Nanostructured Hydroxyapatite Research Articles

Polycaprolactone Microsphere‐Encapsulated Fluconazole‐Loaded Zinc Oxide and Hydroxyapatite Nanocomposites for Enhanced Biological Performance

AbstractOsteomyelitis (OM), a debilitating disease caused by a microbial infection of the bones, continues to pose a formidable obstacle for orthopedic surgeons. The conventional methods for the prevention and treatment of OM are insufficient. In this research work, we developed a strategic green nanostructure using the antifungal drug Fluconazole (FCZ)‐assimilated zinc oxide nanoparticles (ZnO‐NPs) and hydroxyapatite (HAp) nanostructures as filler and hydrophobic polycaprolactone (PCL) as matrix by a solution‐based chemical method. The ceramic carrier‐like nanostructures ZnO and HAp were synthesized by the in situ precipitation method. The physicochemical characterization of the prepared polymer‐coated drug ceramic nanocomposite (FCZ‐ZnO‐HAp‐PCL) was achieved using Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), particle size distribution (PSD), X‐ray diffraction (XRD), and Energy‐dispersive X‐ray (EDX) analysis. Furthermore, the biocompatibility and anticancer activity of the nanocomposite were explored by an MTT assay study. Successfully synthesized FCZ‐ZnO‐HAp‐PCL nanocomposite exhibited profound antimicrobial activity against targeted microbe species and potential cytotoxicity towards MCF‐7 human breast adenocarcinoma cell lines, which may be potentially used for the treatment of OM and prospective infections.

High-aspect-ratio nanostructured hydroxyapatite: towards new functionalities for a classical material.

Hydroxyapatite-based materials have been widely used in countless applications, such as bone regeneration, catalysis, air and water purification or protein separation. Recently, much interest has been given to controlling the aspect ratio of hydroxyapatite crystals from bulk samples. The ability to exert control over the aspect ratio may revolutionize the applications of these materials towards new functional materials. Controlling the shape, size and orientation of HA crystals allows obtaining high aspect ratio structures, improving several key properties of HA materials such as molecule adsorption, ion exchange, catalytic reactions, and even overcoming the well-known brittleness of ceramic materials. Regulating the morphogenesis of HA crystals to form elongated oriented fibres has led to flexible inorganic synthetic sponges, aerogels, membranes, papers, among others, with applications in sustainability, energy and catalysis, and especially in the biomedical field.

Probing the influence of strontium doping and annealing temperature on the structure and biocompatibility of hydroxyapatite nanorods.

Among numerous biologically important metal cations, strontium (Sr2+) has received much attention in bone tissue regeneration because of its osteoinductive properties combined with its ability to inhibit osteoclast activity. In this study, strontium-doped hydroxyapatite (Sr-HAp) nanorods with varying molar ratios of Ca : Sr (10 : 0, 9 : 1, 5 : 5, 3 : 7 and 0 : 10) were synthesized using the chemical precipitation technique. The synthesized Sr-HAp nanostructures were characterized using powder X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy, energy dispersive X-ray spectroscopy, and Raman and Fourier transform infrared (FTIR) spectroscopies to understand their structural and morphological features, and composition. XRD results revealed the formation of HAp nanostructures, whose unit cell volume increased as a function of the dopant level. The reaction process investigation showed the formation of hydroxyapatite (HAp), strontium apatite (SAp) and various Sr-HAp phases. FESEM micrographs displayed the morphological transformation of Sr-HAp from nanorods to nanosheets upon increasing the dopant level. In the FTIR spectra, the bands of the PO43- group shifted towards a lower wavenumber upon increasing the dopant concentration in Sr-HAp that signifies the structural distortion due to the presence of a large amount of strontium ions. The peaks of PO43- and OH- vibrations in the Raman spectra were further analysed to corroborate the structural distortion of Sr-HAp. Selected area electron diffraction patterns obtained using TEM reveal the reduced crystallinity of Sr-HAp due to Sr-doping, which is in line with the XRD results. Finally, the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay showed that the synthesized Sr-HAp has no toxic effect on the survival and growth of mesenchymal stem cells. In summary, the synthesized novel Sr-HAp nanorods exhibit great promise for bone tissue engineering applications.

