Nano Hydroxyapatite for Biomedical Applications Derived from Chemical and Natural Sources by Simple Precipitation Method

Characterization and potential usage of selected eggshell species

Today's awareness of environmental pollution and the idea of creating a reuse area for waste is one of the trend topics. The base opinion, regarding the reuse of any material is that all resources are inherently limited in the world. In the ethical approach, it is a moral issue that people take responsibility for future generations to protect nature. Eggshells are one of the most used natural biomasses. And natural harmless eggshells deserve to be researched to reveal their potential. The aim of this study, blending the characterization processes with the research published until now, finding criteria for the unique structures and application capacities of eggshell species, ensures choosing the right type as biomass in the industry, and directing the eggshell usage to the appropriate applications and industries. In many industries, finding benchmarks of eggshell types in their unique structures and application capacity gives a clue to selecting the right type and directing the eggshells to a suitable place. In this study, different species of eggshell (Coturnix Coturnix Japonica, Anser Anser, Denizli Hen, Alectoris Chukar, and Struthio Camelus) were characterized by XRD, FTIR, AFM, Stereo Microscope, SEM, XRF, and TGA analysis. Calcined forms of eggshell samples were characterized by XRD, FTIR, and XRF analysis. TGA analysis results are used as a precursor to determine the temperature of calcination (800-900°). XRD results show that the CaCO3 peak is 2Ɵ=29.58° for all eggshells. The reason why this peak is not observed after the calcination process is that the entire CaCO3 structure is converted to CaO. In FTIR results, the C-O stretching band which is observed at 1424 cm- 1 is the main characteristic band of selected eggshell species. When AFM images are examined, it is seen that the surface of small eggshells is rougher, while the surface of the eggshell becomes smoother as the egg size increases. SEM and stereo microscope images show that the shell thickness increases as the egg size increases.

Scrutinizing the effect of rGO-cuttlefish bone hydroxyapatite composite infused carrageenan membrane towards wound reconstruction

Carrageenan is an emerging biopolymer for wound healing and regenerative applications. In this study, reduced graphene oxide (rGO) and hydroxyapatite (HAp) nano-composites infused carrageenan bioactive membrane was fabricated. Here, hydroxyapatite was synthesized from cuttlefish bone (CF-HAp) and its properties were compared with that of chemically synthesized HAp. Crystalline Ca5(PO4)3(OH) and Ca3(PO4)2) phases were obtained in cuttlefish bone derived HAp. Reduced graphene oxide was synthesized and composites were prepared with chemical HAp and CF-HAp. FT-IR spectral analysis showed the imprints of hydroxyapatite on the membrane and also nano-structured particles were evident through morphological estimations that confirm the distribution of nano-particles on the carrageenan membrane. Nano-particulates infused carrageenan membrane showed the maximum tensile strength, in which graphene incorporated carrageenan bioactive membrane showed highest stability of 15.26 MPa. The contact angle of chemical HAp infused carrageenan membrane (CAR-HAp) showed more hydrophilic in nature (48.63° ± 7.47°) compared to control (61.77° ± 1.28°). Bio-compatibility features enunciate the optimal compatibility of fabricated bioactive membrane with fibroblast cell line; simultaneously, CAR-rGO-CF-HAp showed tremendous wound healing behavior with zebrafish model. Hence, fabricated bioactive membrane with the infusion of rGO- hydroxyapatite derived from cuttlefish bone was found to be a versatile biopolymer membrane for wound healing application.

Morphologically different hydroxyapatite nanoparticles exert differential genotoxic effects in Drosophila

