Mechanochemical synthesis of hydroxyapatite using cuttlefish bone and chicken eggshell as calcium precursors

In-depth knowledge of the low-temperature hydrothermal synthesis of nanocrystalline hydroxyapatite from waste green mussel shell (Perna Viridis)

ABSTRACTThis study presents the use of a low-temperature hydrothermal method for extracting calcium sources from green mussel shell (P. Viridis) wastes and converting them into synthetic nanosized hydroxyapatite (HA). In this study, raw mussel shells were washed, pulverised, and sieved to start producing a fine calcium carbonate-rich powder. XRD quantitative analysis confirmed that the powder contains 97.6 wt. % aragonite. This powder was then calcined for 5 h at 900 °C to remove water, salt, and mud, yielding a calcium-rich feedstock with major minerals of calcite (68.7 wt.%), portlandite (24.7 wt.%), and minor aragonite (6.5 wt.%). The calcined powders were dissolved in aqueous stock solutions of HNO3 and NH4OH before hydrothermally reacting with phosphoric acid [(NH4)2HPO4], yielding pure, nanoscale (16-18 nm) carbonated HA crystals, according to XRD, FT-IR, and SEM analyses. The use of a low-temperature hydrothermal method for a feedstock powder produced by the calcination of low-cost mussel shell wastes would be a valuable processing approach for the industry's development of large-scale hydroxyapatite nanoparticle production.

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.

Chemical-physical behavior of Hydroxyapatite: A modeling approach

Hydroxyapatite (HAp) is a ceramic composed of calcium phosphate, frequently employed as a bone substitute material due to its biocompatibility and bioactivity. Over the past century, there has been substantial attention in fields such as orthopedics and plastic surgery. Remarkably, synthetic HAp exhibits properties akin to those found in natural bone and teeth. Computational theoretical chemistry focuses on numerically computing molecular electronic structures and interactions. As chemistry education evolves, it's imperative to acknowledge the increasing significance of computational tools in research. Density Functional Theory (DFT) stands out as the most widely adopted method in contemporary computational chemistry. In this study, we synthesized Hydroxyapatite (HAp) via the double decomposition method using synthetic sources. The synthesized materials underwent thorough characterization, including X-ray Diffraction (XRD), UV-visible spectroscopy, and Fourier Transform Infrared (FTIR) spectroscopy under various conditions. Additionally, we performed quantum mechanical computations on the HAp molecule using density functional theory. Our results were then compared with experimental data. Our experimental findings highlight the successful synthesis of HAp, particularly under specific temperature conditions. Moreover, the quantum chemistry calculations exhibited excellent agreement with the experimental results, especially in terms of spectroscopic characterizations.

Synthesis of nano-hydroxyapatite using emulsion, pyrolysis, combustion, and sonochemical methods and biogenic sources: a review

Hydroxyapatite (HAp) is comparable to materials in bone because its chemical components are similar to those contained in animal bone, and thus, its bioactive and biocompatible properties are similar. There are applications for HAp and relevant calcium phosphate in the medical and industrial sectors, and due to the rising demand for HAp nanoparticles, considerable work has been performed to develop a variety of synthetic pathways that incorporate scientifically and practically novel aspects. Numerous studies have been conducted to examine how changes in reaction parameters will successfully influence crucial HAp features. HAp can also be synthesized from biogenic sources such as HAp-rich fish scales or animal bones as an alternative to chemical precursors. Various preparation techniques produce crystals with varying sizes, but it has been found that nano-sized HAp exhibits a greater number of bioactive properties as compared to micron-sized HAp. Rather than considering conventional methods, this review focuses on alternative approaches such as emulsion, pyrolysis, combustion, and sonochemical methods along with waste bio-sources (biogenic sources) to obtain HAp. We summarize the currently accessible information pertaining to each synthesis process, while also focusing on their benefits and drawbacks.

Synthesis and in vitro characteristics of biogenic-derived hydroxyapatite for bone remodeling applications

The inorganic component of bone matrix, hydroxyapatite (HAp) (with formula Ca10(PO4)6(OH)2), can be obtained from inexpensive waste resources that serve as excellent calcium precursors. In the present study, HAp nano-powder was synthesized from eggshells (ES) and crab shells (CS) by wet chemical precipitation method. Also, a hybrid sample was considered which is a mixture of HAp nano-powder synthesized from eggshells (25%) and crab shells (75%) (EC). The presence of phosphate, carbonate, and hydroxyl groups in the synthesized powder was confirmed through FTIR analysis. The phase composition was determined using XRD, and elemental analysis revealed a Ca/P ratio ranging from 1.5 to 1.8, confirming the HAp nature of the nano-powder, which ranged in size from 73 to 375 nm. Importantly, preliminary in vitro tests were conducted using mouse preosteoblast cell line MC3T3-E1 to evaluate the cytotoxic effects of the synthesized HAp. The results indicated excellent biocompatibility. Moreover, sample EC exhibited a significantly higher proliferation on days 3, 6, 9, and 12. EC demonstrated promising antimicrobial properties by exhibiting a significantly higher inhibitory effect against the bacteria Streptococcus mutans and Escherichia coli, and the fungi Candida albicans and Aspergillus niger. Additionally, EC displayed notable antioxidant activity, with IC50 values of 271.543 µg/ml and 407.764 µg/ml in DPPH and H2O2 assays, respectively. Furthermore, it showed strong anti-inflammatory properties, with a dose-dependent inhibition against protein denaturation. Given these findings, the synthesized HAp holds promise as a potential bone filler and could be beneficial for bone remodeling applications.

