Strontium Hydroxyapatite Research Articles

An alternative approach in the synthesis of strontium-hydroxyapatite and strontium hydroxyapatite embedded in graphitic carbon nitride nanocomposites for potential tissue engineering applications

Sr-hydroxyapatite has drawn much attention with promising applications in biomedical engineering especially in drug delivery and tissue repair. A novel protocol for the preparation of Strontium hydroxyapatite (Sr-HAP) and Strontium hydroxyapatite encapsulated by graphitic carbon nitride (Sr-HAP@gCN) with high purity and better homogeneity was adopted for potential use in orthopaedic surgeries. The physiological pathway of Strontium and calcium inside humans follow the same trend leading to the mineral deposition of the bone. In the present study, a novel attempt in synthesizing Sr-HAP and Sr-HAP@gCN by the hydrothermal method is proposed for obtaining an ideal biomaterial with potential biocompatibility and pharmacological activity. Phase identification by X-ray diffraction (XRD), Fourier transform Infra-Red spectroscopic analysis (FTIR), Electron & atomic force microscopic studies, Thermogravimetric and Raman spectroscopic analysis was performed on the prepared Sr-HAP and Sr-HAP@gCN to characterize the incorporation efficiency of Strontium. Resazurin microtiter assay and MTT assay were used to evaluate antimicrobial susceptibility and biocompatibility. The typical crystal phase of Sr-HAP and a phase change in Sr-HAP@gCN have been demonstrated with special reference to the interfacial connection between gCN and Sr-HAP through FT-IR studies. Raman spectroscopy revealed the archetypal signature of symmetric and asymmetric PO vibrations pertaining to linearity change with the addition of Strontium. The biological effect of Sr-HAP and Sr-HAP@gCN was quite significant in inducing mineralization when kept immersed in simulated body fluid (SBF) for 21 days. Promising results pertaining to antimicrobial susceptibility and biocompatibility have been proved as an encouraging choice for drug delivery applications and bone filling applications.

PCL reinforced nano strontium hydroxyapatite-Butea monosperma-scaffold for bone regeneration

Biocomposite materials, composed of biodegradable polymers and supplements, are promising for bone regenerative matrices due to their mechanical strength and excellent osteoconductivity. This study focuses on fabricating electrospun composite scaffolds using the bark extract of Butea monosperma (BM), nano strontium hydroxyapatite (nSrHA), and polycaprolactone (PCL). Four types of scaffolds were prepared: PCL (control), BM-PCL, nSrHA-PCL, and BM-nSrHA-PCL. The scaffolds were evaluated through various techniques: bright field microscopy for standardization, SEM for structural evaluation, and SEM-EDX for elemental analysis. Additionally, mechanical strength, release study, degradation, and protein adsorption were assessed. Furthermore, cytotoxicity, proliferation, and cytocompatibility of the scaffolds were evaluated using rat adipose-derived mesenchymal stem cells (rADMSCs) through SEM, MTT assay, LDH assay, DAPI staining, and Direct contact assay. SEM analysis confirmed that all four fabricated scaffolds were nano-fibrous in nature. The incorporation of phytochemicals and nSrHA was confirmed via SEM-EDX. Mechanical testing revealed that the BM-nSrHA-PCL scaffolds had superior mechanical properties compared to the control PCL scaffolds. Protein adsorption studies indicated enhanced protein binding in BM-nSrHA-PCL scaffolds. Degradation studies showed that BM-nSrHA-PCL scaffolds had a controlled degradation rate suitable for tissue engineering applications. Cytotoxicity tests confirmed that all scaffolds were noncytotoxic. Proliferation and cytocompatibility assays demonstrated that BM-nSrHA-PCL scaffolds significantly promoted cell proliferation compared to other scaffold types. These results suggest that the BM-nSrHA-PCL scaffolds exhibit improved mechanical properties, protein adsorption, controlled degradation, and enhanced cell proliferation, making them promising candidates for bone tissue engineering applications.

