Immersion In Simulated Body Fluid Research Articles

Bioactivity of radiopaque 45S5 bioactive glass with progressive additions of Bi2O3: A dissolution study under static conditions

The integration of bioactive glasses (BGs) into hard tissues in in-vivo models can be evaluated through X-ray radiographs. The image contrast plays an important role and should be enhanced to improve accurate minimal invasive diagnostics of the performance of BGs containing implants after surgery. The present work shows the effect of the progressive addition of Bi2O3 (up to 12.2 wt%) on the structure, thermal properties, radiopacity, and bioactivity of 45S5-like BG obtained by quenching of the melt prepared from oxide precursors. The BG chemical composition, phase composition, structure, chemical state, thermal properties, and radiopacity were respectively investigated by X-ray fluorescence (XRF), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and radiopacity analysis according to the ISO13116:2014 norm. The bioactivity of the glasses was monitored by immersing them in a simulated body fluid (SBF) under static conditions. The apatite formation ability and ion concentration in SBF after 3, 7, 14, and 21 days were investigated by XRD, scanning electron microscopy (SEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), and ICP mass spectrometry (ICP-MS). All samples were found to be X-ray amorphous. Simultaneous formation of [BiO3] and [BiO6] units is noted in the BG. The glass radiopacity increased up to 1.8 and 4.2 times compared to the reference glasses without Bi2O3. Bi2O3 additions in the glass slow down the formation of apatite-like structures as a result of the network forming role of [BiO3] and [BiO6] units in the BG. Nevertheless, the BGs with the 12.2 wt % Bi2O3 still shows the ability to form apatite deposits after 7 days of immersion in simulated body fluid (SBF).

Degradation Behavior and Osteogenic Activity of Octacalcium Phosphate Modified MgO Coatings on Magnesium

To further enhance the corrosion resistance and osteogenic activity of the porous micro-arc oxidation (MAO) derived MgO ceramic coating on biomedical magnesium (Mg), octacalcium phosphate (OCP) layers with different microstucture were prepared on MAO coating by chemical deposition (CD) method to fabricate MAO/CD composite coatings. The in vitro degradation behaviors of MAO/CD-coated samples were evaluated by immersion in simulated body fluid (SBF) and electrochemical impedance spectroscopy (EIS) measurement. Their effects on in vitro MC3T3-E1 cell differentiation were investigated by examining alkaline phosphatase (ALP) activity and expression of main osteogenic-related genes. The in vitro immersion tests show that MAO/CD coatings rarely experience destruction and only micro-cracks occur after 96h. EIS tests indicate that MAO/CD coatings slow down the degradation rate of Mg observably. In addition, MAO/CD coatings improve osteogenic differentiation of MC3T3-E1 cells compared to MAO coating, which is ascribed the lightened alkalization of the surrounding medium as well as up-regulated intracellular Ca2+. MAO/CD coating deposited in 2h endows Mg the slowest degradation rate and excellent osteogenic differentiation induction activity.

Microstructure and Corrosion Behavior of Ti-10Cu Fabricated by Selective Laser Melting

This study investigates the influence of scan rotation and remelting on the microstructure and corrosion performance of Ti-10Cu alloy fabricated via selective laser melting (SLM). By analyzing the interplay between processing parameters and material properties, the work provides key insights for optimizing SLM-produced Ti-Cu alloys for improved functionality. Our work demonstrates that combining simultaneous remelting with reduced scan rotation yielded a homogenous microstructure with lower stress, surpassing the benefits of copper alone. This optimized configuration led to the highest polarization resistance (9 MΩ cm²) and thickest passive layer after simulated body fluid immersion, showcasing the synergism between process control and alloying for enhanced corrosion resistance. This opens doors for tailoring SLM-produced Ti-10Cu for demanding biomedical and marine applications.

