Days Of Immersion In Simulated Body Fluid Research Articles

Monitoring of Carbonated Hydroxyapatite Growth on Modified Polycrystalline CVD-Diamond Coatings on Titanium Substrates

Production of diamond coatings on titanium substrates has demonstrated as a promising strategy for applications ranging from biosensing to hard tissue engineering. The present study focuses on monitoring the nucleation and growth of bone-like carbonated-hydroxyapatite (C-HA) on polycrystalline diamond (PCD) synthetized on titanium substrate by means of a hot filament chemical vapor deposition (HF-CVD) method. The surface terminations of diamond coatings were selectively modified by oxidative treatments. The process of the C-HA deposition, accomplished by precipitation from simulated body fluid (SBF), was monitored from 3 to 20 days by Raman spectroscopy analysis. The coupling of morphological and structural investigations suggests that the modulation of the PCD surface chemistry enhances the bioactivity of the produced materials, allowing for the formation of continuous C-HA coatings with needle-like texture and chemical composition typical of those of the bone mineral. Specifically, after 20 days of immersion in SBF the calculated carbonate weight percent and the Ca/P ratio are 5.5% and 2.1, respectively. Based on these results, this study brings a novelty in tailoring the CVD-diamond properties for advanced biomedical and technological applications.

The Effect of Silver and Samarium on the Properties of Bioglass Coatings Produced by Pulsed Laser Deposition and Spin Coating.

The current study reports the use of silver (Ag) and samarium (Sm) as dopants to improve the properties of standard bioglass in terms of biological performance. This experiment considers thin films of doped bioglass obtained by pulsed laser deposition (PLD) and spin coating (SC). For both methods, some parameters were gradually varied, as the main objective was to produce a bioglass that could be used in biomedical fields. In order to study the morphology, the phase composition and other properties, the samples obtained were subjected to multiple analyses, such as thermal analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared (FT-IR), Raman spectroscopy, and x-ray diffraction (XRD). Furthermore, the in vitro bioactivity of the samples, as assessed through simulated body fluid (SBF) immersion, as well as immunocytochemistry and evaluation of actin filaments, assessed through fluorescence microscopy, are reported. The results confirmed the formation of the designed vitreous target employed as the source of material in the PLD experiments only at sintering temperatures below 800 °C; this vitreous nature was preserved in the grown film as well. The presence of Ag and Ce dopants in the parent glassy matrix was validated for all stages, from powder, to target, to PLD/SC-derived coatings. Additionally, it was demonstrated that the surface topography of the layers can be adjusted by using substrates with different roughness or by modulating the processing parameters, such as substrate temperature and working pressure in PLD, rotation speed, and number of layers in SC. The developed material was found to be highly bioactive after 28 days of immersion in SBF, but it was also found to be a potential candidate for inhibiting the growth of Gram-negative bacteria and a suitable support for cell growth and proliferation.

Exploring the potential of silica mixed zinc phosphate bioactive glasses for bone regeneration: In vitro bioactivity and antibacterial activity analysis

Biomaterials development is currently the main active research area in the field of bone tissue engineering. In the present study, the bioactive glasses with different chemical compositions (mol %) of zinc oxide, silica, calcium oxide, sodium oxide, and phosphates were synthesized by the melt-quench technique. We studied the thermal, physical, and other structural characteristics of the glasses to know the structural stability and potentiality to use as implant material. The in-vitro studies were performed to test the apatite forming ability and biocompatible nature of the prepared bioglass samples by immersing in simulated body fluid (SBF) solution with ion concentrations nearly equal to those in human blood plasma (pH =7.4 at 37 °C). All glass samples showed the formation of a clear layer of hydroxyapatite (HAP) on their surfaces after 14, and 21 days of immersion in SBF and the crystallization phases, morphology and functional groups of the hydroxyapatite layer (HAP) were confirmed by the characterizations of X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared (FTIR) analyses respectively. The antimicrobial studies of the silica containing phosphate bioglasses against Escherichia coli (E. coli), carried out for 24 h confirmed their potential antibacterial activity. The overall obtained results of the as developed silica containing phosphate bioglasses with enhanced properties suggested to use as potential bone regenerative implant material in the field of biomedicine.