Synthesis and characterisation of magnesium-wrapped hydroxyapatite nanomaterials for biomedical applications

The advancement of novel nanobiomaterials holds significant importance in the fields of drug delivery and environmental remediation. Hydroxyapatite, which falls under the category of bioceramic materials, has demonstrated efficacy as a bone graft material. The substitution of cations in hydroxyapatite has been found to enhance its biological properties, making it a promising material for various biomedical applications. In this study, the synthesis of Mg2+ substituted hydroxyapatite nanostructures was conducted through the sol-gel method employing different surfactants, namely polyethylene glycol and cetyltrimethylammonium bromide. The resulting nanoparticles were subjected to analysis to evaluate their structural, morphological, and optical characteristics. The antimicrobial and antioxidant behavior of the Mg2+ doped hydroxyapatite nanoparticles were also studied. The XRD analysis showed a hexagonal crystal structure for Mg2+ doped hydroxyapatite nanostructures for all samples. The Raman and FTIR results also confirmed the successful substitution of divalent cation Mg2+ in hydroxyapatite. EDAX results exhibited the qualitative elemental composition and stoichiometric nature of synthesized hydroxyapatite. The optical study showed higher transmission in the visible region for the Mg2+ doped hydroxyapatite prepared using various surfactants. The microbial restriction efficacy of Mg2+ doped hydroxyapatite prepared using various surfactants was examined against human pathogenic bacterias Shigella flexneri (MTCC-2197), Escherichia coli (MTCC-4213), Pseudomonas aeruginosa (MTCC-3131), Klebseilla pneumoniae (MTCC-1214), and Staphylococcus aureus (MTCC-3123). The hydroxyapatite nano biomaterial doped with Mg2+ demonstrates remarkable antibacterial, antifungal, and antioxidant properties. The HeLa cell lines exhibited significant cytotoxicity when exposed to magnesium ion-doped hydroxyapatite nanoparticles.

Extraction of Natural Nanostructured Hydroxyapatite from Pacific Cod (Gadus macrocephalus) Bone with a Thermostable Collagenolytic Protease and Its ex vivo Intestinal Bioavailability

Extraction of Natural Nanostructured Hydroxyapatite from Pacific Cod (Gadus macrocephalus) Bone with a Thermostable Collagenolytic Protease and Its ex vivo Intestinal Bioavailability

Histomorphometric evaluation, SEM, and synchrotron analysis of the biological response of biodegradable and ceramic hydroxyapatite-based grafts: from the synthesis to the bed application.

This study aimed to analyze the physicochemical and histological properties of nanostructured hydroxyapatite and alginate composites produced at different temperatures with and without sintering, and implanted in rabbit tibiae. Hydroxyapatite-alginate (HA) microspheres (425-600µm) produced at 90 and 5 ºC without (HA90 and HA5) or with sintering at 1000ºC (HA90S and HA5S) were characterized by XRD, FT-IR, SEM, and in vitro degradation assay; also were implanted in bone defects on rabbit's tibiae (n=12). The animals were randomly divided into five groups (blood clot, HA90S, HA5S, HA90, and HA5) and euthanized after 7 and 28 days. The samples were assessed by light (histomorphometry) and polarized light microscopy, SEM-BSE microscopy, EDS-SEM elemental analysis, and synchrotron radiation X-ray microfluorescence. The non-sintered biomaterials had a lower crystallinity than sintered materials, being more degradable in vitro and in vivo. However, the sinterization of HA5 led to the apatite phase's decomposition into tricalcium phosphate (TCP). Histomorphometric analysis showed the highest (p<0.01) bone density in the blood clot group, similar bone levels among HA90S, HA90, and HA5, and significantly less bone in the HA5S. HA90 and HA5 groups presented higher degradation and homogeneous distribution of the new bone formation onto the surface of biomaterials fragments, compared to HA90S, presenting bone only around intact microspheres (p<0.01). EDS-SEM and μXRF-SR mapping techniques showed the elemental distribution of Ca, P, and Zn in the newly formed bone similar to the cortical bone indicating the bone maturity at 28 days. The synthesized biomaterials are biocompatible and osteoconductive. The heat treatment directly influenced the material's behavior, where non-sintered HA90 and HA5 showed higher degradation allowing a better distribution of the new bone onto the surface of the biomaterials fragments compared to HA90S presenting the same level of new bone, but only on the surface of the intact microspheres, potentially reducing the bone-biomaterial interface.

Experimental Early Stimulation of Bone Tissue Neo-Formation for Critical Size Elimination Defects in the Maxillofacial Region.

