zhou1,* 1Department of Plastic Surgery, Tongren Hospital of Wuhan University (Wuhan Third Hospital), Wuhan, 430060, People’s Republic of China; 2Medical Aesthetic Department, The Second People’s Hospital of China Three Gorges University, The Second People’s Hospital of Yichang, Yichang, Hubei, People’s Republic of China; 3The Centre of Analysis and Measurement of Wuhan University, Wuhan University, Wuhan, 430072, People’s Republic of China; 4Department of Plastic Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, People’s Republic of China; 5Department of Plastic Surgery, Hangzhou First People’s Hospital, Hangzhou, Zhejiang, 310006, People’s Republic of China*These authors contributed equally to this workCorrespondence: Hanxiao Cheng; Chuchao Zhou, Email chxmomo@sina.com; chuchaozhou@163.comIntroduction: The formation of bone-like apatite (Ap) on natural polymers through biomimetic mineralization using simulated body fluid (SBF) can improve osteoconductivity and biocompatibility, while lowering immunological rejection. Nonetheless, the coating efficiency of the bone-like Ap layer on natural polymers requires improvement. Carbonyls (-COOH) and hydroxyls (-OH) are abundant in graphene oxide (GO), which may offer more active sites for biomimetic mineralization and promote the proliferation of rat bone marrow stromal cells (BMSCs).Methods: In this study, gelatin methacryloyl (GelMA) microgels were infused with GO (0, 0.5, 1, and 2 mg/mL) and embedded into microgels in SBF for 1, 7, and 14 days. Systematic in vitro and in vivo experiments were performed to evaluate the structure of the microgel and its effect on cell proliferation and ability to repair bone defects in rats.Results: The resulting GO-GelMA-Ap microgels displayed a porous, interconnected structure with uniformly coated surfaces in bone-like Ap, and the Ca/P ratio of the 1 mg/mL GO-GelMA-Ap group was comparable to that of natural bone tissue. Moreover, the 1 mg/mL GO-GelMA-Ap group exhibited a greater Ap abundance, enhanced proliferation of BMSCs in vitro and increased bone formation in vivo compared to the GelMA-Ap group.Discussion: Overall, this study offers a novel method for incorporating GO into microgels for bone tissue engineering to promote biomimetic mineralization.Graphical-Abstract: Keywords: graphene oxide, gelatin methacryloyl, bone-like apatite, biomimetic mineralization, simulated body fluid, bone repair

In this present work, the pure fatigue (PF) behaviors of AM60 magnesium alloys were investigated for the as-received samples, compared to the pre-corroded specimens in simulated body fluid (SBF). The standard fatigue testing specimens were held for 28 days in the SBF, so-called corrosion fatigue (CF) samples, while their weights were recorded. Afterward, bending fatigue experiments were carried out under fully-reversed rotary conditions, within high-cycle fatigue regimes. Moreover, the fracture mechanism was also investigated using field-emission scanning electron microscopy (FE-SEM). The obtained results indicated that the weight of the samples first increased and then decreased with time. The CF lifetime was 71 % of the relative difference, shorter than PF under the lowest stress level (80 MPa) and 38 % of the relative difference, shorter than PF at the highest stress level (140 MPa). The CF lifetime was entirely behind the PF lifetime, and fracture mechanisms were mostly brittle.

Simulated body fluid (SBF) and artificial saliva (AS) are used in biomedical and dental research to mimic the physiological conditions of the human body. In this study, the biomimetic precipitation of double-doped amorphous calcium phosphate in SBF and AS are compared by thermodynamic modelling of chemical equilibrium in the SBF/AS-CaCl2-MgCl2-ZnCl2-K2HPO4-H2O and SBF/AS-CaCl2-MgCl2-ZnCl2-K2HPO4-Glycine/Valine-H2O systems. The saturation indices (SIs) of possible precipitate solid phases at pH 6.5, close to pH of AS, pH 7.5, close to pH of SBF, and pH 8.5, chosen by us based on our previous experimental data, were calculated. The results show possible precipitation of the same salts with almost equal SIs in the two biomimetic environments at the studied pHs. A decrease in the saturation indices of magnesium and zinc phosphates in the presence of glycine is a prerequisite for reducing their concentrations in the precipitates. Experimental studies confirmed the thermodynamic predictions. Only X-ray amorphous calcium phosphate with incorporated Mg (5.86–8.85 mol%) and Zn (0.71–2.84 mol%) was obtained in the experimental studies, irrespective of biomimetic media and synthesis route. Solid-state nuclear magnetic resonance (NMR) analysis showed that the synthesis route affects the degree of structural disorder of the precipitates. The lowest concentration of dopant ions was obtained in the presence of glycine. Further, the behaviour of the selected amorphous phase in artificial saliva was studied. The dynamic of Ca2+, Mg2+, and Zn2+ ions between the solid and liquid phases was monitored. Both direct excitation 31P NMR spectra and 1H-31P CP-MAS spectra proved the increase in the nanocrystalline hydroxyapatite phase upon increasing the incubation time in AS, which is more pronounced in samples with lower additives. The effect of the initial concentration of doped ions on the solid phase transformation was assessed by solid-state NMR.

