Proportion Of Hydroxyapatite Research Articles

On biodegradability of 3D printed polyvinylidene fluoride composites

Polyvinylidene fluoride (PVDF) is one of the established biocompatible thermoplastics for scaffolding applications. But due to its partial biodegradability, its use as a bio-absorbable implant is limited. Some studies have outlined that reinforcement of hydroxyapatite (HAp), and chitosan (CS) helps in improving the biodegradability of the PVDF composite matrix. But hitherto little has been reported on the biodegradability comparison for virgin PVDF, and PVDF composite matrix (with different proportions of HAp and CS as reinforcement). This study reports the biodegradability of virgin PVDF, 90% PVDF–10% HAp, 90% PVDF–8% HAp–2% CS, and 90% PVDF–9% HAp–1% CS based on a corrosion testing (open circuit potential, polarization resistance, corrosion current, corrosion rate [CR], surface roughness (Ra), and porosity %) in simulated bodily fluid (SBF) for possible bio-absorbable implant applications. The study suggests that the biodegradability of 90% PVDF–9% HAp–1% CS is maximum having CR 26.389mm2/year, mainly due to the presence of more hydroxyl group (-OH). The corresponding porosity % and Ra (after corrosion testing) were noticed as 12.45% and 19.12 µm. The results are supported by scanning electron microscopy (SEM) images.

Development of chemically synthesized hydroxyapatite composite with reduced graphene oxide for enhanced mechanical properties

A successful attempt has been made to improve the mechanical properties of Hydroxyapatite (HAp) and reduced graphene oxide (rGO) composite nanoparticles (NPs). Various proportions of HAp and rGO were synthesized to improve the mechanical properties. HAp NPs were prepared using the wet precipitation method and further calcined to form crystalline particles. The physicochemical characterization of the HAp NPs revealed that the crystalline size and percentage of crystallinity were calculated to be 42.49 ± 1.2 nm and 44% post calcination. Furthermore, the rGO-HA composites were prepared using ball milling and obtained in the shape of pellets with different ratios of rGO (10, 20, 30, 40, 50% wt.). The mechanical properties have been evaluated through a Universal testing machine. Compared to calcined HAp (cHAp), the strength of variants significantly enhanced with the increased concentration of rGO. The compressive strength of HA-rGO with the ratio of the concentration of 60:40% by weight is a maximum of about 10.39 ± 0.43 MPa. However, the porosity has also been bolstered by increasing the concentration of rGO, which has been evaluated through the liquid displacement method. The mean surface roughness of the composites has also been evaluated from the images through Image J (an image analysis program).

In vitro and in vivo study on the osseointegration of magnesium and strontium ion with two different proportions of mineralized collagen and its mechanism.

To explore the optimal combination of Mg2+, Sr2+ and mineralized collagen (nHAC) with two different proportions of hydroxyapatite (HA) and collagen (COL) on differentiation of MC3T3-E1 and the underlying mechanism, as well as achieve bone osseointegration. MC3T3-E1 cells were cultured in a complete medium with Mg2+ at the concentration of 0, 4, 8, 12, 16, 20 mmol/L, Sr2+ at the concentration of 0, 3, 6, 12 mmol/L, and the impregnation solution of 3:7 and 5:5nHAC. The differentiation of MC3T3-E1 was measured by expression of osteogenic genes and proteins including Runx-2, BMP-2 and OCN and determined the activation of PI3K/AKT/GSK3β/β-catenin signaling pathway in 12 mmol/LMg2++3 mmol/LSr2++3:7nHAC group. Osteoporosis was induced in 18 female rats by means of ovariectomy, the implants were immersed in 60 mmol/LMg2++15 mmol/LSr2++3:7nHAC impregnation solution and implanted into the mesial alveolar fossa for immediate implantation. The osseointegration of the implants was observed by Confocal laser scanning microscopy (CLSM) and histology at 4 and 8 weeks. The groups cultured with 12 mmol/LMg2+, 3 mmol/LSr2+ and 3:7nHAC impregnation solution showed the osteogenic genes and proteins were significantly higher respectively (P < 0.05), as well as p-Akt, p-GSK3β and β-catenin proteins (P < 0.05). CLSM and histology showed that the implant surface was surrounded by thick lamellar bone plate, and the trabecular bone were dense and continuous in the impregnation solution. These results found that magnesium and strontium ion-loaded mineralized collagen play an critical role in up-regulating the cells activity through PI3K/AKT/GSK3β/β-catenin signaling pathway and could be promote the formation of osseointegration.