Effect of Starch Binders on the Properties of Bioglass Tablets for Bone Tissue Engineering Applications

AbstractThis study focuses on the synthesis and characterization of SiO2–CaO–P2O5–Na2O nanofiber bioglass (BG) tablets using cellulose nanofibers (CNFs) as a template and starch binders. Three types of tablets are prepared: sago starch binder tablets, xanthan gum binder tablets, and dry press tablets (used as a control). The tablets are investigated for their physicochemical structure, mechanical properties, in‐vivo bioactivity, and antibacterial efficiency using various characterization techniques such as Fourier transform infrared (FTIR), field emission scanning electron microscope (FESEM), XRD, ICP, etc. The results indicate the formation of a hydroxyapatite (HA) layer on the surface of the tablets after immersion in simulated body fluid (SBF) for 28 days, demonstrating their bioactivity. FESEM analysis reveals the formation of HA crystals with different morphologies, including oval‐shaped crystals in sago tablets and needle‐like crystals in xanthan tablets. The binder tablets exhibit higher Ca/P ratios compared to the press‐dried tablets. Among the binder tablets, sago starch tablets show superior mechanical properties. Additionally, the binder tablets display efficient antibacterial activity against Staphylococcus aureus and Escherichia coli bacteria. These findings highlight their potential as promising candidates for bone tissue engineering applications.

Investigation of physical, mechanical and in-vitro bioactivity of bioactive glass-ceramics fabricated from waste soda-lime-silica glass doped P2O5 by microwave irradiation sintering

The ever-increasing generation of waste glass, poses a major environmental challenges due to its large volume and limited recycling options. This research explores a novel sustainable approach to repurposing this waste by transforming it into silicate based bioactive glass-ceramics (SBGCs). The glass waste was recycled into powder form and homogeneously mixed with sodium dihydrogen orthophosphate (NaH2PO4) in the step of 2, 4, 6, 8 and 10 wt % respectively with addition of organic binder and sintered by microwave irradiation approach. The obtained SBGCs were then characterized for its phase constituents, microstructure, physical, mechanical, and in-vitro bioactivity behaviour. The results showed that the samples exhibited considerable density and porosity while both the micro-hardness and compressive strength decreased with increased phosphate content. Sample SLP2% showed optimum hardness and compressive strength of 7.3 GPa and 87 MPa respectively. Combeite was obtained as the major phase while wollastonite and quartz were also detected. The developed SBGCs also showed increased hydroxyapatite (HA) formation after immersion in simulated body fluid (SBF) and displayed good antibacterial capacity when reacted with four bacteria strains. The results obtained indicate that the developed SBGCs might be considered a potential candidate for biomedical applications. However, sample SLP8% is the best sample to serve as bioactive glass-ceramics considering the combination of its high HA and good CHA formation, besides its considerable density and mechanical properties.

Development of a Novel Formulation of Bioactive Glass Based Calcium Phosphate Cement for Bone Grafting

AbstractParticulate bone grafting material can travel from the implantation site and diminish the magnitude of required bone formation response and hence its effectiveness. An easily prepared moldable graft that rapidly sets rigid in situ would alleviate this problem and in this study, such an injectable bone graft material is presented. By combining calcium phosphate (CP) salts with a bioactive glass (BG) mixed with a 2.5% Na2HPO4 solution a novel BG‐based calcium phosphate cement (CPC) is produced. Immersion in Tris buffer and simulated body fluid (SBF) solutions result in the rapid generation of octacalcium phosphate (OCP) and hydroxyapatite (HA) phases – a pre‐requisite for “bioactivity”. Cement‐conditioned media does not result in any cytotoxic potential with respect to MTT activity, DNA content, or alkaline phosphatase activity with an osteoblastic cell line. Application of the cement into standardized surgical defects in the minipig mandible results in short‐term, moderate irritation at 3 and 6 weeks and complete replacement of cement with new bone at 12 weeks.

Enhancing the degradation rate and biomineralization nature of antiferromagnetic Fe-20Mn alloy by groove pressing.