The experimental work focuses on the detailed monitoring of the interaction of commercial hydroxyapatite (HA) granules with various morphologies and surfaces with simulated body fluid (SBF) under varied in vitro test conditions. The ISO 23317:2014 standard, which specifies methods for the detection of apatite formation on the surface of materials in a simulated body fluid, mainly focuses on one-piece samples (tablets, rectangular shaped samples) under static conditions. The SBF solution modelling the inorganic part of blood plasma is buffered with a Tris buffer which can, under certain conditions, affect the in vitro test results by its own interaction with the tested material. Changes on the surfaces of the tested bioceramic granules with varied porosity and leachates from the buffered and unbuffered SBF solutions were characterised at selected time intervals using the available methods (SEM, BET, AAS, UV-VIS). The kinetics of the formation and morphology of the precipitated hydroxyapatite (HAp) was found to vary under different in vitro test conditions. The leachates from the solutions confirmed different rates of calcium and phosphate ions depletion, especially at the beginning of the assay. The pH analyses of the buffered and unbuffered SBF solutions also showed a Tris buffer effect.

Abstract Background To analyse the changes in surface and nickel ion release characteristics of fractured root canal shaping instruments in a simulated body fluid environment. Methods A total of 54 new instruments were studied. The instrument groups consisted of five different NiTi alloys and a stainless-steel alloy. To standardize instrument fracture, a torsional type of failure was created on each instrument. The fractured specimens of each instrument group were randomly divided into three static immersion subgroups of 1 h, 7-day, and 30-day (n = 3). Simulated body fluid (SBF) was prepared to mimic human blood plasma by Kokubo&Takadama protocol for ex situ static immersions at 37ºC. The surfaces were examined via scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. To determine the quantitative ion release, the retrieved SBFs were analyzed using inductively coupled plasma mass spectrometry. Two-way ANOVA and Tukey post hoc tests sought the statistical significance of the nickel ion values(p 0.05). Conclusions Within the limitations of the presented study, it was concluded that the fractured SS and NiTi root canal instruments release Ni ions in contact with body fluid. However, the Ni ion release values determined during the observation periods are lower than the critical toxic or allergic thresholds defined for the human body. This was due to the ionic dissolution cycle reaching a stable state from 1-hour to 30-day exposure to the body fluid of fractured instruments.

The demand for synthetic bone grafts has increased in recent years. Hydroxyapatite (HA) is one of the highly suitable candidates as a bone graft material due to its excellent biocompatibility and high osteoconductive properties with low toxicity. HA has disadvantageous mechanical strength showing relatively fragile and brittle behavior due to its high hygroscopic properties. This leads to improper mechanical properties for such grafting applications. Therefore, HA should be combined with another material with similar biocompatibility and high hardness, such as SiO2. In this work, HA/SiO2 (HAS) composite material was prepared via a hydrothermal method to obtain the high purities of HA with a particle size of approximately 35 nm and around 50% crystallinity. It was found that the addition of SiO2 stimulated the composite system by forming an orthosilicic acid complex that can reduce the overall solution’s pH, thus contributing to the integrity and stability of the HAS composite. Therefore, higher SiO2 contents in the HAS composite can enhance its mechanical stability when immersed in simulated body fluid (SBF). Our work demonstrated that HAS can highly improve HA material’s hardness and mechanical stability under immersion of SBF. The Vickers test showed that the 0.05 GPa hardness in 10% SiO2 increased to 0.35 GPa hardness with the addition of 20% SiO2. The crystal structures of HAS were analyzed using X-ray diffraction, and the morphology of the HAS composites was observed under electron microscopy.

Bone cement is one of the materials used in orthopaedics that serves various functions, such as binding bone implants, replacing damaged bones and filling spaces within bones. Various materials have been used to synthesize bone cement, and one promising material for further research is fish bone waste-based bone cement. This study investigates the potential of fish bone waste-based bone cement by incorporating nano fish bone (NFB) and L-arginine (L-Arg) protein into polymethyl methacrylate (PMMA) to examine apatite growth. NFB derived from the Salmo salar fish positively influences osteoblast cell proliferation and differentiation, while L-Arg enhances biocompatibility and antibiotic properties. The NFB/L-Arg combination holds promise in accelerating new bone formation and cell growth, both of which are crucial for fracture healing and bone remodelling. Tensile strength tests reveal the superior performance of BC-PMMA-1-NFB/L-Arg (36.11 MPa) compared with commercial PMMA (32 MPa). Immersion tests with simulated body fluid (SBF) solution for 7 days reveal accelerated apatite layer formation, emphasizing the potential benefits of NFB/L-Arg in bone cement applications.

