Nanocrystalline Hydroxyapatite Research Articles

Clinical evaluation of advanced platelet rich fibrin combined with nano-crystalline hydroxyapatite bone substitute for management of mandibular molar grade II furcation defects: a randomized controlled clinical trial.

Clinical evaluation of advanced platelet rich fibrin combined with nano-crystalline hydroxyapatite bone substitute for management of mandibular molar grade II furcation defects: a randomized controlled clinical trial.

Calcination-based direct extraction of hydroxyapatite from bovine bone waste

ABSTRACT The main chemical components of waste cow bones are apatite minerals, especially those containing calcium and phosphorus. This study investigated whether this bone could produce extracted hydroxyapatite through calcining at 900° C for different holding times (1–6 h). An average mass loss of 45% occurred in this experiment during the preparation of bone powders, which involved crushing and further calcining at this temperature. The quantitative XRD analysis showed that 99.97 wt.% hydroxyapatite and over 0.3 wt.% calcite were present in the raw and as-calcined bone powders, with trace amounts of CaFe3O5 (calcium ferrite) phases appearing in the calcined product. Depending on the holding calcining times, SEM images of the calcined bovine powders revealed aggregate sizes ranging from 0.5–3 µm and crystallite (grain) sizes ranging from 70 to 340 nm in all calcium-phosphate powder products. Following EDX analysis of all sample surfaces, possible calcium-deficient hydroxyapatite instead of hydroxyapatite formed, as evidenced by the calcined product's Ca/P ratio exceeding 1.67. Additionally, calcining cow bones for 5–6 h at 900° C yielded a high-purity nano-crystalline hydroxyapatite powder precursor in biomedical applications.

Enhanced defluoridation by nano-crystalline alum-doped hydroxyapatite and artificial intelligence (AI) modeling approach

The study aimed to investigate the defluoridation capacity of nano-hydroxyapatite (HAP) [Ca10(PO4)6(OH)2] and alum-doped hydroxyapatite (AHAP) [Ca8Al(PO4)6.(OH)2] as an environmental friendly adsorbent. The physicochemical characteristics of both the material (HAP and AHAP) were examined using XRD, FE-SEM-EDS, and BET techniques. The batch adsorption study revealed a fluoride removal efficiency of up to 83% (AHAP) and 74% (HAP) under acidic conditions (pH-2). The doping of alum alters the surface chemistry and enhances the affinity of AHAP for fluoride adsorption. The pseudo-second-order kinetic (R2–0.9941) and Langmuir isotherm (R2–0.9425) models best describe the adsorption mechanism and behavior. The thermodynamic analysis indicated the spontaneous and endothermic nature of the adsorption process. The study also tested the applicability of the artificial neural network (ANN) modeling approach using MATLAB R2013a to simulate the simulated absorptive efficiency of AHAP. This study suggests that AHAP proved an effective adsorbent for defluoridation.

Apatite/Chitosan Composites Formed by Cold Sintering for Drug Delivery and Bone Tissue Engineering Applications.

In the biomedical field, nanocrystalline hydroxyapatite is still one of the most attractive candidates as a bone substitute material due to its analogies with native bone mineral features regarding chemical composition, bioactivity and osteoconductivity. Ion substitution and low crystallinity are also fundamental characteristics of bone apatite, making it metastable, bioresorbable and reactive. In the present work, biomimetic apatite and apatite/chitosan composites were produced by dissolution-precipitation synthesis, using mussel shells as a calcium biogenic source. With an eye on possible bone reconstruction and drug delivery applications, apatite/chitosan composites were loaded with strontium ranelate, an antiosteoporotic drug. Due to the metastability and temperature sensitivity of the produced composites, sintering could be carried out by conventional methods, and therefore, cold sintering was selected for the densification of the materials. The composites were consolidated up to ~90% relative density by applying a uniaxial pressure up to 1.5 GPa at room temperature for 10 min. Both the synthesised powders and cold-sintered samples were characterised from a physical and chemical point of view to demonstrate the effective production of biomimetic apatite/chitosan composites from mussel shells and exclude possible structural changes after sintering. Preliminary in vitro tests were also performed, which revealed a sustained release of strontium ranelate for about 19 days and no cytotoxicity towards human osteoblastic-like cells (MG63) exposed up to 72 h to the drug-containing composite extract.