Long-Term Estimation of Depositions on Heating Surface During Boiling of Long-Life Coolant

Abstract Long-term boiling experiments with long-life coolant have been made with the aim to apply a boiling cooling technology to the next generation high exothermic electronic devices. The long-life coolant commonly used for cooling electronic devices is a mixture of ethylene glycol and water with multiple antirust inhibitors as additives, which may result in some depositions on the heat transfer surface during the boiling. In this study, the heat transfer surface made of copper was set vertically, and long-term experiments have been performed under the pool boiling. The deposition process was monitored for constant heating conditions. From experimental results, a distinct surface temperature change was observed under constant heat flux conditions. Just after keeping constant heat flux, the surface temperature increases with time, a certain time later decreases, and finally takes a stable value. During the temperature rise, the deposition adheres to the heat transfer surface in dots, which may cause an increase in thermal resistance between the wall surface and the working fluid. However, during the temperature drop, large growth of dot-like depositions on the heat transfer surface could alter wettability and surface roughness, enhancing boiling heat transfer. In addition, to investigate the characteristics of the depositions adhered to the heat transfer surface, a component analysis has been performed, which shows that the main substance was strontium hydroxyapatite, which might be formed by chemical reaction between components in the additives under the boiling.

Electrochemical and corrosion protection performance of Sr-HaP/PoPD coated LN stainless steel

BackgroundStainless steel is a common implant material used in orthopaedic surgeries. However, metallic ions are released from the implants when it placed inside the human body. Coating of biocompatible material such as strontium hydroxyapatite (Sr-HaP) is one of the methods to reduce the release of metallic ions into the body. MethodIn the present work, we have developed a bilayer coating namely poly-orthophenylenediamine (PoPD) on Sr-HaP deposited low nickel stainless steel (LNSS) via electrochemical deposition followed by electropolymerization methods. The Sr-HaP/PoPD coating was confirmed with Fourier transform infrared spectroscopy (FTIR) and high resolution scanning electron microscopy (HR-SEM). The corrosion protection performance of the coated LN SS specimens in Ringer's solution was investigated using potentiodynamic polarisation and electrochemical impedance spectroscopic techniques. The leach out characteristics of the coating was determined at the impressed potential. Significant findingsThe studies revealed that the passive film underneath the PoPD layer is acting like a shield and prevent the LN SS from corrosion. Furthermore, the potential bioactivity of LN SS is due to the presence of top porous Sr-HaP layer. Hence, the PoPD/Sr-HaP bilayer coating on LN SS substrate could be a promising material for orthopaedic implant applications.

Physicochemical and Biological Characterization of Gelatin/Alginate Scaffolds Reinforced with β-TCP, FDBA, and SrHA: Insights into Stem Cell Behavior and Osteogenic Differentiation.

Bone tissue engineering necessitates the development of scaffolds with optimal properties to provide a suitable microenvironment for cell adhesion, proliferation, and osteogenic differentiation. The selection of appropriate scaffold materials remains a critical challenge in this field. In this study, we aimed to address this challenge by evaluating and comparing the performance of hydrogel scaffolds reinforced with β-tricalcium phosphate (β-TCP), allograft, and a combination of allograft and strontium hydroxyapatite (SrHA). In this study, scaffolds containing the following compounds with a weight ratio of 75 : 25 : 50 were made using a 3D printer: group (1) alginate + gelatin + β-TCP (TCP), group (2) alginate + gelatin + allograft (Allo), and group (3) alginate + gelatin + allograft + strontium hydroxyapatite (Str). Stem cells extracted from rat bone marrow (rBMSCs) were cultured on scaffolds, and cell proliferation and differentiation tests were performed. Also, the physical and chemical properties of the scaffolds were investigated. The two/one-way analysis of variance (ANOVA) by Tukey's post hoc test was performed. There was no significant difference between scaffolds with pore size and porosity. TCP scaffolds' mechanical strength and degradation rate were significantly lower than the other two groups (P < 0.05). Also, the swelling ratio of Allo scaffolds was higher than in other samples. The amount of cell proliferation in the samples of the TCP group was lower than the other two, and the Allo samples had the best results in this concern (P < 0.01). However, the scaffolds containing strontium hydroxyapatite had significantly higher bone differentiation compared to the other two groups, and the lowest results were related to the scaffolds containing β-TCP. Hydrogel scaffolds reinforced with allograft or its combination with strontium showed better physicochemical and biological behavior compared to those reinforced with β-TCP. Besides, adding strontium had a limited impact on the physicochemical features of allograft-containing scaffolds while improving their potential to induce osteogenic differentiation.