The durability of a metallic biomaterial to withstand weight loss is a key factor in determining its service life and performance. Therefore, it is essential to create biomaterials with high wear resistance to ensure the biomaterial has a long service life. Thus, this study aims to explore the dry and wet sliding wear characteristics of the developed Ti-15Mo-xSi as-cast alloys (where x equals 0, 0.5, 1, 1.5, and 2 wt.%) in order to assess the impact of the Si addition on the microstructure, mechanical properties, and wear resistance and to consider them for biomedical applications. The wear experiments were conducted using a pin-on-desk wear testing machine at a load of 20 N and a sliding distance of 1000 m with and without applying simulated body fluid (SBF). Different techniques were utilized in the evaluation of the developed Ti-15Mo-xSi alloys. The results showed that significant grain refining was attained with the Si addition. The hardness, compressive strength, and wear resistance of the Ti-15Mo-xSi as-cast alloys increased with the increase in Si content. The Ti-15Mo-2Si as-cast alloy exhibited the highest dry and wet wear resistance of all the Ti-15Mo-xSi alloys. The worn surfaces were investigated, the roughness and main features were reported, and the wear mechanisms were also discussed. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate collagen scaffolds (CS) in terms of their in vitro resorption behavior, surface structure, swelling behavior, and mechanical properties in physiologically simulated environments, compared with porcine native connective tissue. Materials and methods: Three test materials—one porcine collagen matrix (p-CM), two acellular dermal matrices (porcine = p-ADM, allogenic = a-ADM)—and porcine native connective tissue (p-CTG) as a control material were examined for resorption in four solutions using a high-precision scale. The solutions were artificial saliva (AS) and simulated body fluid (SBF), both with and without collagenase (0.5 U/ml at 37 °C). In addition, the surface structures of CS were analyzed using a scanning electron microscope (SEM) before and after exposure to AS or SBF. The swelling behavior of CS was evaluated by measuring volume change and liquid absorption capacity in phosphate-buffered saline (PBS). Finally, the mechanical properties of CS and p-CTG were investigated using cyclic compression testing in PBS. Results: Solutions containing collagenase demonstrated high resorption rates with significant differences (p < 0.04) between the tested materials after 4 h, 8 h and 24 h, ranging from 54.1 to 100% after 24 h. SEM images revealed cross-linked collagen structures in all untreated specimens. Unlike a-ADM, the scaffolds of p-CM and p-ADM displayed a flake-like structure. The swelling ratio and fluid absorption capacity per area ranged from 13.4 to 25.5% among the test materials and showed following pattern: p-CM > a-ADM > p-ADM. P-CM exhibited higher elastic properties than p-ADM, whereas a-ADM, like p-CTG, were barely compressible and lost structural integrity under increasing pressure. Conclusions and clinical implications: Collagen scaffolds vary significantly in their physical properties, such as resorption and swelling behavior and elastic properties, depending on their microstructure and composition. When clinically applied, these differences should be taken into consideration to achieve the desired outcomes. [ABSTRACT FROM AUTHOR]

In the present study, Fabrication and modeling of nanocomposites with bioceramic nanoparticles for rapid wound healing with (0wt. %, 5wt. %, 10wt. %, 15wt. % NPs) were investigated. After the fabrication of nanocomposites using the freeze-drying technique, X-ray diffraction (XRD) test is performed to show the crystallinity of hydroxyapatite and titanium oxide. Scanning electron microscopy (SEM) tests are performed to demonstrate the morphology of the structure, atomic force microscope (AFM) test is performed to show surface roughness and pores. Finally by placing nano scaffolds in a simulated body fluid (SBF) for 21 days, their weight and pH changes are measured. Then, by performing the tensile test, the results related to the tensile strength of the scaffolds are examined. In this paper, the sum of mechanical and physical laboratory results are compared with the results obtained by molecular dynamics simulation (MDs). The results show that with the increase of titanium nanoparticles, the physical and mechanical properties, as well as the healing properties of the wound dressing, have increased significantly. Also, the comparison of laboratory results and MDs results determine the accuracy of this method. Therefore fabricating these nanocomposites helps a lot for rapid wound healing. [ABSTRACT FROM AUTHOR]