A biomaterial is proposed for closing extensive bone defects in the maxillofacial region. The composition of the biomaterial includes high-molecular chitosan, chondroitin sulfate, hyaluronate, heparin, alginate, and inorganic nanostructured hydroxyapatite. The purpose of this study is to demonstrate morphological and histological early signs of reconstruction of a bone cavity of critical size. The studies were carried out on 84 white female rats weighing 200-250 g. The study group consisted of 84 animals in total, 40 in the experimental group and 44 in the control group. In all animals, three-walled bone defects measuring 0.5 × 0.4 × 0.5 cm3 were applied subperiosteally in the region of the angle of the lower jaw and filled in the experimental group using lyophilized gel mass of chitosan-alginate-hydroxyapatite (CH-SA-HA). In control animals, the bone cavities were filled with their own blood clots after bone trepanation and bleeding. The periods for monitoring bone regeneration were 3, 5, and 7 days and 2, 3, 4, 6, 8, and 10 weeks. The control of bone regeneration was carried out using multiple morphological and histological analyses. Results showed that the following process is an obligatory process and is accompanied by the binding and release of angiogenic implantation: the chitosan construct actively replaced early-stage defects with the formation of full-fledged new bone tissue compared to the control group. By the 7th day, morphological analysis showed that the formation of spongy bone tissue could be seen. After 2 weeks, there was a pronounced increase in bone volume (p < 0.01), and at 6 weeks after surgical intervention, the closure of the defect was 70-80%; after 8 weeks, it was 100% without violation of bone morphology with a high degree of mineralization. Thus, the use of modified chitosan after filling eliminates bone defects of critical size in the maxillofacial region, revealing early signs of bone regeneration, and serves as a promising material in reconstructive dentistry.

Augmentation of photocatalytic activity of nano-crystallite hydroxyapatite by fluoride doping

In this study, we synthesized hydroxyapatite (HAp) with added dopants and utilized it for the degradation of a model dye, Congo red, Congo red in an aqueous solution. In particular, to enhance photocatalytic activity, the HAp nanostructure was engineered via doping with different percentages (0.25 %, 0.5 %, 1 %, and 2 %) of fluoride ions. However, this newly developed fluoride-doped HAp (F-HAp) was characterized by several instrumental techniques, e.g. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and UV–vis spectrometry. Crystallographic characterization of the synthesized pure and F-doped HAp was performed from the XRD data. On the other hand, the efficiency of F-HAp as a photocatalyst was investigated via the halogen light-induced degradation of Congo red. F-HAp nano-photocatalyst effectively degraded Congo red in aqueous solution and process variables such as pH, reaction time, doses of catalyst, source of photons (sunlight degradation), temperature, and Congo red concentration were optimized. Compared to pure HAp, altering the percentages of dopant ions within the HAp structure resulted in an enhanced photocatalytic performance for the degradation of Congo red dye across all tested conditions. It was noted that under specific conditions, such as a pH of 7 and 150 min of halogen lamp irradiation, employing a 0.1 g dosage of 0.25 % F-HAp led to nearly 99 % degradation of a 20 ppm Congo red solution. Notably, this level of degradation surpassed that achieved with pure HAp.

Mechanical alloying and high-repetition-pulsed-laser based manufacturing method for nanostructured hydroxyapatite films on cobalt-chromium substrates

In this study, we report a manufacturing process for coating nanostructured and hierarchically porous Hydroxyapatite (HA) films on cobalt-chromium (CoCr) substrates. Nanoparticles of HAP are prepared using three different methods: ball milling of sol–gel synthesized HAP, mechanical alloying of calcium oxide (CaO) and diammonium phosphate (DAP), and mechanical alloying of eggshell and diammonium phosphate. The nanoparticle's characterization showed the presence of nanophase HAP in sol–gel synthesized powders and synthesis of apatite phases in mechanically alloyed powders. Small droplets of nanoparticle ethanol suspensions were injected on the substrate and irradiated with high-repetition-rate picosecond pulsed laser to coat the CoCr samples. Characterization of the deposited films showed bonding of HAP nanoparticles to a film with nanostructured morphology and hierarchical porosity and the incorporation of CoCr from the substrate into the first few deposited layers of HAP nanoparticles. The two-step manufacturing process results in bioactive and biocompatible HAP films with morphology that is desirable for the growth and infiltration of biological cells.

