Combination Of Hydroxyapatite Research Articles

Study on ex-situ catalytic pyrolysis of poplar to produce aromatics over a dual-catalyst system of hydroxyapatite and HZSM-5

The ex-situ catalytic pyrolysis of poplar in a dual-catalyst system of hydroxyapatite (HAP) and HZSM-5 was performed using a bench-scale device to enhance the aromatics production. Results indicated that the introduction of HAP could effectively achieve the deoxygenation of macromolecular oxygenates, which were then converted into hydrocarbon precursors. The combination of HAP and HZSM-5 exceedingly promoted the production of aromatics especially monocyclic aromatics (MAHs) than single HZSM-5. The effects of operating conditions on aromatics yield and distribution were investigated. Under the catalyst layout of mode B, with the optimum conditions reaching the catalytic temperature of 500 °C, HAP to HZSM-5 ratio of 2:4, and catalyst to biomass ratio of 1:1, the maximum aromatics yield of 9.10 wt% was achieved, accompanied by the monocyclic aromatics/polycyclic aromatics ratio enhanced to 2.33. At this point, the synergistic effect for MAHs and total aromatics reached 170.09% and 214.14%, respectively. Compared to the conventional metal oxides, the HAP/HZSM-5 dual-catalyst system exhibited superior performance in aromatics production. Besides, the anti-coking capability of HZSM-5 in the dual-catalyst system was also better than that of pure HZSM-5. This research provided a new perspective for the efficient utilization of biomass energy.

Synthesis and Comparison of Chemical Changes Using FTIR Spectroscop for Copper Substituted Hydroxyapatite

The study aims to scrutinise and compare the chemical modifications present in copper-substituted hydroxyapatite utilising FT-IR spectroscopy. The synthesis of both HAp and Cu-modified HAp was conducted via the chemical precipitation method, involving specific chemicals like ammonium hydroxide (HN4OH) solution, diammonium hydrogen phosphate ((NH4)2HPO4), copper chloride hexahydrate (CuCl2.6H2O), and calcium nitrate tetrahydrate (Ca(NO3)2.4H2O). The overall sample size was determined through clinlac.com considering the copper-substituted dataset (N=4), an alpha error of 0.05, G power at 80%, an enrolment ratio of 0.1, and a confidence interval of 95%. The acquired FT-IR spectra denote minimal differences between the CuHAp and HAp samples. Each peak bears a resemblance to the distinctive features of HAp, indicating structural similarity between pure hydroxyapatite and the copper-substituted variant. The investigation utilised SPSS 27.0.1 software to compute the copper-doped hydroxyapatite percentages at 0%, 1%, 5%, and 10%. A One Sample T-test revealed a statistically significant difference with a p-value of 0.001 (p<0.05), particularly highlighting the statistical significance of copper hydroxyapatite weight percentage (p=0.006). Significant alterations in peak values were observed in the novel copper-substituted hydroxyapatite concentrations of 1%, 5%, and 10%. Notably, the study identifies the 10% copper and hydroxyapatite combination as yielding the most noteworthy chemical modifications via spectroscopy. This finding suggests the potential utility of these compounds in medicinal applications.

Physical and biological changes of copper oxide and hydroxyapatite filled in polycaprolactone scaffolds: Cellular growth behavior and antibacterial activity

Burns have placed a devastating burden on public health because of leading to an increased risk of infection. Therefore, the development of an effective antibacterial dressing for wound healing is essential. The present work is mainly based on the fabrication of biodegradable polycaprolactone (PCL) films through a simple and cheap process of polymer casting using a novel combination of hydroxyapatite (HAP), cuprous oxide (Cu2O) NPs and graphene oxide (GO) nanosheets which have a great effect in preventing colonization and to modify the wound dreasing. The compositions played a key role in decreasing the contact angle of PCL from 47.02° to 11.53°. Further, the cell viability exhibited a viable cell ratio of 81.2% after 3 days of culturing. Moreover, the highest antibacterial activity was obtained from the film of Cu2O@PCl and showed high impact results in antibacterial behavior.

