Effect Of Hydroxyapatite Content Research Articles

Effects of hydroxyapatite content on cytotoxicity, bioactivity and strength of metakaolin/hydroxyapatite composites

The development of new materials is a critical challenge in advancing bone repair technology. Nowadays, the use of high strength geopolymers is extended to various fields, including biomedical research. This study investigates the influence of hydroxyapatite (HAp) content on the in vitro properties and characteristics of the metakaolin/HAp (MK/HAp) composites for potential application as bone substitutes. The MK/HAp composites with varying HAp contents were fabricated and subjected to cytotoxicity, bioactivity, physical and mechanical testing. PrestoBlue assay results confirmed acceptable osteoblast cell compatibility for all composites, with cell viability increases with increasing HAp content. Simulated body fluid (SBF) immersion demonstrated enhanced bioactivity and bone-like apatite formation on the composite surfaces with increasing HAp content. The compressive strength of the composite decreased mainly due to the reduced amount of silica and alumina contents and the increased porosity with higher HAp. Based on the present results, the relationship between bioactivity and strength with variations in HAp content indicates a promising composite. The HAp content of the MK/HAp composites for a bone substitute material should be 50% or higher to match the apatite formation and strength of specific human bones.

Electrochemical deposition of bilayer PPy/PPy-HA coating on AZ31 Mg alloy: Effect of HA content on characteristics and corrosion protection

This study aimed to examine the impact of naturally derived hydroxyapatite (HA) particles on the surface characteristics and corrosion behavior of polypyrrole (PPy)/polypyrrole-HA bilayer coatings. The coatings were applied onto AZ31 Mg alloy substrates using the potentiostatic electrodeposition method. Varying concentrations of HA particles (1, 3, and 5 wt%) were incorporated into the electrodeposition baths to create the top composite layers. Morphological analysis using FESEM revealed that the presence of HA particles led to PPy coatings with reduced porosity and more compact structures. EDS analysis and elemental mapping confirmed the presence of HA particles within the PPy matrix. AFM topography parameters indicated a slight increase in roughness values as the concentration of HA particles increased, with the average roughness rising from 46 nm for pure PPy coating to 53 nm for the coating with the highest HA content. Wettability results showed that the water contact angle (WCA) decreased from 56.6° for unreinforced PPy to 35.6° for the bilayer PPy/PPy-5 wt%HA coating. The corrosion behavior of the samples was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. It was observed that HA particles effectively reduced the corrosion current density (icorr), with the icorr of the optimal bilayer coating containing 3 wt% HA being 3.7 × 10−7 A cm−2, approximately two times lower than that of unreinforced PPy coating. Furthermore, the adhesion strength of the coatings was not affected by the inclusion of HA particles.

The effect of hydroxyapatite concentration on the mechanical properties and degradation rate of biocomposite for biomedical applications

Biocomposite is a material that have potential to heal injured bones and teeth due to their biocompatible, non-toxic, non-inflammation, and bioactive properties which can prevent infections that occurs frequently during surgical processes. Biocomposites made of PLA, PCL, and HA from bovine bone as a substitute for metal materials in medical applications have been widely studied. However, there are limited studies on the biocomposites made of PLA, PCL, and HA from green mussel shells. Therefore, this study aims to produce biocomposites from Polylactic Acid (PLA), Polycaprolactone (PCL), and Hydroxyapatite (HA) from green mussel shells and to determine the effect of HA concentration on the mechanical properties and degradation rate of the resulting biocomposite. 80 ml of chloroform was used to dissolve 16 grams of a PLA/PCL mixture with a composition of 80% and 20%. After 30 minutes, the solution was agitated for 30 minutes with a magnetic stirrer at 50°C and 300 rpm. After obtaining a homogenous solution, hydroxyapatite was added in percentages of 5%, 10%, 15%, and 20% of the total weight of the PLA/PCL mixture. The resulting mixture is poured into a glass mold in accordance with ASTM D790. Three-point bending, density, and biodegradable test were performed to investigate the effect of HA content on the mechanical properties and degradation rate of the biocomposite. The results of this study indicate that the mechanical properties of the biocomposite improved with the HA concentration increases. However, the more HA content used, the faster the biocomposite degrades.

