Hydroxyapatite Group Research Articles

Bone samples' behavior in sunlight, IR light, and temperature increase with FEM simulation.

Biological and environmental factors produce biochemical processes that modify the bone structure. A few studies have attempted to show the adverse biological effects of sun radiation. The bone tissue exposures to infrared and sunlight radiation are analyzed by using focused sound, characterization spectroscopy techniques, and image processing. The study is complemented with a finite element method simulation on temperature behaviors. The crystal morphology on the bone hydroxyapatite and functional groups was characterized by X-ray diffraction and infrared spectroscopy. The infrared spectra confirmed the hydroxyl group of bovine hydroxyapatite, amines, and lipids are also correlated with modifications of the hydroxyapatite. The diffractograms showed the characteristic peaks of hydroxyapatite, with the main intensity at 2θ = 32.02°. Bone samples exposed to sun radiation presented a peak at 2θ = 27.5°, evidencing the possible formation of β-TCP y α-TCP. The analysis with the spectroscopy techniques about the structural changes in the samples suggests interpreting an increase of sound obtained by expanding the exposure time. It is possible to verify that there are some structural changes in the bone samples due to exposure to non-ionizing radiation. These results show an increase in the registered intensity sound correlated with the interpretation of the structural changes of bone. Thanks to the different novel analysis techniques established in the present study, it could establish the changes that experienced the bone structure under different sources of radiation, which will help to better detect scenarios of bone deficiency.

The effects of boron nitride/hydroxyapatite compounds on bone defects in osteoporotic rats

This study investigated the effects of poly-(lactide-co-glycolide) (PLGA) scaffolds containing different concentrations of boron nitride (BN) and/or hydroxyapatite (HA) on bone defects in osteoporotic rats. The control group consisted of healthy rats. A standard non-critical size defect was induced in the osteoporotic rat femurs 12 weeks post-ovariectomy. PLGA scaffolds containing different concentrations of BN+HA were then applied to the defect area. In one group, defect was induced but no PLGA was applied. Computed tomography images were obtained and tissue samples were collected in the first, second, and fourth weeks postoperatively. PLGA scaffolds were classified as no BN + HA, only 10% HA, 2.5% BN + 10% HA, 5% BN + 10% HA, 10% BN + 10% HA or only 2.5%, 5% or 10% BN. No healing was determined in the first and second weeks postoperatively. However, in the fourth week healing was observed in the groups treated with PLGA scaffolds containing 10% HA, 2.5% BN + 10% HA, 2.5% BN and 5% BN, and especially in the 2.5% BN + 10% HA group. The findings of this study suggest that BN may represent a novel target for treating osteoporotic bone defects for physicians and engineers.

Effect of Nano-sized Hydroxyapatite Filler on Remineralization Efficacy of an Adhesive Resin: an in vitro study

Aim The aim of this study was to evaluate the remineralization efficacy of an adhesive resin containing nano-sized hydroxyapatite filler. Methodology The study consisted of four groups: control (without filler), 2% hydroxyapatite (HA), 5% HA, and 7% HA. Nano-hydroxyapatite powder was mixed with Scotchbond Multi-Purpose®. The teeth were sectioned to expose the midcoronal dentine. Bonding agents and resin composite restorations were applied. Teeth were incubated in simulated body fluid for 24-h, 30-day, and 90-day intervals. After incubation, the teeth were sliced. Hardness and elasticity modules were obtained for the three different time periods (for a total of n = 360 samples). The detection and measurement of mineral deposition areas were obtained by confocal laser scanning microscopy (CLSM) (for 120 samples). Elemental analysis was performed with energy-dispersive X-ray spectroscopy (EDS) (n = 360 samples). The statistical analysis of each parameter was performed using two-way ANOVA and group comparisons by post hoc tests. Results Study groups and storage periods affected the hardness (p = 0.00) and elasticity scores (p = 0.00). The CLSM results showed that increasing the storage periods and amount of HA resulted in mineral deposition areas (p = 0.02). The calcium and phosphor ion values of dentine that were obtained using EDS were increased (p = 0.00). Conclusion Hydroxyapatite fillers positively affect the remineralization activity of adhesive resins. In terms of remineralization efficacy, the best results were obtained in the 7% HA group.