Background: To analyse the changes in surface and nickel ion release characteristics of fractured root canal shaping instruments in a simulated body fluid environment. Methods: A total of 54 new instruments were studied. The instrument groups consisted of five different NiTi alloys and a stainless-steel alloy. To standardize instrument fracture, a torsional type of failure was created on each instrument. The fractured specimens of each instrument group were randomly divided into three static immersion subgroups of 1 h, 7-day, and 30-day (n = 3). Simulated body fluid (SBF) was prepared to mimic human blood plasma by Kokubo&Takadama protocol for ex situ static immersions at 37ºC. The surfaces were examined via scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. To determine the quantitative ion release, the retrieved SBFs were analyzed using inductively coupled plasma mass spectrometry. Two-way ANOVA and Tukey post hoc tests sought the statistical significance of the nickel ion values(p < 0.05). Results: In 1 h of immersion, the newly formed structures, exhibiting mostly oxygen signals, were widespread and evident on NiTi surfaces. In contrast, fewer structures were detected on the SS surface in that subgroup. In 7 days of immersion, a tendency for a decrease in the density of the new structures was revealed in NiTi groups. The oxygen signals on NiTi group surfaces significantly increased, contrary to their decrease in SS. Signals of sodium, chlorine, and calcium were detected, indicating salt precipitates in groups. In 30 days of immersion, salt precipitates continued to form. The Ni-ion release values in all instrument groups presented significant differences in comparison to the SBF control in all immersion periods(p < 0.001). No significant differences were observed in immersion time periods or instrument groups(p > 0.05). Conclusions: Within the limitations of the presented study, it was concluded that the fractured SS and NiTi root canal instruments release Ni ions in contact with body fluid. However, the Ni ion release values determined during the observation periods are lower than the critical toxic or allergic thresholds defined for the human body. This was due to the ionic dissolution cycle reaching a stable state from 1-hour to 30-day exposure to the body fluid of fractured instruments. [ABSTRACT FROM AUTHOR]

Zn-Li-based alloys have drawn great attention as promising candidates for load-bearing sites, such as intramedullary nails and bone plates. They possess high monotonic strength (over 500MPa) and better pitting resistance with lithium-rich layers acting as barriers for corrosion attack under (quasi-)static conditions. However, their response to dynamic loadings such as fatigue is still unknown. Herein, the corrosion fatigue behavior of a series of Zn-Li binary alloys with different lithium addition amounts was tested in simulated body fluid. Tensile and fatigue strength of the materials were proportional to lithium content while corrosion fatigue strength was not. Extremely long cracks that extended parallel to the loading direction were found in Zn-1.0wt.%Li alloys. These cracks propagated by selective dissolution of the lithium-rich phase in the eutectoid regions and drastically reduced the corrosion fatigue strength of Zn-1.0wt.%Li alloy owing to exacerbated crack propagation. To sum up, Zn-Li binary alloys showed fatigue strength comparable to pure iron and pure titanium, which confirmed their loading capacity under dynamic conditions. Zn-Li-based alloys are qualified as biodegradable metals and are dedicated to load-bearing applications. Current research has shown that lithium can suppress pitting corrosion by the formation of lithium-rich layers on the alloy surface during (quasi-)static conditions. However, how these materials respond to dynamic loading is still unknown. The present study investigated the influence of lithium amount (0.1∼1.0wt.%) on the corrosion fatigue behavior of binary Zn-Li alloys. The results showed that lithium effectively improved the mechanical strength but can harm corrosion fatigue strength at high content due to selective dissolution of lithium-rich phase. This demonstrated that the amount of lithium should be controlled for optimal properties. Zn-0.8wt.%Li alloy demonstrated a good combination of tensile and corrosion fatigue strength, which can be further improved by proper alloying and thermomechanical treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

The treatment of critical-size bone defects remains a complicated clinical challenge. Recently, bone tissue engineering has emerged as a potential therapeutic approach for defect repair. This study examined the biocompatibility and repair efficacy of hydroxyapatite-mineralized bionic polylactic acid (PLA) scaffolds, which were prepared through a combination of 3D printing technology, plasma modification, collagen coating, and hydroxyapatite mineralization coating techniques. Physicochemical analysis, mechanical testing, and in vitro and animal experiments were conducted to elucidate the impact of structural design and microenvironment on osteogenesis. Results indicated that the PLA scaffold exhibited a porosity of 84.1% and a pore size of 350 μm, and its macrostructure was maintained following functionalization modification. The functionalized scaffold demonstrated favorable hydrophilicity and biocompatibility and promoted cell adhesion, proliferation, and the expression of osteogenic genes such as ALP, OPN, Col-1, OCN, and RUNX2. Moreover, the scaffold was able to effectively repair critical-size bone defects in the rabbit radius, suggesting a novel strategy for the treatment of critical-size bone defects. [ABSTRACT FROM AUTHOR]