Synthesis and physicochemical inverstigation of hydroxyapatite and wollastonite composite granules

Creation of osteoinductive materials based on biocompatible synthetic salts, with a sufficiently high strength and porosity, with the shape which allow filling bone defects with various shapes and sizes is an actual task of modern biomaterial science. In this work, a series of granular materials were obtained from synthetic powders with various proportions of hydroxyapatite and wollastonite using a suspension technology based on the principle of immiscible liquids. Ceramic particles have a spherical shape, microhardness at least 17 HV and open porosity about 50 %. These materials can be used for reparation of bone defects of various locations, shapes and sizes in surgical dentistry, traumatology and orthopaedics.

Influence of bone formation by composite scaffolds with different proportions of hydroxyapatite and collagen

Composite scaffolds with different proportions of hydroxyapatite (HA) and collagen (COL) produced different bone induction results. ObjectiveTo examine the composite scaffolds with optimal proportion of HA and COL to achieve earlier bone induction and maximum bone formation. MethodsComposite scaffolds with the HA/COL weight ratio of 7:3, 3:7, 5:5 and 9:1 were prepared, as HA powder was added to collagen solution at 130℃ for 48 h. Then, the composites with different proportions of HA/COL were implanted into the extraction socket of right upper central incisor of C57BL/6 J mice. The bone formation of the extraction socket was observed by Hematoxylin-eosin (HE) and Masson-trichrome (Masson) staining at 1 and 2 weeks after operation. Five weeks later, the bone formation of extraction socket was observed by micro computed tomography (micro-CT). After MC3T3-E1 cells were co-cultured with materials of different proportions for 3 days, the number of cells attached on the surface of the materials and entering the materials were counted, and the expression of osteogenic related genes (Runx2, Ocn. Osx and Alp) was detected by reverse transcription polymerase chain reaction (RT-PCR). The composite scaffolds with different proportion of HA/COL with and without mouse bone marrow mesenchymal stem cells (BMMSCs) were implanted into the back of adult mice and cultured subcutaneously for 30 days, and observed histologically by HE and Masson staining. ResultsAfter one week implantation with the composite HA/COL scaffolds with the weight ratio of 7:3, 3:7, 5:5 and 9:1, there was no new bone formation in the extraction socket in mouse. However, two weeks later, new bone was firstly observed in the tooth socket with the composite HA/COL scaffolds of 7:3. 5 weeks later, micro-CT scanning showed that the total amount of newly formed bone, trabecular width and bone mineral density of the HA/COL scaffolds of 7:3 were higher than the other HA/COL scaffolds (P < 0.05). After MC3T3-E1 cells were co-cultured with different composite HA/COL scaffolds for 3 days. The number of cells on the surface and inside of the HA/COL scaffolds of 7:3 was more than the other materials, and the difference was statistically significant (P < 0.05). The expression levels of Ocn and Osx of MC3T3-E1 cells were also the highest in the HA/COL scaffolds of 7:3 (P < 0.01). Bone formation was observed in the composite HA/COL scaffold of 7:3 with BMMSCs subcutaneously in mouse for 30 days, while only osteoid formation was observed in the same scaffold without BMMSCs. but bone formation was not detected in the other proportions of the HA/COL scaffolds. SignificanceCompared with other proportions of HA/COL, the composite HA/COL scaffolds of 7:3 has stronger ability to promote bone formation, recruit osteoblasts to attach and enter into the scaffolds, and promote the osteogenesis of BMMSCs.

Phase contents of bone mineral of the hipbone in streptozotocin-induced diabetic pre-senile rats after surgical perforation of the tibia

Aim to investigate changes in phase contents of bone mineral of the hipbone in pre-senile streptozotocin-induced diabetic rats after surgical perforation of the tibia.&#x0D; Material and methods. Diabetes was induced in 35 animals with an initial weight of 290-310 g at the age of 17-18 months by a single intraperitoneal injection of streptozotocin in dosage of 55 mg per kg of body weight. Surgical perforation of the tibia was modeled as 2.0 mm opening in the proximal metadiaphysis (35 animals). Another group comprised 35 animals with both perforation and diabetes. 35 intact animals comprised the control group. The content of whitlockite, calcite and hydroxylapatite in bone mineral of the hipbone was determined.&#x0D; Results. Surgical perforation of the tibia resulted in instability of phase contents of bone mineral of the hipbone by the 15th day of observation; peak of deviations was registered on the 90th day of observation, when the proportions of whitlockite and calcite increased by 7.20% and 8.91%, while the proportions of hydroxyapatite decreased by 3.53% in comparison with the controls. In diabetic animals, the destabilization of the phase composition of bone mineral was observed by the 7th day of the experiment. By the 90th day, the proportion of whitlockite and calcite exceeded those of the controls by 9.00% and 9.01% while the proportion of hydroxylapatite decreased by 4.00%. Surgical perforation of the tibia in diabetic pre-senile animals resulted in more marked increase of hipbone mineral amorphousness from the 7th day of observation; by the 90th day the proportion of whitlockite exceeded this in rats with perforation by 7.95%, while the proportion of hydroxylapatite decreased by 2.35%.&#x0D; Conclusion. Surgical perforation of the tibia in diabetic pre-senile rats results in increasing of the amorphousness of bone mineral of the hipbone, which grows starting from the 7th day after operation.