New Nano-Crystalline Hydroxyapatite-Polycarboxy/Sulfo Betaine Hybrid Materials: Synthesis and Characterization.

Hybrid materials based on calcium phosphates and synthetic polymers can potentially be used for caries protection due to their similarity to hard tissues in terms of composition, structure and a number of properties. This study is focused on the biomimetic synthesis of hybrid materials consisting of hydroxiapatite and the zwitterionic polymers polysulfobetaine (PSB) and polycarboxybetaine (PCB) using controlled media conditions with a constant pH of 8.0-8.2 and Ca/P = 1.67. The results show that pH control is a dominant factor in the crystal phase formation, so nano-crystalline hydroxyapatite with a Ca/P ratio of 1.63-1.71 was observed as the mineral phase in all the materials prepared. The final polymer content measured for the synthesized hybrid materials was 48-52%. The polymer type affects the final microstructure, and the mineral particle size is thinner and smaller in the synthesis performed using PCB than using PSB. The final intermolecular interaction of the nano-crystallized hydroxyapatite was demonstrated to be stronger with PCB than with PSB as shown by our IR and Raman spectroscopy analyses. The higher remineralization potential of the PCB-containing synthesized material was demonstrated by in vitro testing using artificial saliva.

A Review of 3d Printing Model of New Blood Vessel Formation For Pharmaceutical Applications

Cardiovascular diseases (CVDs) are the primary cause of death in older individuals. An established medical approach for treating CVDs involves replacing blocked or restricted arteries. This surgery, known as vascular transplant, is now considered the most effective method and uses the patient's tissue for transplanting. Artificial Blood Vessels (ABVs) are often not utilized for numerous cardiac individuals due to an individual's advanced age, narrow veins, prior medical history, and aberrant conditions. Hence, it is essential to consider the necessity of vascular substitutes, particularly in vascular transplanting involving extremely narrow dimensions and the presence of suitable alternatives. This work aimed to create a new type of synthetic blood vessel by combining polymer-reinforced materials with bioceramic nanomaterials. Research has been conducted on the biomechanical and chemical characteristics of artificial blood arteries for their potential application in bypass surgery of the coronary arteries for atherosclerosis as part of biological development. The work involved the preparation of thermoplastic polyurethane (TPU) by combining nanocrystalline hydroxyapatite (HA) tiny particles utilizing the extrusion process to create the ABVs. The ideal sample was examined using X-ray diffraction (XRD) and Scanned Electron Microscopy (SEM). The ABVs had a significant capability to determine the elasticity modulus, wetting, and permeability of the veins. These characteristics were evaluated using fused lamination modeling and 3D printing. The findings indicate that the constricted arteries, made of TPU composites with nanocrystalline HA small particles, had superior chemical resistance and structural properties.

To Analyze the Efficacy of Platelet-rich Plasma in Contrast to Platelet-rich Fibrin along with Synthetic Nanocrystalline Hydroxyapatite and β-tricalcium Phosphate Bone Graft in Regeneration of Bony Defects in Children.

To analyze the efficacy of platelet-rich plasma (PRP) in contrast to platelet-rich fibrin (PRF) along with synthetic nanocrystalline hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) bone graft in the regeneration of bone defects in children. A total of 20 children in whom bone defect was present were selected and divided into two groups of 10. In group I, the bone defect was filled with PRP + nanocrystalline HA with β-TCP and group II, with PRF + nanocrystalline HA with β-TCP. Radiographs using VistaScan with a mesh grid were taken to analyze the bone density and bone regeneration. Clinical evaluation with respect to the color of overlying mucosa, sinus formation, pus discharge, and seepage of bone graft was done. The parameters used to analyze the radiographs included gray scale analysis, residual bone defect calculation in pixels both performed in CorelDraw version 13 software, and radiopaque scoring scale. The mean bone defect density measured using gray scale was higher in the PRF than PRP group. The percentage of bone formation analyzed using residual bone defect calculation and mean radiopaque score revealed that the PRF group showed better outcomes compared to the PRP group. Both PRP and PRF are equally effective in promoting bone regeneration with PRF showing slight superiority over PRP. Koksi Sangma Shadap NM, Yadav G, Saha S, et al. To Analyze the Efficacy of Platelet-rich Plasma in Contrast to Platelet-rich Fibrin along with Synthetic Nanocrystalline Hydroxyapatite and β-tricalcium Phosphate Bone Graft in Regeneration of Bony Defects in Children. Int J Clin Pediatr Dent 2023;16(6):842-849.

