Stimulated Body Fluid Research Articles

Fabrication of poly(caprolactone) nanofibers containing hydroxyapatite nanoparticles and their mineralization in a simulated body fluid

In the present study, we introduce poly(caprolactone) (PCL) nanofibers that contain hydroxyapatite (HAp) nanoparticles (NPs) as a result of an electrospinning process. A simple method that does not depend on additional foreign chemicals has been employed to synthesize HAp NPs through calcination of bovine bones. Typically, a colloidal gel consisting of PCL/HAp has been electrospun to form nanofibers. Physiochemical aspects of prepared nanofibers were characterized for FE-SEM, TEM, XRD and FTIR which confirmed nanofibers were well-oriented and had good dispersion of HAp NPs. Parameters affecting the utilization of the prepared nanofibers in various nano-biotechnological fields have been studied; for instance, the bioactivity of the produced nanofiber mats was investigated while incubated with stimulated body fluid (SBF). The results from incubation of nanofibers in SBF indicate that incorporation of HAp strongly activates precipitation of the apatite-like materials because the HAp NPs act as seeds that accelerate crystallization of the biological HAp from the utilized SBF.

Chemical Synthesis, Characterization and Bioactivity Evaluation of Hydroxyapatite Prepared from Garden snail (Helix aspersa)

A novel attempt is made to convert the calcium carbonate skeleton of widely available garden snail shell (Helix aspersa) to hydroxyapatite based bioceramics. The snail shell was found to decompose within 8500C to all the carbonate phases. The calcined snail shells were then treated with acids followed by different chemicals in ammoniacal media maintaining proper stoichemetry to produce fine Hydroxyapatite (HAP) as filter cake with Ca/P molar ratio of 1.67. The dried HAP powder was extremely pure with specific surface area of 15m2/g. The different characterization techniques were adopted both for calcined snail shell and HAP synthesized like X-ray Diffraction (XRD), Thermal Analysis (DTA/TGA), Fourier Transform Infra red Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The surface area and the particle size, of the HAP powder prepared by chemical precipitation route, were also determined by BET and Malvern particle size analyzer respectively. The synthesized powder was soaked in stimulated body fluid (SBF) medium for various periods of time in order to evaluate its bioactivity. The changes of the pH of SBF medium were measured. High bioactivity of prepared HAP powder due to the formation of apatite on its surface was observed.

Investigation on Biological Properties of Dental Implant by Ce-TZP/Al2O3/ HA Bio-nano-composites

An attempt is made to convert the calcium carbonate skeleton of widely available garden snail shell (Helix aspersa) to hydroxyapatite based bioceramics. The snail shell was found to decompose within 850°C to all the carbonate phases. The calcined snail shells were then treated with acids followed by different chemicals in ammoniacal media maintaining proper stoichemetry to produce fine Hydroxyapatite (HAP) as filter cake with Ca/P molar ratio of 1.67. The dried HAP powder was extremely pure with specific surface area of 15m2/g. The different characterization techniques were adopted both for calcined snail shell and HAP synthesized like X-ray Diffraction (XRD), Thermal Analysis (DTA/TGA) Figure 1, Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The surface area and the particle size, of the HAP powder prepared by chemical precipitation route, were also determined by BET and Malvern particle size analyzer respectively. The synthesized powder was soaked in stimulated body fluid (SBF) medium for various periods of time in order to evaluate its bioactivity. The changes of the pH of SBF medium were measured. High bioactivity of prepared HAP powder due to the formation of apatite on its surface was observed.

Effects of In Situ and Physical Mixing on Mechanical and Bioactive Behaviors of Nano Hydroxyapatite–Chitosan Scaffolds

Nano hydroxyapatite (HAP) was employed to intensify chitosan (CS) scaffolds by two methods. The first one is nano HAP crystallized in situ from the CS matrix by a biomimetic method (in situ scaffold). In the second method the sol–gel nano HAP powder was added directly to the CS solution (physical mixing scaffold). The distribution status of nano HAP was examined by scanning electron microscopy. The compressive performance was measured by a universal material testing machine. The in vitro study in stimulated body fluid was performed to evaluate the biological properties of both scaffolds. MTT testing and alkaline phosphatase activity from human bone mesenchymal stem cell culture showed differences in biocompatibility and bioactivity between the scaffolds. The results indicated that the in situ scaffold possessed more excellent mechanical and bioactive behaviors than that of the physical mixing scaffold.