Strontium-containing nanostructured hydroxyapatite microspheres for bone regeneration

The aim of this study was to analyze the biological behavior and osteogenic potential of nanostructured hydroxyapatite microspheres substituted with strontium (nHASr). Therefore, twenty adult male Wistar rats were randomly distributed into two groups: GnHASr – critical bone defect filled with nHASr microspheres; e CG (control group) – critical bone defect without implantation of biomaterial; evaluated at the biological points of 30 and 60 days. The collected specimens were processed and stained with hematoxylin-eosin (HE) and Masson-Goldner trichrome (TG) and examined by light microscopy. Posteriorly, they were analyzed histomorphometrically to measure the percentage of neoformed osteoid matrix (%OM). In both groups studied, at all biological points, deposition of reparative osteoid matrix (OM) was observed near the bone edges; discrete chronic inflammatory response; connective tissue formation and neovascularization in the residual area of the defect. In the GnHASr, in the two evaluated periods, the deposition of OM was also noticed, both around and inside the microspheres. At 60 days, an area of 7.54% of OM deposition in relation to the total defect area was evidenced in the GnHASr, while in the CG this value was 6.80%. It is concluded that the nHASr microspheres evaluated were biocompatible, biodegradable, bioresorbable, bioactive and osteoconductive. In both groups, the formation of neomineralized tissue occurred in a limited way, which indicates that the concentration of metal used in the replacement did not favor greater osteogenic potential for the biomaterial. The evaluated biomaterial it's adequate for use as a filling material.

Enhancing the Strength of Microporous Nanofibrous PVA Mats by Incorporating Nanostructured Hydroxyapatite Synthesized by a Combustion Route for Bone Tissue Regeneration

Enhancing the Strength of Microporous Nanofibrous PVA Mats by Incorporating Nanostructured Hydroxyapatite Synthesized by a Combustion Route for Bone Tissue Regeneration

Resistive coupled microwave sintering of hydroxyapatite/titania nano-biocomposite and tailoring its mechanical properties

Tailoring the mechanical properties of bioceramics plays a crucial role in the fabrication of hard tissue substitutes. In this work, phase pure nanostructured hydroxyapatite and titania were synthesized using a single-step combustion technique. To study the influence of titania in the mechanical properties of hydroxyapatite, hydroxyapatite/titania (TiO2-0%, 10%, 20%, and 30%) nanocomposites were prepared. The sample containing 20% titania showed maximum sinterability and was analysed in detail. The samples were sintered by a novel resistive coupled microwave sintering to 98.9% of the theoretical density at 1020 °C for a soaking duration of 20 min. A substantial reduction in sintering temperature of ∼165 °C and a significantly low soaking duration were observed in the samples sintered using the new technique and it yielded pellets with reduced grain size compared to the samples sintered via conventional resistive heating. They have shown better microhardness of 7.7 GPa, enhanced compressive strength of 194.9 MPa, and improved elastic modulus of 136.2 GPa without compromising the cell viability, cell adhesion, differentiation, proliferation, and biomineralization. The results indicate that by varying the titania content in hydroxyapatite and by adopting a suitable low-temperature sintering strategy like resistive coupled microwave sintering, one can tailor the mechanical properties of bone implants.

Preparation and characterization of hydroxyapatite nanoparticles doped with nickel, tin, and molybdate ions for their antimicrobial effects

Background Hydroxyapatite (HAp) nanoparticles doped with some ions have shown anticancer and antibacterial properties and are of great interest for the development of new biomedical applications. Therefore, the present study aimed to investigate the preparation and in vitro characterization of HAp nanoparticles doped with (Ni2+), tin (Sn2+), molybdate (Mo3+) ions for prevention of infections specially in bone tissue engineering. Methods HAp and HAp nanocrystal powders doped with nickel (Ni2+), tin (Sn2+), molybdate ions (Mo3+) with concentrations of 500, 1000, and 2000 ppm were prepared by the sol-gel method using a combination of calcium nitrate and phosphorous pentoxide as chemical reagents. The nanoparticles were characterized by FT-IR, XRD, EDAX and SEM. Their antimicrobial effect was studied by disk diffusion method on two types of bacteria: Pseudomonas aeruginosa and Staphylococcus aureus. Results FT-IR and XRD tests confirmed the formation of HAp nanoparticles. SEM images showed the morphology and nanostructure of HAp and Ni@HAp. Ni@HAp showed significantly more antimicrobial effects than the other two ions on S. aureus. EDAX confirmed the presence of Ni2+ ions in the Ni@HAp structure and the element map also showed very good dispersion of elements in both HAp and Ni@HAp structures. Conclusions HAp nanoparticles doped with nickel ions may be considered as a promising antibacterial treatment in bone tissue engineering and repairing of skeletal injuries contaminated with S. aureus.