Enhanced in-vitro biodegradation, bioactivity, and mechanical properties of Mg-based biocomposite via addition of calcium-silicate-based bioceramic through friction stir processing as resorbable temporary bone implant

Bioabsorbable Mg and alloys have been used as metallic biomaterials for orthopedic implant applications due to their similar mechanical properties to human natural bone. High biodegradation rate is the main reason for limiting clinical applications of Mg and alloys in biological media. In order to achieve long-lasting bio applications of bioabsorbable WE43 Mg alloy, it is necessary to improve strength and bioactivity and control biodegradation rate of this material. In this study, Mg-based biocomposites are produced using friction stir processing (FSP) by addition of wollastonite (CaSiO3) calcium-silicate-based bioactive reinforcing particle into Mg matrix. The results showed that applied severe plastic deformation during FSP caused formation of ultra-fine grain structure with homogenous distribution of secondary phase particles, which resulted in a remarkable improvement of ductility, strength and load bearing capacity of FSPed Mg matrix. Also, biodegradation behavior of resulting biocomposite was evaluated using electrochemical methods and in-vitro immersion test in simulated body fluid (SBF) and phosphate-buffered saline (PBS) at 37.5 °C. The results revealed that processed bioabsorbable Mg alloy showed a lower biodegradation rate compared to monolithic Mg alloy. Furthermore, the presence of wollastonite bioceramic particles significantly enhanced strength and reduced biodegradation of the Mg-based biocomposite. Moreover, the addition of wollastonite bioceramic particles positively affected the bioactivity of Mg matrix by forming a cauliflower shaped bone-like hydroxyapatite layer on the surface after 28 days of immersion in SBF and stimulate bone tissue regeneration.

Synthesis, characterization, and in vitro apatite formation of strontium-doped sol-gel-derived bioactive glass nanoparticles for bone regeneration applications

The morphology of bioactive glass nanoparticles has been reported to impact apatite-forming ability, biocompatibility, and cell functions. In this study, mesoporous bioactive glass nanoparticles (MBGNs) of mixed morphologies with nominal compositions (%mol) given by 74Si O2_(26−x)CaO_xSrO, (where x=0,1,3,and5) were prepared through a modified sol-gel method. The MBGNs were characterized by thermal gravimetric analysis (TGA), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption, X-ray diffraction (XRD), solid-state nuclear magnetic resonance (NMR), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). In particular, the effect of Sr concentration on the glass structure, surface morphology, particle size, microstructure, chemical durability, ion release, and in vitro mineralization on the MBGNs was studied. All compositions showed similar thermal degradation profiles irrespective of Sr concentrations. SEM observation showed a mixture of aggregated spherical- and rod-shaped particles in which particle sizes decreased with increasing Sr concentration. Textural analysis showed a decrease in specific surface area with increasing Sr concentration. NMR analysis revealed a reduction in glass network polymerization with increasing Sr concentration. NMR analysis showed hasty depletion of modifier cations from the MBGNs to the simulated body fluid (SBF), the effect more prominent in the pristine sample. We observed prompt surface modifications on MBGNs as a response to their interaction with SBF that led to interconversion of 29Si speciation in the order QCa,Sr1+QCa,Sr2→QH2→QH3. SEM, EDX, and XRD revealed the formation of crystalline hydroxyapatite (HA) on the MBGNs after three days of immersion in SBF. In vitro apatite-forming ability of MBGNs decreased with increasing Sr concentration. The MBGNs revealed promising potential properties for applications in orthopedics, dentistry, wound healing, and drug delivery systems.