Biphasic Resorbable Calcium Phosphate Ceramic for Bone Implants and Local Alendronate Delivery

AbstractA novel biphasic calcium phosphate ceramic composed of tricalcium phosphate (TCP) and calcium pyrophosphate (CP) is synthesized in order to tailor the biodegradation behavior of the ceramic. The results show that biphasic TCP/CP ceramic has a strength of 62.2 ± 2.1 MPa, which is superior to single‐phase TCP and CP ceramics, which show strengths of 44.3 ± 3.0 and 53.0 ± 4.8 MPa, respectively. In addition, biphasic TCP/CP ceramic displays a controlled strength degradation from 62.2 ± 2.1 to 40.5 ± 1.0 MPa in stimulated body fluid over a period of 28 d. An in vitro cell materials interaction study using human fetal osteoblast cells indicates that TCP/CP ceramic is cytocompatible. TCP/CP ceramic also show a good loading capacity for alendronate. Adsorption of alendronate (AD) on the TCP/CP surface is found to proceed via ligand exchange mechanism and the in vitro release profile of AD from TCP/CP surface is characterized by an initial fast release followed by a slow and sustained release. Strong electrostatic interactions between AD groups and surface Ca2+ ions enable the slow and sustained release of AD. These results demonstrate that the newly developed biphasic ceramic, with its controlled strength degradation and drug release, shows promise for use in orthopedic and tissue engineering applications.

Characterization and degradation comparison of DLC film on different magnesium alloys

Recently, magnesium (Mg) alloys have been attracted as biodegradable implants. However, high degradation rate in human body limits its application. Modifying material surfaces with a coating layer is an effective means to control degradation, and biocompatibility. In this study, thin diamond-like carbon (DLC) films were synthesized on different magnesium alloy substrates by radio frequency plasma assisted chemical vapor deposition (RFPACVD). The morphology, composition and structure of the coating layers were investigated with scanning electron microscopy (SEM) with an energy dispersive spectroscopy (EDS), micro-raman spectra (RAMAN), and Atomic force microscopy (AFM). Static contact angle measurement and nanoindentation test were also used to analyze surface properties. The degradation behavior of naked and coated Mg alloy were evaluated in stimulated body fluid (SBF), and DLC layers on different Mg alloy substrates significantly decreased the degradation rate of substrate, which is useful for the biological applications especially in bone tissue and cardiovascular stent.

Ceramic Coatings of Magnesium Alloy for Biomaterial Applications

Ceramic coatings were produced on magnesium (Mg) alloy of AZ91D for biomaterial applications by micro-arc oxidation (MAO) and electrodeposition methods. The morphology, microstructure, phase composition and corrosion properties of the prepared coatings were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and potentiodynamic polarization tester, etc. The results indicated that a porous oxide layer was grown on the Mg alloy sheets after MAO process and the compositions of oxides were mainly Mg2SiO4 and MgO. After further electrodeposition and alkaline treatment, a flake-like structure diverging from centre to periphery was grown on the MAO coating and the coating was mainly made up of hydroxyapatite (HA). Moreover, the corrosion resistance of the Mg alloy after being treated with MAO and electrodeposition technique increases obviously, which was evaluated in stimulated body fluid (SBF).

Synthesis of poly(vinyl alcohol) (PVA) nanofibers incorporating hydroxyapatite nanoparticles as future implant materials

This study examined the mechanical properties of a disc consisting of electrospun poly(vinyl alcohol) (PVA) nanofibers incorporated with high purity hydroxyapatite (HAp) nanoparticles (NPs) for potential hard tissue engineering applications. As HAp NPs are insoluble in a PVA aqueous solution, electrospinning of a colloidal solution was used instead of the conventional process, which is based on completely miscible solutions. The PVA/HAp colloidal solutions were characterized by dynamic light scattering (DLS) and electrophoratic light scattering (ELS), which indicated a unimodal size distribution and negative zeta potential. The physiochemical characterizations confirmed the production of PVA electrospun nanofibers incorporating HAp NPs. To investigate the bioactivity of the produced nanofiber mats, compacted mats with a disc shape were incubated in stimulated body fluid (SBF) at 37 °C for 6 days. SEM indicated that the incorporation of HAp strongly activates the precipitation of the apatite-like materials because the HAp NPs act as seeds that accelerate the crystallization of biological HAp from the utilized SBF.