Comparative study of hydroxyapatite synthesized using Schiff base and wet chemical precipitation methods

Hydroxyapatite (HAp) exists as an inorganic and crystalline composition present in bones and dental enamel, and hence can be utilized as a direct element or as part of the composition of biomaterials and implants for dental and orthopaedic applications. Listed below are a few synthesis techniques for HAp that are listed in the literature: solid-state and mechano-chemical methods (dry methods), wet chemical precipitation and sol-gel methods (wet methods), and combustion and pyrolysis methods (high-temperature processes). Nevertheless, there are new and more productive techniques that result in HAp with a regulated morphology, such as the Schiff base method, which, on reaction with calcium and phosphate precursors, forms chelating complexes to produce HAp nuclei. This research paper presents the comparison in characteristics between HAp synthesized using Schiff base (HAp-SB), wet chemical precipitation (HAp-WC) methods, and commercial HAp (HAp-CM) in their powdered and pelleted form. The average size of HAp-WC particles in the spherical form was found to be 603 nm ± 176, HAp-SB were found to have rod-like morphology, which is very similar to human bone-like HAp, with an average length and width of 1522 nm ± 759 and 400 nm ± 112, respectively, and HAp-CM were found to have spherical morphology with dimensions of 52 nm ± 25. Biological studies show that cell viability of HAp-SB pellet (202.01% ± 8.16) seemed to have higher cell proliferation properties than HAp-WC pellet (145.7% ± 5.11) and HAp-CM pellet (71.53% ± 3.61) due to its higher aspect ratio, and hence higher surface area for the cells to adhere. In a detailed study, it is observed that both techniques had their advantages, and there were no significant disadvantages observed.

Design Strategies for Hydroxyapatite-Based Materials to Enhance Their Catalytic Performance and Applicability

Hydroxyapatite (HAP) is a green catalyst that has a wide range of applications in catalysis due to its high flexibility and multifunctionality. These properties allow HAP to accommodate a large number of catalyst modifications that can selectively improve the catalytic performance in target reactions. To date, many studies have been conducted to elucidate the effect of HAP modification on the catalytic activities for various reactions. However, systematic design strategies for HAP catalysts are not established yet due to an incomplete understanding of underlying structure-activity relationships. In this review, tuning methods of HAP for improving the catalytic performance are discussed: 1) ionic composition change, 2) morphology control, 3) incorporation of other metal species, and 4) catalytic support engineering. Detailed mechanisms and effects of structural modulations on the catalytic performances for attaining the design insights of HAP catalysts are investigated. In addition, computational studies to understand catalytic reactions on HAP materials are also introduced. Finally, important areas for future research are highlighted.

Processing and characterization of egg shell derived nano-hydroxyapatite synthetic bone for Orthopaedic and Arthroscopy implants and substitutes in dentistry

The present work is focused on the nano-Hydroxyapatite (nHAp) synthesis with two different Indian breed Aseel and Kadaknath eggshells. The alloplast implants were developed through the foam replica method with polyurethane 45-PPI as a porous template. The synthesized nHAp was characterized by Field Emission Scanning Electron Microscopy (FE-SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The FE-SEM images of the nHAp showed the one dimensional clustered nanoparticles and the X-ray diffraction spectrum confirms that the major phase was hydroxyapatite with a small trace of β-tricalcium phosphate. The maximum compression strength of the sample was 5.49 ± 0.12 MPa which is in the range of the compression strength of human trabecular bone. The thermal and degradability studies results confirmed that these are highly stable and provides necessary a resorption needed for new bone tissue formation. Besides, the antimicrobial activity against tested human microbiome are satisfactory and the cell viability towards MG 63 human osteoblast-like cells provides a potential pathway for developing the nHAp implants for bone tissue engineering.

