Stimulated Body Fluid Research Articles

Processing and Characterization of Poly (butylene adipate-co-terephthalate) / Wollastonite Biocomposites for Medical Applications

By melt blending process Poly (butylene adipate-co-terepthalate) (PBAT) based composites were prepared using PBAT with 0 to 7 wt% of wollastonite (W). The prepared PBAT biocomposites were characterized for XRD, FTIR, SEM, TGA, cell viability, swelling studies, and tensile properties. XRD reveals that PBAT was attained crystalline nature after the addition of filler into the polymer matrix. SEM micrographs confirmed that the morphology of the blend has homogeneous dispersion of the filler and after soaking in SBF (stimulated body fluid) for 5 days showed that good formation of HA layer on the PBAT/W composite (3 wt%). TGA study reveals that the thermal stability slightly increases with filler loading. The tensile strength of PBAT increases by the addition of wollastonite up to 5 wt% and then it tends to decreases. The effect of filler on the PBAT for biocompatibility level was evaluated through in vitro cytotoxicity test (MTT Assay). Cytotoxicity tests showed that good cell viability at 3 wt% filler content at short incubation periods. The potential benefits of the developed biocomposites can be used as new biomaterials in biomedical field.

Compatibility and Bone Bonding Efficiency of Gamma Irradiated Hench’s Bioglass

This research focuses on investigating and characterizing the effects of gamma irradiation through successive doses on the bioactivity or bone bonding efficiency of samples from patented Hench’s bioglass upon immersion for extended times in stimulated body fluid (SBF). Combined analytical techniques including FT infrared, X-ray diffraction and scanning electron microscopic measurements were carried out to follow up and identify the changes of the studied properties with both gamma irradiation doses and time of immersion. FTIR spectra before and after both irradiation and immersion processes reveal vibrational bands due to main silicate groups and sharing of some mixed phosphate units in mid wavenumbers. Such collective studies show mainly the growth of the vibrational bands due to water, OH or related groups upon irradiation while the vibrational modes due to the main network forming groups remain unaffected by irradiation. The X-ray diffraction data indicate that gamma irradiation with 10 Mrad causes no changes in the amorphicity of the Hench’s bioglass as before irradiation while diffraction patterns of immersed samples reveal distinct peaks after 4 weeks of immersion. The gamma irradiated sample with 10 Mrad, shows only a peak after 2 weeks and more different peaks after 4 weeks of immersion. SEM micrographs are distinct revealing the appearance and growth of nodular shaped micro-crystallites with prolonged times of immersion confirming the formation of hydroxyapatite.

Microstructure-related in vitro bioactivity of a natural ceramic of Saxidomus purpuratus shell

To explore some new approaches to designing novel mimetic architecture for bone implant materials, the conversion of a natural ceramic of Saxidomus purpuratus shell to hydroxyapatite (HAp) was investigated in the present study by using a pre-treatment in phosphate buffer solution (PBS) and an in vitro assessment in stimulated body fluid (SBF) solution. The main concern was focused on a comparison of in vitro bioactivity on the outer layer (porous fibrous/blocky structure) and inner layer (complex crossed-lamellar) of the shell. It is found that the apatites are deposited more compactly on the surface of porous blocky layer than crossed-lamellar layer in the preliminary stage of immersion in PBS for the same time. However, after a subsequent in vitro mineralization in SBF for a relatively long time of 4weeks, the bioactive bone-like apatite layers are formed on the both inner and outer layers with different structures. Importantly, the results have demonstrated that the crossed lamellar structure with a good combination of mechanical and biological performances can be well referenced as a bio-inspired composite structure for hard tissue replacements.

Effect of microwave heating time on bonding strength and corrosion resistance of Ca-P composite layers for carbon/carbon composites

Three coated Ca-P composite layers were fabricated by microwave-assisted hydrothermal (MH) and supersonic atmospheric plasma spray (SAPS) method. This multilayer coating aims to promote the bonding strength as well as the corrosion property against stimulated body fluid (SBF) on carbon/carbon (C/C) composites. The morphologies and the chemical composition of the Ca-P composite layers were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The bonding strength was evaluated by scratch test and the bioactivity was measured using SBF. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were investigated for the corrosion resistance. The results reveal that Ca-P composite layers exhibit excellent bonding strength which reaches to the loading force of 39.5 N. In SBF solution, the Ca-P composite layers can induce a new and uniform apatite layer. Additionally, potentiodynamic polarization and EIS results indicate that adding MH influences the corrosion resistance of the Ca-P composite layers. The above conclusion illustrate that MH approach could become a very useful route to enhance the long-term protection and corrosion resistance of the layers on C/C substrates for orthopedic application.