The demand for synthetic bone grafts has increased in recent years. Hydroxyapatite (HA) is one of the highly suitable candidates as a bone graft material due to its excellent biocompatibility and high osteoconductive properties with low toxicity. HA has disadvantageous mechanical strength showing relatively fragile and brittle behavior due to its high hygroscopic properties. This leads to improper mechanical properties for such grafting applications. Therefore, HA should be combined with another material with similar biocompatibility and high hardness, such as SiO2. In this work, HA/SiO2 (HAS) composite material was prepared via a hydrothermal method to obtain the high purities of HA with a particle size of approximately 35 nm and around 50% crystallinity. It was found that the addition of SiO2 stimulated the composite system by forming an orthosilicic acid complex that can reduce the overall solution's pH, thus contributing to the integrity and stability of the HAS composite. Therefore, higher SiO2 contents in the HAS composite can enhance its mechanical stability when immersed in simulated body fluid (SBF). Our work demonstrated that HAS can highly improve HA material's hardness and mechanical stability under immersion of SBF. The Vickers test showed that the 0.05 GPa hardness in 10% SiO2 increased to 0.35 GPa hardness with the addition of 20% SiO2. The crystal structures of HAS were analyzed using X-ray diffraction, and the morphology of the HAS composites was observed under electron microscopy. [ABSTRACT FROM AUTHOR]

Samples prepared with the AZ80 magnesium alloy were immersed in simulated body fluids (SBF) with different flow rates (0 and 3 mL/s) and different pH values (4, 7.4 and 9). During the immersion process, the electrochemical impedance spectrum (EIS) and the dynamic potential polarization curves were measured using an electrochemical work station. Scanning electron microscope (SEM) and energy spectrometer (EDS) were used to observe the corrosion morphology of the sample surface and the chemical composition of the corrosion products. The results showed that the corrosion resistance of samples increases with increasing pH values, and decreases with increasing flow rates. In the SBF with different pH values, the effect of the flow rate on the corrosion resistance of the magnesium alloy is different. The corrosion resistance of magnesium alloy was the least affected by the flow rate in pH4 environment, and the most affected in pH9 environment. The corrosion mechanism of magnesium alloy under the interaction of flow rate and pH value was discussed. [ABSTRACT FROM AUTHOR]

In the present research, friction stir processing technique was performed to ameliorate the MB3 magnesium alloy surface through grain reduction and integration of bio-ceramic Nano particles. The friction stir processing was carried out at 1140 rpm and 100 mm/min by using a tapered tool pin profile. The incorporated bio-ceramic Nano particles are hydroxyapatite, tri-calcium phosphate and aluminum oxide. The results revealed that all processed samples have finer grain structure than that of the magnesium matrix, which caused an increase in the average microhardness values in the stirred zone. Furthermore, the tensile properties revealed an enhancement in elongation of all processed samples with deterioration in both ultimate tensile and yield strength values. On the other hand, the electrochemical impedance spectroscopy results exposed larger capacitive radius of all samples compared with the base material which reflects the improvement in the corrosion resistance. Accordingly, the potentiodynamic polarization results of all manufactured samples showed better bio-corrosion resistance in simulated body fluid than that of the base material, where the best corrosion resistance was achieved by magnesium-hydroxyapatite composite. The results obtained from the immersion test results manifested lower corrosion rates of all processed samples; where the friction stir processed and magnesium-hydroxyapatite samples corrosion rates were about 66% and 31% respectively of the base material. The corroded surfaces of all samples contained filiform and pitting corrosions after 72 h of immersion in simulated body fluid. [Display omitted] [ABSTRACT FROM AUTHOR]

The powder metallurgy method was used to manufacture three Ti-based alloys: Ti-15%Zr-2%Ta-4%Sn (Ti-Zr-Ta-4Sn), Ti-15%Zr-2%Ta-6%Sn (Ti-Zr-Ta-6Sn), and Ti-15%Zr-2%Ta-8%Sn (Ti-Zr-Ta-8Sn). Electrochemical measurements and surface analyses were used to determine the effect of Sn concentration on the corrosion of these alloys after exposure to a simulated body fluid (SBF) solution for 1 h and 72 h. It was found that the passivation of the alloy surface significantly increased when the Sn content increased from 4% to 6% and then to 8%, which led to a significant reduction in corrosion. The impedance spectra derived from the Nyquist graphs also explained how the addition of Sn significantly improved the alloys' polarization resistances. According to the change in the chronoamperometric current at an applied anodic potential over time, the increase in Sn content within the alloy significantly reduced the currents over time, indicating that the uniform and pitting corrosion were greatly decreased. The formation of an oxide layer (TiO2), which was demonstrated by the surface morphology of the alloys after exposure to SBF solution for 72 h and corrosion at 400 mV (Ag/AgCl) for 60 min, was supported by the profile analysis obtained by an X-ray spectroscopy analyzer. It was clear from all of the findings that the tested alloys have a remarkable improvement in resistance to corrosivity when the Sn content was increased to 8%. [ABSTRACT FROM AUTHOR]

