Hydroxyapatite-based Materials Research Articles

Enhanced antimicrobial efficacy of hydroxyapatite-based composites for healthcare applications

Hydroxyapatite (HAp) and hydroxyapatite-based materials show promising potential in the healthcare sector due to their distinctive properties such as biocompatibility, antimicrobial efficacy, non-toxicity, and robust mechanical characteristics. This makes HAp materials play an important role in hindering infection spreading in healthcare provider institutions. This study assesses the antimicrobial efficacy of the developed hydroxyapatite-based composites incorporating copper, zinc, and silver nanoparticles. The synthesized HAp and its modified composite variants (Cu/HAp, Zn/HAp, and Ag/HAp) with varying ratios ranging from 0 to 15% (wt) were characterized using XRD, XPS, SEM, and TEM analyses. Furthermore, the antibacterial and antifungal properties of the synthesized HAp and HAp-based composites were evaluated. The antibacterial effectiveness of the HAp and its composites was evaluated using a modified disc diffusion test, where the resulting inhibition zones on the agar surface were observed. All the HAp and HAp-based composites (HAp, Cu/HAp, Zn/HAp, and Ag/HAp materials) elicited in the formation of inhibitory zones. The most substantial inhibition values were observed for the 5% Ag/HAp formulation, with values of 19.7 and 13.8, against E. coli and S. aureus, respectively. The 5% Ag/HAp concentration may strike an ideal balance, providing high antimicrobial activity without adverse effects on biocompatibility or material stability. These findings underscore the recommendation of the proposed HAp-based composites for infection control measures through their application on medical instruments, textiles, healthcare personnel attire, and patient garments.

Immersion Behavior Study of Hydroxyapatite Scaffolds Derived from Bovine Sources In Acidic, Basic, and Neutral Solutions

This research investigates the effects of particle size and compaction pressure on the dissolution behavior of hydroxyapatite scaffolds synthesized from bovine bone in acidic neutral and basic solutions. Hydroxyapatite was extracted through a process involving cutting, cleaning, boiling, soaking in NaOH, sun drying, grinding into powder and calcination at 800°C. The powder was then sieved into two size fractions (75 and 150 microns) and compacted at pressures of 200, 250, and 300 MPa. The mass and dimensions of the scaffolds were measured to calculate porosity, followed by immersion in the respective solutions for 24 hours to determine dissolution rates. Results indicated that smaller particle sizes and higher compaction pressures resulted in reduced porosity and enhanced structural integrity. The dissolution rates varied significantly with pH levels, exhibiting the highest rates in acidic conditions up to 215.83 mg/cm2 and the lowest in basic solutions up to 11.32 mg/cm2. Additionally, scaffolds with smaller particles and higher compaction pressures demonstrated lower dissolution rates across all pH levels due to lower porosity. In conclusion, both particle size and compaction pressure are critical factors influencing the dissolution behavior of hydroxyapatite scaffolds. These findings have significant implications for the design and optimization of hydroxyapatite-based materials for biomedical applications, where controlled dissolution rates are crucial for performance and longevity.

Quantification of lithium and calcium in novel hydroxyapatite-based materials for osteoplasty using flame photometry

Quantification of lithium and calcium in novel hydroxyapatite-based materials for osteoplasty using flame photometry

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.

Metal Ion-Doped Hydroxyapatite-Based Materials for Bone Defect Restoration.

Hydroxyapatite (HA)-based materials are widely used in the bone defect restoration field due to their stable physical properties, good biocompatibility, and bone induction potential. To further improve their performance with extra functions such as antibacterial activity, various kinds of metal ion-doped HA-based materials have been proposed and synthesized. This paper offered a comprehensive review of metal ion-doped HA-based materials for bone defect restoration based on the introduction of the physicochemical characteristics of HA followed by the synthesis methods, properties, and applications of different kinds of metal ion (Ag+, Zn2+, Mg2+, Sr2+, Sm3+, and Ce3+)-doped HA-based materials. In addition, the underlying challenges for bone defect restoration using these materials and potential solutions were discussed.