Synthesis and evaluation of factors affecting the in vitro bioactivity and antibacterial activity of bioactive glass ceramics

In the present study, two novel silicate glass-ceramics having chemical composition 38SiO2–41CaO–6P2O5–([Formula: see text])Na2O–[Formula: see text]CaF2 ([Formula: see text], 0.43 mol%) were synthesized. These glass derivatives were subjected to stimulated body fluid for 24 days in SBF under static condition at [Formula: see text]C in order to evaluate the bioactive properties of specimens. The antibacterial activity of glass ceramics against three pathogenic bacteria was determined using the modified Kirby Bauer method. It was found that the antibacterial activity primarily depends on the dissolution rate; faster release of ions caused rapid increase in the pH of the solution. Antibacterial properties were found to be strongly affected by changes in the pH of supernatant. The in vitro bioactivity assays showed that both glass derivatives were capable of bonding with bone and secondly effectively inhibit bacteria. However, the glass ceramic without CaF2 (B2) showed high dissolution rate, better bioactive ability and stronger antibacterial efficacy.

Corrosion Behaviour of Mg-Zr Alloy in Stimulated Body Fluid

Corrosion Behaviour of Mg-Zr Alloy in Stimulated Body Fluid

One-step fabrication of biomimetic superhydrophobic surface by electrodeposition on magnesium alloy and its corrosion inhibition

A facile, rapid and one-step electrodeposition process has been employed to construct a superhydrophobic surface with micro/nano scale structure on a Mg-Sn-Zn (TZ51) alloy, which is expected to be applied as a biodegradable biomedical implant materials. By changing the electrodeposition time, the maximum contact angle of the droplet was observed as high as 160.4°±0.7°. The characteristics of the as-prepared surface were conducted by field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FT-IR). Besides, the anti-corrosion performance of the coatings in stimulated body fluid (SBF) solution were investigated by electrochemical measurement. The results demonstrated that the anti-corrosion property of superhydrophobic surface was greatly improved. This method show beneficial effects on the wettability and corrosion behavior, and therefore provides a efficient route to mitigate the undesirable rapid corrosion of magnesium alloy in favor of application for clinical field.

Ca-P bioactive coating prepared by combining microwave-hydrothermal and supersonic atmospheric plasma spraying methods

Ca-P based coatings on carbon/carbon composite (C/C) were manufactured via a combined method comprising of microwave-hydrothermal (MH) and supersonic atmospheric plasma spraying (SAPS) techniques. However, a weak mutual interaction between the coating and C/C substrate has been a critical issue for a long time. Herein, we reported a new method for shear strength enhancement without compromising the osteoconductivity and osteoproductivity. Results showed that the inner layer has a strong mechanical interlocking with C/C substrate and the failure mode of outer layer changed from the coating cohesion (within the coating) to adhesive (at the coating/substrate interface) fracture. The shear strength between Ca-P bioactive coating-C/C substrate by MH/SAPS was significantly improved as compared to that prepared by SAPS. The Ca-P bioactive coating exhibited a good bioactivity as evidenced by the formation of a uniform carbonate-apatite layer formed on coating after immersing into stimulated body fluid for a specified period of time.

Corrosion resistance and in vitro bioactivity of Si-containing coating prepared on a biodegradable Mg-Zn-Ca bulk metallic glass by micro-arc oxidation

A Mg-Zn-Ca bulk metallic glass (BMG) with a critical casting size of 5mm was successfully developed. A porous and rough silicon-containing coating was achieved on the BMG by micro-arc oxidation (MAO) technique. The degradability and bioactivity of the coatings were analyzed by immersion tests in the stimulated body fluid (SBF). The results indicated that the corrosion resistance of the BMG specimens was significantly improved after MAO treatment. The spontaneous formation of carbonated hydroxyapatite (HA) on the porous layer demonstrated that the prepared MAO coating has a high bioactivity as a result of its phase composition and porous surface structure. The present work may provide a promising way for surface modification of Mg-based BMGs through fabrication of MAO coatings with good corrosion resistance and high bioactivity.

