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- MakaleYayıncıda açık erişim2024Scopus SJRQ1Investigation of in-vitro bioactivity, electrochemical corrosion, wettability and adhesion properties of bioglass-based coatings modified with Y2O3 and Zr on novel β-type Ti-30Zr-5Mo alloys
Dikici, B.; Say, Y.; Zhao, X.; Niinomi, M.; Szechyńska-Hebda, M.
In this study, the in-vitro bioactivity, electrochemical corrosion resistance, wettability, and adhesion properties of bioglass-based coatings modified with Y2O3 and ZrO2 on Ti-30Zr-5Mo alloy were investigated. The coatings were prepared using the sol-gel method and applied to the alloy substrates through dip-coating. The surface morphology and elemental composition of the coatings were analyzed using SEM/EDS and XRD techniques. Potentiodynamic polarization (PDS) and electrochemical impedance spectroscopy (EIS) were employed to assess the electrochemical behavior of the coatings under in-vitro conditions. Contact angle measurements were conducted to evaluate the wettability of the surfaces. Adhesion strength was measured using tensile testing in accordance with ISO 13779-2 standards. Bioactivity tests were performed by immersing the samples in simulated body fluid (SBF). The results demonstrate that the addition of Y2O3 and ZrO2 improves adhesion strength and corrosion potential, but introducing localized galvanic effects that increase the corrosion current density. Besides, the coatings maintained their structural integrity after the bioactivity tests, and promoted new apatite formation.
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İncele - MakaleAçık Erişim2023Scopus SJRQ1Influence of chemical etchings on surface properties, in-vitro degradation and ion releases of 316l stainless steel alloy for biomedical applications
Say, Y.; Aslan, N.; Alla, A.M.A.; Özmen, H.
Different surface treatments are applied to improve the surface properties of metallic biomaterials. Chemical etching is one of the common techniques used for roughening the surface. In this regard, the effects of different chemical media on the surface roughness, degradation, and ion release of 316L SS steel were investigated in this study. The 316L SS steel was exposed to chemical etching in six different chemical media including HNO3, H2SO4, HCl, HClO4, NaOH and Na2CO, at four different concentrations (1, 2, 4, and 8 Molar), and at three immersion times (10, 60, and 180 min). SEM, EDS, and XRD analyses were used to examine the morphological and chemical impacts of chemical etching on sample surfaces, and roughness was measured on all sample surfaces. The effect of surface treatment on the degradation and ion release of the samples was comparatively examined. Characterization analyses indicated that the HNO3, H2SO4, and HCl media did not cause a significant reaction on the surface of the 316L SS. On the other hand, different phases were observed on the sample surfaces exposed to HClO4, NaOH, and Na2CO3 media. It was determined that the roughness had no linear correlation with the concentration and immersion time, and similarly, the degree of degradation and amount of ion release displayed no change depending on the roughness. Samples etched in H2SO4, HClO4, NaOH and Na2CO3 provided the highest roughness. It was found that H2SO4 caused a significant increase in the amount of ion release.
AtıfScopus18WoS17OpenAlex20İncele - MakaleAçık Erişim2022Scopus SJRQ2Effects of silver/selenium/chitosan doped hydroxyapatite coatings on REX-734 alloy: Morphology, antibacterial activity, and cell viability
Aksakal, B.; Say, Y.; Sinirlioglu, Z.A.