High‐Content Hydroxyapatite Carbon Composites for the Electrochemical Detection of Heavy Metal Cations in Water

AbstractThe great performance of nanostructured hydroxyapatite (Hap) in adsorbing heavy metal cations with the good electrical conductivity of high‐surface carbon materials was here combined for the crafting of high‐content hydroxyapatite electrodes (Hap 84–96 wt.%) endowed with the synergistic capability of detection and adsorption of heavy metal cations by water solutions. To improve the sustainability of the sensor, a mesoporous carbon (derivable by bio‐waste) was selected as scaffold for depositing Hap by simply co‐precipitation. The composite with 92 wt.% of Hap, which exhibited ca. 1 : 1 ratio between the exposed area of Hap and carbon (by Brunauer‐Emmett‐Teller method), invariably showed an average stripping oxidation peak intensity of ca. 250 μA cm−2 and 150 μA cm−2 for a 50 μM Pb2+ and Cu2+ solution, respectively. Control experiments showed that the above sensor outperformed the sensibility of two low‐content Hap electrodes (4 and 8 wt.%), representative of the best performing Hap‐carbon composites available in literature.

Poly(methacrylic acid)/gelatin interpenetrating network hydrogels reinforced by nano-structured hydroxyapatite particles—improved drug delivery systems

Novel poly(methacrylic acid)/gelatin (PMAG) interpenetrating networks reinforced by different amounts of nanostructured particles of hydroxyapatite (HA) (HA/polymer weight ratios from 0% to 40%) were synthesized. The introduction of HA significantly enhanced mechanical properties, but slightly reduced swelling ability, pH sensibility and porosity. The increase of HA/polymer ratio to 40% increased the compressive strength from 29.83 (pure PMAG hydrogel) to 68.16 kPa. Drug release behavior investigated in simulated physiological conditions, using ciprofloxacin (hydrophilic) and oxaprozin (hydrophobic), demonstrated different drug release kinetics. In vitro antimicrobial testing demonstrated bactericidal and fungicidal activity of the drug-loaded hydrogels against E. coli, S. aureus and C. albicans.

Bioactive Glass-Ceramic Scaffolds Coated with Hyaluronic Acid-Fatty Acid Conjugates: A Feasibility Study.

Promoting bone healing is a key challenge in our society that can be tackled by developing new implantable biomaterials provided with regenerative properties. In this work, the coating of three-dimensional porous glass-derived scaffolds with hyaluronic acid (HA)-fatty acids was investigated for the first time. The starting scaffolds, based on bioactive silicate glass, were produced by foam replication followed by sintering; then, HA-palmitate and HA-oleate conjugate coatings were deposited on the scaffold struts through a dipping procedure. FT-IR analysis confirmed the successful deposition of the coatings on the surface and struts of the scaffolds, the foam-like architecture of which was maintained as assessed by SEM investigations. The in vitro bioactivity of the HA-fatty-acid-coated scaffolds was studied by immersion tests in simulated body fluid and the subsequent evaluation of hydroxyapatite formation. The deposition of the polymeric coating did not inhibit the apatite-forming ability of scaffolds, as revealed by the formation of nanostructured hydroxyapatite agglomerates 48 h from immersion. These promising results motivate further investigation of these novel bioactive systems, which are expected to combine the bone-bonding properties of the glass with the wound-healing promotion carried out by the polymeric conjugates.

Application of Early Loading on Surface Implants with Nanostructured Hydroxyapatite Coating

The objective of this work was to describe the variation in the stability of nanostructured HA coatied implants installed in the upper premolar area by means of resonance frequency analysis (RFA, measured in ISQ) during the first 4 weeks, in partially edentulous patients. The study design is quantitative, observational, descriptive, longitudinal and prospective. The implants used were the UNITITE line of S.I.N Implant System® of 3.5 mm x 11.5 mm, which have HAnano® surface. These implants have a surface treatment with a nanostructured hydroxyapatite coating, which increases hydrophilicity and would accelerate the process of new bone formation and remodeling after installation. The surgeries were carried out by students of the Oral Maxillofacial Implantology department, at Universidad Mayor, Santiago. A descriptive analysis was performed on a sample of 8 implants, resulting in a variation of 1 to 2 ISQ points during the four weeks studied. The results suggest that as the stability of the implants keeps constant, it would be possible to carry out early loading at 4 weeks in the implants studied, however, a greater number of samples, comparative studies and longer-term studies are required to generate more robust conclusions on this subject.