Fabrication of silver- and strontium-doped hydroxyapatite/TiO2 nanotube bilayer coatings for enhancing bactericidal effect and osteoinductivity

Hydroxyapatite (HA)-coated implants are more susceptible to bacterial infection because their bioactive surface, which is favourable for osseointegration, could also become a reservoir for bacterial colonisation. To solve this problem, an electrodeposition method for preparing silver- and strontium-modified antibacterial HA layers onto TiO2 nanotubes (TNs) was developed. Ag was incorporated into the HA coating to improve its antimicrobial properties. Sr was added as a second binary element to offset the potential cytotoxicity of Ag. Results showed that Sr2+ and Ag+ could be evenly incorporated into the HA lattice to form SrAgHA coatings. The TN layer with a diameter of 100nm strengthens the adhesion via the anchoring effect. In vitro electrochemical corrosion studies demonstrated that the SrAgHA/TN coating sustains the stimulated body-fluid (SBF), thus indicating excellent corrosion resistance with a lower corrosion penetration rate than the bare commercially pure (CP)-Ti substrate. The composite coatings were found to be bioactive, based on the promotion of additional apatite onto the SrAgHA coating surface from SBF. Staphylococcus aureus growth was inhibited by SrAgHA/TN coatings, whereas the coatings without Ag had no effect on bacterial growth. MC3T3-E1 cell culture revealed that SrAgHA/TN demonstrated better cytocompatibility, and permitted stimulated cell proliferation, attachment and differentiation capacities than uncoated CP-Ti substrate. The addition of Sr to the AgHA coatings effectively counteracted the potentially negative effects and improved the performance compared with CP-Ti. The improved antibacterial effects, correlated with superior cytocompatibility and mechanical behaviour, suggested that SrAgHA/TN can be an alternative to pure HA for the preparation of reliable implant coatings for orthopaedic applications.

Tribocorrosion of Type 316L Stainless Steel with Nanopore Arrays in Stimulated Body Fluid

Type 316L stainless steel is widely used as a biomaterial because of high corrosion resistance owing to the passive films that form spontaneously on the surface. However, if the passive films are broken by mechanical damages corrosion will be accelerated in the body, resulting in the failure of the integrity. Wear causes the breakdown of passive films, which accelerates corrosion of metallic implant, as a result so-called tribocorrosion is induced. In order to suppress tribocorrosion, friction between materials should be well-controlled. For the control of friction, various surface treatments have been reported. Recently we reported the formation of nanopore arrays on Type 316L stainless steel by a simple anodization.In the present work, we examined tribocorrosion of Type 316L stainless steel with nanopore arrays in simulated body fluid. The tribocorrosion of Type 316L stainless steel was examined in pin-on-disk wear test. UHMWPE (ultrahigh molecular weight polyethylene) and Type 316L stainless steel were used as a pin and disk materials, respectively. Two different surface morphologies were prepared for the disk of the stainless steel; mirror and nanopore arrays. The nanopore arrays were formed by anodization in an ethylene glycol containing sodium perchlorate. The pin-on-disk wear test was carried out in 0.9% NaCl solution or 30% FBS (fetal bovine serum) at 37 °C. During the test, the friction coefficient and the corrosion potential of the disk specimen were monitored simultaneously with time. The corrosion potential decreased immediately after the test was commenced and then recovered gradually with time. After the test wear debris with the size of several micrometers was observed on the surface. In the presentation, the effects of surface nanostuture and organic components included in FBS on the tribocorrosion behavior of Type 316L stainless steel will be discussed.

Effect of Mineralized Layer Topographies on Stem Cell Behavior in Microsphere Scaffold

Modifying substrates through mineralization is a popular way to improve the osteogenic performance. Screening of the best mineralization characteristics on specific substrates for stem cells is meaningful but not fully studied. In this paper, poly(lactic-co-glycolic acid)/hydroxyapatite (PLGA/HA, PH) microsphere scaffolds with superficial pores were fabricated by a low-temperature fusion method. After the mineralization in the 5× stimulated body fluid (SBF) for 0, 7, 12 and 24 h, four mineralized scaffolds (MPH-0, MPH-7, MPH-12 and MPH-24) with different apatite topographies were obtained. It was found that the surface of MPH-7 was evenly decorated with abundant micro-pores, MPH-12 with dense and plain apatite layer, and MPH-24 with small spherical bumps. The responses of mouse bone mesenchymal stem cells (mBMSCs) to the four scaffolds were further studied. The results showed that MPH-7 and MPH-24 had more obvious effects on mBMSCs attachment, proliferation and differentiation than MPH-0 and MPH-12. This work indicated that to obtain the maximum improvement, the mineralization characteristics had to be carefully chosen. This was noteworthy in the chemical modification of surfaces to form the functionalized scaffolds for bone repair.