Physicochemical characterization tungsten oxide modified hydroxyapatite embedded into polylactic acid nanocomposite for biomedical applications

To compensate for the feeble antimicrobial potential of hydroxyapatite (HAp), the compound has been incorporated into different nanocomposites (NCs) in addition to powder and fibrous structure. Hydroxyapatite (HAp)/tungsten oxide/graphene oxide (GO) ternary nanocomposite introduces a significant enhance in the cell viability to 96.7 ± 3% towards the osteoblast cells. The chemical compositions were approved by various analytical techniques such as XRD, FTIR, XPS, and EDS. TEM shows well-defined, rod-like HAp grains. The triple ingredient HAp/WO3/GO nano-composite exhibits an 22.8 nm grain size. FESEM introduces grain shape deviation via changing HAp additives from semi-spherical to needle-like with macro-porous structure within the composite of HAp/WO3/GO. Moreover, compatibility of ternary nanocomposite inside the PLA environment led to decrease in the contact angle of the nanofibrous structure reached 16.5 ± 4.4°. The combination of HAp and organic/inorganic elements might represent a good characterization for the target biological applications. HAp/WO3/GO composite exhibits a significant improvement in anti-microbial activity to be around 85.6 ± 1.6 % and 110.1 ± 2.0 % in for E. coli and S. aureus.

The Cytokine and Bone Protein Expression by Ellagic Acid-Hydroxyapatite in Bone Remodelling Model.

Ellagic acid, a phenolic compound with anti-inflammatory potential, can be used to accelerate the bone healing process and affect human health, while hydroxyapatite is the most commonly used bone graft material. Using a combination of the two materials results in reduced inflammation and increased osteogenesis. This study aimed to determine the effects of combining ellagic acid and hydroxyapatite in bone marker remodelling by analysing the expression of tumour necrosis factor-α (TNF-α), interleukin 10 (IL-10), bone morphogenetic 4 protein (BMP-4), and osteopontin (OPN). Thirty Wistar rats were used in the study. A defect was created in each animal's femur using a low-speed diamond bur. In the control group, the bone was then treated with polyethylene glycol (PEG). In one of the other groups, the bone was treated with hydroxyapatite, and in the other, with ellagic acid-hydroxyapatite. The femur was biopsied 7 days after the procedure and again 14 days after the procedure, and an indirect immunohistochemical (IHC) examination was performed for TNF-α, IL-10, BMP-4, and OPN expression. The ellagic acid-hydroxyapatite decreased TNF-α expression in the bone tissue after 7 days and again after 14 days (p < 0.05). On the other hand, it increased IL-10, BMP-4, and OPN expression (p < 0.05) during the same time periods. Ellagic acid-hydroxyapatite plays a role in bone marker remodelling by decreasing the expression of TNF-α and increasing the expression of IL-10, BMP-4, and OPN. This hydroxyapatite combination can therefore be recommended for use as bone graft material.

Comparative Evaluation of Hydroxyapatite Bone Alloplast with Combination Bone Alloplast (Hydroxyapatitie and ?-Tricalcium Phosphate) in Grade II Mandibular Furcation Involvements.

The management of furcation involvements by regenerative surgery with bone alloplast have been used with varying degrees of success in periodontal therapy. The aim of the study was to clinically and radiographically compare the effectiveness of Hydroxyapatite bone alloplast with combination bone alloplast (Hydroxyapatite and ?-Tricalcium phosphate) for the treatment of Grade II mandibular furcation involvements. Thirty patients with bilateral Grade II mandibular furcation involvements were distributed in Group A (Hydroxyapatite) and Group B (Hydroxyapatite and ?-Tricalcium phosphate). Clinical parameters such as Plaque Index, Gingival Index, Probing Pocket Depth, Clinical Attachment Level and Horizontal Probing Depth were recorded at baseline and at one, three and six mths postoperatively. Radiographic bone fill measurements were recorded at baseline and six months post-operatively. Both the groups showed statistically significant (p <0.01) improvement in clinical and radiographic parameters at each recall visits. Inter-group comparison of clinical parameters showed no significant difference in both the groups whereas radiographic measurements following six months post-surgery showed significantly (p <0.05) greater amount of bone fill in Group B compared to Group A. It can be concluded that at six months post-operative, both the alloplastic materials resulted in significant improvement in clinical parameters and no significant difference was found between both groups. There was a statistically significant radiographic bone fill when a combination of Hydroxyapatite and ?-Tricalcium phosphate was used demontrating its effectiveness in the treatment of Grade II Furcation involvement.