Application Of The Sol-Gel Hydroxhapatite Synthesis Method From Green Clam Shell

Hydroxyapatite is the main mineral that makes up bones and teeth so that it has a level of similarity with the mineral parts of bones and can be used as an alternative bone substitute material. As an alternative material for bone substitution, hydroxyapatite has a fairly high economic value and is still dominated by imports from foreign countries. In an effort to reduce the level of imports of hydroxyapatite, research was carried out on green mussel shells as a source of calcium for the synthesis of hydroxyapatite. The synthesis of hydroxyapatite was carried out using the sol-gel method with raw materials for calcium precursors obtained from green mussel shells and varied concentrations of phosphoric acid (0.1 M, 0.5 M, 1 M; 1.5 M; and 2 M). Based on the analysis of the hydroxyapatite product produced using Atomic Absorption Spectrophotometry analysis, it was found that the ratio of Calcium-Phosphate (Ca/P) for H3PO4 concentrations was 0.1 M, 0.5 M, 1 M; 1.5M; and 2 M respectively by 1.73; 1.70; 1.67; 1.63; and 1.61. In addition, based on the results of the Fourier Transform Infra Red analysis, a random sample also found a Ca-O group; PO43; and OH- which is the main group of Hydroxyapatite and from SEM analysis the crystal morphology is known to be spherical, uneven and agglomerated so that in this study the synthesis of Hydroxyapatite using the sol-gel method was successfully carried out..

Histological and Histomorphometric Evaluation of Socket Healing After Application of Epidermal Growth Factor with synthetic hydroxyapatite powder in Rats

Background: One of the serious challenges in dental treatment is socket healing after tooth extraction. Various researchers have attempted to develop efficient therapies for healing and regenerating damaged tissues after extraction. Many tissue engineering technologies have been used now a day to enhance tissue healing.
 Aim: The present study was planned to evaluate the efficacy of epidermal growth factor with synthetic hydroxyapatite powder in socket healing.
 Methods: six-Thirty male rats were included in this study and their lower incisors teeth were subjected to extraction. Animals were divided into the following three groups according to socket treatment. (A) control, socket hole left to heal without any application, (B)application of hydroxyapatite powder (HAP) in the socket, (C) application of epidermal growth factor (EGF) with hydroxyapatite powder in the socket. Histological evaluation for bone formation, bone cell and inflammatory cell count with histomorphometry of bone trabeculae percentage had been done to all study groups and for three periods (5,14 &28 days).
 Results: Epidermal growth factor with hydroxyapatite group showed early bone formation, more bone cell count, and less inflammatory cell infiltration in comparison to the HAP group and control at periods (5,14&28 days) and with a statistically significant difference (p<0.05).
 
 Bone trabeculae percentage was recorded to be high in the HAP&EGF group that filled the socket hole at (14 ,28 days) intervals in comparison to hydroxyapatite and control group. Complete re-epithelialization was observed only in the EGF&HAP group.
 Conclusions: Both the HAP&EGF group and the hydroxyapatite group show bone formation and good socket healing, but the EGF&HAP group showed to be faster in filling of boney socket hole with complete epithelization than hydroxyapatite group, therefor using EGF with HAP is more efficient and suggested the material of choice used for socket healing.