In vitro controlled drug delivery of cationic substituted hydroxyapatite nanoparticles; enhanced anti-chelating and antibacterial response

Hydroxyapatite is naturally found in bones and it is used to deliver antibacterial agents such as chlorhexidine and gentamicin to bones. This study covered the development of hydroxyapatite and nickel (Nix ​= ​0.3,0.5) substituted hydroxyapatite nanoparticles by co-precipitation method. The characterization of nickel (Nix ​= ​0.3,0.5) substituted hydroxyapatite was done by X-ray diffraction, Infra-Red studies and Scanning Electron Microscopy. This study also includes in vitro controlled drug delivery of nickel (Nix ​= ​0.3,0.5) substituted hydroxyapatite nanoparticles which were loaded with widely consumed drug, ciprofloxacin. The antibacterial and antioxidant activity of nickel (Nix ​= ​0.3,0.5) substituted hydroxyapatite was also checked. Our results indicated that nickel substitution in hydroxyapatite increased the percentage of drug (ciprofloxacin) loading up to 96% and cumulative drug release up to 95% in a tunable controlled mode of action. Free radical scavenging or antioxidant comparative analysis of pure and cationic substituted hydroxyapatite further revealed significant enhancement in iron-chelating potential. Nonetheless, nickel (Nix ​= ​0.3,0.5) substituted hydroxyapatite nanoparticles loaded with ciprofloxacin showed strong antibacterial activity (22 ​mm and 24 ​mm zone of inhibition against E. coli (ATCC 35218) and P. aeruginosa (ATTC 27853) strains respectively). This development allows the researchers in the area to get a prompt comparison and sort out the best solutions for the cationic substitution of hydroxyapatite-based materials and enable the development of multi-functional biomedical drug delivery systems and designs for the most commonly used antibiotic molecules.

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.

An Overview of Antibacterial Dental Restorative Materials

Antibacterial dental restorative materials (ADRM) have been developed to prevent or treat dental caries and other infections. Glass ionomer cements (GICs), composite resins, calcium hydroxide-based materials, mineral trioxide aggregate (MTA), bioactive glasses, silver-containing materials, quaternary ammonium compounds (QACs), chlorhexidine, nanoparticles, and photodynamic therapy (PDT) are common types of ADRMs. They have antibacterial properties due to the release of fluoride ions, QACs, silver nanoparticles, calcium and hydroxyl ions. ADRMs can prevent tooth decay, promote healing of pulp tissue and regenerate damaged tissues. Researchers are exploring new agents like nanoparticles and antimicrobial peptides to improve the antibacterial properties of ADRMs. PDT is a promising technology for improving the antibacterial properties of dental restorative materials. Antibacterial bioactive dental materials like bioactive glasses, calcium phosphate-based materials, hydroxyapatite-based materials, antibacterial peptides, and silver-containing materials have been developed to provide an additional layer of protection against infection and improve the longevity of dental restorations.

A “Zero-Cost” Adsorbing Hydroxyapatite-Based Material from Amazon Fishery Waste for Water Remediation and Nutrient Release for Agriculture

This paper puts forward the use of “low-cost/low-end” hydroxyapatite-based adsorbing materials prepared from Tambaqui fish cleaning residues (i.e., bones) by grinding and/or thermal annealing. The nature of raw materials and treatments practically resulted in a “zero-cost” adsorbent for atrazine pesticide and Co2+ ion remediation in an aqueous solution. Despite the distinctive character of the two contaminants, all adsorptions were found to follow pseudo-second order kinetics and Freundlich isotherm models. Pristine hydroxyapatite proved to be more effective in adsorbing atrazine at low concentrations due to interactions with collagen residues. Conversely, heat-treated materials demonstrated better adsorption performances for cobalt due to the removal of organic residues hindering access to the surface. On the other hand, lower adsorption affinities resulted into a faster and more efficient Co2+ release into water. The different behavior in terms of phosphate and cobalt release shown by the three hydroxyapatite-based absorbents can be exploited for differential liberation of targeted nutrients, with high seed germination rates. Considering circular economic principles, waste-derived hydroxyapatites may be potentially attractive for removing ionic species, minimizing water pollution stemming from heavy industry, and for their subsequent targeted release to edible plants, enhancing agricultural availability of mineral nutrients for soil fertilization.