Biomimetic Hydroxyapatite Composite Coatings with a Variable Morphology Mediated by Silk Fibroin and Its Derived Peptides Enhance the Bioactivity on Titanium.

Various modifications performed on titanium alloy surfaces are shown to improve osteointegration and promote the long-term success of implants. In this work, a bioactive nanostructured hydroxyapatite (HA) composite coating with a variable morphology mediated by silk fibroin (SF) and its derived peptides (Cs) was prepared. Numerous experimental techniques were used to characterize the constructed coatings in terms of morphology, roughness, hydrophilicity, protein adsorption, in vitro biomineralization, and adhesion strength. The mixed protein layer with different contents of SF and Cs exhibited different secondary structures at different temperatures, effectively mediating the electrodeposited HA layer with different characteristics and finally forming proteins/HA composite coatings with versatile morphologies. The addition of Cs significantly improved the hydrophilicity and protein adsorption capacity of the composite coatings, while the electrodeposition of the HA layer effectively enhanced the adhesion between the composite coatings and Ti surface. In the in vitro mineralization experiments, all the composite coatings exhibited excellent apatite formation ability. Moreover, the composite coatings showed excellent cell growth and proliferation activity. Osteogenic induction experiments revealed that the coating could significantly increase the expression of specific osteogenic markers, including ALP, Col-I, Runx-2, and OCN. Overall, the proposed modification of the Ti implant surface by protein/HA coatings had good potential for clinical applications in enhancing bone induction and osteogenic activity of implants.

Does Melatonin Associated with Nanostructured Calcium Phosphate Improve Alveolar Bone Repair?

Background and objectives: Calcium phosphates have been widely used as bone substitutes, but their properties are limited to osteoconduction. The association of calcium phosphates with osteoinductive bioactive molecules has been used as a strategy in regenerative medicine. Melatonin has been studied due to its cell protection and antioxidant functions, reducing osteoclastic activity and stimulating newly formed bone. This study aimed to evaluate the effect of topical application of melatonin associated with nanostructured carbonated hydroxyapatite microspheres in the alveolar bone repair of Wistar rats through histological and histomorphometric analysis. Materials and Methods: Thirty female Wistar rats (300 g) were used, divided randomly into three experimental groups (n = 10), G1: nanostructured carbonated hydroxyapatite microspheres associated with melatonin gel (CHA-M); G2: nanostructured carbonated hydroxyapatite (CHA); G3: blood clot (without alveolar filling). The animals were euthanized after 7 and 42 days of the postoperative period and processed for histological and histomorphometric evaluation. Kruskal-Wallis and Dunn's post-test were applied to investigate statistical differences between the groups at the same time point for new bone and connective tissue variables. Mann-Whitney was used to assess statistical differences between different time points and in the biomaterial variable. Results: Results showed a greater volume of residual biomaterial in the CHA-M than the CHA group (p = 0.007), and there were no significant differences in terms of newly formed bone and connective tissue between CHA and CHA-M after 42 days. Conclusions: This study concluded that both biomaterials improved alveolar bone repair from 7 to 42 days after surgery, and the association of CHA with melatonin gel reduced the biomaterial's biodegradation at the implanted site but did not improve the alveolar bone repair.

Morphological evaluation of HAp nanostructures and its shape-dependent protein adsorption study

The main purpose of contemporary biomaterial research is to use cost-efficient bioactive and biocompatible materials to replace damaged bone. In the current study, cuttlefish (Sepiaofficinalis) bone powder was used as a precursor in the production of hydroxyapatite nanostructures (HAp NS) utilizing the silicon oil bath-mediated precipitation technique. The reaction was performed in various time periods such as 6, 12, 24, 48 and 60 h (h) at 90 °C to prepare HAp nanostructures with diverse morphologies. XRD, FTIR, and FESEM were used to characterize the produced HAp NS, and its capacity for protein adsorption was also assessed. Furthermore, it was evidenced that modulation of cellular activities and tissue functions in human bones is mostly controlled by the shape and crystallographic properties of hydroxyapatite (HAp) nanostructures.