The Fe-Mn alloys are potential candidates for biodegradable implant applications. However, the very low degradation rates of Fe-Mn alloys in the physiological environment are a major disadvantage. In this study, the degradation rate of a Fe-20Mn alloy was improved using the groove pressing (GP) technique. Hot rolled sheets of 2 mm thickness were subjected to GP operation at 1000°C. Uniform fine-grained (UFG) Fe-Mn alloys were obtained using the GP technique. The influence of GP on the microstructure, mechanical properties, degradation behavior in simulated body fluid (SBF), surface wettability, biomineralization, and cytocompatibility was investigated and compared to the annealed (A Fe-Mn) and rolled (R Fe-Mn) sample. The groove-pressed Fe-Mn (G Fe-Mn) alloy had a grain size of approximately 40 ± 16 μm whereas the A Fe-Mn and R Fe-Mn samples had grain sizes of 303 ± 81 and 117 ± 14.5 μm, respectively. Enhanced strength and elongation were also observed with the G Fe-Mn sample. The potentiodynamic polarization test showed the highest Icorr, lowest polarization resistance, and lowest Ecorr for the G Fe-Mn sample among all other samples indicating its higher degradation rate. The weight loss data from immersion tests also shows that the percentage of weight loss increases with time indicating the accelerated degradation behavior of the sample. The static immersion test showed an enhancement in weight loss of 0.46 ± 0.02% and 1.02 ± 0.05% for R Fe-Mn and G Fe-Mn samples, respectively, than A Fe-Mn sample (0.31 ± 0.03%) after 56 days in immersion in SBF. The greater biomineralization tendency in UFG materials is confirmed by the G Fe-Mn sample's stronger hydroxyapatite deposition. When compared to the A Fe-Mn and R Fe-Mn samples, the G Fe-Mn sample has a better wettability, which promotes higher cell adhesion and vitality, showing higher biocompatibility. This study demonstrates that Fe-20Mn processed by GP has potential applications for the manufacture of biodegradable metallic implants.

Processing and cytocompatibility of Cu-doped and undoped fluoride-containing bioactive glasses

Sintered or additive-manufactured bioactive glass (BG) scaffolds are highly interesting for bone replacement applications. However, crystallization often limits the high-temperature processability of bioactive glasses (BGs). Thus, the BG composition must combine high bioactivity and processability. In this study, three BGs with nominal molar (%) compositions 54.6SiO2-1.7P2O3-22.1CaO-6.0Na2O-7.9K2O-7.7MgO (13–93), 44.8SiO2-2.5P2O3-36.5CaO-6.6Na2O-6.6K2O-3.0CaF2 (F3) and 44.8SiO2-2.5P2O3-35.5CaO-6.6Na2O-6.6K2O-3.0CaF2-1.0CuO (F3–Cu) were investigated. The dissolution and ion release kinetics were investigated on milled glass powder and crystallized particles (500–600 μm). All glasses showed the precipitation of hydroxyapatite (HAp) crystals after 7 days of immersion in simulated body fluid. No significant differences in ion release from glass and crystalline samples were detected. The influence of surface roughness on cytocompatibility and growth of pre-osteoblast cells (MC3T3-E1) was investigated on sintered and polished BG pellets. Results showed that sintered BG pellets were cytocompatible, and cells were seen to be well attached and spread on the surface after 5 days of incubation. The results showed an inverse relation of cell viability with the surface roughness of pellets, and cells were seen to attach and spread along the direction of scratches.

Strontium and Zinc Co-Doped Mesoporous Bioactive Glass Nanoparticles for Potential Use in Bone Tissue Engineering Applications.

Mesoporous bioactive glass nanoparticles (MBGNs) have attracted significant attention as multifunctional nanocarriers for various applications in both hard and soft tissue engineering. In this study, multifunctional strontium (Sr)- and zinc (Zn)-containing MBGNs were successfully synthesized via the microemulsion-assisted sol-gel method combined with a cationic surfactant (cetyltrimethylammonium bromide, CTAB). Sr-MBGNs, Zn-MBGNs, and Sr-Zn-MBGNs exhibited spherical shapes in the nanoscale range of 100 ± 20 nm with a mesoporous structure. Sr and Zn were co-substituted in MBGNs (60SiO2-40CaO) to induce osteogenic potential and antibacterial properties without altering their size, morphology, negative surface charge, amorphous nature, mesoporous structure, and pore size. The synthesized MBGNs facilitated bioactivity by promoting the formation of an apatite-like layer on the surface of the particles after immersion in Simulated Body Fluid (SBF). The effect of the particles on the metabolic activity of human mesenchymal stem cells was concentration-dependent. The hMSCs exposed to Sr-MBGNs, Zn-MBGNs, and Sr-Zn-MBGNs at 200 μg/mL enhanced calcium deposition and osteogenic differentiation without osteogenic supplements. Moreover, the cellular uptake and internalization of Sr-MBGNs, Zn-MBGNs, and Sr-Zn-MBGNs in hMSCs were observed. These novel particles, which exhibited multiple functionalities, including promoting bone regeneration, delivering therapeutic ions intracellularly, and inhibiting the growth of Staphylococcus aureus and Escherichia coli, are potential nanocarriers for bone regeneration applications.