Environmentally conscious biomedical implant manufacturing method

The significant advantage of using magnesium as a surgical implant is its ability to biodegrade in situ, eliminating the requirement for implant removal surgery. However, investigating biomedical implant fabrication processes required the study analyses from the perspective of the process plan and environmental impact for better sustainable solutions. In the present study, magnesium and hydroxyapatite-based composite material have been selected for fabricating the bio-medical implant. The real-time data has been observed in the production processes. The environmental impacts of the produced bio-implant material are compared with those of the bio-implant produced using friction-stir processing and laser-based powder metallurgy. It is observed from the analysis that conventional methods can be utilized for making bio-medical implants cost-effectively after careful modifications in the process sequence and parameters. The environmental impact analysis provided a detailed visualization of major hotspots and supported effective decision-making toward improving the production process. At the same time, the comparative analysis provides a clear picture of the hotspots in the bio-implant production processes. The study compared the environmental impact of two bio-implant production processes and provided valuable insights to reduce overall cost and improve environmental impact across the supply chain. A bio-implant prototype has been made with a cheaper alternative to additive manufacturing.

Immunomodulatory Properties: The Accelerant of Hydroxyapatite-Based Materials for Bone Regeneration.

The immunoinflammatory response is the prerequisite step for wound healing and tissue regeneration, and the immunomodulatory effects of biomaterials have attracted increasing attention. Hydroxyapatite [Ca10(PO4)6(OH)2] (HAp), a common calcium phosphate ceramic, due to its structural and functional similarity to the inorganic constituent of natural bones, has been developed for different application purposes such as bone substitutes, tissue engineering scaffolds, and implant coatings. Recently, the interaction between HAp-based materials and the immune system (various immune cells), and the immunomodulatory effects of HAp-based materials on bone tissue regeneration have been explored extensively. Macrophages-mediated regenerative effect by HAp stimulation occupies the mainstream status of immunomodulatory strategies. The immunomodulation of HAp can be manipulated by tuning the physical, chemical, and biological cues such as surface functionalization (physical or chemical modifications), structural and textural characteristics (size, shape, and surface topography), and the incorporation of bioactive substances (cytokines, rare-earth elements, and bioactive ions). Therefore, HAp ceramic materials can contribute to bone regeneration by creating a favorable osteoimmune microenvironment, which would provide a more comprehensive theoretical basis for their further clinical applications. Considering the rapidly developed HAp-based materials as well as their excellent biological performances in the field of regenerative medicine, this review discusses the recent advances concerning the immunomodulatory methods for HAp-based biomaterials and their roles in bone tissue regeneration. Impact statement This review summarized the immunomodulatory methods for hydroxyapatite-based biomaterials in bone tissue regeneration, and further discussed the affecting factors of immunomodulation as well as the challenges for the immunomodulatory strategies. The comprehensive understanding of immunomodulatory strategies for tissue regeneration would provide more guidance for the development of novel hydroxyapatite composite biomaterials.

Gypsum-related compensation of ions uptake by highly porous hydroxyapatite ceramics – Consequences for osteoblasts growth and proliferation

Hydroxyapatites of high calcium and phosphate ions adsorption capacity are highly bioactive. However, they cause the removal of these ions from tissue liquids and cell culture media, thus reducing viability and proliferation potential of osteoblasts. Addition of small amount of gypsum (calcium sulfate dihydrate) to such hydroxyapatite-based composites may help to compensate the ions removal and stimulate the osteoblasts growth and proliferation. Therefore, the aim of this work was to enrich the highly porous hydroxyapatite-based composite with gypsum and verify its effect on ions adsorption as well as osteoblasts viability and proliferation. The results showed that addition of 1.5–1.75% gypsum caused short-term calcium ions compensation in media incubated with the composite and time-shifted increase of osteoblasts proliferation. Moreover, presence of gypsum in the composite increased the content of large pores in SBF-incubated biomaterials with no effect on their microstructure or mechanical parameters. Overall, gypsum addition improves the compatibility of hydroxyapatite-based materials with no critical disadvantages for other properties.

Mechanical Properties of Differently Nanostructured and High-Pressure Compressed Hydroxyapatite-Based Materials for Bone Tissue Regeneration