In this study, the applicability of hydroxyapatite (HA) coatings on Al-Cu-Mg alloys (Al2024) was investigated by electrochemical techniques. The structural characterizations of the coated layers were investigated by SEM, EDS, and XRD equipment. The surface adhesion resistance and electrochemical degradation behavior were tested by scratch and potentiodynamic scanning (PDS) tests, respectively. It was observed that the HA coating had a homogeneous structure on the Al2024 surfaces, but some local areas could not be adequately coated with HA from the cross-section images. Also, the coating surfaces were microporous morphology, which is specific to the HA coatings. From the scratch test results of the coating, it was predicted that the critical load resistance (Lc1), 12N, would be sufficient for biomedical applications. Electrochemical corrosion tests revealed that HA coating decreased the corrosion current density (Icorr) and corrosion rate of the Al2024 alloy (0.885 and 5.260 μA·cm-2 for HA-coated and uncoated Al2024 alloy, respectively). However, despite the low Icorr value obtained with HA coating, it was observed that both Icorr and passivation current density (Ipass) values (3.15 μA·cm-2 for HA coating, 0.03 to 0.08 μA·cm-2 for different types of titanium alloys) were insufficient when compared to commercial titanium alloys. [ABSTRACT FROM AUTHOR]

Bioactive calcium phosphate composites were obtained, consisting of open-pore multiphase calcium phosphate foam ceramic based on α / β-tricalcium phosphate, β-calcium pyrophosphate, biomimetic apatite and 5% hydroxyapatite gel at a mass ratio (ceramic foam / hydroxyapatite gel) of 1:3 and 1:10. Preliminary modification of the calcium phosphate foam ceramic with biomimetic apatite in a concentrated SBF×5 solution allows increasing the static strength to 0,05 MPa with a slight decrease in porosity and maintaining the open-pore structure of polyurethane foam. Calcium phosphate composites have increased resorbability in SBF×5 and are resorbed 3–5 times faster compared to calcium phosphate foam ceramic. The presence of a significant amount of hydroxyapatite gel increases the rate of resorption of calcium phosphate foam ceramic and the ongoing processes of apatite formation with the participation of SBF×5 ions due to its high reactivity. The obtained calcium phosphate composites are used in regenerative treatments to fill bone defects in unloaded areas.

Ceramic biomaterials have been used for the treatment of bone defects and have stimulated intense research on such materials. We have previously reported that a salt composed of calcium ions and a phosphate ester (SCPE) transformed into hydroxyapatite (HAp) in a simulated body fluid (SBF) modified with alkaline phosphatase (ALP), and proposed SCPEs as a new category of ceramic biomaterials, namely bioresponsive ceramics. However, the factors that affect the transformation of SCPEs to HAp in the SBF remained unclear. Therefore, in this study, we investigated the behaviour of calcium salts of methyl phosphate (CaMeP), ethyl phosphate (CaEtP), butyl phosphate (CaBuP), and dodecyl phosphate (CaDoP) in SBF with and without ALP modification. For the standard SBF, an X-ray diffraction (XRD) analysis indicated that these SCPEs did not readily transform into calcium phosphate. However, CaMeP, CaEtP, and CaBuP were transformed into HAp and octacalcium phosphate in the SBF modified with ALP; therefore, these SCPEs can be categorised as bioresponsive ceramics. Although CaDoP did not exhibit a sufficient response to ALP to be detected by XRD, it is likely to be a bioresponsive ceramic based on the results of morphological observations. The transformation rate for the SCPEs decreased with increasing size of the linear alkyl group of the phosphate esters. The rate-determining steps for the transformation reaction of the SCPEs were changed from the dissolution of the SCPEs to the hydrolysis of the phosphate esters with increasing size of the phosphate ester alkyl groups. These findings contribute to designing novel bioresponsive ceramic biomaterials.

Titania and silica have been recognized as potential drug delivery system (DDS) carriers. For this application, controllable biocompatibility and the suppression of the initial burst are required, which can be provided by a calcium phosphate (CP) coating. However, it is difficult to control the morphology of a CP coating on the surface of carrier particles owing to the homogeneous nucleation of CP. In this study, we report the development of a CP-coating method that homogeneously corresponds to the shapes of silica–titania (SiTi) porous nanoparticles. We also demonstrate that controlled surface roughness of CP coatings could be achieved in SBF using SiTi nanoparticles with a well-defined spherical shape, a uniform size, and a tunable nanoporous structure. The precipitation of CP was performed on mono-dispersed porous SiTi nanoparticles with different Si/Ti molar ratios and pore sizes. The pore size distribution was found to significantly affect the CP coating in SBF immersion; the surfaces of the nanoparticles with bimodal pore sizes of 0.7 and 1.1–1.2 nm became rough after CP precipitation, while those with a unimodal pore size of 0.7 nm remained smooth, indicating that these two pore sizes serve as different nucleation sites that lead to different surface morphologies. [ABSTRACT FROM AUTHOR]

