Investigation on antibacterial and hemolytic properties of magnesium-doped hydroxyapatite nanocomposite

Citrate Improves Biomimetic Mineralization Induced by Polyelectrolyte-Cation Complexes Using PAsp-Ca&Mg Complexes

Magnesium ions are highly enriched in early stage of biological mineralization of hard tissues. Paradoxically, hydroxyapatite (HAp) crystallization is inhibited significantly by high concentration of magnesium ions. The mechanism to regulate magnesium-doped biomimetic mineralization of collagen fibrils has never been fully elucidated. Herein, it is revealed that citrate can bioinspire the magnesium-stabilized mineral precursors to generate magnesium-doped biomimetic mineralization as follows: Citrate can enhance the electronegativity of collagen fibrils by its absorption to fibrils via hydrogen bonds. Afterward, electronegative collagen fibrils can attract highly concentrated electropositive polyaspartic acid-Ca&Mg (PAsp-Ca&Mg) complexes followed by phosphate solution via strong electrostatic attraction. Meanwhile, citrate adsorbed in/on fibrils can eliminate mineralization inhibitory effects of magnesium ions by breaking hydration layer surrounding magnesium ions and thus reduce dehydration energy barrier for rapid fulfillment of biomimetic mineralization. The remineralized demineralized dentin with magnesium-doped HAp possesses antibacterial ability, and the mineralization mediums possess excellent biocompatibility via cytotoxicity and oral mucosa irritation tests. This strategy shall shed light on cationic ions-doped biomimetic mineralization with antibacterial ability via modifying collagen fibrils and eliminating mineralization inhibitory effects of some cationic ions, as well as can excite attention to the neglected multiple regulations of small biomolecules, such as citrate, during biomineralization process.

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.

Morphological and fractal features of cancer cells anchored on composite layers based on magnesium-doped hydroxyapatite loaded in chitosan matrix

In the present study, we report the development and characterization of composite layers (by spin coating) based on magnesium-doped hydroxyapatite in a chitosan matrix, containing human osteosarcoma MG63 cells anchored. Studies regarding the biocompatibility of the composite layers were performed with the aid of a MTT (3-4,5-Dimethylthiazol 2,5-diphenyltetrazolium bromide) assay. The data determined that the composite layers did not inhibit the growth and adhesion of MG63 cells to their surfaces exhibiting good biocompatibility properties. Furthermore, the attachment and development of MG63 cells on the surface of MgHApCh composite layers were investigated using atomic force microscopy (AFM). AFM topographical maps emphasized that the HApCh and 8MgHApCh composite layers surface promoted the attachment and proliferation of MG63 cells on their surface. Meanwhile, in the case of 30MgHApCh layers incubated for 48 h, a slight modification of the morphological features of the MG63 cells. In addition, the effects of the composite layers against Candida albicans ATCC 10231 were also evaluated. The data results from the in vitro antifungal assay depicted that the composite layers successfully inhibited the growth of the fungal cells onto their surface. Morphological and fractal analyses unveil cancer cell surfaces on Mg-containing composite layers with intricate 3D patterns, driven by high-frequency components. Their remarkable complexity and roughness arises from a strong multifractal nature, supporting more effective vertical growth compared to Si and HApCh surfaces. The cell viability reduced of uncoated Si surface is highlighted by its less intense 3D pattern growth. Our results show that the uncoated Si surface promotes lower viability of MG63 cancer cells, with less rough and complex 3D spatial patterns.

High biocompatible polyacrylamide hydrogels fabricated by surface mineralization for subchondral bone tissue engineering

The subchondral bone is an important part of cartilage which contains a large amount of hydroxyapatite. The mineral components of subchondral bone is the key factor which determines the biomechanical strength, and then affects the biological function of articular cartilage. Here, a mineralized polyacrylamide (PAM-Mineralized) hydrogel with good ALP activity, cell adhesion and biocompatibility was fabricated for subchondral bone tissue engineering. The micromorphology, composition and mechanical properties of PAM and PAM-Mineralized hydrogels were studied. The PAM hydrogels showed a porous structure, while the PAM-Mineralized hydrogels had well-distributed layers of hydroxyapatite mineralization on the surface. The XRD results show that the characteristic peak of hydroxyapatite (HA) was measured in PAM-Mineralized, indicating that the main component of the mineralized structure formed on the surface of the hydrogel after mineralization is HA. The formation of HA ectively decreased the rate of equilibrium swelling of the PAM hydrogel, with PAM-M reaching swelling equilibrium at 6 h. Meanwhile, compressive strength of PAM-Mineralized hydrogel (moisture state) reached 290 ± 30 kPa, compressive modulus reached 130 ± 4 kPa. PAM-Mineralized hydrogels did not affect the growth and proliferation of MC3T3-E1 cells. Surface mineralization of PAM hydrogel could significantly improve osteogenic differentiation of MC3T3-E1 cells. These results showed that PAM-Mineralized hydrogel could possess potential application in the field of subchondral bone tissue engineering.