Hydroxyapatite (HAp) has long been considered the gold standard in the biomedical field, considering its composition and close resemblance to human bone. However, the brittle nature of hydroxyapatite (HAp) biomaterial, constrained by its low fracture toughness (of up to 1.2 vs. 2–12 MPa m1/2 of human bone), remains one of the significant factors impairing its use in bone regeneration. In the present study, HAp nanoparticles synthesized by the solid-state (SHAp) and sonochemical (EHAp) approaches using eggshell-derived calcium hydroxide and ammonium dihydrogen orthophosphate as precursors are compared with those synthesized using commercially available calcium hydroxide and ammonium dihydrogen orthophosphate as precursors (CHAp) employing sonochemical method. The HAp samples were then compressed into compact materials using a uniaxial high-pressure compression technique at a preoptimized load and subsequently characterized for mechanical properties using the Vickers indentation method and compressive strength testing. The analysis revealed that the material with smaller particle size (30–40 nm) and crystalline nature (EHAp and CHAp) resulted in mechanically robust materials (σm = 54.53 MPa and 47.72 MPa) with high elastic modulus (E = 4011.1 MPa and 2750.25 MPa) and density/hardness-dependent fracture toughness (σf = 4.34 MPa m1/2and 6.57 MPa m1/2) than SHAp (σm =28.40 MPa, E = 2116.75 MPa, σf = 5.39 MPa m1/2). The CHAp material was found to be the most suitable for applications in bone regeneration.

Advanced Materials Based on Nanosized Hydroxyapatite.

The development of new materials based on hydroxyapatite has undergone a great evolution in recent decades due to technological advances and development of computational techniques. The focus of this review is the various attempts to improve new hydroxyapatite-based materials. First, we comment on the most used processing routes, highlighting their advantages and disadvantages. We will now focus on other routes, less common due to their specificity and/or recent development. We also include a block dedicated to the impact of computational techniques in the development of these new systems, including: QSAR, DFT, Finite Elements of Machine Learning. In the following part we focus on the most innovative applications of these materials, ranging from medicine to new disciplines such as catalysis, environment, filtration, or energy. The review concludes with an outlook for possible new research directions.

Features of Bone Regeneration of the Jaws Alveolar Ridge Using Hydroxyapatite-Based Material

Background. Currently, using of osteointegrated titanium implants has become a key component for restoring lost function in various areas of clinical medicine. The actual issue remains preservation or reconstruction of bone tissue for optimal use of titanium implants in traumatology and orthopedics, as well as in maxillofacial surgery. One of the most common grafts are hydroxyapatite-based material with various inclusions, for example, an antibiotic.The aim of the study is to characterize the regeneration of bone tissue of the jaws alveolar ridge using the hydroxyapatite-based material “Collapan-L” in clinical practice.Material and Methods. The study of the material “Collapan-L” (Intermedapatit, Russia) using involved 30 patients with a diagnosis “chronic periodontitis of the tooth”. Patients underwent complex surgical and orthopedic treatment to restore masticatory function. At the first stage, teeth were removed with the “Collapan-L” material used to preserve the alveolus. 4 months after extraction, dental implantation was performed with simultaneous trephine biopsy from the augmentation zone for histomorphometric analysis. At the stage of implant placement and before prosthetics the stability dynamics was measured.Results. The study involved 42 tissue samples obtained at periods from 9 to 32 weeks after removal. The morphological assessment of bone tissue from the implantation zone determined that after 4 months trabeculae from the newly formed bone, including small fragments of biomaterial, were revealed; at the same time, there were signs of biodegradation of the implanted material fragments, there was no inflammatory infiltrate. After 6 months in a significant part of cases the granules of bone material were not found, which indicates a pronounced osseointegration of the material. In its structure, the formed bone tissue differences barely noticeable from the native one, which allows us to conclude that by the time of 24 weeks, the processes of reparative osteogenesis in the alveolus are completed.Conclusion. Histological examination and assessment of changes in the stability showed that using of bone replacement material after tooth extraction can increase the regenerative potential of bone tissue, avoid additional surgical interventions to increase the volume of bone tissue in the area of future implantation, and the formed bone tissue is close in its structure to the native one.

Preparation of Sr-substituted Hydroxyapatite Nanorods for Liquid Crystal Phase Transition

A citrate-assisted hydrothermal method was utilized for the preparation of Sr-substituted hydroxyapatite (HA) nanoparticles. The influences of Sr-substituting degree on the phase identifications, microstructures and colloidal stability of the resultant products were studied. The experimental results show that the crystalline structures and morphologies of final resultants are significantly changed by controlling the Sr-substituting degree. As the Sr-substituting degree increases, the colloidal stability of samples first increases and then decreases rapidly; the morphology of the product first changes from nanorods to short nanorods rod and then becomes nanowires. Uniform HA hexagonal nanorods with high aspect ratio (>4.0) and excellent aqueous colloidal stability were prepared by 6 h hydrothermal reaction at 180 °C without Sr substitution. The dispersion underwent the phase transition from isotropic to liquid-crystalline state upon the increasing concentration of 25wt% and the complete liquid-crystalline phase was achieved when at the concentration above 31wt%. These novel findings provide new insights into the role of Sr substitution on both the citrate-assisted hydroxyapatite crystallization and tailoring of colloidal stability. Moreover, HA liquid crystal behavior was successfully observed, which lays a foundation for the fabrication of macroscopically assembled hydroxyapatite-based biomimetic materials for biomedical applications.

