Biological and Physico-Chemical Properties of Composite Layers Based on Magnesium-Doped Hydroxyapatite in Chitosan Matrix

Visible Light-Sensitive Sustainable Quantum Dot Crystals of Co/Mg Doped Natural Hydroxyapatite Possessing Antimicrobial Activity and Biocompatibility

Cutting-edge research in advanced materials is increasingly turning toward the development of novel multifunctional nanomaterials for use in high-tech applications. This research uses the solid-state method as a solvent-free technique to create multifunctional quantum dot (QD) hydroxyapatite (HA) crystals from bovine bone waste. By incorporating cobalt (Co) and magnesium (Mg) into the HA structure, the crystallinity of the hexagonal HA nanoparticles (99.7%), showing QD crystals is enhanced. Oxygen vacancies on the surfaces of the HA nanoparticles contributed to their bandgap falling within the visible light range. In addition, the dopants substituted calcium in the HA crystal structure and generated a divalent oxidation state, shifting the bandgap of natural HA toward red wavelengths (3.26 to 1.94 eV). Moreover, the incorporation of Co led to magnetization within the HA structure through spin polarization. Additionally, the doped QD crystals of HA nanoparticles showed significant antimicrobial activity against Escherichia coli, Staphylococcus aureus, and bacteriophages MS2, particularly under visible light exposure. In short, the Co/Mg co-doped HA nanoparticles exhibited ferromagnetic properties, sensitivity to visible light, biocompatibility, and considerable antimicrobial effects, establishing their potential as sustainable multifunctional materials for biomedical applications, especially in anti-infection treatments.

Development of Novel Biocomposites with Antimicrobial-Activity-Based Magnesium-Doped Hydroxyapatite with Amoxicillin

Background/Objectives: A biocomposite based on magnesium-doped hydroxyapatite and enriched with amoxicillin (MgHApOx) was synthesized using the coprecipitation method and is presented here for the first time. Methods: The stability of MgHAp and MgHApOx suspensions was evaluated by ultrasound measurements. The structure of the synthesized MgHAp and MgHApOx was examined with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The crystalline structure was determined by X-ray diffraction. The FTIR data were collected in the range of 4000-400 cm-1. The morphology of the nanoparticles was evaluated by scanning electron microscopy (SEM). Furthermore, the biocompatible properties of MgHAp, MgHApOx and amoxicillin (Ox) suspensions were assessed using human fetal osteoblastic cells (hFOB 1.19 cell line). The antimicrobial properties of the MgHAp, MgHApOx and Ox suspension nanoparticles were assessed using the standard reference microbial strains Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Candida albicans ATCC 10231. Results: X-ray studies have shown that the biocomposite retains the characteristics of HAp and amoxicillin. The SEM assessment exhibited that the apatite contains particles at nanometric scale with acicular flakes morphology. The XRD and SEM results exhibited crystalline nanoparticles. The average crystallite size calculated from XRD analysis increased from 15.31 nm for MgHAp to 17.79 nm in the case of the MgHApOx sample. The energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analysis highlighted the presence of the constituent elements of MgHAp and amoxicillin. Moreover, XPS confirmed the substitution of Ca2+ ions with Mg2+ and the presence of amoxicillin constituents in the MgHAp lattice. The results of the in vitro antimicrobial assay demonstrated that MgHAp, MgHApOx and Ox suspensions exhibited good antimicrobial activity against the tested microbial strains. The results showed that the antimicrobial activity of the samples was influenced by the presence of the antibiotic and also by the incubation time. Conclusions: The findings from the biological assays indicate that MgHAp and MgHApOx are promising candidates for the development of new biocompatible and antimicrobial agents for biomedical applications.