On the way to increase osseointegration potential: Sequential SI-ATRP as promising tool for PEEK-based implant nano-engineering

In the search of the ideal bone implant material, surface initiated atom transfer radical polymerization (SI-ATRP) techniques were successfully employed to modify the polyetheretherketone (PEEK) surface with complex architecture nanolayers featuring hydrophilic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) or poly(2-hydroxyethyl methacrylate) (PHEMA) branches. As a result, polymer layers with height up to over 300 nm were synthesized to decrease the water contact angle from 92.8° to 23.0°. In-depth analysis of layer topography, structure and elemental composition realized with atomic force microscopy (AFM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), time-of-flight secondary ions mass spectroscopy (TOF-SIMS) and X-ray photon spectroscopy (XPS) confirmed successful surface modification. Additionally, to demonstrate the applicability of proposed PEEK functionalization, the biomineralization assay in simulated body fluid (SBF) solution was conducted. The high density of hydroxyl and amine groups in branched polymer brushes structure enhanced the rate of hydroxyapatites (HAp) formation substantially. Compared to untreated PEEK, modification with polymer brushes resulted in the creation of cauliflower-like structures with high specific surface area and Ca/P ratio equal to 1.83–1.87 for PEEK grafted with brushes composed of PHEMA backbone segment and PDMAEMA or PHEMA as block polymer branches (PEEK-g-PHEMA-g-PDMAEMA or PEEK-g-PHEMA-g-PHEMA) after 2 weeks. Finally, the process of the hydroxyapatite formation and increase of the layer thickness in a range of 14 days to 6 weeks of immersion in SBF was thoroughly visualized by scanning electron microscopy (SEM).

Improvement of Mg alloy corrosion resistance and apatite formation ability via PEO/Alginate/Akermanite hybrid coatings for biomedical purposes

The rapid degradation of Mg alloys in biodegradable orthopedic applications is a significant concern to be investigated. In this study, a bilayer composite coating based on alginate/akermanite and plasma electrolytic oxidation (PEO/ALG-AK) on the AZ31 Mg alloy was intended to enhance its corrosion resistance. For this purpose, akermanite nanopowder was synthesized using the sol-gel method and characterized by TEM and XRD. The influence of the PEO/ALG-AK coating layer on the physicochemical properties, electrochemical, and immersion behaviors in simulated body fluid (SBF) was compared to that of uncoated and PEO-coated samples. The AFM images revealed that the bilayer coating exhibited the highest average roughness (Ra = 781 ± 49.3 nm) among the other samples. The EIS test was conducted after 2, 72, and 168 h of immersion in SBF. The bilayer coatings on Mg alloy consistently demonstrated the highest corrosion resistance due to the ALG/Ak layer covering the PEO coating pores. The results of the polarization test also confirmed the achieved results. Furthermore, the implementation of the coatings, particularly the PEO/ALG-AK coating, illustrated a significant reduction in the release of Mg2+ ions and hydrogen bubbles, resulting in corrosion resistance improvement. Finally, the ability of samples to induce apatite formation was also assessed. The results displayed that the deposits on the bare Mg alloy, PEO, and PEO/ALG-AK coatings exhibited Ca/P ratios of 0.83, 1.11, and 1.57, respectively, which closely resembled the natural bone in the PEO/ALG-AK sample. Hence, this developed bilayer coating can be a suitable candidate for enhanced corrosion resistance and bioactivity (apatite formation ability) in the field of Mg biodegradable implants.

Modulating antibacterial properties of titanium surface coatings: The role of low intensity pulsed ultrasound and light stimuli

Medical titanium and titanium alloys were susceptible to infection following implantation due to their limited antibacterial properties. One effective approach to mitigate this risk was the application of antibacterial coatings on the medical titanium materials surface. Additionally, there was a pressing need in clinical practice to develop a titanium surface coating that can modulate antibacterial properties in response to external conditions. In this study, a zinc oxide-loaded silver nanorod arrays coating was fabricated on the titanium surface using intensity pulsed ultrasound and light as stimuli, aiming to achieve the desired regulation of antibacterial properties. The coating morphology and the silver distribution within the coating were investigated. The surface roughness and wetting angle were tested. The effect of low intensity pulsed ultrasound and light on the cumulative release of silver ions was studied, and its mechanism was analyzed. The bacteriostasis rate of the polarized ZnO-loaded silver nanorods array coating reached 99.96%. The synergistic bactericidal mechanism of piezoelectric effect, catalysis, silver ion bactericidal effect and nanorod puncture effect on bacteria was expounded. Finally, the ZnO-loaded silver nanorod array coating exhibited non-cytotoxicity and supported full osteoblast adherence morphology. The polarized coating was observed to be coated with abundant granular hydroxyapatite after immersion in simulated body fluids for 7 days. The results provide a possibility for modulating the antibacterial properties of titanium surface coatings in vitro.