Evaluation of the mechanical properties of hydroxyapatite-silica aerogel/epoxy nanocomposites: Optimizing by response surface approach

This study attempted to investigate the effects of adding hydroxyapatite and silica aerogel nanoparticles on the density, tensile, Izod impact, and morphological properties of epoxy using the Response Surface Methodology (RSM). RSM relied on Box–Behnken Design (BBD) was used to design the mechanical tests. The concurrent effects of two parameters including hydroxyapatite content and silica aerogels content on the mechanical properties have been evaluated. Finally, by using the equations obtained from regression for each of the responses, their optimal states were obtained using both the desirability approach and the Multi-Objective Particle Swarm Optimization (MOPSO) method. The results from tensile, and Izod impact tests indicated the combination of hydroxyapatite and silica aerogel nanoparticles led to an improvement in the tensile properties and energy absorption of epoxy matrix. The findings related to density test demonstrated that with addition of silica aerogel to the hydroxyapatite/epoxy nanocomposites, density of these samples was decreased. The maximum tensile strength of 86.9 MPa was obtained with hydroxyapatite content of 2.38 wt% and silica aerogels content of 4 wt%. Also, the maximum impact strength of 18.14 kJ/m2 was obtained with hydroxyapatite content of 1.11 wt% and silica aerogels content of 3.51 wt%. The field emission scanning electron microscope images showed the homogeneous distribution of combined hydroxyapatite and silica aerogel nanoparticles in epoxy matrix, except in 5 wt% of hydroxyapatite nanoparticles.

Comparative Evaluation of Platelet Rich Fibrin Membrane vs. Collagen Membrane in Combination with Hydroxy-Apatite (HA) for the Treatment of Mandibular Molar Furcation Defects – A Randomized Clinical Control Trial

Aim: A clinical trial to compare the relative efficacy of hydroxyapatite in combination with either PRF (Platelet rich fibrin) or collagen membrane in treatment of grade II furcation defects of mandibular molars. Methodology: The sample consisted of 35 Grade II mandibular molar furcation defects planed for open flap debridement (OFD) (Group 1, n=12), Platelet-rich fibrin membrane + Hydroxyapatite (HA) with OFD (Group 2, n=12), and Collagen membrane (CM) + HA with OFD (Group 3, n=11). These were recorded at baseline and 9 months postoperatively for plaque index (PI), gingival index (GI), probing depth (PPD), relative vertical and relative horizontal clinical attachment levels (RVCAL and RHCAL), and intrabony defect depth (IBD). Results: PI and GI scores decreased significantly in all three groups at 9 months postoperatively as compared to baseline scores. After 9 months of follow up visits mean PD reduction was greater in Group 2 (3.66 ± 0.98 mm) and Group 3 (3.45 ± 1.5 mm) than Group 1 (2.08 ± 0.90 mm), and mean RVCAL and RHCAL gain were greater in Group 2 (3.25 ± 0.75 mm and 3.92 ± 0.29 mm, respectively) and Group 3 (3.09 ± 0.70 mm and 3.89 ± 0.54 mm) compared with Group 1 (1.33 ± 0.77 mm and 2.25 ± 0.62 mm). A significant reduction in IBD depth was found in Groups 2 (2.16*0.38 mm) and 3 (1.58*0.35 mm) than in Group 1 (0.70*0.15 mm). The differences in PI, GI, PPD, RVCAL, and RHCAL between Groups 2 and 3 at baseline and 9 months were not statistically significant. There was a statistically significant difference in the depth reduction of IBD between Groups 2 and 3 at nine months. Conclusion: Within the scope of this study, it can be stated that the use of HA in conjunction with PRF or CM in the treatment of grade II mandibular furcation abnormalities resulted in a considerable reduction in GI PI, PPD, RVCAL, RHCAL, and IBD depth on follow up visit at 9 months after surgery. However, the combination of HA with PRF membrane exhibited significant improvement in radiographic parameters in comparison to the combination of HA with Collagen membrane.