Influence of bioactive particles and onium salt on the physicochemical properties of experimental infiltrants.

This study evaluated physicochemical properties of experimental infiltrants after addition of hydroxyapatite nanoparticles (HAp) or 58S bioactive glass (BAG) and diphenyliodonium hexafluorophosphate (DPI). The resin matrix was composed of TEGDMA/Bis-EMA (3:1), 0.5 mol% CQ, and 1 mol% EDAB. The blends received or not 0.5 mol% DPI and 10% wt BAG or HAp. Icon was used as commercial control. The groups were characterized by XRD, FT-IR spectrometry, and SEM before and after simulated body fluid (SBF) immersion for up to 7 days. Polymerization kinetics (n =3 ), water sorption and solubility (n=10), and viscosity (n = 3) were surveyed. For polymerization kinetics, the samples were polymerized for 5 min and the data were obtained from 40 s and 5 min. Statistical analysis was made using ANOVA and Tukey's test (a = 0.05). After 7 days of SBF immersion, XRD and FT-IR showed that the HAp crystalline phase was present only in the HAp groups. A lower degree of conversion (DC) and polymerization rate were observed for the Icon and BAG groups, whereas HAp showed higher values. For the BAG group, DPI increased polymerization rate and DC in 40 s. After 5 min, all groups presented DC above 80%. In groups with particles, the HAp groups exhibited higher viscosity, whereas DPI groups showed a decrease in viscosity. Icon had the highest water sorption. To conclude, BAG neither improved the physicochemical properties studied, nor did it show bioactive properties. The addition of DPI reduced viscosity caused by particle addition and also attenuated the DC decrease caused by BAG addition. The addition of bioactive particles to infiltrants should be seen with caution because they increase viscosity and may not bring major clinical improvements that justify their use. DPI might be indicated only if any component is added to the infiltrant to act as a compensation mechanism.

Development of a borosilicate bioactive glass scaffold incorporating calcitonin gene-related peptide for tissue engineering.

Protein delivery and release from synthetic scaffold materials are major challenges within the field of bone tissue engineering. In this study, 13-93B1.5 borosilicate bioactive glass (BSG) base paste was 3D printed to produce BSG-based scaffolds with high porosity (59.85±6.04%) and large pore sizes (350-400μm) for functionalization with a sodium alginate (SA)/calcitonin gene-related peptide (CGRP) hydrogel mixture. SA/CGRP hydrogel was uniformly filled into the interconnected pores of 3D printed BSG constructs to produce BSG-SA/CGRP scaffolds which were subject to bioactivity and biocompatibility analysis. BSG scaffolds filled with SA hydrogel underwent dissolution in simulated body fluid (SBF), resulting in the precipitation of hydroxyapatite (HA) on the borosilicate glass evidenced by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Around 90% of CGRP was released from scaffolds after 7days of immersion in SBF, reaching a final released concentration of 893.00±63.30ng/mL. Cellular adhesion, proliferation, and differentiation of human bone marrow mesenchymal stem cells (HBMSCs) cultured with BSG-SA/CGRP scaffolds revealed improved biocompatibility and osteogenic capabilities compared with BSG-SA scaffolds in the absence of CGRP. When subcutaneously implanted in rat models, BSG-SA/CGRP scaffolds induced low localized inflammation without causing bodily harm in vivo. Findings revealed that bioactive glass scaffolds incorporating CGRP met the scaffold requirements for bone regeneration and that the addition of CGRP promoted osteogenic differentiation where it may potentially be utilized for future regenerative applications.