Bone formation on apatite-coated titanium with incorporated BMP-2/heparin in vivo

The objective of this study was to investigate whether the in vivo osteoinductive activity of an implant material is enhanced by covering the surface of apatite with incorporated bone morphogenetic protein 2 (BMP-2) and heparin which maintains the activity of BMP-2. Titanium implants were alkaline treated, heat activated, and soaked in stimulated body fluid with or without BMP-2/heparin to coat the apatite around them. Treated implant bars were then implanted in rat tibiae. After 3 weeks, nondecalcified sections were prepared and the new bone formation around the implants was examined. A greater amount of bone formed on the apatite-coated implants containing BMP-2/heparin than on apatite-coated implants containing BMP, with >or=3 microg/mL heparin. Apatite-coated titanium implants with BMP-2/heparin had significantly enhanced new endosteal bone formation, with increases vertically (134%) and horizontally (124%). Bone formation was stimulated around the apatite-covered titanium coated with BMP-2/heparin, which may be useful in improving implant therapy.

Formation of hydroxyapatite crystallites using organic template of polyvinyl alcohol (PVA) and sodium dodecyl sulfate (SDS)

Biomimetic mineralization is a method to form natural materials. We have synthesized hydroxyapatite (HAP) by using an organic template of polyvinyl alcohol (PVA) and sodium dodecyl sulfate (SDS) as the surfactant. The X-ray diffractometer (XRD) patterns show the sizes of the HAP particles to be in the nanosize (15–30 nm) range. The chemical functional groups of the HAP were investigated by Fourier transform infrared (FT-IR) which shows the formation of the hydroxyl group (OH) −1 and the phosphate group (PO 4) −3. The transmission electron microscopy (TEM) images show the particles to be in the range of 20–30 nm. The SDS looks like globular sphere, while the crystals of the HAP in the SDS/PVA appear as polyhedron crystal. The average size of each globular sphere is about 3–5 μm. As-prepared HAP samples were studied for their bioactive property by immersing them in a stimulated body fluid (SBF). After soaking them in SBF for one week, the SEM images show the accumulation of calcium carbonate or calcium phosphate SBF on surface of the HAP. This indicates that there might be an increased bioactive activity on the surface of the HAP prepared by this method.

Electrodeposition of hydroxyapatite coating on AZ91D magnesium alloy for biomaterial application

Magnesium and its alloys are potential biodegradable implant materials due to their attractive biological property. But their poor corrosion resistance may result in the sudden failure of the implants. The bioactive hydroxyapatite (HA) coating was electrodeposited on AZ91D magnesium alloy surface to improve its biodegradation performance. The biodegradable behavior of HA coating was investigated by electrochemical tests and immersion tests. The experimental results indicated that the as-deposited coating consisting of dicalcium phosphate dehydrate ((DCPD, CaHPO 4 ·2H 2O) and β-tricalcium phosphate (β-TCP, Ca 3 (PO 4) 2) was transformed into uniform hydroxyapatite (HA, Ca 10 (PO 4) 6(OH) 2) coating after immersion in 1 M NaOH solution for 2 h. The HA coating can obviously slow down the biodegradation rate of AZ91D magnesium alloy in stimulated body fluid (SBF).