BiOCl/SrHA nanoparticle for photocatalytic degradation of a malachite green dye

In this research, we discuss the removal of malachite green dye by strontium hydroxyapatite supported BiOCl. A modified hydrolysis model, one can synthesise BiOCl/SrHA. BiOCl/SrHA was characterized using Fourier transform-infrared spectroscopy (FTIR), UV-visible (UV-vis) analysis, X-ray diffraction (XRD), energy diffraction X-ray (EDX), and scanning electron microscopy (SEM). SEM outcome confirmed the dispersion of BiOCl onto strontium hydroxyapatite. The shape of the BiOCl catalytic samples overlapped with each other to form 3D hierarchical flower-like structures. The UV-visible was used as a radiation source during photocatalysis. BiOCl/SrHA had an effect on malachite green dye degradation. The oxidative removal occurred through hydroxyl radical formation. UV-visible (UV-vis) /BiOCl/SrHA showed perfect photocatalytic property for the decay of malachite green (MG) from an aqueous solution. According to kinetics analysis, the dye degradation rates could be in a pseudo-first-order model.

Bismuth oxyiodide nanocomposites supported on strontium hydroxyapatite enhance UV-Vis light-driven photocatalytic activity

In this research, we discuss the removal of basic fusion (BF), and crystal violet (CV) dyes by strontium hydroxyapatite supported BiOI. In a modified hydrothermal model, one can synthesize BiOI/SrHA. BiOI/SrHA was characterized using Fourier transform-infrared spectroscopy (FTIR), UV-visible (UV-vis) analysis, X-ray diffraction (XRD), energy diffraction X-ray (EDX), and scanning electron microscopy (SEM). SEM outcome confirmed the dispersion of BiOI onto strontium hydroxyapatite. The shape of the BiOI catalytic samples overlapped with each other to form 3D hierarchical flower-like structures. The UV-visible was used as a radiation source during photocatalysis. BiOI/SrHA had an effect on malachite green dye degradation. The oxidative removal occurred through hydroxyl radical formation. UV-visible (UV-vis) BiOI/SrHA showed perfect photocatalytic property for the decay of Basic Fuchsin (BF) and Crystal Violet (CV) from an aqueous solution. According to kinetics analysis, the dye degradation rates could be in a pseudo-first-order model

Activity of Nickel Supported Over Nanorod-Shaped Strontium Hydroxyapatite Catalysts in Selective Methanation of CO & CO2

Nickel modified strontium hydroxyapatite (Ni/Sr-HAP) supported catalysts are studied in selective methanation of CO/CO2. In this work, a new type of nano rod-shaped strontium hydroxyapatite-based catalysts with two different sizes and aspect ratios were prepared by sol–gel method and in next step, Ni precursor was wet impregnated i.e., denoted as Ni/Sr-HAP and Ni/Sr-HAP(F127). The catalytic tests were performed in CO and CO2 methanation reactions and evaluated the light-off temperatures curves (225–450 °C) under ambient pressure in a fixed-bed flow reactor. The physicochemical properties of the prepared catalysts were characterized by XRD, N2 physisorption, TEM, SEM, TPR, CO2/H2-TPD and H2-chemisorption techniques. From XRD analysis, both Ni/Sr-HAP and Ni/Sr-HAP(F127) were identified as the hydroxyapatite type structure with high crystallinity and very low intensity peaks corresponds to strontium phosphates as the main phase and structure. The TEM and SEM micrographs of Ni/Sr-HAP catalysts displayed a nano- rod shaped morphology with different dimensions and exhibited average Ni particle size of ~ 9.2 nm. While Ni/Sr-HAP(F127) shown the rod size in the length in the range of 100–250 nm and width in the range of 20–40 nm with average Ni particle size 5.7 nm. The F127 mediated support Sr-HAP synthesis i.e., Ni/Sr-HAP(F127) mesoporous catalyst possessed higher metal surface with smaller Ni particles size and possessed higher CO2 adsorption capacity. The medium strength basic sites of Ni/Sr-HAP catalyst played an important role in methanation reactions. Based on the characterization and the catalysts activity results, small sized nanorods of Ni/Sr-HAP(F127) is the most active and selective catalyst due to the higher Ni dispersion, higher amounts of medium basic sites, and reducibility character than the bigger nanorods based Ni/Sr-HAP catalyst.