Synthesis of nano-crystallite hydroxyapatites in different media and a comparative study for estimation of crystallite size using Scherrer method, Halder-Wagner method size-strain plot, and Williamson-Hall model

Hydroxyapatite (HAp) [Ca10(PO4)6(OH)2] is remarkably similar to the hard tissue of the human body and the uses of this material in various fields in addition to the medical sector are increasing day by day. In this research, mustered oil, soybean oil, as well as coconut oil were employed as liquid media for synthesizing nanocrystalline HAp using a wet chemical precipitation approach. The X-ray diffraction (XRD) study verified the crystalline phase of the HAp in all the indicated media and discovered similarities with the standard database. Several prominent models such as the Scherrer's Method (SM), Halder-Wagner Method (HWM), linear straight-line method (LSLM), Williamson-Hall Method (W-M), Monshi Scherrer Method (MSM), Size-Strain Plot Method (SSPM), Sahadat-Scherrer Method (S–S) were applied for the determination of crystallite size. The stress, strain, and energy density were also computed from the above models. All the models, without the Linear straight-line technique of Scherrer's equation, resulted in an appropriate value of crystallite size for synthesized products. The calculated crystallite sizes were 6.5 nm for HAp in master oil using Halder-Wagner Method, and 143 nm for HAp in coconut oil using the Scherrer equation which were the lowest and the largest, respectively.

Chemical and Ultrastructural Characterization of Dentin Treated with Remineralizing Dentifrices.

The aim of this study is to investigate dentin chemical and ultrastructural changes upon exposure to remineralizing dentifrices. Dentin disks were obtained from permanent human molars and treated for 7 days with the dentifrices: (1) C group-control (no dentifrice); (2) S group-Sensodyne Repair & Protect; (3) D group-Dentalclean Daily Regenerating Gel; and (4) DB group-D group + Dentalclean regenerating booster. Afterwards, samples were submitted to an additional 7 days of toothbrushing associated with daily acidic challenge. Samples were imaged and analyzed (days 1, 7, and 14) for Young's modulus by atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). SEM and AFM revealed precipitate deposition on dentin surfaces in groups S, D, and DB, formed as early as day 1. Surface elemental analysis showed a Si increase on all brushed surfaces. Similar surface morphology was maintained after the acidic challenge period. Bright-field TEM/SAED revealed the formation of nanocrystalline hydroxyapatite inside the dentin tubules of groups S, D, and DB after day 7. Group C presented a gradual reduction of Young's modulus from days-1-14, whereas all remaining groups had increased values. All evaluated dentifrices led to successful formation of hydroxyapatite and increased dentin stiffness.

Enhancement of antimicrobial properties by metals doping in nano-crystalline hydroxyapatite for efficient biomedical applications

In this study, we have introduced a method for the synthesis of various metal-doped nano-crystalline hydroxyapatites (HAp) using a standard wet chemical precipitation technique. Both divalent (Ni and Zn) and trivalent (Al and Fe) metals were selected for the doping process. Additional research work was also conducted to assess the antimicrobial efficacy of these doped-HAps against a range of gram-positive and gram-negative microorganisms. All the synthesized metal-doped hydroxyapatite (HAp) exhibited notable antibacterial characteristics against gram-negative bacterial strains, namely Escherichia coli (E. coli) and Salmonella typhi (S. typhi), outperforming the pure HAp. The inhibition zone observed for the metal-doped HAp ranged from 14 to 16 mm. The Fe ion displayed a notable inhibitory zone measuring 16 mm, proving to be the most expansive among all tested ions against both E. coli and S. typhi bacterial strains. The Zn-HAp exhibited a comparable inhibitory zone size of 14 mm against both S. typhi and E. coli. Additional characterization methods, such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and Scanning electron microscopy (SEM), were used to validate the structural properties of the synthesized metal-doped hydroxyapatite (HAp) samples. The biocompatibility assessment of metal-doped hydroxyapatite (HAp) samples was carried out by haemolysis tests, which revealed that all synthesized hydroxyapatite (HAp) samples have the potential to serve as reliable biomaterials.