Preparation and bioactivity evaluation of bone-like hydroxyapatite nanopowder

Abstract Calcium phosphate ceramic such as hydroxyapatite (HA) is good candidate for bone substitutes due to their chemical and structural similarity to bone minerals. The bone mineral consists of tiny hydroxyapatite crystals in the nanoregime. Nanostructured hydroxyapatite is also expected to have better bioactivity than coarser crystals. This paper reports on the preparation and in vitro evaluation of bone-like hydroxyapatite nanopowder. The sol–gel prepared hydroxyapatite nanopowder was characterized for its phase purity, chemical homogeneity and bioactivity. Fourier transform infrared (FTIR) spectroscopy was used to identify the functional groups. X-ray diffraction (XRD) analysis was carried out to study the phase composition, crystallinity and the crystallite size of hydroxyapatite nanopowders that were sintered at different temperatures. The in vitro test was performed in a stimulated body fluid (SBF) medium. The changes of the pH of SBF medium were measured at pre-determined time intervals using a pH meter. The dissolution of calcium ions in SBF medium was determined by an atomic absorption spectrometer (AAS). FTIR result combined with the X-ray diffraction exhibited single phase of hydroxyapatite with carbonate peaks in the FTIR spectrum. The results indicate that increasing the sintering temperature increases the crystallinity and the crystallite size of hydroxyapatite nanopowders. Photomicrograph of transmission electron microscopy (TEM) showed that the obtained powder after sintering at 600 °C is composed of hydroxyapatite nanoparticles (20–30 nm). Dissolution rate of hydroxyapatite nanopowders was higher than conventional hydroxyapatite powders and closer to biological apatite due to its nanostructure dimensions. It was concluded that sol–gel prepared hydroxyapatite nanopowders had superior bioresorption and similar chemical and crystal structure to natural bone apatite.

Preparation of nanocrystalline bredigite powders with apatite-forming ability by a simple combustion method

Nanocrystalline bredigite (Ca 7MgSi 4O 16) powders were synthesized by a simple solution combustion method. Phase pure bredigite powders with particle sizes ranging from 234 to 463 nm could be obtained at a relatively low temperature of 650 °C. The apatite-forming ability of the bredigite powders was examined by soaking them in a stimulated body fluid. The compositional and morphological changes of the powders before and after soaking were analyzed by X-ray diffraction and scanning electron microscopy and the results showed that hydroxyapatite was formed after soaking for 4 days.

Bioactive ceramic composites sintered from hydroxyapatite and silica at 1200∘C: preparation, microstructures and in vitro bone-like layer growth

Bioceramic composites were synthesized by sintering the powders of hydroxyapatite (HAp) mixed directly with additive of 0.5, 1.0, 2.0, 5.0 and 10 wt.%SiO(2), respectively, at 1,200( composite function)C. X-ray diffraction (XRD) analysis indicated that the phase transformation from HAp to tricalcium phosphate (TCP) comprising alpha-TCP and Si-TCP occurred and became more prominent with the addition of SiO(2) and the increase in SiO(2) content. The observations of their surface microstructures showed that the addition of SiO(2) suppressed the grain growth and promoted the formation of crystalline-glassy composites denoted HAp + TCP/Bioglass. As the SiO(2) content is as high as 5 wt.%, the composite made a feature of crystalline clusters with different sizes consisting of HAp and TCP grains surrounded by the matrix of glassy phase. Furthermore, the dependence of in vitro bioactivity of these composites on the SiO(2) content was biomimetically assessed by determining the changes in surface morphology, i.e., bone-like apatite layer growth, after soaking in an acellular stimulated body fluid (SBF) for 3 days at 36.5( composite function)C. It was found that the HAp-SiO(2) composites showed a much faster bone-like layer growth than pure HAp, and the propensity of composites to exhibit a better bioactivity was getting more notable with increasing SiO(2) content, except for the case of the highest content of 10 wt.%. It was believed that the formation of the bone-like layer on the surfaces of these bio-composites is closely related to the increasingly provided silanol groups and transformed TCP phase in materials associated with the content of SiO(2) added.

Bioactive Gelatin-Siloxane Hybrids as Tissue Engineering Scaffold

Ca2+-containing porous gelatin-siloxane hybrids were prepared using sol-gel process, post-gelation soaking, and freeze-drying. The porosity and pore size of the hybrids could be well controlled by the freezing temperature and the pH value of the soaking solution. The pore characteristics were related to the structure change during the soaking treatment. A bone-like apatite layer was able to form in the Ca2+-containing porous gelatin-siloxane hybrids upon soaking in a stimulated body fluid. The porous gelatin-siloxane hybrids could release gentamicin sulfate which is an antibiotic drug in bone chemotherapy. Thus, those hybrid materials are proposed to find application as novel bioactive and biodegradable scaffolds in bone tissue engineering.