Properties of hydroxyapatite from tilapia (Oreochromis niloticus) bones: An approach towards its potential use as a dye adsorbent

The properties of hydroxyapatite (HAp) obtained from tilapia (Oreochromis niloticus) bones and its potential use as a dye adsorbent using methyl orange (MO) as a model dye were evaluated. HAp was produced by the calcination of dried tilapia bones at 900 °C for 4 h. Then, HAp was characterized using thermogravimetric (TGA) and differential thermogravimetric (dTG) analyses, Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), x-ray diffraction (XRD), among others. The HAp obtained was used for MO dye adsorption in a batch process. The yield of HAp was 51.6%. FTIR showed characteristic bands of functional groups of HAp [OH- and (PO4)3-]. FESEM images showed HAp with different morphologies and a porous surface. The EDS analysis indicated the presence of calcium and phosphorus with an atomic ratio of Ca/P of 1.60, TEM images revealed the formation of agglomerates and an average particle size of 655.1 nm. HAp and β-tricalcium phosphate (β-TCP) phases were identified through XRD. The HAp point of zero charge (pHpzc) was 9.7 indicating a possible adsorption of anionic dyes at pH< pHpzc and cationic dyes at pH> pHpzc. The HAp was able to successfully adsorb 82.6% of MO dye from aqueous solution. These findings demonstrated that the HAp obtained from tilapia (O. niloticus) bones possesses suitable properties to be used as a potential material to remove dyes.

Hydroxyapatite-chitosan composites derived from sea cucumbers and shrimp shells ameliorate femoral bone defects in an albino rat model.

A bone defect is defined as a critically sized autologous bone and a bone gap. Bone grafting is one of the most commonly used surgical methods to enhance bone regeneration in orthopedic procedures. A composite of collagen, hydroxyapatite (HA), and chitosan (Ch) is suitable as a bone matrix and stimulates ossification. This study aimed to evaluate the use of natural HA-Ch composites derived from sea cucumbers and shrimp shells and quantify the levels of cytokines, polymorphonuclear neutrophils (PMNs), serum liver enzymes, calcium, phosphate, and procollagen type 1 N-terminal propeptide (PINP) in albino rats with femoral bone defects. A total of 48 albino rats with femoral bone defects were divided into 4 groups (n = 12 each): (C-) placebo, (C+) polyethylene glycol, (T1) HA, and (T2) HA-Ch groups. Each group was divided into two subgroups (n = 6 each), with euthanization on 7- and 42-day post-treatment, respectively. Procollagen Type 1 N-terminal propeptide and the cytokines interleukin (IL)-4, IL-6, IL-10, and tumor necrosis factor-alpha were quantified using enzyme-linked immunosorbent assay. Flow cytometry was performed to evaluate PMNs. A clinical chemistry analyzer was used to measure the serum levels of liver enzymes, calcium, and phosphate. There was a significant decrease in the level of IL-6 on 7 days and in the level of IL-10 on 42 days in the HA-Ch group. The level of PMNs also decreased significantly on 7 and 42 days in the HA-Ch group. Regarding serum liver enzymes, alkaline phosphatase (ALP) levels in the HA-Ch group increased significantly on 42 days. Calcium and phosphate levels increased significantly on 7 and 42 days in the HA and HA-Ch groups, and PINP levels increased significantly on 7 and 42 days in the HA-Ch group. The HA-Ch composite derived from sea cucumbers and shrimp shells ameliorated femoral bone defects in albino rats. The HA-Ch composite modulated the levels of IL-6, IL-10, PMNs, ALP, calcium, phosphate, and PINP on 7- and 42-day post-treatment.

A biomechanical analysis of the effect of hydroxyapatite augmentation for trochanteric femoral fractures.