Optimized synthesis of cysteine-functionalized nanocrystalline hydroxyapatite for synchronous decontamination of Cd(II) and Pb(II)

The synchronous removal of toxic heavy metals (e.g., cadmium (Cd), lead (Pb), and etc.) from the contaminated water environment is an urgent demand in the pollution control field. Herein, an innovative adsorbent synthesis idea was proposed and a series of cysteine-functionalized nanohydroxyapatite (CysHAP) composites were prepared by adopting different reaction temperatures, cysteine/HAP ratios, and synthesis methods. According to the single factor tests, a co-precipitation temperature of 25 °C with a molar cysteine/HAP ratio of 2.0 was selected to synthesize the optimum CysHAP2.0–25 composite. Multiple characterization results showed that cysteine markedly altered the morphology, crystallinity, and crystal structure of HAP, leading to the formation of CysHAP2.0–25 composite with a superior dispersity, a smaller crystal size, a higher specific surface area, and a greater number of binding sites. Compared with HAP-25, the CysHAP2.0–25 composite exhibited a better Cd(II) sorption performance and a 100% Pb(II) removal in a wide range of solution pH and background electrolyte concentration. The removal performance of CysHAP2.0–25 composite towards Cd(II) was suppressed by the coexisting aqueous components with an obviously stronger inhibiting action of humic acid (HA) than low molecular weight organic acids (LMWOAs) and mixed inorganic components (IC). Pb(II) slightly reduced the sorption ratio of Cd(II) and forced Cd(II) to bind on the -SOx sites derived from sulfhydryl oxidation. In contrast, Cd(II) had no impact on the sorption behaviors of Pb(II). Overall, the synthesized CysHAP2.0–25 composite could be potential applied for the purification of Cd- and Pb-bearing water systems.

Expedient recycling of peptide organocatalysts using a nanocrystalline hydroxyapatite catching system

Peptide catalysts represent versatile alternatives to metal-based catalysts and other organocatalysts, due to facile synthesis, modularity, and often high activity and stereoselectivity. In particular, in tripeptides the distance between the catalytic groups is expected to promote 1,4-addition reactions. Immobilization of the catalyst allows easy recovery, but this strategy requires the modification of the sequence by introducing a suitable linker, with the risk of losing catalyst effectiveness. Another option is the inclusion or adsorption on an appropriate material. Herein, we describe the expedient use of nanocrystalline hydroxyapatite (HAp) as a biocompatible, inert peptide-catching system. In contrast to the immobilization strategy, HAp can be utilized with the native sequences. Encouraging results have been obtained in the capture and recycle of the peptide-acid Pro-Pro-AspNH2, utilized for the asymmetric conjugate addition of aldehydes to nitrostyrene.

The Biocompatibility and Self-Healing Effect of a Biopolymer’s Coating on Zn Alloy for Biomedical Applications

The objective of this study was to formulate dip coatings, incorporating casein, NaOH, and nanocrystalline hydroxyapatite (nanoHAp), with self-healing properties for application on ZnMg3.2 wt.% alloy in the field of biomedical applications. This study hypothesizes that the self-healing mechanism within the layer will impede substrate degradation by progressively filling defects where chlorides from simulated body fluids intervene. Furthermore, it aims to mitigate potential damage effects during the implantation process by the layer’s self-healing capabilities. The research focused on the dip-coating process parameters and chemical composition of baths for producing casein coatings on Zn alloy surfaces. This study investigated the impact of casein and NaOH concentration, along with the immersion time of ZnMg3.2 wt.% samples in the coating bath, on the self-healing capability of the coating under simulated human body fluid conditions (Ringer’s solution, temperature: 37 °C). Effective technology was developed by selecting specific chemical compositions and immersion times in the coating bath, enhancing the self-healing progress against coating damage in Ringer’s solution at 37 °C. The most significant self-healing effect was observed when the ZnMg3.2 wt.% substrate underwent a 1 h immersion in a coating bath containing 2 g of casein, 4 g of NaOH, and 0.1 g of nanoHAp powder. Electrochemical tests were instrumental in determining the optimal casein concentration and immersion time of the Zn alloy in the coating bath.