The goal of this study was to improve the antibacterial activity and cell viability of the Rex-734 alloy in biomedical applications. Various biocomposite coatings, such as single-layer hydroxyapatite (HAp), HAp/silver(Ag), and HAp/selenium(Se)/chitosan(Chit), were applied to Rex-734 alloy at various film thicknesses. The surface coatings were characterized by scanning electron microscopy, SEM, EDX, XRD and coating thickness and hardness of surface coatings were measured. The in vitro antibacterial activities of the coated and uncoated substrates were tested against Esherichia coli JM 103 and Staphylococcus aureus ATCC29293. In vitro cell–material interactions using Saos-2 osteoblast cells were characterized by the 3-(4,5-dimethylthiazol2-yl)− 2,5-diphenyltetrazolium bromide (MTT) assay for cell viability. The post-coating sintering parameters were shown to have a significant effect on the surface morphology. When compared to single HAp and HAp/Ag coatings, Se and Chit additions to HAp powders revealed good crack-free coating surfaces. Crack-free coating morphologies were achieved with a sintering speed of 3 °C/min. While single-HA coatings had an antimicrobial efficiency of 83% against E. coli, this value increased to 94% with Ag additive and to 85% with Se additive. Similarly, Ag and Se additives improved HAp's antimicrobial efficiency against Staphylococcus aureus. Cell viability decreased in the HAp/Ag coating at 86.5% and 90.93%, but increased significantly (p < 0.05) in the HA/Se-Chit coating at 137,43% and 158.23% at the end of the first and seventh days of incubation, respectively. The addition of Ag/Se/Chit to HAp increased the viability of the Rex-734 cells. Furthermore, it was revealed that the HAp-doped Se/Chit duplex biocomposite coating groups increased bone cell viability at much higher rates than the single-layer HAp coatings.
AtıfScopus12WoS8OpenAlex8İncele - MakaleAçık Erişim2020Scopus SJRQ1Enhanced corrosion properties of biological NiTi alloy by hydroxyapatite and bioglass based biocomposite coatings
Say, Y.; Aksakal, B.
Enhanced corrosion resistance is always an obligatory property in biomedical applications. For this purpose, the surfaces of NiTi alloy were duplex coated both by Hydroxyapatite (HA)/Silver (Ag) and BioGlass (BG)/Silver (Ag) using the sol-gel method. The surface morphologies, and corrosion behaviours of the coatings were examined via SEM, EDS, XRD, and mechanically, by means of hardness as well as adhesion and corrosion tests. SEM analyses showed that the homogenous and crack-free structures were obtained in the biocomposite coatings. Spherical-like structures in the coatings were observed and pitting type of corrosion was formed in the biocomposite coated NiTi surfaces. After the corrosion tests, enhanced corrosion resistance was observed in both HA- and BG- based coatings. However, HA-based HA/Ag coatings on NiTi alloys were obtained to have higher adhesion strength as well as higher corrosion resistance compared to the BG-based biocomposite coatings. The findings in the present study can help the design of future implants with higher corrosion resistance.
AtıfScopus38WoS37OpenAlex42İncele - MakaleYalnız künye2019Scopus SJRQ2Silver/Selenium/Chitosan-doped Hydroxyapatite coatings on biological NiTi alloy: In vitro biodegradation analysis
Say, Y.; Aksakal, B.
Abstract: Nitinol (NiTi) substrates were bioceramic coated by single layer Hydroxyapatite (HA), double layer HA/Silver (Ag) and double-layered HA/Selenium (Se)–Chitosan (Cht) substitutions by sol–gel method. Surface morphologies and adhesion strengths of the obtained coatings were characterized by means of SEM, EDX, XRD, and adhesion tests. Crack-free coatings were obtained in single layer-HA (S1), double layer HA/Ag (S2), and double-layered HA/Selenium–Cht (S3) coatings on NiTi alloys executed via the sol–gel method. Degradation behavior was analyzed in via simulated body fluid (SBF) environment by means of weight loss (%) and ion release rates for 1–4 weeks of immersion periods. The degraded coating particles were measured and metallic ions were detected quantitatively by an inductively coupled plasma–mass spectrometer (ICP–MS). The results show that such coatings could minimize and/or prevent the degradation of metallic ions and weight loss (%) from the coated substrates. From the overall results, HA/Ag double layer biocomposite (S2)-coated NiTi substrates revealed the highest adhesion strength and lowest weight loss and degradation. It was also shown in all groups that the Ni ion release from the NiTi substrates was prevented by the coatings. [Figure not available: see fulltext.].
AtıfScopus10WoS9OpenAlex11İncele - MakaleYalnız künye2018Scopus SJRQ3Synthesis and Characterization of Hydroxyapatite/TiO2 Coatings on the β-Type Titanium Alloys with Different Sintering Parameters using Sol-Gel Method
Dikici, B.; Niinomi, M.; Topuz, M.; Say, Y.; Aksakal, B.; Yilmazer, H.; Nakai, M.