Hydrothermal Synthesis of Biphasic Calcium Phosphate from Cuttlebone Assisted by the Biosurfactant L-rhamnose Monohydrate for Biomedical Materials

The motivation of this research work is to develop novel medical material from cuttlebone (calcium source) by L-rhamnose monohydrate (biosurfactant) for aged people. The process can be synthesized biphasic calcium phosphate which is eco-friendly to environment. One of the most important aspects for this work is to use cuttlebone as a naturally occurring calcium source from a local beach in Thailand. It usually contains 90% calcium carbonate. The objective of this research work is to synthesize the biphasic calcium phosphate by hydrothermal reaction. Critical micelle concentrations (CMCs) of 10, 20, 100, 500 and 1000 of L-rhamnose monohydrate were used to control particle size and shape. XRD revealed a mixture of β-tricalcium phosphate and hydroxyapatite powder. SEM reported that the size of particles can be effectively controlled by the addition of L-rhamnose monohydrate, and with the addition of surfactant, size uniformity was achieved. The cytotoxicity test was reported to be in the range of 70–75%. It was remarkable to note that biphasic calcium phosphate synthesized from cuttlebone with the aid of L-rhamnose monohydrate will be considered an excellent candidate as a scaffold material.

Influence of Composition and Preparation Conditions on the Structure and Properties of Composite Materials TiO2-SiO2/CaO with a Spherical Particle Shape Based on Tokem-200 Cationic Exchange Resins

Spherical biomaterials based on Tokem-200 cationic exchange resin were synthesized from solutions by the sol-gel method. The material framework is represented by TiO₂-SiO₂, and the inner part is filled with CaO (sample TiO₂-SiO₂/CaO). A stepwise heat treatment (drying at 60 °C) annealing at 150, 250, and 350 °C, each for 30 min, at 600 °C for 6 h, and 800 °C for 1 h is required to obtain a homogeneous material. In simulated body fluid solution, the sample exhibited bioactive properties, and gelatin could be used as a binding additive.

Speedy bioceramics: Rapid densification of tricalcium phosphate by ultrafast high-temperature sintering

Due to unique osteogenic properties, tricalcium phosphate (TCP) has gained relevance in the field of bone repair. The development of novel and rapid sintering routes is of particular interest since TCP undergoes to high-temperature phase transitions and is widely employed in osteoconductive coatings on thermally-sensitive metal substrates. In the present work, TCP bioceramics was innovatively obtained by Ultrafast High-temperature Sintering (UHS). Ca-deficient hydroxyapatite nano-powder produced by mechanochemical synthesis of mussel shell-derived calcium carbonate was used to prepare the green samples by uniaxial pressing. These were introduced within a graphite felt which was rapidly heated by an electrical current flow, reaching heating rates exceeding 1200 °C min^-1. Dense (> 93%) ceramics were manufactured in less than 3 min using currents between 25 and 30 A. Both β and α-TCP were detected in the sintered components with proportions depending on the applied current. Preliminary tests confirmed that the artifacts do not possess cytotoxic effects and possess mechanical properties similar to conventionally sintered materials. The overall results prove the applicability of UHS to bioceramics paving the way to new rapid processing routes for biomedical components.

Phosphate removal from food industry wastewater by chemical precipitation treatment with biocalcium eggshell

The physicochemical treatment (PT) of food industry wastewater was investigated. In the first stage, calcium magnesium acetate (CaMgAc₄) was synthesized using eggshell (biocalcium), magnesium oxide and acetic acid in a 1:1:1 stoichiometric ratio. In the synthesis process, the thermodynamic parameters (ΔH, ΔS and ΔG) indicated that the reaction was endothermic and spontaneous. The samples were characterized by infrared spectroscopy (IR), scanning electronic microscopy (SEM), X-ray diffraction (XRD) and electron X-ray dispersive spectroscopy (EDS). CaMgAc₄ was used to precipitate the phosphate matter. IR analysis revealed that the main functional groups were representative of the acetate compounds and the presence of OH^- groups and carbonates. In the physicochemical treatment, a response surface design was used to determine the variables that influence the process (pH, t, and concentration), and the response variable was phosphorus removal. The treatments were carried out in the wastewater industry with an initial concentration of 658 mg/L TP. The optimal conditions of the precipitation treatment were pH 12, time 12 min, and a CaMgAc₄ concentration of 13.18 mg/L. These conditions allowed the total elimination (100%) of total phosphorus and phosphates, 81.43% BOD₅ and 81.0% COD, 98.9% turbidity, 95.01% color, and 92% nitrogen matter.