Synthesis Technology of Magnesium-Doped Nanometer Hydroxyapatite: A Review

Ion substitution techniques for nanoparticles have become an important neighborhood of biomedical engineering and have led to the development of innovative bioactive materials for health systems. Magnesium-doped nanohydroxyapatite (Mg-nHA) has good bone conductivity, biological activity, flexural strength, and fracture toughness due to particle doping technology, making it an ideal candidate material for biomedical applications. In this Review, we have systematically presented the synthesis methods of Mg-nHA and their application in the field of biomedical science and highlighted the pros and cons of each method. Finally, some future prospects for this important neighborhood are proposed. The purpose of this Review is to provide readers with an understanding of this new field of research on bioactive materials with innovative functions and systematically introduce the latest technologies for obtaining uniform, continuous, and morphologically diverse Mg-nHA.

Complex Evaluation of Nanocomposite-Based Hydroxyapatite for Biomedical Applications

A magnesium-doped hydroxyapatite in chitosan matrix (MgHApC) sample was developed as a potential platform for numerous applications in the pharmaceutical, medical, and food industries. Magnesium-doped hydroxyapatite suspensions in the chitosan matrix were obtained by the coprecipitation technique. The surface shape and morphological features were determined by scanning electron microscopy (SEM). The hydrodynamic diameter of the suspended particles was determined by Dynamic light scattering (DLS) measurements. The stability of MgHApC suspensions was evaluated by ultrasonic measurements. The hydrodynamic diameter of the MgHApC particles in suspension was 29.5 nm. The diameter of MgHApC particles calculated from SEM was 12.5 ± 2 nm. Following the SEM observations, it was seen that the MgHApC particles have a spherical shape. The Fourier-transform infrared spectroscopy (FTIR) studies conducted on MgHApC proved the presence of chitosan and hydroxyapatite in the studied specimens. In vitro antimicrobial assays were performed on Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231 microbial strains. The antimicrobial experiments showed that MgHApC exhibited very good antimicrobial properties against all the tested microorganisms. More than that, the results of the in vitro studies revealed that the antimicrobial properties of the samples depend on the incubation time. The evaluation of the sample's cytotoxicity was performed using the human colon cancer (HCT-8) cell line. Our results suggested the great potential of MgHApC to be used in future applications in the field of biomedical applications (e.g., dentistry, orthopedics, etc.).

Latest Research of Doped Hydroxyapatite for Bone Tissue Engineering

Bone tissue engineering has attracted great interest in the last few years, as the frequency of tissue-damaging or degenerative diseases has increased exponentially. To obtain an ideal treatment solution, researchers have focused on the development of optimum biomaterials to be applied for the enhancement of bioactivity and the regeneration process, which are necessary to support the proper healing process of osseous tissues. In this regard, hydroxyapatite (HA) has been the most widely used material in the biomedical field due to its great biocompatibility and similarity with the native apatite from the human bone. However, HA still presents some deficiencies related to its mechanical properties, which are essential for HA to be applied in load-bearing applications. Bioactivity is another vital property of HA and is necessary to further improve regeneration and antibacterial activity. These drawbacks can be solved by doping the material with trace elements, adapting the properties of the material, and, finally, sustaining bone regeneration without the occurrence of implant failure. Considering these aspects, in this review, we have presented some general information about HA properties, synthesis methods, applications, and the necessity for the addition of doping ions into its structure. Also, we have presented their influence on the properties of HA, as well as the latest applications of doped materials in the biomedical field.