Ferrimagnetic glass-ceramics comprising maghemite crystals were synthesized for magnetic fluid hyperthermia (MFH) usage. The present work is focused on the result of the chemical composition and heat treatment temperature on the magnetic behavior of (60−x)SiO2−(10+x)FeO−20CaO−10Na2O,0≤x≤30 glass-ceramic system. It was observed that with the increasing of FeO from 10 to 40 wt% in the glass-ceramic compound, the percentage of maghemite phase increased. It was also seen that in the low heat treatment temperature (680 °C), by adding iron oxide up to 30 wt%, iron cations acts as a network former, and more than this amount acts as a network modifier. In contrast, iron cations in the same composition range at high temperatures (840 °C), acts as a network modifier. According to the VSM results, the maximum magnetization of glass-ceramics incremented from 0.23 emu/g to 0.30 emu/g with the increase in FeO percentage. It was also observed that with the increment of iron oxide percentage, the morphology of maghemite crystals changed from spherical to dumbbell-shaped.

Titanium and its based alloys are frequently selected for designing biomedical implants and it is thus necessary to study as detailed as possible their corrosion behavior in biological solutions, such as those in the human body environment. In this paper, with the use of molecular orbital calculation, we designed and developed alloys in the Ti-19Mo-xW system (x = 7, 8, 9, and 10 wt%) and investigated the influence of different contents of tungsten on the behavior of Ti-19Mo-xW alloy samples following corrosion in simulated body fluid (SBF). The values of B o ¯ (bond order) and M d ¯ (the metal—orbital energy level) were calculated for each alloy and correlations were established between B o ¯ and the content of tungsten. It was found that with the increase in tungsten content, the value of B o ¯ increases. Regarding the values of the corrosion resistance in SBF that resulted from the investigated alloys, the Ti19Mo7W alloy is distinguished by the lowest value of the corrosion current density and the lowest corrosion rate. [ABSTRACT FROM AUTHOR]

Magnesium alloy, with high specific strength and stiffness, biocompatibility and degradability, has become a potential orthopedic implant material. However, the application of magnesium alloys in the medical field is limited by the excessively fast corrosion rate and poor wear resistance. The corrosion and wear behaviors of AZ80 magnesium alloy in simulated body fluid (SBF) with different pH values (pH 4, 7.4 and 9) were investigated by electrochemical and reciprocating wear tests respectively to understand the corrosive wear behavior of orthopedic magnesium alloys. The wear morphology was characterized by three-dimensional white light interference profiler, scanning electron microscope (SEM), energy dispersive x-ray spectroscopy (EDS) and x-ray diffractometer (XRD). It was found that the test environment played a major role in the corrosion and wear behavior of the specimen. The corrosion resistance of the specimen enhanced with increasing pH value. Compared with the dry environment, the lubrication effect of SBF was not observed. Although the coefficient of friction (COF) of the specimen was not decreased by SBF, the wear volume of the specimen was significantly reduced by SBF. The synergistic effect of corrosion and wear caused the wear rate of the specimen in SBF to decrease with the increase of pH value. The stability of the block Mg(OH)2 film enhanced with the pH value, which was the reason why the corrosion and wear resistance of the specimen in SBF improved with the pH value. [ABSTRACT FROM AUTHOR]

In this study, Ca₂SiO₄ powders were synthesised using solid state reaction. The starting powders were sintered at 1050 ° C for 2 h. Moreover, the in vitro bioactivity of β- Ca₂SiO₄ was investigated by soaking the powders in a simulated body fluid (SBF) for various time periods to analyse the growth of hydroxyapatite (HA) on the surface of these powders. The synthesised powders were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) analysis. The simulated body fluid results showed that the β- Ca₂SiO₄ powders had good bioactivity to induce hydroxyapatite formation on their surface The results obtained showed that (HCA) can be formed on the surface of β- Ca₂SiO₄ soaked in the SBF solution for 1 day, and a continuous layer of dense HCA deposits covered the surface of β- Ca₂SiO₄ powders after 3 days of soaking in the SBF solution. Finally, the results obtained suggest that β- Ca₂SiO₄ ceramics are promising candidates for bone regeneration.