Synthesis of Hydroxyapatite/Bioglass Composite Nanopowder Using Design of Experiments.

Composite scaffolds of hydroxyapatite (HAp) nanoparticles and bioactive glass (BG) were applied as an appropriate selection for bone tissue engineering. To this end, HAp/BG composite was synthesized by a hydrothermal method using Design of Experiments (DOE) with a combined mixture–process factor design for the first time. The input variables were hydrothermal temperature at three levels (i.e., 100, 140, 180 °C) as a process factor and two mixture components in three ratios (i.e., HAp 90, 70, 50; BG 50, 30, 10). The degree of crystallinity and crystal size in the composite were the output variables. XRD showed that only a small fraction of BG was crystallized and that a wollastonite phase was produced. The XRD results also revealed that incorporation of Si into the HAp structure inhibited HAp crystal growth and restricted its crystallization. The FTIR results also showed that the intensity of the hydroxyl peak decreased with the addition of silicon into the HAp structure. DOE results showed that the weight ratio of the components strongly influenced the crystal size and crystallinity. SEM and FTIR results identified the greatest bioactivity and apatite layer formation in the Si-HAp sample with an HAp70/BG30 ratio after 14 days immersion in simulated body fluid (SBF) solution, as compared to other ratios and HAp alone. Therefore, the combination of HAp and BG was able to yield a HAp/BG composite with significant bioactivity.

Three-dimensionally printed biphasic calcium phosphate blocks with different pore diameters for regeneration in rabbit calvarial defects

BackgroundBiphasic calcium phosphate (BCP) is the most frequently used synthetic bone substitutes, which comprises a combination of hydroxyapatite (HA) and beta-tricalcium phosphate (b-TCP). Thanks to the recent advances in digital dentistry and three-dimensional (3D) printing technology, synthetic block bone substitutes can be customized to fit individual defect morphologies. The diameter of the pores can influence the rate of bone formation and material resorption. The aim of this study was to compare three-dimensionally printed biphasic calcium phosphate (BCP) block bone substitutes with different pore diameters (0.8-, 1.0-, and 1.2- mm) for use in the regeneration of rabbit calvarial defects.MethodsFour circular defects were formed on the calvaria of ten rabbits. Each defect was randomly allocated to one of the following study groups: (i) control group, (ii) 0.8-mm group, (iii) 1.0-mm group, and (iv) 1.2-mm group. All specimens were postoperatively harvested at 2 and 8 weeks, and radiographic and histomorphometric analyses were performed on the samples.ResultsHistologically, the BCP blocks remained unresorbed up to 8 weeks, and new bone formation occurred within the porous structures of the blocks. After the short healing period of 2 weeks, histomorphometric analysis indicated that new bone formation was significantly greater in the BCP groups compared with the control (p < 0.05). However, there were no significant differences between the groups with different pore diameters (p > 0.05). At 8 weeks, only the 1.0-mm group (3.42 ± 0.48 mm2, mean ± standard deviation) presented a significantly larger area of new bone compared with the control (2.26 ± 0.59 mm2) (p < 0.05). Among the BCP groups, the 1.0- and 1.2-mm groups exhibited significantly larger areas of new bone compared with the 0.8-mm group (3.42 ± 0.48 and 3.04 ± 0.66 vs 1.60 ± 0.70 mm2, respectively).ConclusionsWithin the limitations of this study, the BCP block bone substitutes can be applied to bone defects for successful bone regeneration. Future studies should investigate more-challenging defect configurations prior to considering clinical applications.