Hydroxyapatite (HA) augments are used to treat trochanteric femoral fractures. However, the efficacy of HA augmentation has not been fully described in trochanteric femoral fracture surgery. In total, 85 patients were enrolled in the present study; all had trochanteric femoral fractures between January 2016 and October 2020, 45 with HA (HA group) and 40 without HA (N group). The intraoperative lag screw insertion torque was directly measured and the amount of lag screw telescoping with and without HA augmentation after surgery was analyzed. Maximum lag screw insertion torque (max-torque), bone mineral density in the opposite femoral neck (n-BMD), tip apex distance (TAD) of the lag screw, radiographic findings including fracture union, the amounts of lag screw telescoping and occurrence of complications were evaluated. A total of 12 patients were excluded if they were aged under 60 years old, had ipsilateral surgery and disorders in the hip joint, TAD of the lag screw ≥26 mm on postoperative radiographs and had measurement errors. A total of 73 fractures could be analyzed: HA group (n=36) and N group (n=37). Max-torque/n-BMD ratios were higher in the HA group compared with in the N group (7.23±2.71 vs. 5.93±1.91 g/cm2·N·m; P=0.04). The amounts of lag screw telescoping in the HA group were smaller compared with the N group (1.41±2.00 vs. 2.58±2.34; P=0.05). Evaluation of screw insertion torque showed maximum screw insertion torque correlated well with n-BMD in both groups, HA (R=0.57; P<0.01) and N group (R=0.64; P<0.01). No correlation was found between maximum screw insertion torque and TAD in both groups, HA (R=-0.10; P=0.62) and N group (R=0.02; P=0.93). All fractures were radiographically united without any complications. These results support the effectiveness of HA augmentation, indicating higher resistance against rotational instability and reduced lag screw telescoping in trochanteric femoral fracture treatment.

TAVŞAN OMURGASINDA ANTERİOR BODY KAFES BORON UYGULAMASININ KEMİK FÜZYONUNA VE FÜZYON KALİTESİNDE ETKİSİ

OBJECTIVE: Our aim in this study was to demonstrate the effectiveness of hydroxyapatite (HA) and Boron compounds in operations using an Anterior Lumbar Interbody Fusion (ALIF). MATERIAL AND METHODS: In the study, 18 male rabbits of New Zealand breed weighing 2.5-3 kg were used. The animals who were hospitalized on the left side underwent flank incision after surgical cleaning. Lumbar 5-6 distance was reached from the lumbar retroperitoneal region. Following anterior discectomy; ALIF was performed using PEEK (polyethylene ether ketone) cage (Group I) in the control group, PEEK cage and 50 mg/kg boron (borax pentahydrate) (Group II) in the boron group, PEEK cage and 50 mg/kg powder ProOsteon (Group III) in the HA group. The ALIF operation has been applied to all groups. Six weeks later, the animals underwent a computed tomography (CT) scan. Then the lower and upper vertebrae of the sacrificed animals at the distance at which discectomy was performed and the cage was placed were removed, separated for pathology. After being microscopically detected with buffered 10% formaldehyde overnight, the sections prepared from the sample tissues that were routinely followed were stained with hematoxin-eosin and examined histopathologically with light microscopy. RESULTS: While the osteoclast score was 1 in 83.3% of the boron group, it was 2 in 16.6%. In the same group, the osteoblast score was found to be 1 in 50% and 2 in 50%. The osteoclast score of the HA group was 1 in 50%, 2 in 50%, while the osteoblast score was found in 50%, 1 in 2, 2 in 16.6%, and 3 in 33.4%. Higher osteoblast and osteoclast scores were observed in HA group compared to Boron and control groups. It was observed that the boron group had higher osteoblast and osteoclast scores than the control group and lower than the HA group. CONCLUSIONS: Boron and Hydroxyapatite have been shown to form stones of the same size. Although morphologically not as much as boron, hydroxyapatite, histopathological examination showed that it formed a better amount of fusion compared to the control group. The osteoblastic activity was most common in the hydroxyapatite group.

Evaluation of carbonate apatite as a bone substitute in rat extraction sockets from the perspective of mesenchymal stem cells.