Eco-friendly approaches of mycosynthesized copper oxide nanoparticles (CuONPs) using Pleurotus citrinopileatus mushroom extracts and their biological applications

This current study aims to develop a unique biomaterial that can fight against oxidative stress and microbial infections without causing any harm. As a result, an easy-to-make, environment-friendly, long-lasting, and non-toxic copper oxide nanoparticle (CuONP) was synthesized using an edible mushroom Pleurotus citrinopileatus extract. The UV-visa spectroscopy analyses reflected a sharp absorbance peak at 250 nm. The FTIR, XRD, SEM, HR-TEM, and EDX instrumental tools were used to characterize the myco-produced CuONPs. The face-centred cubic (FCC) CuONPs were found to have diffraction peaks at the planes of (110), (002), (111), (112), (020), (202), (113), (310), (220), and (004). The HR-TEM result showed the particles having a spherical structure and an average nanoparticles size of 20 nm. The antimicrobial activity results expressed the broad spectrum of antibacterial effect and the better growth inhibition zone was recorded in P. aeruginosa (8.3 ± 0.1), E. coli (7.4 ± 0.3), K. pneumoniae (7.2 ± 0.1), S. aureus (7.1 ± 0.3), S. pneumoniae (6.3 ± 0.2), and B. cereus (6.2 ± 0.3). The cytotoxicity efficacy of myco-synthesized CuONPs tested against a cancer cell line (HT-29) observed the best result in low doses of mushroom extract (45.62 μg/mL). Based on the outcome of the study suggests that the mycosynthesized CuONPs using Pleurotus mushroom extract might serve as an alternative agent for biomedical applications in the near future.

Effect of rare earth oxide microparticles on mechanical, corrosion, antibacterial, and hemolytic behavior of Mg-Hydroxyapatite composite for orthopedic applications - A preliminary in-vitro study

The current study focused on developing a multifunctional Mg-based biodegradable composite that mitigates the trade-off between strength, antibacterial, and cytotoxicity behavior for orthopedic bone implants. The composite has been reinforced with natural mineral-based Hydroxyapatite and rare earth oxide (REO): Neodymium oxide. The effect of different concentrations of REO on the mechanical, antibacterial, and corrosion properties was analyzed. The antibacterial properties were assessed against gram-positive B. Subtilis and gram-negative E. Coli bacterial pathogens. Moreover, the cytotoxicity of the composites was assessed via Hemolysis percentage calculations. In addition, the microstructure characterization was performed via FESEM, XRD, and EDS techniques, and different intermetallic phase formations were recorded. Contact angle measurements were done via the sessile drop method to analyze the impact of rare earth oxide on the surface properties of the synthesized composites and their relationship with bacterial adhesion. The corrosion studies and swelling rates were performed under PBS and DMEM solutions. The composite with the addition of 1.5% REO outperformed the experiments with a compressive strength of 126.4 MPa, and a corrosion rate less than 0.2 mm/yr. The corrosion rates and degree of swelling were seen to be more stable in DMEM solution as compared to PBS. Improved antibacterial rates were observed against both pathogens after the addition of REO along with a hemolysis percentage less than 5% for Mg-HA-1.5Nd₂ O₃ . The composites showed increased hydrophobicity (>75%) by the addition of 1.5% REO. Hence, it was concluded that REO (Nd₂ O₃ ) addition to the Mg-Hydroxyapatite composite is a feasible choice as a biomaterial for bone implant applications.

Drug Molecular Immobilization and Photofunctionalization of Calcium Phosphates for Exploring Theranostic Functions

Theranostics (bifunction of therapeutics and diagnostics) has attracted increasing attention due to its efficiency that can reduce the physical and financial burden on patients. One of the promising materials for theranostics is calcium phosphate (CP) and it is biocompatible and can be functionalized not only with drug molecules but also with rare earth ions to show photoluminescence that is necessary for the diagnostic purpose. Such the CP-based hybrids are formed in vivo by interacting between functional groups of organic molecules and inorganic ions. It is of great importance to elucidate the interaction of CP with the photofunctional species and the drug molecules to clarify the relationship between the existing state and function. Well-designed photofunctional CPs will contribute to biomedical fields as highly-functional ormultifunctional theranostic materials at the nanoscales. In this review, we describe the hybridization between CPs and heterogeneous species, mainly focusing on europium(III) ion and methylene blue molecule as the representative photofunctional species for theranostics applications.