Composites of hydroxyapatite and their application in adsorption, medicine and as catalysts

Composites of hydroxyapatite, recognized by its peculiar crystal architecture and distinctive attributes showcased the potential in adsorbing heavy metal ions and radioactive elements as well as selected organic substances. In this paper, the intrinsic mechanism of adsorption by composites hydroxyapatite was proved for the first time. Subsequently, selectivity and competitiveness of composites of hydroxyapatite for a variety of environments containing various interferences from cations, anions, and organic molecules are elucidated. Next, composites of hydroxyapatite were further categorized according to their morphological dimensions. Adsorption properties and intrinsic mechanisms were investigated based on different morphologies. It was shown that although composites of hydroxyapatite were characterized by excellent adsorption capacity and cost-effectiveness, their application is often challenging due to inherent fragility and agglomeration, technical problems required for their handling as well as difficulty in recycling. Finally, to address these issues, the paper discusses the tendency of hydroxyapatite composites to adsorb heavy metal ions and radioactive elements as well as the limitations of their applications. Summarizing the limitations and future directions of modification of HAP in the field of heavy metal ions and different substances contamination abatement, the paper provides insightful perspectives for its gradual improvement and rational application.

Chitosan-Clay Mineral Nanocomposites with Antibacterial Activity for Biomedical Application: Advantages and Future Perspectives

Polymers of natural origin, such as representatives of various polysaccharides (e.g., cellulose, dextran, hyaluronic acid, gellan gum, etc.), and their derivatives, have a long tradition in biomedical applications. Among them, the use of chitosan as a safe, biocompatible, and environmentally friendly heteropolysaccharide has been particularly intensively researched over the last two decades. The potential of using chitosan for medical purposes is reflected in its unique cationic nature, viscosity-increasing and gel-forming ability, non-toxicity in living cells, antimicrobial activity, mucoadhesiveness, biodegradability, as well as the possibility of chemical modification. The intuitive use of clay minerals in the treatment of superficial wounds has been known in traditional medicine for thousands of years. To improve efficacy and overcome the ubiquitous bacterial resistance, the beneficial properties of chitosan have been utilized for the preparation of chitosan-clay mineral bionanocomposites. The focus of this review is on composites containing chitosan with montmorillonite and halloysite as representatives of clay minerals. This review highlights the antibacterial efficacy of chitosan-clay mineral bionanocomposites in drug delivery and in the treatment of topical skin infections and wound healing. Finally, an overview of the preparation, characterization, and possible future perspectives related to the use of these advancing composites for biomedical applications is presented.

Exploring the physicochemical traits, antifungal capabilities, and 3D spatial complexity of hydroxyapatite with Ag+Mg2+ substitution in the biocomposite thin films

The silver/magnesium doped hydroxyapatite (AgMgHAp, Ca10-x-yAgxMgy(PO4)6(OH)2, xAg=0.05 and yMg=0.02) nanocomposites coatings were deposited on Si substrate using the dip coating technique. The resulting coatings were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR-ATR) spectroscopy, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The EDS analysis highlighted the presence of the constitutive elements of the silver/magnesium doped hydroxyapatite (AgMgHAp) nanocomposites coatings. The surface microtexture of the AgMgHAp was assessed by atomic force microscopy (AFM) technique. The AFM data suggested the obtaining of a uniform deposited layer comprised of equally distributed nanoconglomerates. FT-IR studies highlighted the presence of vibrational modes associated with the phosphate and hydroxyl groups. No bands associated with silver or magnesium were observed. The XPS analysis highlighted the presence of the constituent elements of hydroxyapatite (Ca 2p, P 2 s, O 1 s), as well as dopants (Ag 3d, Mg 1 s and Mg 2p). The antifungal evaluation of AgMgHAp coatings was carried out using the Candida albicans ATCC 10231 fungal strain. The results of the antifungal assay revealed that the AgMgHAp coatings exhibited a strong inhibitory antifungal activity. Furthermore, the data highlighted that the AgMgHAp inhibited the development of biofilm on their surface. The results revealed that the antifungal activity of the coating varied based on the duration of incubation. On the other hand, the data also showed that AgMgHAp nanocomposites coatings inhibited the fungal cell adhesion and development from the early stages of the incubation. In addition to morphological analysis, we additionally take advantage of AFM images to investigate and explore the domain of fractal and multifractal analysis applied to the films under evaluation. Our studies indicates that nanocomposite coatings made from AgMgHAp demonstrate strong antifungal properties. Our studies indicates that nanocomposite coatings made from AgMgHAp demonstrate strong antifungal properties. These results suggest the potential of AgMgHAp nanocomposite coatings as a promising solution for developing innovative antifungal devices in biomedical applications.