Carbonate apatite (CO3Ap) is a major inorganic bone component and an effective bone substitute. To clarify the function of CO3Ap, we compared differences among CO3Ap, hydroxyapatite (HAp), and β-tricalcium phosphate (β-TCP) by focusing on mesenchymal stem cells (MSCs) that have a role in wound healing. For in vivo experiments, maxillary molars were removed and the bone substitute was inserted. MSC accumulation around extraction sockets was significantly promoted in CO3Ap and β-TCP groups. For in vitro experiments, MSCs were cultured with bone substitutes. The differentiation potential and amount of calcium deposition were significantly lower in CO3Ap and HAp groups than in the β-TCP group. Increases in insulin-like growth factor-I and vascular endothelial growth factor were found only in the CO3Ap group. CO3Ap-filled extraction sockets accumulated MSCs, and MSCs cultured in the presence of CO3Ap produced large amounts of growth factors. These results suggest that CO3Ap promotes healing of tooth extraction sockets.

Regeneration Analysis of Bone Char Used in Water Defluoridation: Chemical Desorption Route, Surface Chemistry Analysis and Modeling

High concentrations of fluoride (F−) in drinking water represent a public health threat, and consequently, effective and sustainable methods are required to improve the water quality, mainly in developing and low-income countries. This study focused on the thermodynamics of fluoride adsorption on bone char regenerated with NaOH for water defluoridation. A detailed analysis of the number of fluoride adsorption/desorption cycles, their impact on the performance and surface chemistry of bone char using different NaOH concentrations, and modeling of the adsorption mechanism using statistical physics theory was carried out. The results showed that 0.075 mol/L NaOH was effective in recuperating the defluoridation properties of bone char with a regeneration efficiency higher than 90% during five adsorption/desorption cycles. Bone char regeneration efficiency decreased up to 64% after ten adsorption/desorption cycles with a maximum fluoride adsorption capacity of 0.18 mmol/g. NaOH restored the bone char surface properties for ligand exchange of the fluoride anions via the hydroxyapatite functionalities contained in this adsorbent. It was calculated that around 0.25–0.46 mmol/g hydroxyapatite ligand exchange sites of regenerated bone char samples could be involved in the fluoride adsorption, which was also expected to be a mono-ligand mechanism. The reduction in defluoridation properties of bone char during the regeneration cycles was attributed to the decrease in the ligand exchange capacity as well as the deactivation and blocking of some functional groups of hydroxyapatite, which limited their participation in consecutive adsorption processes. This study contributes to the optimization of the recycling and reuse of bone char for fluoride removal from water to reduce the operating defluoridation costs, thus enhancing the application of this technology in low-income areas where fluorinated water represents a threat to public health.

The effect of temperature on the synthesis and characterization of hydroxyapatite-polyethylene glycol composites by in-situ process

Hydroxyapatite (HAp) is a vital material in various biomaterials but has low flexibility. Because of that, research has been done to increase the efficiency of hydroxyapatite by combining it with polyethylene glycol (PEG). HAp-PEG composite synthesis using blood cockle shell waste (Anadara granosa) as Ca precursor. The HAp-PEG composite was synthesized by in-situ to avoid high agglomeration. It was carried out with various temperatures to study the effect of temperature on the formation of the HAp-PEG composite and to determine the effect of temperature on its morphology and degradation properties. Fourier-Transform infrared (FTIR) characterization showed the presence of HAp and PEG functional group vibrations. X-Ray Diffraction (XRD) analysis showed that the composite had HAp peaks that matched the standard HAp ICSD #97849 and corresponded to pure PEG peaks. Characterization of Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) It is known that the synthesis temperature affects the morphology and hydroxyapatite ratio. Thermogravimetric Analysis-Differential Thermal Analysis (TGA-DTA) analyzed weight reduction in HAp-PEG composite samples, showing that the composite experienced a significant decrease in mass at 176–306, indicating PEG decomposition. The HAp-PEG composite degradation behavior test confirmed that the optimum temperature for degradation occurred at 70 ​°C.