Chemico-Vector and Mechanochemico-Vector Properties of Polarized Glass-Ceramic Silicophosphate of Narpsio

Glass-ceramics of Na2O-R2O3-P2O5-SiO2 (Narpsio) consist of a skeleton structure of 12-tetrahedra-membered rings and exhibit a super Na+ conductivity. Glass-ceramic Narpsio was proved to be electrically polarized through highly mobile sodium ions. Narpsio also shows relatively higher solubility in water. Taking into account of the water solubility and the chemical composition, the reactivity of polarized and non-polarized glass-ceramic Narpsio in the stimulated body fluid (SBF) were investigated in relation to bioactivity. After the 6 days' immersion of SBF, hydroxyapatite microcrystals aggregated semispherically were grown on the glass-ceramic Narpsio surfaces. Although the acceleration effects were under study, the growth rate was recognized to be higher in both of the negatively and positively charged surfaces. In analogy with polarized bioglasses, we confirmed the chemico-vector effects of glass-ceramic Narpsio for biomedical purpose. Additionally, glass-ceramic Narpsio, prepared by the locally biasing crystallization method, showed unreported microstructural changes of surfaces during chemical polishing with water, depending upon the direction of a biasing field. The phenomenon was interpreted as a mechanochemico-vector effect.

Synthesis of nanocrystalline hydroxyapatite powders in stimulated body fluid

Synthesis of nanocrystalline hydroxyapatite powders in stimulated body fluid

Aqueous mediated synthesis of bioresorbable nanocrystalline hydroxyapatite

An attempt was made to enhance the bioresorbability of hydroxyapatite (HA) by controlling its particle size to nano/submicron level. A wet chemical method was employed for the synthesis of HA nanocrystals at low temperature in an aqueous medium having the ability of bioresorbtion in stimulated body fluid. The prepared free flowing nano HA was characterized for its phase purity, chemical homogeneity and functionality. The obtained results indicated that it has nanoscale morphological structure with mean particle size of 220 nm in diameter. Further, its ionic dissolution rate was found to be quite higher than conventional HA and closer to biological apatite owing to its nanostructure processing. Accordingly, it suggests that the nano-HA has superior bioresorbtion and close chemical and crystallographic structure with natural bone apatite.

In vitro and in vivo evaluation of alginate/sol–gel synthesized aminopropyl-silicate/alginate membrane for bioartificial pancreas

Alginate/aminopropyl-silicate/alginate (Alg/AS/Alg) membrane was prepared on Ca-alginate gel beads by a sol–gel process. The membrane has ≡Si–O–Si≡ bonds as well as electrostatic bonds between amino groups of AS and carboxyl groups of alginate. Permeability and stability were investigated for the membrane. Furthermore, rat islets encapsulated in the membrane (499±32 μm in diameter, 1000 islets/recipient) were transplanted to the peritoneal cavities of the mice with streptozotocin-induced diabetes. Our data show that the membrane had the molecular weight cut-off point of between 70 and 150 kDa, and hardly inhibited the permeation of glucose and insulin. The Alg/AS/Alg microcapsule was more stable than the well-known Alg/poly- l-lysine (PLL)/Alg microcapsule. After 30 days of soaking in stimulated body fluid, the percentages of intact microcapsule were 98.4±0.5 (mean±SEM)% and 88.0±1.5% ( p<0.001) for the Alg/AS/Alg and Alg/PLL/Alg microcapsules, respectively. The maximum maintenance period of normoglycemia was 105 days without administration of immunosuppressive drugs.

Sol–gel preparation and in vitro deposition of apatite on porous gelatin–siloxane hybrids

Ca(II) containing porous hybrids of gelatin and 3-(glycidoxypropyl)trimethoxysilane (GPSM) were prepared using a sol–gel process, post-gelation soaking, and freeze-drying. The porosity and pore size of the hybrids could be well controlled by the freezing temperature and the pH value of the soaking solution. The pore characteristics were related to the structure change during the soaking treatment. A second soaking of the porous hybrids introduced a binary-pore distribution. The rate of biodegradation in a trishydroxymethylaminomethane (Tris) buffer solution decreased with an increased GPSM content. A bone-like apatite layer was able to form in the Ca(II) containing porous gelatin–siloxane hybrids upon soaking in a stimulated body fluid (Kokubo recipe). These hybrid materials are proposed to find application as novel bioactive and biodegradable scaffolds in bone tissue engineering.