Tri-Component Hydrogel as Template for Nanocrystalline Hydroxyapatite Deposition Using Alternate Soaking Method for Bone Tissue Engineering Applications.

Composite hydrogels containing apatite-like particles can act as scaffolds for osteoblast proliferation, with applications in bone tissue engineering. In this respect, porous biocompatible hydrogels were obtained from chitosan, oxidized pullulan, and PVA in different ratios. The stability of the hydrogels was ensured both by covalent bonds between aldehyde groups of oxidized pullulan and free amino groups of chitosan, and by physical bonds formed during freeze-thaw cycles and lyophilization. The deposition of calcium phosphates was performed by alternate soaking of the porous hydrogels into solutions with calcium and phosphate ions, assuring a basic pH required for hydroxyapatite formation. The mineralized hydrogels were characterized using FTIR spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis, showing that inorganic particles containing between 80 and 92% hydroxyapatite were deposited in a high amount on the pore walls of the polymeric matrix. The composition of the organic matrix influenced the crystallization of calcium phosphates and the mechanical properties of the composite hydrogels. In vitro biological tests showed that mineralized hydrogels support the proliferation of MG-63 osteoblast-like cells to a greater extent compared to pristine hydrogels.

Photothermal Conversion Efficiency of Silver and Gold Incorporated Nanosized Apatites for Biomedical Applications.

The aim of this research was to investigate the photothermal ability of nanocrystalline hydroxyapatite (nHAp) incorporated with silver and gold. It was studied by using a recently developed technique evaluating the photothermal conversion efficiency. The heating performance of aqueous dispersions was examined under 445 and 532 nm excitation. The largest increase in temperature was found for the 2% Ag-nHAp and reached above 2 °C per mg/mL of sample (445 nm) under 90 mW laser continuous irradiation and an external light-to-heat conversion efficiency of 0.11 L/g cm. The obtained results have shown a new functionality of nanosized apatites that has not been considered before. The studied materials have also been characterized by XRPD, TEM, BET, and UV-Vis techniques. Finally, in this work, a new idea for their application was proposed: photothermal therapy.

Comparison of Nanocrystalline Hydroxyapatite Bone Graft with Empty Defects in Long Bone Fractures: A Retrospective Case-Control Study.

BACKGROUND The regeneration of bone defects is indicated to restore lost tissue mass and functionality. Ostim®, an absorbable nanocrystalline hydroxyapatite (NCHA) paste, is indicated to enhance bone regeneration in bone defects due to trauma or surgery. This retrospective study of 110 patients with long-bone fracture defects presenting at a single trauma center between 2010 and 2012 aimed to compare outcomes with and without the use of Ostim® absorbable nanocrystalline hydroxyapatite paste. MATERIAL AND METHODS The study encompassed fractures in 110 patients - 55 patients received any defect augmentation (ED) and 55 patients were treated with NCHA augmentation. Fractures were located at the distal radius (66.4%, n=73), proximal humerus (5.5%, n=6), and proximal tibia (28.2%, n=31). Evaluating the clinical follow-up, the study encompassed post-surgery complications (eg, non-unions, infection). Bone healing was evaluated by conventional radiographs. RESULTS Postoperative complications occurred in 45.5% of patients regardless of the treatment (P=1.0). The non-union rate in both groups was 5.5% (n=8, P=1.0), and the risk for infection was lower in the NCHA group (3.6%, ED: n=3, NCHA: n=1, p=0.62). Patients suffered open fractures were treated in the NCHA group (100%, n=7, P=0.003). Radiological assessment demonstrated comparable healing of the fracture border, fracture gap, and articular surface (P>0.05). CONCLUSIONS The findings from this retrospective study support previous studies that have shown Ostim® absorbable nanocrystalline hydroxyapatite paste enhances outcomes and reduces the risk of complications when used to repair bone defects in long-bone fractures in trauma patients. NCHA paste augmentation is suitable for use in traumatic long-bone fractures.