Effect of Ti+ 4 on in vitro bioactivity and antibacterial activity of silicate glass-ceramics

A novel glass-ceramic series in (48-x) SiO2-36 CaO-4 P2O5-12 Na2O-xTiO2 (where x=0, 3.5, 7, 10.5 and 14mol %) system was synthesized by crystallization of glass powders, obtained by melt quenching technique. The differential scanning calorimetric analysis (DSC) was used to study the non-isothermal crystallization kinetics of the as prepared glasses. The crystallization behaviour of glasses was analyzed under non-isothermal conditions, and qualitative phase analysis of glass-ceramics was made by X-ray diffraction. The in vitro bioactivity of synthesized glass-ceramics was studied in stimulated body fluid at 37°C under static condition for 24days. The formation of hydroxyl-carbonated apatite layer; evident of bioactivity of the material, was elucidated by XRD, FTIR, AAS, SEM and EDX analysis. The result showed that partial substitution of TiO2 with SiO2 negatively influenced bioactivity; it decreased with increase in concentration of TiO2. As Ti+4 having stronger field strength as compared to Si+4 so its replacement became the cause for reduction in degradation that in turn improved the chemical stability. The compressive strength was also enhanced with progress addition of TiO2 in the system. The antibacterial properties were examined against Staphylococcus Epidermidis. Strong antibacterial efficacy was observed with the addition of TiO2 in the system.

Strontium and copper co-substituted hydroxyapatite-based coatings with improved antibacterial activity and cytocompatibility fabricated by electrodeposition

Bacterial infection are serious complications for biomedical implants in the orthopedic and dental fields, and the ideal implants should combine good antibacterial ability and bioactivity. In this paper, we have fabricated the strontium/copper substituted hydroxyapatite (SrCuHA) coating on the commercially pure titanium (CP-Ti) and studied their effect on antibacterial and in vitro cytocompatible properties. Cu was incorporated into HA in order to improve its antimicrobial properties. Sr was added as a second binary element to improve the biocompatibility. The structural and morphological characteristics of the SrCuHA coatings were investigated using various analytical techniques. The presence of Sr2+ and Cu2+ in solution led to reduced roughness of the coating and finer nucleus size formed. The results highlight that Sr2+ and Cu2+ were homogenously incorporated into HA lattice to form SrCuHA coatings. Inductively coupled plasma mass spectrometry (ICP-MS) was used for the leach out analysis of the samples. A low contact angle value revealed the hydrophilic nature. In vitro electrochemical corrosion studies indicated that the SrCuHA coating sustain in the stimulated body-fluid (SBF), exhibiting superior corrosion resistance with a lower corrosion penetration rate than the bare CP-Ti substrate. The SrCuHA coatings can kill Escherichia coli to a certain extent during the first few days, which might be due to the Cu substitution in the coating. An enhancement of in vitro osteoblast adhesion, proliferation, and alkaline phosphatase activity was observed, which could lead to the optimistic orthopedic and dental applications.

Tribological properties, corrosion resistance and biocompatibility of magnetron sputtered titanium-amorphous carbon coatings

Amorphous carbon incorporated with titanium (a-C:Ti) was coated on 316L stainless steel (SS) by magnetron sputtering technique to attain superior tribological properties, corrosion resistance and biocompatibility. The morphology, topography and functional groups of the nanostructured a-C:Ti coatings in various concentrations were analyzed using atomic force microscopy (AFM), Raman, X-Ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Raman and XPS analyses confirmed the increase in sp2 bonds with increasing titanium content in the a-C matrix. TEM analysis confirmed the composite nature of the coating and the presence of nanostructured TiC for Ti content of 2.33at.%. This coating showed superior tribological properties compared to the other a-C:Ti coatings. Furthermore, electrochemical corrosion studies were performed against stimulated body fluid medium in which all the a-C:Ti coatings showed improved corrosion resistance than the pure a-C coating. Preosteoblasts proliferation and viability on the specimens were tested and the results showed that a-C:Ti coatings with relatively high Ti (3.77at.%) content had better biocompatibility. Based on the results of this work, highly durable coatings with good biocompatibility could be achieved by incorporation of optimum amount of Ti in a-C coatings deposited on SS by magnetron sputtering technique.

Bioactivity analysis of the Ta (V) doped SiO2–CaO–Na2O–P2O5 ceramics prepared by solid state sintering method

The main objective of the study was to control the degradation rate of material at a higher degradation rate improving the chemical stability of the material. Ta is known to have good chemical resistance, biocompatibility and show no adverse biological response. In the present study, SiO2–Na2O–CaO–P2O5 bioceramics with different Ta2O5 contents was prepared by solid state sintering method at 1000°C. The as-sintered ceramics were subjected to immersion studies in stimulated body fluid (SBF) for 21 days under static condition and characterized by XRD, FTIR, SEM, and AAS. The findings of the research indicate that the addition of Ta2O5 controlled degradability, and all samples showed sufficient bioactivity.