The Impact of Nano-Crystal Hydroxyapatites on the Regeneration of Bone Defects

Abstract Calcium hydroxyapatite is a widely used material for replacing bone defects. However, the effectiveness of nano-crystalline calcium hydroxyapatite produced from eggshells in the replacement of bone defects has not been investigated yet. The study aimed to evaluate the effectiveness of using nano-crystalline calcium hydroxyapatite made from eggshell for the healing of bone defect of the femur in rats. Forty-eight (n=48) rats underwent a surgical procedure to simulate femoral defect. The animals were sub-divided into 4 groups (each with n=12) depending on the methods of bone defect replacement: I control group (CG) (without bone defect replacement); II intervention group (the bone defect was replaced by PRP (PRP); III intervention group (the bone defect was replaced by nano-crystalline hydroxyapatite obtained from eggshell) (HA) and IV interventional group (the bone defect was replaced by a combination of hydroxyapatite and PRP) (HA+PRP). The degree of effectiveness of studied methods was assessed using radiological (on the 14th day), histological (on the 61st day), and biomechanical analysis (on the 61st day). According to radiographic data, the CG group had the lowest level of bone regeneration after 14 days (4.2 ±1.7%). In the HA + PRP group, the level of bone regeneration was 22.1±7.1 %, which was higher in comparison with the rates of consolidation of bone defects in the HA group (20.7± 9.3) (p = 0.023). According to the histo-morphometry data, the rates of bone tissue regeneration in the PRP group (19.8 ±4.2%) were higher in comparison with the CG group (12.7 ± 7.3%), (p&gt;0.05). In the HA+PRP group, bone regeneration rates (48.9±9.4 %) were significantly higher (p=0.001) than in the HA group (35.1±9.8%). According to the results of biomechanical assessment under the maximum stress (121.0722), the maximum bending deformation of the contralateral bone without defect was 0.028746, which was higher than the indicators of the HA+PRP group, where at the maximum stress (90.67979) the bending deformation was 0.024953 (p&gt;0.05). Compared to CG, PRP, and HA, biomechanical bone strength was significantly higher in the HA + PRP group (p≤0.01). At the maximum stress (51.81391), the maximum bending strain in the CG group was 0.03869, which was lower than in the PRP group, where the maximum stress and bending strain were 59.45824 and 0.055171, respectively (p&gt;0.05). However, the bone strength of the HA group was statistically significantly higher compared to the CG and PRP groups (p&lt;0.01). The results demonstrated the effectiveness of the use of nanocrystalline calcium hydroxyapatite obtained from eggshell in the healing of a bone defect. The best results were observed in the group of the combined use of nano-crystalline calcium hydroxyapatite and PRP.

Polyphenols from Grape Pomace: Functionalization of Chitosan-Coated Hydroxyapatite for Modulated Swelling and Release of Polyphenols.

Chitosan is known for its specific antibacterial mechanism and biodegradability, while polyphenols are known for their antioxidant and anti-inflammatory properties: coupling these properties on a surface for bone contact, such as hydroxyapatite, is of great interest. The system developed here allows the combination of hydroxyapatite, chitosan, and polyphenol properties in the same multifunctional biomaterial in order to modulate the host response after implantation. Crosslinked chitosan is used in this research to create a stable coating on hydroxyapatite, and then it is functionalized for a smart release of the polyphenols. The release is higher in inflammatory conditions and lower in physiological conditions. The properties of the coated and functionalized samples are characterized on the as-prepared samples and after the samples are immersed (for 24 h) in solutions, which simulate the inflammatory and physiological conditions. Characterization is performed in order to confirm the presence of polyphenols grafted within the chitosan coating, the stability of grafting as a function of pH, the morphology of the coating and distribution of polyphenols on the surface, and the redox reactivity and radical scavenging activity of the functionalized coating. All the results are in line with previous results, which show a successful coating with chitosan and functionalization with polyphenols. Moreover, the polyphenols have a different release kinetics that is faster in a simulated inflammatory environment compared to that in the physiological environment. Even after the release tests, a fraction of polyphenols are still bound on the surface, maintaining the antioxidant and radical scavenging activity for a longer time. An electrostatic bond occurs between the negative-charged polar groups of polyphenols (carboxyls and/or phenols) and the positive amide groups of the chitosan coating, and the substitution of the crosslinker by the polyphenols occurs during the functionalization process.