Impact of residual carbon after DLP and SPS-Sintering on compressive strength and in-VITRO bioactivity of calcium phosphate scaffolds

Digital Light Processing was used to fabricate bioactive ceramic scaffolds for bone regeneration using β-tricalcium phosphate (β-TCP) powder as a starting material. The 3D structures were de-binded in vacuum and divided in two batches: Carbon Containing samples and Carbon Free samples (obtained by firing at 750 °C in air after de-binding). All samples were then sintered in pressure-less SPS either at 1200 °C or 1500 °C, resulting in two different polymorphs (β and α -TCP). The influence of the de-binding method, the in-situ formation of a carbonaceous phase and different phase composition of resulting scaffolds was evaluated in terms of mechanical performance and in vitro bioactivity and solubility in simulated body fluid (SBF). All scaffolds exhibited compressive strengths within the range of cancellous bone and bone-like apatite precipitates were visible on their surface after 21 days of immersion in SBF, with the exception of carbon-free samples sintered at 1200 °C.

Electrospun nano-fibrous bilayer scaffold prepared from polycaprolactone/gelatin and bioactive glass for bone tissue engineering

This work is focused on integrating nanotechnology with bone tissue engineering (BTE) to fabricate a bilayer scaffold with enhanced biological, physical and mechanical properties, using polycaprolactone (PCL) and gelatin (Gt) as the base nanofibrous layer, followed by the deposition of a bioactive glass (BG) nanofibrous layer via the electrospinning technique. Electrospun scaffolds were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy. Surface area and porosity were evaluated using the nitrogen adsorption method and mercury intrusion porosimetry. Moreover, scaffold swelling rate, degradation rate and in vitro bioactivity were examined in simulated body fluid (SBF) for up to 14 days. Mechanical properties of the prepared scaffolds were evaluated. Cell cytotoxicity was assessed using MRC-5 cells. Analyses showed successful formation of bead-free uniform fibers and the incorporation of BG nanoparticles within fibers. The bilayer scaffold showed enhanced surface area and total pore volume in comparison to the composite single layer scaffold. Moreover, a hydroxyapatite-like layer with a Ca/P molar ratio of 1.4 was formed after 14 days of immersion in SBF. Furthermore, its swelling and degradation rates were significantly higher than those of pure PCL scaffold. The bilayer’s tensile strength was four times higher than that of PCL/Gt scaffold with greatly enhanced elongation. Cytotoxicity test revealed the bilayer’s biocompatibility. Overall analyses showed that the incorporation of BG within a bilayer scaffold enhances the scaffold’s properties in comparison to those of a composite single layer scaffold, and offers potential avenues for development in the field of BTE.

In vitro corrosion study of PLA/Mg composites for cardiovascular stent applications

The present investigation explores the impact of Mg volume fraction (VMg) as a controlling parameter of degradation rate in designing patient-specific cardiovascular stents made of PLA/Mg composites. For the purpose of this research, PLA/Mg composite plates containing 1, 3, 5, and 10% VMg are produced by melt blending and hot press molding. Characterization techniques such as scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) are employed to study the microstructure of PLA/Mg composites. For in vitro corrosion tests, stent prototypes and composite samples are immersed in baths of simulated body fluid (SBF). According to in vitro corrosion tests, increasing VMg increases the corrosion rate of the composites by accelerating the corrosion of the particles and the crystalline zones surrounding them. In addition, a 2% raise in the Mg content (from 1% to 3%), increases the overall Mg weight loss by more than 4 times. Composite samples and prototype stents containing more than 5% VMg exhibit cracking and brittleness after 7 days of immersion in SBF. In light of the compression tests results and also the failures and cracks observed during immersions, the upper limit of Mg content for PLA/Mg stent fabrication purposes is found to be below 3%.