In this study, hydroxyapatite (HA) based composite films were successfully syntheses on the β-type Ti29Nb13Ta4.6Zr (TNTZ). The solutionized TNTZ substrates coated with HA and HA/Titania (TiO2) bioactive composite coatings by sol-gel method under various sintering parameters related to sintering temperatures and heating ramp rates. Microstructural observations of the coatings revealed that apatite was formed on the substrates. The hardness values of the coatings increase with increasing both the sintering temperature and the TiO2 concentration in the coatings layer. However, it was found that the heating ramp rate of the sintering was not affecting the hardness values so much. Also, the hardness values of the HA/TiO2 composite coatings at all sintering temperatures were higher than only HA coated TNTZ samples due to the existence TiO2 phases in the HA matrix. Results indicating that the doping of HA with TiO2, improve the physical consistency between the coating layer and the substrates and provide a better inter-particle bonding due to the existence TiO2 phases in the HA.
AtıfScopus42OpenAlex43İncele - MakaleYalnız künye2017Scopus SJRQ1Biodegradation of hydroxyapatite coated Rex-734 alloy with silver and selenium/chitosan substitutions: In vitro analysis
Aksakal, B.; Say, Y.; Buyukpinar, Ç.; Bakirdere, S.
Hydroxyapatite (HA) based bioceramic coatings; such as single-HA, double layered with Silver-Ag, Selenium-Se and Chitosan substitutions on Rex-734 alloy were executed by using the sol-gel method. Surface morphologies and adhesion strengths of the obtained coatings were investigated and coating material weight losses and metal ion releases from the substrates were determined in SBF (Simulated Body Fluid) environment. The coatings were characterized by SEM, EDS, XRD and adhesion strengths between the substrate and bioceramic coatings were measured with adhesion tests. SEM analyses revealed that crack-free surface morphologies were obtained in all bioceramic coatings. The coatings were kept in SBF for immersion periods from one to four weeks and the weight loss (%) in coatings and changes in ion release rates were determined. HA/Ag double layered coatings applied on the Rex-734 alloy increased the adhesion strength and accordingly reduced the weight losses (%) of coating materials in SBF. Se/Chitosan double layered coatings were found to decrease the adhesion strength and increase the weight losses (%) in SBF. Additionally, all bioceramic coatings were observed to prevent the elemental ion release by physical barrier effect for the release of metal ions during the four weeks immersion period in SBF.
AtıfScopus12WoS11OpenAlex12İncele - MakaleAçık Erişim2016Scopus SJRQ3Biomechanical comparison of straight and helical compression plates for fixation of transverse and oblique bone fractures: Modeling and experiments
Sezek, Sinan; Aksakal, Bunyamin; Gürger, Murat; Malkoc, Melih; Say, Y.
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İncele - MakaleYalnız künye2016Scopus SJRQ2Effects of hydroxyapatite/Zr and bioglass/Zr coatings on morphology and corrosion behaviour of Rex-734 alloy
Say, Y.; Aksakal, B.
To improve corrosion resistance of metallic implant surfaces, Rex-734 alloy was coated with two different bio-ceramics; single-Hydroxyapatite (HA), double-HA/Zirconia(Zr) and double-Bioglass (BG)/Zr by using sol-gel method. Porous surface morphologies at low crack density were obtained after coating and sintering processes. Corrosion characteristics of coatings were determined by Open circuit potential and Potentiodynamic polarization measurements during corrosion tests. Hardness and adhesion strength of coating layers were measured and their surface morphologies before and after corrosion were characterized by scanning electron microscope (SEM), XRD and EDX. Through the SEM analysis, it was observed that corrosion caused degradation and sphere-like formations appeared with dimples on the coated surfaces. The coated substrates that exhibit high crack density, the corrosion was more effective by disturbing and transmitting through the coating layer, produced CrO3 and Cr3O8 oxide formation. It was found that the addition of Zr provided an increase in adhesion strength and corrosion resistance of the coatings. However, BG/Zr coatings had lower adhesion strength than the HA/Zr coatings, but showed higher corrosion resistance.
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