Impact of Gamma Irradiation on the Properties of Magnesium-Doped Hydroxyapatite in Chitosan Matrix

This is the first report regarding the effect of gamma irradiation on chitosan-coated magnesium-doped hydroxyapatite (x_Mg = 0.1; 10 MgHApCh) layers prepared by the spin-coating process. The stability of the resulting 10 MgHApCh gel suspension used to obtain the layers has been shown by ultrasound measurements. The presence of magnesium and the effect of the irradiation process on the studied samples were shown by X-ray photoelectron spectroscopy (XPS). The XPS results obtained for irradiated 10 MgHApCh layers suggested that the magnesium and calcium contained in the surface layer are from tricalcium phosphate (TCP; Ca₃(PO₄)₂) and hydroxyapatite (HAp). The XPS analysis has also highlighted that the amount of TCP in the surface layer increased with the irradiation dose. The energy-dispersive X-ray spectroscopy (EDX) evaluation showed that the calcium decreases with the increase in the irradiation dose. In addition, a decrease in crystallinity and crystallite size was highlighted after irradiation. By atomic force microscopy (AFM) we have obtained images suggesting a good homogeneity of the surface of the non-irradiated and irradiated layers. The AFM results were also sustained by the scanning electron microscopy (SEM) images obtained for the studied samples. The effect of gamma-ray doses on the Fourier transform infrared spectroscopy (ATR-FTIR) spectra of 10 MgHApCh composite layers was also evaluated. The in vitro antifungal assays proved that 10 MgHApCh composite layers presented a strong antifungal effect, correlated with the irradiation dose and incubation time. The study of the stability of the 10 MgHApCh gel allowed us to achieve uniform and homogeneous layers that could be used in different biomedical applications.

Physicochemical and Biological Evaluation of Chitosan-Coated Magnesium-Doped Hydroxyapatite Composite Layers Obtained by Vacuum Deposition

In the present work, the effectiveness of vacuum deposition technique for obtaining composite thin films based on chitosan-coated magnesium-doped hydroxyapatite Ca10−xMgx(PO4)6 (OH)2 with xMg = 0.025 (MgHApCh) was proved for the first time. The prepared samples were exposed to three doses (0, 3, and 6 Gy) of gamma irradiation. The MgHApCh composite thin films nonirradiated and irradiated were evaluated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) studies. The biological evaluation of the samples was also presented. All the results obtained from this study showed that the vacuum deposition method allowed for obtaining uniform and homogeneous layers. Fine cracks were observed on the MgHApCh composite thin films’ surface after exposure to a 6 Gy irradiation dose. Additionally, after gamma irradiation, a decrease in Ca, P, and Mg content was noticed. The MgHApCh composite thin films with doses of 0 and 3 Gy of gamma irradiation showed a cellular viability similar to that of the control. Samples with 6 Gy doses of gamma irradiation did not cause significantly higher fibroblast cell death than the control (p > 0.05). On the other hand, the homogeneous distribution of pores that appeared on the surface of coatings after 6 Gy doses of gamma irradiation did not prevent the adhesion of fibroblast cells and their spread on the coatings. In conclusion, we could say that the thin films could be suitable both for use in bone implants and for other orthopedic and dentistry applications.

The Effects of Electron Beam Irradiation on the Morphological and Physicochemical Properties of Magnesium-Doped Hydroxyapatite/Chitosan Composite Coatings

This work reports on the influence of 5 MeV electron beam radiations on the morphological features and chemical structure of magnesium-doped hydroxyapatite/chitosan composite coatings generated by the magnetron sputtering technique. The exposure to ionizing radiation in a linear electron accelerator dedicated to medical use has been performed in a controllable manner by delivering up to 50 Gy radiation dose in fractions of 2 Gy radiation dose per 40 s. After the irradiation with electron beams, the surface of layers became nano-size structured. The partial detachment of irradiated layers from the substrates has been revealed only after visualizing their cross sections by scanning electron microscopy. The energy dispersive X-ray spectral analysis of layer cross-sections indicated that the distribution of chemical elements in the samples depends on the radiation dose. The X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction analysis have shown that the physicochemical processes induced by the ionizing radiation in the magnesium doped hydroxyapatite/chitosan composite coatings do not alter the apatite structure, and Mg remains bonded with the phosphate groups.