Preface

Anodic oxidation (AO) of titanium is a common electrochemical process for surface modification of metallic surfaces and is conducted in an electrolyte solution. Anodisation of titanium implants can generate a coating with optimal characteristics to accelerate the growth of bone-like apatite. The present work aims to develop a novel AO electrolyte formulation of a CaP base solution containing three different alteration agents. The characteristics of the anodised coating were modified by varying the volume fractions of the alteration agents, namely sulphuric acid, hydrogen peroxide, and acetic acid in a base solution of β-glycerolphosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA). The surface morphology, mineralogy, wettability, and bioactivity of these coatings were analysed using scanning electron microscopy (SEM), X-ray diffraction (XRD), contact angle analysis, and in vitro testing using simulated body fluid (SBF). Anodisation in a mixture of β-GP + CA electrolyte resulted in the formation of Ca-P-rich oxide coating (with surface features with a donut-like shape) and when altered with 12.5 vol% sulphuric acid, highly defined spiky needle-like morphology was seen on the surface. These coatings were composed of hydroxyapatite, tricalcium phosphate, and calcium diphosphate. After 7 days of SBF immersion, the surface was observed to contain a dense layer of bone-like apatite. However, alteration using acetic acid did not result in any significant changes to the surface characteristics and no bone-like apatite formation was observed even after soaking in SBF for 7 days. Alteration using hydrogen peroxide resulted in an anodised coating that assisted the growth of bone-like apatite layer on the coating surfaces after soaking in SBF for 7 days. The differences in coating performance are linked to the presence of different functional ions with hydronium groups (from sulphuric acid) being superior compared to the carboxyl ions (from acetic acid). The coating produced by sulphuric acid alteration demonstrated super hydrophilicity and rougher topographies which are ideal characteristics for cell attachment and proliferation in implant applications.

Influence of altered Ca-P based electrolytes on the anodised titanium bioactivity

Abstract Anodic oxidation (AO) of titanium is a common electrochemical process for surface modification of metallic surfaces and is conducted in an electrolyte solution. Anodisation of titanium implants can generate a coating with optimal characteristics to accelerate the growth of bone-like apatite. The present work aims to develop a novel AO electrolyte formulation of a Ca P base solution containing three different alteration agents. The characteristics of the anodised coating were modified by varying the volume fractions of the alteration agents, namely sulphuric acid, hydrogen peroxide, and acetic acid in a base solution of β-glycerolphosphate disodium salt pentahydrate (β-GP) and calcium acetate monohydrate (CA). The surface morphology, mineralogy, wettability, and bioactivity of these coatings were analysed using scanning electron microscopy (SEM), X-ray diffraction (XRD), contact angle analysis, and in vitro testing using simulated body fluid (SBF). Anodisation in a mixture of β-GP + CA electrolyte resulted in the formation of Ca-P-rich oxide coating (with surface features with a donut-like shape) and when altered with 12.5 vol% sulphuric acid, highly defined spiky needle-like morphology was seen on the surface. These coatings were composed of hydroxyapatite, tricalcium phosphate, and calcium diphosphate. After 7 days of SBF immersion, the surface was observed to contain a dense layer of bone-like apatite. However, alteration using acetic acid did not result in any significant changes to the surface characteristics and no bone-like apatite formation was observed even after soaking in SBF for 7 days. Alteration using hydrogen peroxide resulted in an anodised coating that assisted the growth of bone-like apatite layer on the coating surfaces after soaking in SBF for 7 days. The differences in coating performance are linked to the presence of different functional ions with hydronium groups (from sulphuric acid) being superior compared to the carboxyl ions (from acetic acid). The coating produced by sulphuric acid alteration demonstrated super hydrophilicity and rougher topographies which are ideal characteristics for cell attachment and proliferation in implant applications.