Photothermal effect and antimicrobial properties of cerium-doped bioactive glasses

Cerium (Ce) ions exhibit multifunctional biological properties, such as anti-inflammatory, antioxidant, antimicrobial, and anticancer properties. Consequently, the development of Ce-containing biomaterials with therapeutic characteristics has received considerable research attention. In this study, Ce-doped 13–93 bioactive glass (Ce-BG) was prepared using the conventional melt-quenching method. The physical phases, surface morphologies, elemental contents, and elemental valence states of the samples were analysed. The concentration of the ions released from the samples in deionised water was determined, and their ability to induce hydroxyapatite was evaluated. The photothermal properties were tested by irradiating the samples with an 808 nm laser. The results indicate that an increase in the Ce content within a certain range did not affect the amorphous structure and morphology of the bioactive glass. Ce content variation affected the photothermal effect of Ce-BG. The wet state powder sample could be rapidly heated up to 58.24 °C under 2 W/cm2 laser irradiation at 5 mol% Ce doping, showing the best photothermal performance. Further, bacterial experiments demonstrated the good antimicrobial effect of this sample. Simulated body fluid immersion experiments revealed the ability of the Ce-BG to induce hydroxyapatite production. Furthermore, in vitro cell culture studies showed that the Ce-BG was not toxic to MC3T3-E1 cells and induced cell proliferation after 3 days. Therefore, Ce-BG is a promising bioactive material because of its favourable photothermal effects, antimicrobial properties, and biocompatibility.

Corrosion and biological study on biofunctionalized porous coating on titanium produced by plasma electrolytic oxidation

BackgroundUpon implantation of biomaterials in human body, the risk for electrochemical corrosion within the surrounding environment becomes a critical factor affecting implant biocompatibility. This study endeavors to develop a biofunctionalized and corrosion-resistant TiO2/hydroxyapatite coating using a cost-effective one-step plasma electrolytic oxidation (PEO) process. Initially, magnesium and zinc substituted hydroxyapatite (HA) particles were synthesized to enhance bioactivity and antibacterial properties compared to pure HA. The synthesized particles underwent characterization using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Subsequently, these synthesized particles were utilized in the Plasma Electrolytic Oxidation (PEO) coating process. Polarization and electrochemical impedance spectroscopy (EIS) tests, in addition to bioactivity and antibacterial activity assessments, were conducted to examine the corrosion resistance and biological response of the coatings. The results of biological tests on particle-containing PEO coatings on titanium demonstrated a significant improvement in the bioactivity and antibacterial activity of the biofunctionalized coatings caused by ion-substituted HA particles. Furthermore, polarization and EIS results indicated superior corrosion resistance in the biofunctionalized coatings. Electrochemical tests after one week of immersion in simulated body fluid (SBF) revealed the positive influence of apatite formation on the long-term corrosion behavior of coatings with ion-substituted particles.

Modifying of physical, biodegradation, drug delivery characteristics of bioactive borophosphate glass by addition of molybdenum