Effect of hydroxyapatite content and particle size on the mechanical behaviors and osteogenesis in vitro of polyetheretherketone–hydroxyapatite composite

AbstractPoly‐ether‐ether‐ketone (PEEK) possesses excellent biocompatibility and similar elastic modulus as bones but suffers from poor osseointegration; usually, the addition of hydroxyapatite (HA) is considered as an effective way to improve the osseointegration of PEEK implant interface. To investigate the effect of HA content and particle size on the mechanical behaviors and osteogenesis in vitro of PEEK‐HA composites, the PEEK‐HA specimens with variable HA content and particle size have been fabricated by powder mixing‐heat press method and characterized by mechanical and biological tests. The results showed that the tensile/bending strength and elongation at break of PEEK‐HA are significantly impaired as the increasing HA amount, but the modulus improves. The compressive strength and modulus are improved as the increasing amount of HA. The PEEK‐HA with smaller HA particle size possesses higher‐performance tensile/bending and lower‐performance compressive properties. In osteogenesis tests in vitro, the results reveal that the cells amount attached on the substrate rises and the cells flatten more evenly with numerous cytoplasmic processes on greater area with the increasing HA content and decreasing particle size. The PEEK‐HA group that HA content is 20 wt% and particle size is 20 nm exhibits optimal‐performance osteogenesis in vitro, while maintaining sufficient mechanical properties.

Hydroxyapatite grafted chitosan/laponite RD hydrogel: Evaluation of the encapsulation capacity, pH-responsivity, and controlled release behavior

In this study, a pH-responsive drug carrier was developed for the controllable release of drugs in the gastric environment. Chitosan (CS), a pH-sensitive biopolymer, and laponite RD (LAP), a nano-clay with a high drug-loading capability, were used to design the new carrier. Hydroxyapatite (HA) was grafted into CS/LAP matrix through a simple co-precipitation technique to overcome the burst release of the CS/LAP. The structural analysis and swelling tests of products demonstrated that the co-precipitation method has led to the penetration of HA nanoparticles inside the CS/LAP matrix and occupying its hollow pores. Occupation of the empty pores can lead to the entrapment of drug molecules, thereby reducing the release rate. The nanocomposite showed a high loading capacity to ofloxacin as a drug model. The effects of HA content on release behavior of nanocomposite were investigated at simulated gastric (pH 1.2) and intestine (pH 7.4) environments. The results indicated a high pH sensitivity for CS/LAP/HA. HA grafting reduced the release rate remarkably regardless of pH. The release rate of CS/LAP/HA decreased by 44–63% in pH 1.2 and 41–51% in pH 7.4 compared to CS/LAP. Kinetic studies indicated that grafting the HA in CS/LAP has changed the drug release mechanism.

Microstructured poly(ether-ether-ketone)-hydroxyapatite composites for bone replacements

Utilizing a novel processing method of PEEK foam that produces hierarchical mesoporosity, we explore the use of hydroxyapatite (HA)/PEEK composites for mimicking the structure of human bone. The effect of HA content and processing parameters on the porosity, and interconnective network are studied with respect to the corresponding morphology, mechanical properties, and ultimately the cell viability. Having achieved hierarchical structuration with pore sizes ranging from approx. a hundred nanometers all the way to a few hundred microns, the HA/PEEK composites produced desirable mechanical properties and promising cell proliferation. A strong correlation was not seen with HA loading and the resulting properties, but a combination of the HA loading and variance in porosity is shown to be significant. The development and analysis of this bone mimic structure opens up the potential for this processing method and material as a treatment to bone injuries and bone diseases.