Effect of Atomic-Layer-Deposited Hydroxyapatite Coating on Surface Thrombogenicity of Titanium

This study aimed to evaluate the surface characteristics of a nanocrystalline hydroxyapatite coating made through atomic layer deposition (ALD-HA) on titanium surfaces and to investigate its effect on blood coagulation and platelet adhesion. Grade 2 square titanium discs (0.7 cm, 1 mm thick) were used (n = 108). Half of the substrates (n = 54) were coated with ALD-HA, and the other half were used as the non-coated control. Surface free energy (SFE), contact angle (CA), surface roughness (Ra), and chemical composition were evaluated. Blood thrombogenic properties were assessed on ALD-HA and non-coated surfaces using the kinetic clotting time method. The platelets’ adhesion and morphology were also evaluated. The ALD-HA-coated surfaces demonstrated significantly higher polar SFE (p < 0.001) and lower CA (p < 0.001) values compared to the non-coated surfaces. In addition, the surface roughness was significantly lower for the ALD-HA (p < 0.001) than for the non-coated surfaces. Platelets adhered to both surfaces; however, there was variability in platelet morphologies in different areas with higher platelet density on the ALD-HA surfaces. There was no significant difference in the overall absorbance values of the hemolyzed hemoglobin for both substrates, and the total clotting time was achieved at 60 min. It can be concluded that the ALD-HA coating of titanium can enhance surface wettability, increase surface free energy, and support blood coagulation and platelet adhesion.

Influence of Polymeric Blends on Bioceramics of Hydroxyapatite

Bioceramics are used to repair, rebuild, and replace parts of the human body, e.g., bones, joints and teeth, in the form of powder, coatings or prostheses. The synthetic hydroxyapatite [Ca10(PO4)6(OH)2 (HAP)] based on calcium phosphate has been widely used in the medical and dental areas due to the chemical similarity with the inorganic component of human bone tissue. In this work, hydroxyapatite nanocrystalline powders were synthesized by the solid-state reaction method and sintered with a galactomannan and chitosan blend. The bioceramics studied were prepared from 70%, 80% and 90% of hydroxyapatite with 30%, 20% and 10% of galactomannan and chitosan blends, respectively. The influence of the blend content on the bioceramics was investigated through structural, vibrational, thermal, morphological and dielectric characterizations. It was observed that the increase in the blend percentage promoted an increase in the grain size, which was followed by a decrease in the density and hardness of the samples. The sample with a higher amount of polymeric blend also presented a higher dielectric constant and higher losses.

The effect of pH on the morphological transformation of nanocrystalline hydroxyapatite during wet chemical synthesis

The effect of pH on the morphological transformation of nanocrystalline hydroxyapatite during wet chemical synthesis

Preparation and growth behaviours of low porosity hydroxyapatite with enhanced adhesion by electrochemical deposition on micro-arc oxide coatings

Electrochemical deposition (ED) has been proposed as a low temperature approach for preparing hydroxyapatite (HA) coatings. To overcome the problem of low adhesion, the preparation of thin and low-porosity coatings on Ti substrates pre-treated by micro-arc oxidation (MAO) is a good strategy. In this paper, a thin and dense HA coating was obtained by modifying parameters at pH 6.4, 45 °C, and 0.5 mA·cm−2. The growth behaviours of HA electrodeposited on MAO coatings were investigated by SEM and EDS technology and summarized that the HA was initially generated in the MAO micropores, then covered the entire MAO surface and gradually grew outwards. This growth pattern was also confirmed by ATR-FTIR, XPS, EIS, open potential, and wettability results at different ED cycles. Adjusting 1:1 power-on/off time ratio affected the morphology of HA grown in the pores in the early stage and also increased the interfacial strength, up to 10.69 MPa at duty cycle 12/24.The cross-section of the final specimen was characterised by TEM and EDS, indicating that amorphous layers, nanocrystalline HA, and submicron HA were formed sequentially from the TiO2(Ca)/HA interface outwards. The increase in Ca2+ concentration and the formation of CaO bonds at the interface may be important reasons for the adhesive enhancement. This process provides a strategy to enhance the strength of bioceramic materials on Ti substrates.