Synthesis and Characterisation of Bioactive Glass 13-93 Scaffolds for Bone Tissue Regeneration

A modified sol-gel method was used in the current work to prepare a 13-93 bioactive glass powder, which was selected for the therapeutic actions of its constituent parts. In particular bioactive glass 13-93 can chemically bond with host tissue and induce osteogenesis. The produced gel was calcined at a temperature of 600 °C, while particle size analysis and x-ray diffraction were performed after the preparation of the glass powder. Porous bioactive glass 13-93 scaffolds were synthesised using the polymer foam replication technique that uses polyurethane sponges as a template. Sintering at 700 °C was then performed for one hour to the produce the required structures. After sintering, the microstructure was examined by scanning electron microscope (SEM) and Fourier transform infrared analysis (FTIR). The x-ray diffraction (XRD) results were also examined. The average particle size of bioactive glass 13-93 thus produced was about 2.978 μm, and XRD pattern analysis showed that the porous scaffolds were amorphous. The microstructure of the 13 – 93 glass scaffolds contained interconnected cellular pores and a dense network of bioactive glass, allowing scaffolds with porosity between 80 and 83% to be obtained. An in vitro bioactivity test was performed on the scaffolds by soaking them in a solution of simulated body fluid (SBF). The subsequent SEM images confirmed the bioactivity of the prepared scaffolds based on the formation of obvious and dense hydroxyapatite particles on the surface after 7 days of immersion in SBF. It was thus concluded that bioactive glass scaffold prepared in this work via the polymer foam replication technique has the potential to be used in several future applications.

Titanium Dioxide Nanotubes Incorporated Bioactive Glass Nanocomposites: Synthesis, Characterization, Bioactivity Evaluation and Drug Loading

Nano bioactive glasses are known as suitable alternatives to repair the damaged bone tissues. In this research, novel sol-gel derived bioactive glass composites were synthesized through a reduction in the common weight percent of SiO2 substituted by 15 wt% of titanium dioxide nanotubes (TNTs) at two different steps by the synthetic procedure. The morphology, crystalline structure, and functional groups of the composites were evaluated through scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses. Based on the SEM images, the step in which TNTs were added to the solution completely changed the morphology of the composite. Bioactivity tests were carried out by soaking the samples in the simulated body fluid (SBF) at the intervals ­of 14 and 28 days followed by the investigation of hydroxyapatite (HA) layer formation on the surface of the samples. According to XRD peaks at 2-theta angle of around 31 and 40 degrees, it was found that the presence of titanium dioxide nanotubes improved bioactivity after 14 days of immersion and both 58S-TNT composites were more bioactive than 58S bioglass, while 58S bioactive glass possessed more intense peaks of HA after 28 days of immersion in SBF. Furthermore, the drug loading characteristic of the prepared composites was examined and the results showed that the addition of nanotubes improved the drug loading performance of bioactive composites containing TNTs up to 70% compared to the 58S bioglass with 37% drug loading.

Sputtered crystalline TiO2 film drives improved surface properties of titanium-based biomedical implants

Different crystalline phases in sputtered TiO2 films were tailored to determine their surface and electrochemical properties, protein adsorption and apatite layer formation on titanium-based implant material. Deposition conditions of two TiO2 crystalline phases (anatase and rutile) were established and then grown on commercially pure titanium (cpTi) by magnetron sputtering to obtain the following groups: A-TiO2 (anatase), M-TiO2 (anatase and rutile mixture), R-TiO2 (rutile). Non-treated commercially pure titanium (cpTi) was used as a control. Surfaces characterization included: chemical composition, topography, crystalline phase and surface free energy (SFE). Electrochemical tests were conducted using simulated body fluid (SBF). Albumin adsorption was measured by bicinchoninic acid method. Hydroxyapatite (HA) precipitation was evaluated after 28 days of immersion in SBF. MC3T3-E1 cell adhesion, morphology and spreading onto the experimental surfaces were evaluated by scanning electron microscopy. Sputtering treatment modified cpTi topography by increasing its surface roughness. CpTi and M-TiO2 groups presented the greatest SFE. In general, TiO2 films displayed improved electrochemical behavior compared to cpTi, with M-TiO2 featuring the highest polarization resistance. Rutile phase exhibited a greater influence on decreasing the current density and corrosion rate, while the presence of a bi-phasic polycrystalline condition displayed a more stable passive behavior. M-TiO2 featured increased albumin adsorption. HA morphology was dependent on the crystalline phase, being more evident in the bi-phasic group. Furthermore, M-TiO2 displayed normal cell adhesion and morphology. The combination of anatase and rutile structures to generate TiO2 films is a promising strategy to improve biomedical implants properties including greater corrosion protection, higher protein adsorption, bioactivity and non-cytotoxicity effect.