Effects of hydroxyapatite content on mechanical properties and in-vitro corrosion behavior of ZK60/HA composites

Abstract In this study, hydroxyapatite-reinforced ZK60 Mg alloybased composites were fabricated via a powder metallurgy route. The mechanical properties of these composites were studied by compressive tests and hardness tests. The in-vitro corrosion behavior was also investigated using immersion testing and electrochemical measurement. The influence of hydroxyapatite content on the mechanical properties and invitro corrosion behavior was evaluated. The microstructure and corrosion morphology were characterized by means of X-ray diffraction, optical and scanning electron microscopy. The results showed that the composite materials with 10 wt.% hydroxyapatite exhibited a better combination of mechanical strength and corrosion resistance. Compared with ZK60 alloy, the addition of 10 wt.% hydroxyapatite resulted in an increase in corrosion resistance by 38.6%.

Effects of hydroxyapatite content on mechanical properties and in-vitro corrosion behavior of ZK60/HA composites

Abstract In this study, hydroxyapatite-reinforced ZK60 Mg alloybased composites were fabricated via a powder metallurgy route. The mechanical properties of these composites were studied by compressive tests and hardness tests. The in-vitro corrosion behavior was also investigated using immersion testing and electrochemical measurement. The influence of hydroxyapatite content on the mechanical properties and invitro corrosion behavior was evaluated. The microstructure and corrosion morphology were characterized by means of X-ray diffraction, optical and scanning electron microscopy. The results showed that the composite materials with 10 wt.% hydroxyapatite exhibited a better combination of mechanical strength and corrosion resistance. Compared with ZK60 alloy, the addition of 10 wt.% hydroxyapatite resulted in an increase in corrosion resistance by 38.6%.

Biological properties and enzymatic degradation studies of clindamycin-loaded PLA/HAp microspheres prepared from crocodile bones

Polylactic acid (PLA)/hydroxyapatite (HAp) biocomposite microspheres with a specific core–shell structure for application as drug carriers were synthesised using an ultrasound field. In addition, the loading efficiency of clindamycin phosphate increased when the HAp content was increased to 30%. The effect of HAp content on enzymatic degradation of PLA/HAp microspheres loaded with clindamycin phosphate was that the degradation rate increased with increasing HAp content. Apatite formed on the surfaces of the PLA and PLA/HAp microsphere loading of clindamycin phosphate showed Ca and P peaks in energy-dispersive X-ray spectroscopy (EDX) data. In addition, the PLA and PLA/HAp microspheres loaded with clindamycin phosphate did not show any cytotoxicity against the human lung fibroblast MRC-5.

Study the Effect of HAp Content in PLA/HAp Microsphere on the Efficiency of Drug (Clindamycin) Loading Process

An ultrasound field was applied to obtain Polylactic acid (PLA)/Hydroxyapatite (HAp) biocomposite microspheres with the specific core-shell structure to be applied as a carrier of a drug. The hydroxyapatite was obtained from crocodile bone by thermal process. Sample characterization was achieved by powder X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDX) Scanning electron microscopy (SEM) and High Performance Liquid Chromatography (HPLC). As the result, the PLA/HAp loading clindamycin with different polymer-to-ceramic part wt.% ratio (100:0, 90:10, 80:20, and 70:30) showed the agglomeration of sphere-like particles. In addition, the loading efficiency of clindamycin increased with increasing HAp content up to 20%.

Characterization and Cell Response of Novel Hydroxyapatite/Glyceride-Based Polyurethane Porous Scaffold

The glycerides of castor oil (GCO) were copolymerized with isophorone diisocyanate (IPDI) to generate glyceride-based polyurethane (GCPU), meanwile blending with hydroxyapatite (HA) powder to fabricate porous composite scaffolds. The effect of HA content on mechanical properties of the resulting polymer scaffolds and the in vitro cell response of HA/GCPU scaffolds were investigated, by use of mechanical testing, FTIR, SEM and MTT assay. The results showed that the compressive strength increased with HA content, and the HA/GCPU scaffold with 40 wt% HA reached about 4.6 MPa, much higher than the scaffold without HA (only 605 kPa). The SEM observation, live-dead staining assay and MTT assay demonstrated the excellent biological properties of HA/GCPU scaffolds, which support cell adhesion and proliferation. This novel class of HA/GCPU porous scaffolds have prospect and advantage for bone repair and regeneration.