Bench-scale integrated bone and biochar bed treatment of geogenic fluoride contaminated groundwater from Bongo in Ghana

The article explores the adsorption of fluoride in groundwater and the synergistic properties of a mixture of bone char and biochar. The bone char and biochar were produced using cattle bones and coconut husks, bamboo, neem tree and palm kernel in a locally constructed double-barrel retort with particle size ranging from 0.05 to 0.315 mm. The morphology of the char was examined using a scanning electron microscope and energy dispersive spectroscopy for elements. The surface functional groups were assessed by Fourier-transform infrared spectroscopy. Almost all the fluoride was removed from the groundwater within 15–27 min of column treatment. Cattle bone char standalone treatment was the most effective adsorbent, with a removal rate of 91.4%, which is almost identical to the integrated removal rate of 91.1% for bone char and coconut husk biochar. The presence of the hydroxyapatite groups in the bone char together with the high surface areas of the chars increased the integrated bed's effectiveness in lowering fluoride concentrations in contaminated groundwater from 3.6 mg/L to 1.5 mg/L with an adsorption capacity of 0.084 mg/g. The breakthrough curves were predicted with the bed depth service time model under the same operational conditions. The integrated bed showed almost 100% efficacy in removing fluoride from contaminated groundwater with a 3.6 mg/L fluoride concentration within a breakthrough time of 15–27 min. This was due to the interplay between the chars' high surface areas and the hydroxyapatite groups in the bone char, which enhance adsorption and the synergistic effect of the integrated char.

Injectable platelet-rich fibrin polymerized with hydroxyapatite bone graft for the treatment of three-wall intrabony defects: A randomized control clinical trial.

The study was aimed to compare and evaluate the clinical and radiographic outcomes of injectable platelet-rich fibrin (i-PRF) polymerized with hydroxyapatite (HA) bone graft and HA bone graft alone for treating three-wall intrabony defects (IBDs). The trial was planned as a randomized, prospective clinico-radiographic study with inclusion of 34 three-wall IBDs in patients with stage III periodontitis. IBDs were assigned randomly to one of the groups, i.e., Group I - experimental (i-PRF + HA) and Group II - control (HA alone). At baseline and 6 and 9-month intervals, both the clinical and radiographic measurements were taken and baseline and 9-month data were tabulated and imported into SPSS 22 software. Student unpaired and paired t- tests were used to find significant differences (p<0.05). Both the groups showed substantial changes in all clinical and radiographic measures on comparison from baseline values. On intergroup comparison, the i-PRF + HA group reported significantly higher original defect resolution and original defect fill as compared to the HA group. i-PRF polymerized with HA graft has shown better results as compared to HA graft alone in three-wall IBDs and therefore can be used as a better possible alternative for the treatment of three-wall IBDs.

Effects of hydroxyapatite nanoparticles on the vitrification of bovine metaphase II oocytes