Influence of selenium dioxide (SeO2) on properties of bioglass in SiO2-Na2O-CaO-P2O5 system

The influence of selenium dioxide on bioglass in (45.0-x) SiO2 24.5Na2O 24.5CaO 6.0P2O5 xSeO2 (x = 0.0, 0.5, 1.0, 1.5, and 2.0 wt%) system was investigated by preparing the glass through conventional melting and annealing method. The glass transition temperature (Tg), crystallization temperature (Tc), and density of prepared glasses were measured by differential thermal analysis and Archimedes’ principle respectively. The structural and microstructure analyses of glasses were characterized by Raman spectroscopy, Fourier transformed infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX). The formation of hydroxy apatite carbonate (HCA) layer for glasses was investigated by Raman spectroscopy, FTIR, SEM with EDS, pH measurement, ion concentrations analysis, and (%) weight loss after immersion in simulated body fluid (SBF) for 10 h to 14 days at 37.5°C. Experimental results showed that SeO2 substitution for SiO2 in the glass had increased glass density and molar volume whereas network connectivity was decreased. The addition of selenium oxide reduced the glass transition temperature and also crystallization temperature. The FTIR study of glass confirmed the P–O bonding after immersion for 14 days in SBF, which was also identified in the Raman spectroscopy. SEM of the 14 days immersed sample showed the formation of cauliflower like morphology of HA particles on the glass. pH and ion concentrations analysis also confirmed the formation of HCA layer after 14 days of immersion in SBF.

Bioactivity measurement of commercially pure titanium processed by micro-electric discharge drilling

The surface modification is a pivotal step in the field of the biomedical implant in order to improve its biomedical characteristics. A number of methods can be adopted to improve surface characteristics like coating, evaporation, sputtering, and ion implantation. The surface of any material can also be improved by machining. In the present work, an electric discharge drilling (EDD) was used for the development of quality holes on any conductive material regardless of its hardness. In the present research, commercially pure titanium (CPTi) was drilled for the development of microhole using the EDD. The effect of microholes on the apatite formation and weight gain was determined. The apatite formation was measured in the presence of simulated body fluid (SBF) after 7, 14, and 21 days of immersion. The temperature and pH during the apatite formation were 37 °C and 7.4, respectively. It was found that after the development of microholes, the quantity of apatite formation increases. On the contrary side on the normal CPTi material (without drilling), an insignificant apatite formation was observed. However, after drilling, the elements of calcium and phosphate were observed ever after 4 days of immersion in SBF. The surface area of the apatite formation increases by 24% after the development of microholes. Scanning electron microscopy (SEM) revealed the microstructure of the drilled surface before and after the immersion of CPTi in SBF. In addition, it was observed that with the increase in the number of holes and immersion period, the apatite formation increases.

In vitro studies of solution precursor plasma-sprayed copper-doped hydroxyapatite coatings with increasing copper content.

In this present study, in vitro characterization on bioactivity and biocompatibility of the copper-doped hydroxyapatite (Cu-HA) coatings deposited onto Ti6Al4V alloy with increasing copper content obtained using solution precursor plasma spray process were evaluated under simulated body fluid (SBF) and cytotoxicity tests. The growth of flake-like structures was observed at the coatings' surface after 7 days of immersion in SBF. Elemental composition analysis showed a calcium-deficient carbonate-containing apatite for the grown layer. Broadening of the HA peaks were also observed in the X-ray diffraction patterns and infrared absorption spectra of the immersed coatings associated with the possible formation of an amorphous layer at the surface of the coatings. Copper incorporation does not alter the bioactivity of HA but only slowed down for 10 mol% copper content. Cytotoxicity evaluation using MTT assays showed that 3 mol% Cu-HA coating was not toxic under in vitro characterizations.