In this study, high valence MoO3 was added to bioactive glass based on (50-x) P2O5 - 20 B2O3 – 20 CaO - 10 Na2O (x = 0, 5, 10–15 mol. %; the corresponding samples encoded as 0-Mo, 5-Mo, 10-Mo, and 15-Mo) to modify its physical, biodegradation, drug delivery properties. The glasses were prepared via melt-quenching process. The obtained glasses were analyzed by XRD, FTIR, SEM, Raman, and zeta potential (-42, - 31.8, - 34.5, and - 26.4 mV for 0-Mo, 5-Mo, 10-Mo, and 15-Mo, respectively). The in vitro bioactivity and biodegradation were examined in the simulated body fluid (SBF). The glasses were checked for ability for drug delivery by using ciprofloxacin (CIP) antibiotic as a drug model to attain an anticipated therapeutic response to avoid infections, and the drug release kinetic was studied by fitting the release data with Higuchi and Hixon-Crowell models. Finally, the antibacterial activity of the glasses conjugated with drug and drug-free glasses was tested against gram positive bacteria (Streptococcus aureus), gram negative bacteria (Escherchia coli) and Pathogenic yeast (Candida albicans). The results showed that the glasses were characterized by amorphous structure, and it showed a good bioactivity after immersion in SBF. Moreover, the results presented that addition of molybdenum increased the degradation rate of the glasses and affected their surface charge to less negative. In addition, it increased the drug loading efficiency and drug release rate, where 11.2 %, 56.9 %, 75.4 %, and 83.6 % of the drug released from 0-Mo, 5-Mo, 10-Mo, and 15-Mo, respectively, at the end of incubation time. The drug release occurred by combined diffusion and dissolution mechanism. Finally, antibacterial activity showed that drug-free glasses possessed antibacterial activity against the bacterial, meanwhile the antibacterial activity increased by loading CIP on the glass particles. In conclusion, different physical properties, as well as biodegradation and drug release can be tailored by addition of molybdenum. On the other hand, the prepared glasses are expected to be used successfully as multifunctional bone grafting materials.

Studying the electrical, mechanical, and biological properties of BCZT-HA composites.

The piezoelectric properties of natural bone and their influence on bone growth have inspired researchers to study a range of bio-piezoelectric composite materials. By exploring these materials, researchers aim to understand better, how piezoelectricity can be controlled to promote bone growth and tissue regeneration. In this work, the prominent piezoelectric material, (Ba, Zr) TiO3 -x(Ba,Ca)TiO3 , abbreviated as BCZT, was selected as a possible bone growth enhancer in hydroxyapatite (HA) scaffolds. Initially, BCZT and hydroxyapatite (HA) powders were synthesized using the sol-gel method. Subsequently, various composite samples of BCZT-xHA were prepared using the conventional solid-state method. After sintering the samples at 1300°C, the phase structure, microstructure, density, and electrical properties were characterized. The samples' compressive strength was determined by analyzing the outcomes of basic compression tests. The biological behavior of the samples in terms of in vitro simulated body fluid immersion and MTT tests were evaluated. Our results revealed that among the BCZT-xHA samples, the BCZT-20HA sample had the best composition, considering its electrical, mechanical, and biological properties. A d33 value of 10 pC/N, dielectric permittivity of 110, and the g33 equal to 10.27 mV m/N resulted in the output voltage of 1.03 V. The results of the MTT assay test confirmed the noncytotoxic nature of the samples with the highest optical density in the BCZT-20HA sample.

The role of MgO on physical and bioactive properties of borophosphate glasses for biomedical applications

In this work, a novel series of borophosphate glasses of the system 40B2O3–25P2O5–(20-x)Na2O–15CaF2–xMgO (x = 0, 2.5, 5, 7.5, and 10 mol%) were synthesized using the melt-quenching technique. The effect of replacing Na2O with MgO in the glasses was analyzed by the physical and bioactive properties. The glasses were characterized by density, molar volume, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Differential thermal analysis (DTA), bioactivity tests in simulated body fluid (SBF), pH measurements, mass loss, and verification of cellular compatibility in RAW 247 murine macrophages. XRD and FTIR analyses were performed before and after immersion in SBF to verify the bioactivity. Density, molar volume and FTIR results before SBF showed structural changes in the glasses due to the addition of MgO. The pH and mass loss measurements allowed to verify the degradation behavior of the glass series as a function of MgO concentration. The DTA data showed an increase in Tg, Tx, and thermal stability due to the increase in MgO addition. XRD and FTIR analyses after SBF soaking showed superficial formation of apatites and other calcium phosphates of biological interest in the samples, attesting the bioactivity. Cytotoxicity assessed by MTT assay on the cell line RAW 247 showed that at a concentration of 500 μg/mL all glasses were compatible (non-cytotoxic). The results suggest that the synthesized glasses are bioactive, with the sample containing 5 mol% MgO exhibiting the bioactivity and biocompatibility required for biomaterial applications.

Investigations on the Degradation Behavior of Processed FeMnSi-xCu Shape Memory Alloys.