Fabrication of Wollastonite Coatings on Zirconia by Room Temperature Spray Process.

Wollastonite-based bioceramic powders were synthesized by solid-state reaction between calcite and silica powder. To control the phase and bioactivity of wollastonite, we also prepared four kinds of wollastonite-based bioceramics by adding an enstatite (MgSiO3) powder. After solid state reaction at 1000-1300 degrees C, micron-sized powders were obtained by milling and screening. By using these powders, wollastonite coatings were fabricated on zirconia substrates by a room temperature spray process, and their microstructure and composition under different coating condition were investigated. Wollastonite coatings on zirconia substrates were formed with the homogeneous microstructure and nanoscaled grain size. The phase composition of the resultant wollastonite coatings was similar to that of the starting powders, however, the grain size of the wollastonite particles was reduced to about 100 nm due to their formation by particle impaction and fracture. The wollastonite coating layer exhibited bioactivity in a stimulated body fluid and forming ability of 25 nm sized-hydroxyapatite precipitates of during in vitro test in SBF solution.

Effect of sintering temperature variations on fabrication of 45S5 bioactive glass-ceramics using rice husk as a source for silica

45S5 bioactive glass is a highly bioactive substance that has the ability to promote stem cell differentiation into osteoblasts — the cells that create bone matrix. The aim of this work is to analyze physical and mechanical properties of 45S5 bioactive glass fabricated by using rice husk ash as its silica source. The 45S5 bioactive glass was prepared by melting the batch at 1300°C for 3h. The samples were sintered at different temperatures ranging from 900 to 1050°C with a fixed dwell-time of 2h. The phase transitions, density, porosity and microhardness values were investigated and reported. DTA analysis was used to examine the crystallization temperatures of the glasses prepared. We found that the sintering temperature had a significant effect on the mechanical and physical properties of the bioactive glass. The XRD showed that when the sintering temperature was above 650°C, crystallization occurred and bioactive glass-ceramics with Na2Ca2Si3O9, Na2Ca4(PO4)2SiO4 and Ca3Si2O7 were formed. The optimum sintering temperature resulting in maximum mechanical values was around 1050°C, with a high density of 2.27g/cm3, 16.96% porosity and the vicker microhardness value of 364HV. Additionally, in vitro assay was used to examine biological activities in stimulated body fluid (SBF). After incubation in SBF for 7days, all of the samples showed formations of apatite layers indicating that the 45S5 bioactive glasses using rice husk as a raw material were also bioactive.

Effects of β-TCP ceramics particles on properties of glass bone cement

With bioactive SiO2–CaO–P2O5–CaF2 glass powder as the matrix and ammonium phosphate solution as setting liquid, β-tricalcium phosphate ceramic particles were added to produce a porous bone cement. The crystalline form, chemical composition and microstructure of this bone cement were observed and analysed by XRD, FTIR and SEM. The results indicate that the added β-tricalcium phosphate promotes the nucleation and growth of hydroxyapatite crystals. The degradation of β-tricalcium phosphate increases the apparent porosity of bone cement, but reduces its compressive strength. When β-tricalcium phosphate accounts for 30-wt-% of the total, the apparent porosity is approximately 45% by the 30th day of immersion in stimulated body fluid, and the compressive strength can still reach 20 MPa, which is conducive to the degradation, fusion and shape retention of bone cement.

Formation of calcium phosphate coating on Mg-Zn-Ca alloy by micro-arc oxidation technique

A porous bioceramic containing tricalcium phosphatein (TCP) coating was prepared by micro-arc oxidation (MAO) with different voltages. The degradability and bioactivity of the coatings were measured by immersion tests in the stimulated body fluid (SBF). The thickness, phase composition and morphology of the oxide coating were monitored with X-ray diffraction (XRD), fourier transform infrared spectrometer (FT–IR) and scanning electron microscopes (SEM) with energy energy-disperse spectrometer (EDS). The results show that the TCP-containing coating can be influenced by the increasing applied voltages through affecting the energy of sparking and the effect of electrical field. The MAO coatings have porous surface morphologies with uniform and compact micropores. The results of immersion tests confirm that the TCP-containing MAO coating has bioactivity and could protect Mg–4.75Zn–0.55Ca alloy from corrosion effectively.