Mg and its composites are considered attractive candidates for supplying biomedical implantation. Mg-alloys are gaining popularity for biomedical implant applications, particularly bone regeneration because they have characteristics that are like those of natural bone. Simulated body fluid (SBF) is an electrolyte that is often utilized in vitro corrosion investigations. Using each SBF module individually and in combination, this research evaluates the corrosion effects on the system. pH alterations hasten the degeneration of the organism's pH and it was decided to explore the corrosion of Mg in an SBF. In this study, the effect of pH changes on the corrosion rate of Mg immersed in standard SBF solution was investigated in detail. According to previously published research, the corrosion process of Mg has been substantiated by scanning electron microscopy examinations of damaged surface morphology. In this investigation, pH 7 was determined to be the optimal pH for physiological fluids since it is neutral. To accomplish these aims, researchers examined Mg–2 wt.% Zn–0.5 wt.% Ca (ZC21) alloy pins microstructurally and mechanically, as well as the degradation of the alloy pins and their interactions with the SBF solution. The degradation of bone and its cytocompatibility with other substances. The degradation control of Mg-alloy occurred at a much slower rate than that of Mg alone. Bone cell development on the applied nano alloy is visible on SEM-EDS charts, demonstrating that this alloy is extremely compatible with human bone and that its usage as a stent for bone fracture is highly suggested in this study.

This study is aim to investigate the dielectric properties (dielectric constant, ε′ and loss factor, ε′′) and the biodegradation properties of the nano-hydroxyapatite/starch bone scaffold with various starch proportion in simulated body fluid. The nano-hydroxyapatite/starch bone scaffolds with starch proportions 30, 40, 50, 60, 70, 80, and 90 wt.% were fabricated. The ε′ and ε′′ of nano-hydroxyapatite/starch composite decrease when frequency increases. However, it increases when starch proportion and temperature increase. The biodegradation properties of the nano-hydroxyapatite/starch bone scaffold can be improved when the dielectric properties and porosity are enhanced. The enhancement of dielectric properties and porosity is due to the increment of starch proportion. The nano-hydroxyapatite/starch bone scaffold with the high starch proportion exhibits nano-hydroxyapatite/starch interfaces with strong intermolecular interactions that can stabilize biodegradation and biomineralization. The dielectric properties of the simulated body solutions are highly sensitive to the variation of the ion concentrations (calcium and phosphate). The nano-hydroxyapatite/starch bone scaffold with 80 wt.% starch proportion exhibits significant dielectric and biodegradation properties. It has potential to be a biodegradable inorganic/organic bone scaffold.

In this study, a KrF excimer laser was used to modify the biodegradable Mg-1Ca alloy and the time-evolution degradation behavior of the alloy before and after laser treatment was investigated in simulated body fluid (SBF) solution using immersion tests and electrochemical impedance spectroscopy (EIS). A 5 µm melted layer with a homogeneous microstructure and an MgO film on the surface were achieved by laser radiation. Corrosion observations (hydrogen evolution, morphology and corrosion products) and EIS results revealed an improvement of corrosion resistance after laser treatment for 48 h. It was found a two-layer structure developed after 2 h immersion on both the untreated and laser-treated alloys, but the sequence of forming the two layers was opposite and greatly influenced by the laser-treated layer. The time-evolution corrosion processes on the untreated and laser-treated alloys were discussed, providing a better understanding of corrosion behavior of biodegradable Mg alloys modified by excimer laser.

The addition of rare earth (RE) elements in Magnesium (Mg) alloys could optimize alloy microstructures and improve the mechanical property. The corrosion resistance however is a tough issue that limits its application as biomedical materials in human bodies. In this work, a green, fast and economical method of pulsed laser surface texturing (PLST) was employed to modify the RE WE43 Mg alloys and the corresponding corrosion resistance after the PLST treatment in simulated body fluid (SBF) was further examined. The microstructural results show that the surface exhibits petal-like microstructures and an oxide film composed of various oxides with remelting particles are also generated on laser-processed areas after PLST treatment. The electrochemical results reveal that the WE43 sample treated by PLST exhibits a superior corrosion resistance in SBF compared with the as-cast one. As for the PLST treated sample with 24 W, the corrosion potential (E corr) positively shifts from −1.788 V to −1.556 V after being immersed in SBF for 7 days, which is also nobler than that of the as-cast one, −1.915 V. While the corrosion current density (i corr) drops to the value of 8.3 μA/cm2, considerably lower than that of the as-cast sample, 1380 μA/cm2. The enhancement of corrosion resistance in the early stage is mainly due to the protective oxide film induced by PLST. Furthermore, long-term immersion in SBF further accelerates the formation of deposited hydroxyapatite (HA) products layer on petal-like microstructures, which would further contribute to its enhancement in corrosion resistance in the long-term service in human bodies. • PLST treatment induces petal-shaped microstructures on WE43 Mg alloys. • MgO and Y 2 O 3 form on WE43 alloy surfaces after PLST treatment in air. • PLST improves the corrosion resistance of WE43 alloys in SBF. • PLST treated alloys exhibit a passive behavior after a long-term immersion in SBF. [ABSTRACT FROM AUTHOR]