A new functional Fe-30Mn-5Si-xCu (x = 1.5 and 2 wt%) biomaterial was obtained from the levitation induction melting process and evaluated as a biodegradable material. The degradation characteristics were assessed in vitro using immersion tests in simulated body fluid (SBF) at 37 ± 1 °C, evaluating mass loss, pH variation that occurred in the solution, open circuit potential (OCP), linear and cyclic potentiometry (LP and CP), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and nano-FTIR. To obtain plates as samples, the cast materials were thermo-mechanically processed by hot rolling. Dynamic mechanical analysis (DMA) was employed to evaluate the thermal properties of the smart material. Atomic force microscopy (AFM) was used to show the nanometric and microstructural changes during the hot rolling process and DMA solicitations. The type of corrosion identified was generalized corrosion, and over the first 3-5 days, an increase in mass was observed, caused by the compounds formed at the metal-solution interface. The formed compounds were identified mainly as oxides that passed into the immersion liquid. The degradation rate (DR) was obtained as a function of mass loss, sample surface area and immersion duration. The dynamic mechanical behavior and dimensions of the sample were evaluated after 14 days of immersion. The nanocompounds found on the surface after atmospheric corrosion and immersion in SBF were investigated with the Neaspec system using the nano-FTIR technique.

Thermoplastic polyurethane/POSS nanohybrids: Synthesis, morphology, and biological properties.

Recent studies show good osteoinductive properties of polyurethanes modified with polyhedral oligomeric silsesquioxanes (POSS). In this work, three types of POSS; propanediolisobutyl-POSS (PHI-POSS), disilanolisobutyl-POSS (DSI-POSS), and octahydroxybutyl-POSS (OCTA-POSS) were chemically incorporated into linear polyurethane based on an aliphatic isocyanate, hexamethylene diisocyanate (HDI), to obtain new nanohybrid PU-POSS materials. The full conversion of POSS was confirmed by Fourier transform infrared spectroscopy (FTIR-ATR) spectra of the model reactions with pure HDI. The materials obtained were investigated by FTIR, SEM-EDS, and DSC. The DSC studies showed the thermoplasticity of the obtained materials and apparently good recovery. 30-day immersion in SBF (simulated body fluid) revealed an increase in the rate of deposition of hydroxyapatite (HAp) for the highest POSS loadings, resulting in thick layers of hydroxyapatite (~60-40 μm), and the Ca/P ratio 1.67 (even 1.785). The structure and properties of the inorganic layer depend on the type of POSS, the number of hard segments, and those containing POSS, which can be tailored by changing the HDI/poly(tetramethylene glycol) (PTMG) ratio. Furthermore, the obtained composites revealed good biocompatibility, as confirmed by cytotoxicity tests conducted on two cell lines; normal human dermal fibroblasts (NHDF) and primary human osteoblasts (HOB). Adherent cells seeded on the tested materials showed viability even after a 48-h incubation. After this time, the population of viable, and proliferating cells exceeded 90%. Bioimaging studies have shown the fibroblast and osteoblast cells were well attached to the surface of the tested materials.

Tuning biodegradability, bone-bonding capacity, and wear resistance of zinc-30% magnesium intermetallic alloy for use in load-bearing bone applications

This work aimed to improve the rapid biodegradation, poor wear resistance properties, and lack of bioactivity of metallic biomaterials to be used in orthopedic applications. In this context, zinc–magnesium (Zn–Mg) alloy with successive contents of calcium silicate (CaSiO3) and silicon nitride (Si3N4) was prepared using powder metallurgy technique. After sintering, their phase composition and microstructure were investigated using the X-ray diffraction technique and scanning electron microscopy (SEM), respectively. Furthermore, their degradation behavior and ability to form hydroxyapatite (HA) layer on the sample surface after immersion in simulated body fluid (SBF) were monitored using weight loss measurements, inductively coupled plasma-atomic emission spectroscopy, and SEM. Moreover, their tribo-mechanical properties were measured. The results obtained showed that the successive contents of CaSiO3 were responsible for improving the bioactivity behavior as indicated by a good formation of the HA layer on the samples’ surface. Additionally, ceramic materials were responsible for a continuous decrease in the released ions in the SBF solution as indicated by the ICP results. The tribology properties were significantly improved even after exposure to different loads. Based on the above results, the prepared nanocomposites are promising for use in orthopedic applications.