Green biosynthesis of hydroxyapatite-silver nanoparticle nanocomposite using aqueous Indian curry leaf (Murraya koengii) extract and its biological properties

Implant-associated disease triggered by bacterial colonization would hinder the osseointegration of bone implant at the implantation site and further jeopardize the outcome of bone regeneration. Thus, the use of implant material with intrinsic antibacterial property can be promising to address the shortcoming associated with bacterial infection. In the present study, we aimed to develop an antibacterial implant material based on a combination of hydroxyapatite (HAp) and silver nanoparticle (AgNPs) via a green biosynthetic route. In this work, aqueous extract of Indian curry leaf (Murraya koengii) was employed as a bio-reducing and stabilizing agent for the in-situ fabrication of HAp-AgNPs nanocomposite. According to XRD, EDX, TEM, XPS and FTIR results, AgNPs had been successfully synthesized and deposited to the surface of HAp, where the amount and size of decorated AgNPs were found to rely on the concentration of AgNO3 precursor used. Antibacterial examinations in vitro showed that HAp-AgNPs nanocomposites displayed an effective antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria when AgNO3 precursor concentration used >1 mM. Furthermore, HAp-AgNPs-5 and HAp-AgNPs-7 nanocomposites also exhibit improved bioactivity in comparison with pristine HAp, being able of developing more bone-like apatite after 4 weeks of soaking in Hank's balanced salt solution. These findings significantly demonstrate the feasibility of HAp-AgNPs nanocomposite to be applied as antibacterial implant material for orthopedic application.

Ellagic acid and hydroxyapatite promote angiogenesis marker in bone defect

The combination of hydroxyapatite and the herbal extract ellagic acid is expected to accelerate the bone healing process (osteogenesis) due to the extract's anti-inflammatory and antioxidant properties. The osteogenesis process is closely associated with angiogenesis markers, such as fibroblast growth factor 2 (FGF-2), vascular endothelial growth factor (VEGF) and alkali phosphatase (ALP). The objective of this study is to analyse the combination of ellagic acid and hydroxyapatite to promote FGF-2, VEGF and ALP expression as angiogenesis markers in a bone defect model. The research sample comprised 30 male Wistar rats with a defect introduced on the left femur; these were divided into three groups for treatment with ellagic acid and hydroxyapatite, hydroxyapatite and polyethylene glycol (PEG) (control). On days 7 and 14 days after treatment, the Wistar rats were euthanised, and the femoral bone tissue was removed for the immunohistochemical analysis of FGF-2, VEGF and ALP expression. FGF-2 and ALP expression increased in the group treated with ellagic acid and hydroxyapatite on days 7 and 14 post treatment (p < 0.05), and there was an increase in VEGF expression on day 7 post treatment (p < 0.05). The combination of ellagic acid and hydroxyapatite promoted FGF-2, VEGF and ALP expression as angiogenesis markers in the bone defect model.

Ferrihydrite reduces the bioavailability of copper and cadmium and phosphorus release risk in hydroxyapatite amended soil

Hydroxyapatite (HAP) can effectively decrease bioavailability of trace metals in soils, but the phosphorus (P) release risk was not fully known. In this study, the impacts of ferrihydrite (FH) on passivation of copper (Cu) and cadmium (Cd) and P release risk in soil amended by HAP were investigated under flooding conditions. Results showed that the combinations of HAP and FH increased soil pore water pH by 0.74–2.24 units and reduced phosphate by 71.1–99.5% than single HAP. Soil pore water Cu2+ and Cd2+ in HAP plus 5% FH treated soils were decreased by 96.8–98.6% and 86.6–98.6% than those of single HAP. The combinations of HAP and FH significantly decreased CaCl2 extractable Cu and Cd by 55.9–99% and 13–72.2%, respectively. Moreover, the combinations of HAP and FH significantly decreased exchangeable Cu 47.1–91.5%, but only FH5 decreased exchangeable Cd by 69.4% than the single HAP. Amorphous iron oxide in FH treated soils was 4.06–20 times higher than control, but some of them were transformed into crystalline iron oxide after 42-d flooding incubation. The FH significantly decreased soil labile P by 42.8–78.8% in the presence of HAP and increased stable P by 23.1–33.5% than the single HAP. This study suggested that the addition of FH can not only promote the passivation of HAP on Cu and Cd in the soil, but also reduce the P release risk. Overall, this study highlighted the potential value of the combination of HAP and FH in the passivation of Cu and Cd contaminated soils.