Context Although vitrification is commonly used for oocyte cryopreservation, the cryogenic damage results in poor developmental capacity of oocytes after freezing. Nano-cryopreservation is one of the new methods of vitrification developed in recent years. However, the effect of nano-cryopreservation on mature bovine oocytes remains to be elucidated. Aims This study aimed to verify the effect of using hydroxyapatite (HA) nanoparticles (NPs) on the vitrification of bovine metaphase II (MII)-stage oocytes. Methods Bovine MII-stage oocytes were exposed to different HA concentrations (0.01%, 0.05%, and 0.10%) in vitrification solution (VS). After IVF (in vitro fertilisation) and IVC (in vitro culture), the toxicity of HA was assessed by cleavage and blastocyst rates. A suitable concentration of HA nanoparticles was selected according to the results of the first experiment. and then vitrification-thawing was measured. The effect of HA on the developmental capacity of oocytes was assessed by oocyte cleavage rate and blastocyst rate. The mitochondrial membrane potential (MMP) and the intracellular reactive oxygen levels (ROS) of oocytes were measured by staining with a fluorescence probe (JC-1) and an ROS kit after nano-cryopreservation. Key results The addition of 0.05% HA to the VS did not affect the oocyte morphology; the proportion of oocytes developing with normal morphology was 96.72%. In contrast, this proportion it significantly decreased at a concentration of 0.1% HA in VS (91.69%; P &lt; 0.05). The cleavage rates (56.95% vs 51.20%, 50.67%; P &lt; 0.05) of bovine oocytes exposed to 0.05% HA were significantly higher than in the VS group and VS + 0.1% HA group. After the vitrification-thawing, the oocyte cleavage rates (41.07% vs 33.97%; P &lt; 0.05) and blastocyst rates (12.35% vs 7.38%; P &lt; 0.05) were significantly higher in the VS + 0.05% HA group compared to the VS group. At the 0.05% HA concentration, nano-cryopreserved oocytes had significantly higher MMP (1.35 ± 0.24) and significantly lower ROS (1.43 ± 0.05) than the VS group (P &lt; 0.05, mean ± s.e.m.). Conclusions The addition of 0.05% HA-NPs in VS could promote bovine MII-stage oocytes’ developmental ability after vitrification. This effect may be caused partly by increased mitochondrial membrane activity and decreased ROS. Implications HA-NPs may be a new class of cryoprotective agent suitable as components for oocyte vitrification.

Hydroxyapatite Chromatography (HAC).

Hydroxyapatite (HA) is a mixed-mode media that has been used extensively for the purification of proteins and DNA since the 1950s. Hydroxyapatite possesses a distinctive selectivity that may be applied in the purification of a wide range of biomolecules: immunoglobulins, alkaline proteins, acidic proteins, and DNA. The functional groups of HA can both attract and repel the carboxyl and amino groups on target molecules. This unique selectivity is due to the modalities that can be employed, which are not possible with traditional anion-exchange and cation-exchange chromatography. HA is a powerful chromatography step for reducing host cell-derived impurities and aggregated product, where a 2-4 log reduction in host cell proteins, aggregates, endotoxin, and viruses are routinely achieved. This chapter describes the procedures for: efficiently packing and evaluating a HA column, purifying IgG and acidic proteins respectively using HA chromatography.

Development of Nano-Hydroxyapatite Polymer Composite and it's in vitro Activity for Biomedical Applications

In present work, the composites of hydroxyapatite with polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) were prepared and analyzed for its biodegradability and hemocompatibilty. The individual and the combined combination of polymers with hydroxyapatite (HAP-PVA, HAP-PVP and HAP/PVA-PVP) were characterized by FT-IR, XRD, SEM-EDAX and TGA-DSC analysis. The crystallinity and functional groups of hydroxyapatite (HAP) was confirmed by XRD and FT-IR analysis. The SEM analysis displayed rod shaped morphology and the formation of apatite layer was confirmed by simulated body fluid (SBF) immersion. The Ca/P ratio of the SBF immersed composite was found to be increased to 1.71. This reveals that the polymer in the composite acts as a nucleating site for the development of carbonated hydroxyapatite which chemical composition resembles with natural bone. The hemolysis rate for the composite consisting of HAP/PVA-PVP was found to be less than 3% than the composite consisting of HAP with PVP. Based on these results, it can be concluded that the HAP/PVA-PVP nanocomposite offers superior alternatives in the field of biomedicines.

Effects of calcium salts on experimental characterizations of sodium alginate hydrogels and the drug release of electrospun naringin-loaded microspheres hybrid hydrogel scaffolds

This study utilized four calcium sources (calcium carbonate, hydroxyapatite, calcium sulfate, and calcium chloride) combined with sodium alginate to form different hydrogel scaffolds and investigated differences in their related properties. In addition, the drug release behavior of the scaffolds was characterized by naringin release in vitro. The calcium carbonate and hydroxyapatite groups formed homogeneous hydrogels with better physical and mechanical properties. The hydroxyapatite and calcium sulfate groups had better sustained release ability. These results highlight the importance of proper calcium source selection when preparing sodium alginate hydrogels and demonstrate that hydroxyapatite as a calcium source has potential application in bone tissue engineering.