Phosphorus transformations in plant-based and bio-waste materials induced by pyrolysis

Strategies are needed to increase the sustainability of phosphorus (P) fertiliser management in agriculture. This paper reports on the potential of pyrolysis treatment to recycle P from renewable materials previously regarded as wastes. The study used K-edge X-ray absorption near-edge structure (XANES) spectroscopy to examine chemical forms of P in the waste feedstock materials and corresponding biochars (pyrolysis at 480–500 °C) of four ligno-cellulosic, plant-based residues and five relatively P-rich livestock and water-treatment by-products, to acquire information on changes in potential P fertiliser value. Pyrolysis enriched P in the biochars by factors of 1.3–4.3, thus offering wide-ranging P fertiliser potential. XANES spectroscopy revealed hydroxyapatite (HAP) as one of the dominant chemical P compounds in the feedstocks, ranging from 14% (rice husks) to 98% (animal bone) of total P. For most materials, pyrolysis increased the proportion of HAP, and pyrophosphates were generated in several cases. These alterations possibly lead to diversity in the P solubility characteristics of the biochars if used as soil amendments; this is an important property of environmentally sound P fertilisers.

Influence of bone morphogenetic protein and proportion of hydroxyapatite on new bone formation in biphasic calcium phosphate graft: Two pilot studies in animal bony defect model

PurposeThe purpose of these two pilot studies using animal bony defect models was to evaluate the influence of bone morphogenetic protein (BMP) and proportion of hydroxyapatite (HA)/beta-tricalcium phosphate (β-TCP) in biphasic calcium phosphate (BCP) graft on new bone formation. MethodsIn this study, four kinds of synthetic osteoconductive bone materials known for bone growth scaffold, OSTEON™II(HA:β-TCP 30:70), OSTEON™III (HA:β-TCP 20:80), OSTEON™II Collagen, and OSTEON™III Collagen, were prepared as BCP graft materials. In pilot study 1, three BCP materials (OSTEON™II, OSTEON™III, and OSTEON™II Collagen) were grafted in rabbit calvarial defects after impregnating in rhBMP-2. OSTEON™II without the rhBMP-2 impregnation was included in the study as the control. The amount of new bone was examined and measured histologically at 2, 4, and 8 weeks. In pilot study 2, four BCP materials (OSTEON™II, OSTEON™III, OSTEON™II Collagen, and OSTEON™III Collagen) were grafted in beagle dog mandibular defects after soaking in the rhBMP-2. The amount of total bone and new bone were measured three-dimensionally using microCT and healing process was examined histologically at 2, 4, and 8 weeks. ResultsIn pilot study 1, rhBMP-2 impregnated groups showed more new bone formation than the rhBMP-2 free group. In pilot study 2, increased new bone formation was observed in time-dependent manner after graft of BCP and BCP-collagen (OSTEON™II, OSTEON™III, OSTEON™II Collagen, and OSTEON™III Collagen) impregnated with rhBMP-2. Also, BCP with a higher proportion of HA (30% HA) showed more favorable result in new bone formation and space maintenance, especially at the 8 weeks. ConclusionFrom the results of the pilot studies, rhBMP-2 played positive roles in new bone formation and BCP could become a scaffold candidate for rhBMP-2 impregnation to induce new bone formation. Moreover, BCP with a higher proportion of HA (30% HA) could be considered more appropriate for rhBMP-2 carrier.

Application of hydroxyapatite and cement kiln dust mixture in adsorption of lead ions from aqueous solution

This study describes the preparation of new adsorbent by hydroxyapatite and cement kiln dust as raw materials. In the first part of investigation the adsorption capacity of hydroxyapatite and dust powders were separately studied by measuring the lead concentration in the aqueous solution. Thereafter the mixed powders containing different proportions of hydroxyapatite and dust were shaped by a laboratory single screw extruder in the cylindrical form and the adsorption capacity, porosity of samples and the compressive strength were measured according to standard methods. Regardless the composition used in the purification, the solution did not remain transparent when the adsorbent was prepared with dust only and the distinguishable fine particles were suspended in the lead solution. From visual observations, the solution was clear when the same amounts of hydroxyapatite and dust were used in the preparation of porous media. In order to evaluate the mechanical reliability of extruded samples, the compressive strength data of adsorbents were statistically analyzed by Weibull theory. The results clearly indicated that Weibull modulus of porous media is not affected by hydroxyapatite but the strength increases two times compared to the bed which is manufactured by using dust only. The finding results were confirmed by the observation of the fracture surface of adsorbents with a scanning electron microscopy.