Strontium hydroxyapatite/magnesium oxychloride cement with high strength and high osteogenic activity for bone defect repair

Strontium is a kind of element which can promote the increase of bone density and benefit the growth of bone tissue. This study combined strontium hydroxyapatite (Sr-HAp) with magnesium oxychloride cement (MOC) to prepare a bioactive material with good osteogenic activity and degradability. The results revealed that the incorporation of 10 wt.% Sr-HAp densified the structure of MOC, slowed down the degradation rate of hydration product phase 5 in water, and enhanced the water resistance of MOC. After soaking for 28 days, the compressive strength of Sr-HAp/MOC decreased by 53%, which was lower than that of MOC (93%) and HAp/MOC (61%) without adding Sr-HAp. During the degradation process in vitro, Sr-HAp/MOC continuously released Sr2+ and the cumulative concentration of Sr2+ released in vitro after seven days of immersion was 1.27 ± 0.15 ppm. When Sr-HAp/MOC was soaking in simulated body fluid, Sr-HAp induced the growth and deposition of bone-like component hydroxyapatite crystals on MOC’s surface, improving MOC’s bioactivity. After implantation of femur defect in rats, the new bone tissue grew from outside to inside around Sr-HAp/MOC, which showed Sr-HAp/MOC had better osteogenic activity. MOC was containing 10 wt.% Sr-HAp can not only provide strong support for bone defects but also have the potential to promote bone regeneration.

A facile and general approach to enhance the luminescence efficiency and stability of CsPbBr3 perovskite quantum dots

A facile, general, and synthesis method with low-cost has been explored to improve the stability of the CsPbBr3 perovskite quantum dots (PQDs). During the synthesis process, the CsPbBr3 PQDs are encapsulated into the strontium hydroxyapatite (SrHAp) matrix by a direct calcination process under high temperature in the air without any organic solvents, ligands, or polymer additives. The encapsulation strategy not only improves the luminescence efficiency of the PQDs but also greatly enhances their stability for long-term storage. The as-synthesized CsPbBr3@SrHAp composites possess many advantages including narrow-band emitting, high green color purity, and eminent stability, which may have prospects in the fields of solid-state lighting, optical displays, and optoelectronic devices. Furthermore, this feasible strategy may pave a critical way for improving the stability of all-inorganic CsPbX3 (X = Cl, Br, or I) PQDs.

Evaluation of implant bonding strength for PEKK with strontium hydroxyapatite as composite and coating implant material

To date, there has been a lot of interest in the development of medical/dental implant materials. Many studies have been conducted in recent years on the development of composites, particularly those based on calcium phosphate bio-ceramic, because their structure is comparable to that of human bone. The aim of the study was to evaluate the bond strength between the bone and pekk implant with strontium hydroxyapatite after different periods of implantation (2, 6) weeks in rabbit tibia by push out test.60 polymer implants, 3.0 mm in diameter and 8mm in length (20 control pure PEKK, 20 composite SR HA /PEKK implant and 20 implant coating with strontium hydroxyapatite by RF magnetron sputtering. The assess surface topography was done by using Scanning electron microscope. The screws were implanted in twenty healthy adult new zeeland rabbits each tibia received three, one coated with sr ha, one composite SR HA / PEKK and third pure PEKK. Push out test was done to determine the peak force necessary to remove the implant from tibia bone after different periods (2 and 6 weeks) of implantation.