Effect of High Temperatures on the Microstructure and Properties of Fluorine-Containing Hydroxyapatite-Based Materials

This paper examines the feasibility of improving the strength of hydroxyapatite prepared by precipitation from solution via partial substitution of fluoride ions for hydroxyl groups and the addition of calcium fluoride. A comparative analysis of the resultant materials is carried out using advanced physicochemical characterization techniques. Fluoride ions are shown to influence the thermal stability, sintering behavior, microstructure, and strength of ceramics produced using precipitated hydroxyapatite.

Hydroxyapatite-Based Materials for Heavy Metal Removal in Wastewater Treatment

Nowadays, undisputable environmental pollution requests endeavors to treat wastewater, particularly containing heavy metal, where wastewater treatment technologies are improving hastily. Hydroxyapatite with micro-porous structure and the large surface area turns into an intense research topic as of its high adsorption capacity. Environmentally friendly Hydroxyapatite powder with the large specific surface is a promising cost-effective precipitation method, for the removal of heavy metals (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) from wastewater. Different studies have revealed the efficient removal of all metals using hydroxyapatite or by modified HA using zeolite or chitosan. The increase of Ca2+ ions content in the treated water suggests an ion exchange mechanism

Cytotoxic Effects of Granulated Hydroxyapatite with Various Particle Size Distribution

Hydroxyapatite-based materials show promise in such applications as reconstructive surgery, stomatology and cosmetology, they can also be used as components of toothpaste, disinfectant products and dietary supplements (DS). However, cytotoxicity of hydroxyapatite powders synthesized via various methods towards a variety of biological cells requires a thorough study.Cytotoxicity of hydroxyapatite powder samples with spherical particles in three size ranges: 5-25 μm, 25-45 μm and 40-125 μm, synthesized by hydrothermal synthesis with further ultrasonic and spray-drying treatment, was studied on human blood cells and on gram-negative bacteria E.coli.The examined hydroxyapatite samples have no toxic effect on human blood leukocytes (in concentration 40 mg per 1 ml H2O or normal saline) and on gram-negative bacteria E.coli. (in concentration 40 mg per 1 ml H2O or normal saline) regardless of the contact time and particle size. The obtained data demonstrate safety of the examined materials and absence of toxic effects towards the test objects. This allows us to regard the studied hydroxyapatite samples as biocompatible.The present study results could be used to develop products and medicinal drugs based on hydroxyapatite granules synthesized by means of hydrothermal synthesis technique with further sonication and spray drying.

Removal of Copper(II) Ions from Aqueous Solutions by Hydroxyapatite-Based Materials Prepared from Eggshells

The experimental study aimed to establish the potential applications of the nano- and micrometric powders of hydroxyapatite in the removal processes of Cu(II) ions from synthetic aqueous solutions. For this purpose, hydroxyapatite (HAP) was used in the form of: 1) nanometric powder (labeled nano-HAP), and 2) calcium alginate hydroxyapatite composite microparticles (nicro-HAP-CaAlg). Eggshells have been used as a raw material to obtain HAP. The contact time, pH and Cu(II) concentration in the initial solution have been the main process variables with influence on the Cu(II) ions removal by HAP samples. For both HAP based materials, an optimal pH value of 5 has been established. The nano-HAP powder has a higher Cu(II) adsorption capacity than micro-HAP-CaAlg based on the specific surface area values of nano- and micrometric powders. The adsorption isotherm experiments showed that this process can be described using Langmuir model according to which the adsorption takes place as a monolayer process on an homogeneous surface. The kinetic study revealed that the sorption process of Cu(II) from synthetic aqueous solutions can be described using the pseudo-second order kinetics model according to which the rate-determining step is chemisorption. The values of the retention capacity recommends both powders tested (nano-HAP and micro-HAP-CaAlg) to be used in the Cu(II) loaded water treatment process.