A simple sol-gel technique for synthesis of nanostructured hydroxyapatite, tricalcium phosphate and biphasic powders

Hydroxyapatite (HAP), β-tricalcium phosphate (β-TCP) and biphasic calcium phosphate (BCP) nanocrystalline powders were prepared by a simple sol-gel approach. Because of the unique characteristic of the phosphorous source ((CH3O)3P) and the proper uses of calcic and phosphorous sources with Ca/P molar ratio between 1.4 and 1.67, three different kinds of nanostructured calcium phosphate powders were achieved by changing the ratio of calcic and phosphorous sources. For HAP and β-TCP, pure phases were prepared. For BCP, the proportion of HAP and β-TCP could be changed by thermal treatment.

A comparison of 2 kinds of hydroxyapatite/collagen composites as tissue engineering scaffold

Objective:To prepare 2 composites using different proportions of hydroxyapatite and collagen and to assess their structural and biological properties, so as to pave a way for preparing tissue engineering chest wall scaffold.Methods: Two kinds of hydroxyapatite/collagen composites were prepared according to the weight ratios of 11 and 12; collagen sponge served as control. Then the structures of the 2 composites and the collagen sponge were observed under SEM. In vivo study was conducted to assess the biocompatibility and biodegradation of the composites by gross inspection and histological examination. Results: The collagen sponge had a 3-D network structure with fluey collagen fibers and poor mechanical strength, and its structure was damaged within 2 weeks after implantation and was completely absorbed 4 weeks later. The hydroxyapatite and collagen were well mixed in the composite with a hydroxyapatite to collagen ratio of 12; the composite had homogeneous 3-D porous structure (size of the pore being 100-400 m) and showed good biocompatibility: maintained its porous structure 4 weeks after implantation and was absorbed within 8 weeks. In composite with hydroxyapatite to collagen ratio of 11, the hydroxyapatite particles were separated from collagen fiber and conglomerated into masses, and the composite resulted in severe tissue reaction after implantation.Conclusion: When mixed with a reasonable proportion of hydroxyapatite, the collagen sponge has improved structure, biodegradable performance, and biocompatibility; the composite may be a novel scaffold for tissue engineering chest wall reconstruction.

Ring-opening polymerization of lactones in the presence of hydroxyapatite

The ring-opening polymerization of ε-caprolactone, δ-valerolactone (VL) and d, l-lactide, respectively, in the presence of different proportions of hydroxyapatite (HA) was catalyzed by stannous (II)octoate (SnOct 2) at 130°C and resulted in composites. The lactones were almost completely converted to the polymers within a reaction time of 70 up to 240 min. The number-average molecular weights M n as determined by size exclusion chromatography decreased with increasing content of HA. The initiating efficiency of HA as calculated from the difference of the polymerization degrees P n obtained with and without HA turned out to be relatively low with ca. 11 to 0.5% for 1 to 80 wt% HA, respectively. For the polymerization of VL, the initiating efficiency of HA was on the average threefold higher. The quantitative proof of non-extractable polymer on HA by means of thermogravimetric analysis, fourier transform infrared spectroscopy with photoacoustic detection and differential scanning calorimetry confirmed the initiating efficiency of HA as mentioned above. This poly(lactone) can be debound from HA by treatment with aqueous HCl. Hence it is assumed to be ionically bound.

New composites of hydroxyapatite and bioresorbable macromolecular material.

Composite materials were prepared by mixing in different proportions of hydroxyapatite (HA) and poly(epsilon-caprolactone-oxyethylene-epsilon-caprolactone) block copolymer (PCL-POE-PCL) to produce a new resorbable material for biomedical applications. This material has proved to be very interesting for production of periodontal membranes. Mechanical properties are linearly proportional to the amount of HA introduced. Fourier transform infrared (FTIR) investigations have pointed out that HA is able to influence some close epsilon-caprolactone molecules to start its homopolymerization giving PCL with an end chain ionic bonding. HA grains are therefore surrounded by a film of PCL which grants close connection of HA grains within copolymeric matrix. This interface bond with PCL is, however, an interesting occurrence for preparations of HA/PCL composites.