Formation and growth mechanism of Strontium hydroxyapatite cellular crystal sphere

Strontium hydroxyapatites (SrHAps) find widespread applications in bone tissue engineering and drug carrier material for bone disease treatment because of biocompatibility. Morphology controlled preparation of SrHAps and understanding of the synthesis mechanism are critical to rationalize design hierarchically structured SrHAps and expand their applications. Herein, SrHAp cellular crystal spheres have been synthesized by using (NH4)3C6H5O7– induced (citrate-induced) homogeneous precipitation method under ambient pressure. Morphology characterization has shown that the as-obtained SrHAp is the secondary particle, while the spherical structure constituted the primary cellular crystal. Driving force of Sr2+ concentration gradient in phase transition has been analyzed to explain the synthesis mechanism of unique hierarchically structured SrHAp cellular crystals. The formation of SrHAp cellular crystal spheres can be attributed to the strong coordination within C6H5O73– and Sr2+ to form a 3D grid-like structure. This research has been able to overcome the longstanding limitations of traditional synthesis methods to establish the efficient route for synthesizing SrHAp with special morphology and predictable and controllable hierarchically structured SrHAp.

Surface Characterization of PEKK Modified by stron-tium–hydroxyapatite coating as implant material Via the magnetron sputtering Deposition technique

Background: The best material for dental implants is polyetherketoneketone (PEKK). However, this substance is neither osteoinductive nor osteoconductive, preventing direct bone apposition. Modifying the PEKK with bioactive elements like strontium hydroxyapatite is one method to overcome this (Sr-HA). Due to the technique's capacity to provide better control over the coating's properties, RF magnetron sputtering has been found to be a particularly useful technique for deposition.&#x0D; Materials and methods : With specific sputtering conditions, the RF magnetron technique was employed to provide a homogeneous and thin coating on Polyetherketoneketone substrates.. the coatings were characterized by Contact angle, adhesion test, X-ray diffraction (XRD), atomic force microscope and Elemental Analysis with Energy Dispersive X-Ray (EDX)&#x0D; Results : indicated that strontium hydroxyapatite had successfully deposited onto the surface with significant improvement in the wettability value to provide a suitable environment for cell attachment, spreading, proliferation, and differentiation&#x0D; Conclusion: Coating PEKK with RF magnetron sputtering can provide homogeneous surfaces laying the groundwork for improving PEKK's potential bioactivity, such as surface wettability. Wetting qualities are critical in implantable materials and are used to predict future osseointegration success.

Formation and Growth Mechanism of Strontium Hydroxyapatite Cellular Crystal Sphere

Formation and Growth Mechanism of Strontium Hydroxyapatite Cellular Crystal Sphere

Polarised strontium hydroxyapatite – xanthan gum composite exhibits osteogenicity in vitro

Clinical applications of bone tissue engineering demand that bone filler materials should be extremely biocompatible and osteoinductive so as to accelerate the repair of bone defects. Human bones under stress generate small electric charges thereby acting as a piezoelectric material. This has prompted researchers to investigate the properties of electrically active materials on bone tissue development. Herein, fabrication of bone filler material SrHA-Xanthan gum was done by a freeze-drying method. This study was directed to explore the effect of growth of surface charges on SrHA-Xanthan gum composite with respect to osteoblast activity in an artificial environment. Polarization of SrHA-Xanthan gum composites was carried out to induce negative charge on the composite surface and the specimen was then seeded with MG-63 cells. After 3 and 5 days of culture, cell viability on polarized composites were significantly increased as compared to non-polarized composites. On day 5 of culture, the relative expression of RUNX2, COL1, and OCN on polarized composites were elevated by 19%, 39%, and 35% respectively as compared to non-polarized composites. The present in vitro results suggest that negatively polarized composites can be favored over non-polarized composites (as implant materials) as they enhance osteogenesis and therefore present optimistic applications for bone tissue engineering.