Magnesium-Doped Nano-Hydroxyapatite/Polyvinyl Alcohol/Chitosan Composite Hydrogel: Preparation and Characterization

Background

Polyvinyl alcohol/Chitosan hydrogel is often employed as a carrier because it is non-toxic, biodegradable, and has a three-dimensional network structure. Meanwhile, Magnesium-doped nano-hydroxyapatite(Mg-nHA) demonstrated high characterization to promote the osteogenic differentiation of bone marrow derived mesenchymal stem cell(BMSCs). Therefore, in order to develop a porous hydrogel scaffold for the application of bone tissue engineering, an appropriate-type Mg-nHA hydrogel scaffold was developed and evaluated.

Methods

A composite hydrogel containing magnesium-doped nano-hydroxyapatite (Mg-nHA/PVA/CS) was developed using a magnetic stirring-ion exchange method and cyclic freeze-thaw method design, with polyvinyl alcohol and chitosan as the main components. Fourier transform infrared spectra (FTIR), electron energy dispersive spectroscopy (EDS), X-ray photoelectron spectrometer (XPS) and scanning electron microscopy (SEM) were employed to analyze the chemical structure, porosity, and elemental composition of each hydrogels. The equilibrium swelling degree, moisture content, pH change, potential for biomineralization, biocompatibility, the osteogenic potential and magnesium ion release rate of the composite hydrogel were also evaluated.

Results

SEM analysis revealed a well-defined 3D spatial structure of micropores in the synthesised hydrogel. FTIR analysis showed that doping nanoparticles had little effect on the hydrogel's structure and both the 5% Mg-nHA/PVA/CS and 10% Mg-nHA/PVA/CS groups promoted amide bond formation. EDS observation indicated that the new material exhibited favourable biomineralization ability, with optimal performance seen in the 5% Mg-nHA/PVA/CS group. The composite hydrogel not only displayed favourable water content, enhanced biocompatibility, and porosity (similar to human cancellous bone), but also maintained an equilibrium swelling degree and released magnesium ions that created an alkaline environment around it. Additionally, it facilitated the proliferation of bone marrow mesenchymal stem cells and their osteogenic differentiation.

Conclusion

The Mg-nHA/PVA/CS hydrogel demonstrates significant potential for application in the field of bone repair, making it an excellent composite material for bone tissue engineering.

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.

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.).

Biocomposite Coatings Doped with Magnesium and Zinc Ions in Chitosan Matrix for Antimicrobial Applications

Hydroxyapatite doped with magnesium and zinc in chitosan matrix biocomposites have great potential for applications in space technology, aerospace, as well as in the biomedical field, as a result of coatings with multifunctional properties that meet the increased requirements for wide applications. In this study, coatings on titanium substrates were developed using hydroxyapatite doped with magnesium and zinc ions in a chitosan matrix (MgZnHAp_Ch). Valuable information concerning the surface morphology and chemical composition of MgZnHAp_Ch composite layers were obtained from studies that performed scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), metallographic microscopy, and atomic force microscopy (AFM). The wettability of the novel coatings, based on magnesium and zinc-doped biocomposites in a chitosan matrix on a titanium substrate, was evaluated by performing water contact angle studies. Furthermore, the swelling properties, together with the coating's adherence to the titanium substrate, were also analyzed. The AFM results emphasized that the composite layers exhibited the surface topography of a uniform layer, and that there were no evident cracks and fissures present on the investigated surface. Moreover, antifungal studies concerning the MgZnHAp_Ch coatings were also carried out. The data obtained from quantitative antifungal assays highlight the strong inhibitory effects of MgZnHAp_Ch against C. albicans. Additionally, our results underline that after 72 h of exposure, the MgZnHAp_Ch coatings display fungicidal features. Thus, the obtained results suggest that the MgZnHAp_Ch coatings possess the requisite properties that make them suitable for use in the development of new coatings with enhanced antifungal features.