Hydroxyapatite (HAP) occurs naturally in sedimentary and metamorphic rocks and constitutes the hard structures in many organisms. Since synthetic nano-sized HAP (HAP-NPs) are used in orthopedic applications and for heavy metal remediation in aquatic and terrestrial media, both environment and humans are exposed to them. Due to the concerns about their potential hazards, the genotoxic effects that round/rod forms of HAP-NPs were investigated in Drosophila using the wing-spot and the comet assays. Furthermore, caspase activities were evaluated to examine the activation of cell death pathways. As a novelty, the expression of 36 genes involved in DNA repair was investigated, as a tool to indirectly determine DNA damage induction. Obtained sizes were 35-60 nm (roundHAP-NPs) and 45-90 nm (rodHAP-NPs) with a low Zeta-potential (-1.65 and 0.37 mV, respectively). Genotoxicity was detected in the wing-spot (round form), and in the comet assay (round and rod-like HA-NPs). In addition, increased expression of Caspases 3/7, 8, and 9 activities were observed. For both HAP forms, increased changes in the expression were observed for mismatch repair genes, while decreased expression was observed for genes involved in ATM, ATR, and cell cycle pathways. The observed changes in the repair pathways would reinforce the view that HAP-NPs have genotoxic potential, although more markedly in the round form. Thus, the environmental presence of engineered nanoparticles, including HAPs, raises concerns about potential effects on human health. It is essential that the effects of their use are carefully assessed and monitored to ensure safety and to mitigate any potential adverse effects.

Fabrication, Thermo-Mechanical, and Morphological Characterization of Hydroxyapatite-Reinforced Polyurethane Biocomposites as Dye Adsorbent for Effluent

Petrochemical costs, limited fossil fuel reserves, and concerns about greenhouse gas emissions have raised interest in developing renewable approaches for synthesizing biobased polyurethanes. This study aims to solve these problems by making nanocrystalline hydroxyapatite (HA) reinforcement from waste chicken eggshells and adding it to polyurethane synthesis through in situ polymerization. The novelty of the research lies in the utilization of HA as a reinforcement material and renewable resources for polyurethane production. The results confirm that HA was successfully added to the polyurethane backbone. Fourier transform infrared (FTIR) analysis confirmed that the NCO groups were changed to urethane linkages. TGA examination demonstrated that the samples exhibited thermal stability up to 457 °C with a mass loss of 61%, indicating enhanced thermal stability. DMA measurements showed improved mechanical properties of the synthesized polyurethanes, with storage modulus (E'), complex modulus (E*), and compliance complex (D*) values of 0.177, 22.522, and 0.660 MPa-1, respectively. SEM analysis confirmed the homogeneous surface and well-dispersed HA reinforcement. Swelling characteristics revealed an optimum absorption of 30% H2O, 35% CH3OH, and 45% CCl4. Polyurethane composites exhibited significant chemical resistance and hydrolytic stability in acidic and basic media. Additionally, the composites demonstrated efficient adsorption of methyl orange from wastewater, with the PUHCI series achieving a maximum adsorption capacity of 85.50 mg/g under optimal conditions of 0.030 g/mL dose, 45 °C temperature, 2.5 h contact time, and pH 6.0..

In Situ Facile Synthesis of Low-Cost Biogenic Eggshell-Derived Nanohydroxyapatite/Chitosan Biocomposites for Orthopedic Implant Applications

In situ facile synthesis and the characterization of nanohydroxyapatite/chitosan (nHAP/CS) biocomposites were investigated for examining their potential applications in orthopedic implant technology. Firstly, the bare nHAP, europium-doped hydroxyapatite (Eu-nHAP), yttrium-doped hydroxyapatite (Y-nHAP), and Eu- and Y-codoped hydroxyapatite (Eu,Y-nHAP) nanoparticles were synthesized by the wet precipitation technique using biowaste-eggshell-derived calcium oxide powders. Then, through ultrasonication using the nanohydroxyapatite/chitosan mixtures (molar ratio = 1:2), the nHAP/CS, Eu-nHAP/CS, Y-nHAP/CS, and Eu,Y-nHAP/CS biocomposites were fabricated. Among them, Eu,Y-nHAP/CS showed higher cell viability (94.9%), higher solubility (pH = 7.6 after 21 days), and greater antibacterial activity than those of the other composites. In addition, Eu,Y-nHAP/CS exhibited improved mechanical properties compared with the other composites. For example, the nanoindentation test displayed the Eu,Y-nHAP/CS-coated 316L stainless steel implant to possess a higher Young's modulus value (9.24 GPa) and greater hardness value (300.71 MPa) than those of the others. The results indicate that the biomass-eggshell-derived Eu,Y-doped nHAP is of good use for orthopedic implant applications.