Formation and Growth Mechanism of Strontium Hydroxyapatite Cellular Crystal Sphere

Formation and Growth Mechanism of Strontium Hydroxyapatite Cellular Crystal Sphere

Tunable luminescence and cytotoxicity of Samarium-doped calcium–strontium–hydroxyapatite for cell imaging

Samarium (Sm)-doped calcium–strontium–hydroxyapatite (Ca–Sr–HA:Sm) materials were designed and prepared, and the influence of Sr-introduction on the structure, photoluminescence (PL) and cytotoxicity of samples was revealed. The Sr-doping deduces the shift of some diffraction peaks to smaller angles and enlarges the particle size of samples. The typical red– orange emissions and corresponding luminescence quenching of Sm[Formula: see text] were observed, and the optimal luminescence performance appeared when [Formula: see text](Sr) = 7(Sr/Ca = 7/3) and quenching concentration closes to [Formula: see text](Sm) = 0.8 mol.%. The non-radiative transitions and energy transfers due to the dipole–dipole interactions between ions with different symmetry are essential to the luminescence and quenching of Sm[Formula: see text]. Furthermore, the viability values of human HepG2 cells are calculated larger than 90%, and the red–orange color emission was observed when the particles are incubated with cells.

Highly Stable Apatite Supported Molybdenum Oxide Catalysts for Selective Oxidation of Methanol to Formaldehyde: Structure, Activity and Stability

AbstractMolybdenum oxide (5 to 20 wt.%) supported on calcium or strontium hydroxyapatite were investigated as catalysts for selective oxidation of methanol to formaldehyde. These catalysts were both active and selective, with a maximum yield achieved at 95 % conversion and 96 % selectivity. The main byproducts were CO (3.2 %) and dimethyl ether (DME, 0.7 %). The catalytic performance of the catalysts was measured for up to 600 h at 350 °C. Compared to an industrial iron molybdate catalyst, the hydroxyapatite based catalysts deactivated slower. The active species were found to be a surface layer of MoOx on the hydroxyapatite support, while excess molybdenum formed crystalline (Ca/Sr)MoO4, acting as a reservoir replenishing surface MoOx lost by volatilization with methanol. The excess molybdenum in the form of (Ca/Sr)MoO4 was found to volatilize significantly slower than the excess MoO3 in iron molybdate catalysts. The combination of high activity and selectivity with low rate of Mo volatilization makes this class of catalysts interesting for industrial production of formaldehyde.

Dual response of osteoblast activity and antibacterial properties of polarized strontium substituted hydroxyapatite-Barium strontium titanate composites with controlled strontium substitution.

To mimic the electrical properties of natural bone, controlled strontium substitution of both hydroxyapatite and ferroelectric barium titanate were achieved by mixing in the ratio 30:70 by weight. The composites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy to investigate the phase composition and microstructure of the composites. Unpolarized and polarized strontium hydroxyapatite (SrHA)-barium strontium titanate (BST) composites with controlled degree of Sr substitution were examined, including 5SrHA-5BST (5% Sr substitution in both components) and 10SrHA-10BST composites. The 10SrHA-10BST composite showed a higher osteoblast activity, as observed from the cell viability studies performed using CCK-8 assay. The polarized composites showed promise against Staphylococcus aureus bacteria by minimizing the adhesion and growth of bacteria, as compared with their unpolarized counterparts. The polarized 10SrHA-10BST was found to be superior than all other composites. As a result, the approach of polarization of SrHA-BST composites has been found to be an effective bone substitute material in controlled enhancement of osteoblast growth with simultaneous reduction of bacterial infection.

Electrical conduction mechanism of barium doped strontium hydroxyapatite synthesized by co – precipitation method

The crystalline samples of Barium (Ba) doped Sr10-xBax(PO4)6(OH)2 with x = 0, 0.5 and 1 mol% were prepared by co – precipitation method. The microstructural (SEM) image shows the distribution of densely packed grains over the surface of prepared sample. The nature of cole – cole plots confirm that the conduction mechanism is governed only by the grains with no contribution of grain boundaries for all prepared samples. The resistance of grains decreases with increase in temperature and molar (mol%) concentration, which shows a negative temperature coefficient resistance (NTCR) behaviour for all prepared samples. The a.c. conductivity increases with increase in frequency which shows non – debye nature of the prepared samples.