Bonding properties of mild universal adhesives to dentin pretreated with hydroxyapatite-based desensitizing agents.

The purpose of the study was to evaluate the effect of hydroxyapatite (HA)-based desensiti-zing agents and determine their influence on the bonding performance of mild universal adhesives. Mid-coronal dentin samples were sectioned from human third molars and prepared for a dentin-sensitive model. According to desensitizing applications, they were randomly divided into four groups for the following treatments: no desensitizing treatment (control), Biorepair toothpaste (HA-based desensitizing toothpaste) treatment, Dontodent toothpaste (HA-based desensitizing toothpaste) treatment, and HA paste treatment. Dentin tubular occlusion and occluded area ratios were evaluated by scanning electron microscopy (SEM). Furthermore, All-Bond Universal, Single Bond Universal, and Clearfil Universal Bond were applied to the desensitized dentin in self-etch mode. The wettability and surface free energy (SFE) of desensitized dentin were evaluated by contact angle measurements. Bonded specimens were sectioned into beams and tested for micro-tensile bond strength to analyze the effect of desensitizing treatment on the bond strength to dentin of universal adhesives. SEM revealed that the dentin tubule was occluded by HA-based desensitizing agents, and the area ratios for the occluded dentin tubules were in the following order: HA group>Biorepair group>Dontodent group (P<0.05). Contact angle analysis demonstrated that HA-based desensitizing agents had no statistically significant influence on the wettability of the universal adhesives (P>0.05). The SFE of dentin significantly increased after treatment by HA-based desensitizing agents (P<0.05). The micro-tensile bond strength test showed that HA-based desensitizing toothpastes always decreased the μTBS values (P<0.05), whereas the HA paste group presented similar bond strength to the control group (P>0.05), irrespective of universal adhesive types. HA-based desensitizing agents can occlude the exposed dentinal tubules on sensitive dentin. When mild and ultra-mild universal adhesives were used for subsequent resin restoration, the bond strength was reduced by HA-based desensitizing toothpastes, whereas the pure HA paste had no adverse effect on bond strength.

Histopathological and serological assessment of using rib lamb xenograft reinforced with and without hydroxyapatite nano gel for reconstruction tibial bone defect in dogs

This work aimed to assess repairing tibial bone defects using histopathological and serological examinations. Eighteen stray adult dogs of both sexes were used. The experiment was allocated into two equal groups, 9 of each. An experimental tibia defect of 2.5*0.7 cm was induced at the proxomedial aspect of the tibia. Deproteinized lamb's rib xenograft was used to reconstitute the defective area. The tissue and blood samples were collected for histopathological and serological investigations at different periods. On day seven post-surgery, the serological assessment indicated a significant increase in the level of Insulin-Like Growth Factor (IGF) of both the first and second groups, 0.2±0.03, 0.3±0.02 ng/ml, respectively; however, after 14 days, the levels were significantly reduced in both groups 0.08±0.03, 0.2±0.02 ng/ml, respectively. On day 7, the serum alkaline phosphatase level in the first group was lower, 31.6±3 u/l, than in the treated group, 54.2±1.86 u/l. However, at 14 days post-surgery, the serum alkaline phosphatase level in the first group slightly increased by 35.7±2.1 u/l; nevertheless, the treated group manifested a constant level of 54.1±5.24 u/l. At 60 days post-operation, the histopathological examination presented more organized tissue maturation in the second group. The histochemical results of all specimens of the hydroxyapatite group revealed an increase in calcified bone by showing a red reaction which indicates the formation of thick calcified compact bone at 60 days post defects. In conclusion, the hydroxyapatite Nano gel contributed to ossification across the bone defect and hastened the healing process; the serological investigations indicated an increase in the activity of bone tissue.