Combined application of ferrihydrite and hydroxyapatite to immobilize soil copper, cadmium, and phosphate under flooding-drainage alternations

Hydroxyapatite (HAP) can effectively immobilize soil heavy metals, but excess phosphate would be released to aquatic ecosystem, resulting in eutrophication. This study investigated the effects of ferrihydrite (FH) on the HAP immobilization of copper (Cu) and cadmium (Cd) and their reduction of phosphorus release under flooding-drainage alternation conditions. Results showed that the incorporation of HAP and FH significantly increased soil solution pH and decreased Cu2+ and Cd2+ concentrations. Applications of FH, HAP, and FH-HAP (FH and HAP combination) can all enhance soil pH and reduce CaCl2-extractable and exchangeable Cu and Cd, but HAP addition increased soluble phosphate by 6.60–7.77 times compared to control. However, FH-HAP application can significantly reduce phosphate release by 92.7–99.7% compared to HAP application. FH-HAP was the most effective to reduce exchangeable Cu and Cd by 49.8–93.4% and 50.9–88.8% and decreased labile and moderately labile phosphorus by 34.0–74.4% and 13.5–18.6%, respectively, while increased stable phosphorus by 22–45.1% than single HAP. All FH treatments significantly increased amorphous iron oxides by the factors of 4.66–20.8, but only 3% and 5% of FH applications slightly enhanced crystal iron oxides by the factors of 0.81–1.27. The major implication is that the combination of FH and HAP can not only immobilize of Cu and Cd, but also reduce the risk of phosphate release by HAP addition.

Histomorphological characteristics of bone replacement in rabbits with hydroxyapatite ceramics and Platelet-Rich Fibrin

The results of a histomorphological study of bone regenerates in rabbits after osteosubstitution with platelet-rich fibrin and its combination with hydroxyapatite granules with β-tricalcium phosphate in spongy and compact bone tissue at different periods of reparative osteogenesis are presented. Three groups of rabbits were formed. In the control group, the defects were left to heal under the blood clot. Bone lesions in the first experimental group were filled with platelet-rich fibrin, in the second – with a combination of platelet-rich fibrin and hydroxyapatite with β-tricalcium phosphate. All animals were kept in the same conditions of feeding and housing, had unlimited access to water. During the study, the rabbits were monitored clinically. The animals were taken out of the experiment on the 14th, 21st and 42nd days, samples of bone tissue were taken, they were fixed, decalcified, dehydrated in alcohols of increasing concentration and embedded in paraffin. In the presented study, it is most likely that the newly formed bone tissue is formed precisely due to osteoinduction in the experimental groups. When using granules of hydroxyapatite and β-tricalcium phosphate with platelet-rich fibrin, bone regenerate is between the composite granules and is not associated with contact with the maternal bone. Its cells appear in different places of the defect. In the spongy bone tissue on the 21st day, regeneration proceeded more fully and faster in the second experimental group, as evidenced by the significant density of cells of the osteoblastic row, the thickness of the bone trabeculae and their volume, filling the site of the defect. On the 42nd day, in the second experimental group, when using a combination of autobiomaterial and hydroxyapatite granules with β-tricalcium phosphate, the regenerate contained a significantly larger number of osteogenic cells in the thickness of the trabeculae, which indicated a more intensive course of reparative osteogenesis in comparison with the first experimental and control groups. In the compact bone on day 21, regeneration was more complete and faster in the second experimental group. On the 42nd day, according to the degree of maturity of the bone regenerate, calcium-phosphate ceramics in combination with platelet-rich fibrin optimizes reparative osteogenesis most clearly. According to the degree of intensity of the osteoregeneration process, the groups can be placed in the following sequence: control ˂PRF˂PRF+HA/β-TCP–700. According to histomorphological characteristics, the combination of hydroxyapatite with β-tricalcium phosphate and platelet-rich fibrin gives greater osteoinduction to the composite material, which is confirmed by the high cell density, namely of osteoblasts and osteocytes. The use of PRF in combination with other materials may become promising for the correction of reparative osteogenesis in conditions of limited or reduced regenerative potential of bone tissue.