State-of-the-Art of Eggshell Waste in Materials Science: Recent Advances in Catalysis, Pharmaceutical Applications, and Mechanochemistry

Eggshell waste is among the most abundant waste materials coming from food processing technologies. Despite the unique properties that both its components (eggshell, ES, and eggshell membrane, ESM) possess, it is very often discarded without further use. This review article aims to summarize the recent reports utilizing eggshell waste for very diverse purposes, stressing the need to use a mechanochemical approach to broaden its applications. The most studied field with regards to the potential use of eggshell waste is catalysis. Upon proper treatment, it can be used for turning waste oils into biodiesel and moreover, the catalytic effect of eggshell-based material in organic synthesis is also very beneficial. In inorganic chemistry, the eggshell membrane is very often used as a templating agent for nanoparticles production. Such composites are suitable for application in photocatalysis. These bionanocomposites are also capable of heavy metal ions reduction and can be also used for the ozonation process. The eggshell and its membrane are applicable in electrochemistry as well. Due to the high protein content and the presence of functional groups on the surface, ESM can be easily converted to a high-performance electrode material. Finally, both ES and ESM are suitable for medical applications, as the former can be used as an inexpensive Ca2+ source for the development of medications, particles for drug delivery, organic matrix/mineral nanocomposites as potential tissue scaffolds, food supplements and the latter for the treatment of joint diseases, in reparative medicine and vascular graft producing. For the majority of the above-mentioned applications, the pretreatment of the eggshell waste is necessary. Among other options, the mechanochemical pretreatment has found an inevitable place. Since the publication of the last review paper devoted to the mechanochemical treatment of eggshell waste, a few new works have appeared, which are reviewed here to underline the sustainable character of the proposed methodology. The mechanochemical treatment of eggshell is capable of producing the nanoscale material which can be further used for bioceramics synthesis, dehalogenation processes, wastewater treatment, preparation of hydrophobic filters, lithium-ion batteries, dental materials, and in the building industry as cement.

Calcium phosphate powders synthesized from CaCO3 and CaO of natural origin using mechanical activation in different media combined with solid-state interaction

The highly pure and crystalline calcium carbonate (CaCO₃) and calcium oxide (CaO) with small amounts of As, Cd, Hg, and Pb were prepared by calcinating shells of a golden apple snail. Solid-state reaction and mechanical activation between the CaCO₃ and CaO from calcined golden apple snail shells and dibasic calcium phosphate dihydrate (CaHPO₄•2H₂O, DCPD) were performed to develop calcium phosphate powders. The effects of the milling media used on the mechanical activation were examined. A solid-state reaction of manually mixed CaCO₃ or CaO with DCPD powders at a temperature of 1100 °C produced mostly β-tricalcium phosphate (β-TCP). Hydroxyapatite (HAp) with a small quantity of β-TCP could be produced from a mixed CaCO₃ + DCPD powder using dry and wet mechanical activations with distilled water, alcohol and acetone and from a mixed CaO + DCPD powder using dry mechanical activation combined with a solid-state reaction at a temperature of 1100 °C. A phase change of milled powders to β-TCP was clearly observed from a wet mechanical activation of CaO + DCPD powder with distilled water or alcohol in a solid-state reaction. The thermal instability of HAp powders from a combined mechanical activation with solid-state reaction of CaCO₃ or CaO and DCPD powders could result from two factors. The first is that the pollution was released from the balls and pot mill materials during the mechanical process. Another factor is a reduced level of calcium in the CaO + DCPD mixed powder due to a reaction between CaO and water or alcohol during mechanical milling.

Hydroxyapatite Biosynthesis Obtained from Sea Urchin Spines (Strongylocentrotus purpuratus): Effect of Synthesis Temperature

In this investigation, hydroxyapatite (HA) was synthesized using sea urchin spines (Strongylocentrotus purpuratus) via a precipitation and heat treatment method at three different temperatures (500, 600 and 700 °C). Biosynthesized HA was characterized to determine the vibration of functional groups, morphology, particle size, crystalline structure and chemical composition. For this, Fourier-Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were used, respectively. The FTIR-ATR results reveal that the most defined characteristic HA bonds (O-H, P-O and C-O bonds) were better defined at higher synthesis temperatures. SEM also presented evidence that temperature has a significant effect on morphology. EDS results showed that the Ca/P ratio increased in the samples at higher temperatures. XRD analysis presented the characteristic peaks of HA, showing a lower crystallinity when the synthesis temperature increased. Finally, the XPS confirmed that the material resulting from biosynthesis was HA. Hence, according to these results, the synthesis temperature of HA has a significant effect on the characteristics of the resulting material.

Photoluminescent Hydroxylapatite: Eu3+ Doping Effect on Biological Behaviour

Luminescent europium-doped hydroxylapatite (Eu_XHAp) nanomaterials were successfully obtained by co-precipitation method at low temperature. The morphological, structural and optical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), UV-Vis and photoluminescence (PL) spectroscopy. The cytotoxicity and biocompatibility of Eu_XHAp were also evaluated using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide)) assay, oxidative stress assessment and fluorescent microscopy. The results reveal that the Eu³⁺ has successfully doped the hexagonal lattice of hydroxylapatite. By enhancing the optical features, these Eu_XHAp materials demonstrated superior efficiency to become fluorescent labelling materials for bioimaging applications.