Fabrication and mechanical properties of chitosan composite membrane containing hydroxyapatite particles

This paper described the development of chitosan composites containing precipitated hydroxyapatite particles for potential applications in orthopaedic surgery or waste water treatment. The synthetic process and morphology of hydroxyapatite were reported. The effects of hydroxyapatite content on the microstructure and mechanical properties of composites were investigated. It was found that the Young’s Modulus of the composites decreases with hydroxyapatite content while the failure strength and strain increase with the hydroxyapatite content.

Effect of hydroxyapatite content on the microstructure, thermal and mechanical properties of Ti-based glassy alloy/hydroxyapatite composite prepared by spark plasma sintering

In the present paper, the effects of hydroxyapatite (HA) content on the microstructure, thermal and mechanical properties of Ti-based glassy alloy/HA composite prepared by spark plasma sintering (SPS) are investigated. The microstructure of the composites is homogeneous when the HA is lower than 2 wt%. When the HA content is higher than 3 wt%, the crystalline precipitates with size of less than 5 nm are distributed in the glassy matrix. HA decomposes during sintering procedure for the composite with high HA content. With increasing HA addition, compressive strength decreases. Especially for the HA content is over 2 wt%, the strength decreases sharply because of partial crystallization of glassy alloy matrix.

Synthesis and Swelling Behaviors of Poly (sodium acrylate)/Hydroxyapatite Superabsorbent Nanocomposites

Superabsorbent nanocomposites based on partially neutralized acrylic acid (AA) and hydroxyapatite (HP) were prepared by free radical solution polymerization using N, N′-methylenebisacrylamide (MBA) as the crosslinker and ammonium persulfate (APS) as the initiator. The developed nanocomposites were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of HP content on water absorbency of the nanocomposites were investigated, and the swelling behaviors of the nanocomposites in various pH solutions and their reswelling capability in distilled water were also systematically evaluated. FTIR spectra revealed that the P–OH groups of HP participated in graft polymerization reaction with AA. TEM analysis showed the needle-like crystals of HP present in the PAA/HP nanocomposite with a diameter of about 40 nm and a length of about 270 nm. The swelling rate and reswelling capability of the superabsorbents were improved due to the introduction of HP into PAA polymeric network, and this result implied that the nanocomposites acted as a recyclable water-saving material.

Preparation of Porous Hydroxyapatite Scaffolds for Bone Tissue Engineering

Porous hydroxyapatite (HAp) scaffolds were successfully prepared by using the HAp slurry based on the replication of polymer sponge substrate. The effect of HAp content in slurry on the pore morphology and size, and density, porosity, and mechanical strength of porous scaffolds was investigated. The scaffolds with average pore sizes ranging from 200 to 400 µm had an open, relatively uniform, and interconnected porous structure. As the HAp content increased, the porosity of scaffold decreased while the density increased. These phenomena were attributed to the fact that the pores became interconnected with more dense and thicker pore walls with increasing HAp content in slurry. The results suggest that the density, porosity, and compressive strength of the porous HAp scaffold were significantly affected by the content of the HAp powder in the slurry.

Effect of hydroxyapatite content on physical properties and connective tissue reactions to a chitosan–hydroxyapatite composite membrane

Effect of hydroxyapatite content on physical properties and connective tissue reactions to a chitosan–hydroxyapatite composite membrane

Effect of hydroxyapatite content on physical properties and connective tissue reactions to a chitosan-hydroxyapatite composite membrane.

The present study investigated the effect on certain physical properties of adding various amounts of hydroxyapatite (HAP) to chitosan sol. Also investigated were connective tissue reactions to a composite membrane that is being developed for possible use in guided tissue regeneration and for the limitation of HA particle migration at sites of implantation. The physical properties evaluated were shrinkage, tensile strength, hardness, calcium ion release, and morphology. Assessment of physical properties indicated that a ratio of HA to chitosan sol of 4/11 by weight is optimal in the preparation of the composite membrane. Subperiosteal implantation of the membranes over rat calvaria revealed that the membranes were well tolerated, with fibrous encapsulation and occasional areas of osteogenesis. Increasing the hydroxyapatite content seems to enhance membrane degradation.