Formation and corrosion behaviors of calcium phosphate coatings on plasma electrolytic oxidized Mg under changing chemical environment

Abstract In order to form calcium phosphate (CaPh) coatings in the changing chemical environment, a drop wise addition procedure is performed during electro-deposition process. Two kind of electrolytes of KH2PO4 and K2HPO4, are added into Ca(NO3)2 solution respectively where plasma electrolytic oxidized (PEO) magnesium is placed. Results indicate that the phase composition and morphologies of the CaPh coatings are modified due to the changing chemical composition of electrolyte. Only calcium hydrogen phosphate dihydrate (DCPD) is formed on the PEO surface in the presence of KH2PO4 electrolyte, while a combination of hydroxyapatite (HA) and DCPD is obtained on the PEO surface in the electrolyte containing K2HPO4. The latter coating exhibits superior corrosion resistance in simulated body fluid, which implies the feasibility of the proposed strategy in fabricating biodegradable coating for Mg alloys.

Advances in Osteoporotic Bone Tissue Engineering.

The increase in osteoporotic fracture worldwide is urging bone tissue engineering research to find new, improved solutions both for the biomaterials used in designing bone scaffolds and the anti-osteoporotic agents capable of promoting bone regeneration. This review aims to report on the latest advances in biomaterials by discussing the types of biomaterials and their properties, with a special emphasis on polymer-ceramic composites. The use of hydroxyapatite in combination with natural/synthetic polymers can take advantage of each of their components properties and has a great potential in bone tissue engineering, in general. A comparison between the benefits and potential limitations of different scaffold fabrication methods lead to a raised awareness of the challenges research face in dealing with osteoporotic fracture. Advances in 3D printing techniques are providing the ways to manufacture improved, complex, and specialized 3D scaffolds, capable of delivering therapeutic factors directly at the osteoporotic skeletal defect site with predefined rate which is essential in order to optimize the osteointegration/healing rate. Among these factors, strontium has the potential to increase osseointegration, osteogenesis, and healing rate. Strontium ranelate as well as other biological active agents are known to be effective in treating osteoporosis due to both anti-resorptive and anabolic properties but has adverse effects that can be reduced/avoided by local release from biomaterials. In this manner, incorporation of these agents in polymer-ceramic composites bone scaffolds can have significant clinical applications for the recovery of fractured osteoporotic bones limiting or removing the risks associated with systemic administration.

Current Challenges and Innovative Developments in Hydroxyapatite-Based Coatings on Metallic Materials for Bone Implantation: A Review

Biomaterials are in use for the replacement and reconstruction of several tissues and organs as treatment and enhancement. Metallic, organic, and composites are some of the common materials currently in practice. Metallic materials contribute a big share of their mechanical strength and resistance to corrosion properties, while organic polymeric materials stand high due to their biocompatibility, biodegradability, and natural availability. To enhance the biocompatibility of these metals and alloys, coatings are frequently applied. Organic polymeric materials and ceramics are extensively utilized for this purpose due to their outstanding characteristics of biocompatibility and biodegradability. Hydroxyapatite (HAp) is the material from the ceramic class which is an ultimate candidate for coating on these metals for biomedical applications. HAp possesses similar chemical and structural characteristics to normal human bone. Due to the bioactivity and biocompatibility of HAp, it is used for bone implants for regenerating bone tissues. This review covers an extensive study of the development of HAp coatings specifically for the orthopaedic applications that include different coating techniques and the process parameters of these coating techniques. Additionally, the future direction and challenges have been also discussed briefly in this review, including the coating of HAp in combination with other calcium magnesium phosphates that occur naturally in human bone.