Differential in vitro degradation and protein adhesion behaviour of spark plasma sintering fabricated magnesium-based temporary orthopaedic implant in serum and simulated body fluid

The interaction of proteins with implantable metallic surfaces has a great influence on the bioactivity and biodegradation of orthopaedic implants. Initial osseointegration is known to be critical for the long term success of orthopaedic implants. The surface properties of the implant and electrochemical milieu of the surrounding solution such as electrostatic, hydrophobic, and hydrogen bonding interactions significantly modulate protein adsorption by implants. Magnesium (Mg) is considered to improve the adhesion of osteoblasts via ligand binding of the integrin receptors. Mg-based composites, reinforced with hydroxyapatite (HA), are potential candidates for temporary orthopaedic implants. However, their clinical translation requires enhanced degradation resistance in physiological environment so that it is in sync with the healing rate of the bone. The present study deals with the protein adsorption characteristics and degradation behaviour of Mg-HA-based biodegradable implants. Quantitative analysis of apatite inducing ability of composites was evaluated in terms of mass gain in simulated body fluid (SBF) as well as in foetal bovine serum (FBS), by an in vitro immersion study. Incorporation of 5 and 15 wt% HA to Mg-3Zn improved apatite formation up to 35% and 66%, respectively, after 14 days of immersion in SBF. Compared to FBS, SBF is found to be significantly more effective in precipitating apatite on a Mg-HA surface. However, FBS offered more corrosion resistance to Mg-HA than SBF did, as evident from the significant differences in the protein adhesion capabilities of the composite surface when incubated separately in these two mediums. The addition of 15 wt% HA enhanced the protein adsorption capability by ∼35%. These studies highlight the possibility of modulating the degradation and bioactivity of Mg-based composite by tailoring the composition of HA. These findings, in turn, warrant the suitability of Mg-HA composite in orthopaedic application.

Bovine-derived hydroxyapatite coatings deposited by high-velocity oxygen-fuel and atmospheric plasma spray processes: A comparative study

Bovine-Derived Hydroxyapatite (BHAp) is Ca-deficient natural hydroxyapatite with several ions substitutions that play a crucial role in its biomimetic behavior. Natural quantities of ions such as Mg2+ and CO32– increase the bioactivity and the biological performance of BHAp compared to stoichiometric hydroxyapatite (HAp). In this contribution, BHAp powder was obtained from two years old bovines and thermally sprayed by Atmospheric Plasma Spray (APS) and High-Velocity Oxygen Fuel (HVOF) on 304L stainless steel substrates. BHAp coatings morphology and structure were analyzed by scanning electron microscopy (SEM), Fourier Transformed Infra-Red (FTIR) spectroscopy and Rietveld refinements of the coatings grazing incident X-ray diffraction (GIXRD) patterns. The bioactivity of the coatings was evaluated following the modifications of its structure and surface morphology after immersion in simulated body fluid (SBF) during 3, 5 and 10 days, by SEM and GIXRD. The Ca, P and Mg concentration in SBF was also measured by inductively coupled plasma optical emission spectrometry (ICP-OPS). The obtained BHAp powder was highly crystalline and mainly a B-type HAp. The main differences between BHAp and HAp are CO32– and the Mg2+ contents, which lead to the formation of dolomite in the crystalline content (48.75 wt%) during HVOF spraying. APS coating did not exhibit any secondary phases in its crystalline content. The typical polyhedral grain apatite layer was evident after 3 days of immersion in SBF for both coatings. However, SEM micrographs of HVOF coatings show delamination after 5 days of immersion. Thus, the dolomite phase is detrimental for coating stability and bioactivity.