Synthesis of Biocompatible Hydroxyapatite Using Chitosan Oligosaccharide as a Template

Tri-Component Hydrogel as Template for Nanocrystalline Hydroxyapatite Deposition Using Alternate Soaking Method for Bone Tissue Engineering Applications

Composite hydrogels containing apatite-like particles can act as scaffolds for osteoblast proliferation, with applications in bone tissue engineering. In this respect, porous biocompatible hydrogels were obtained from chitosan, oxidized pullulan, and PVA in different ratios. The stability of the hydrogels was ensured both by covalent bonds between aldehyde groups of oxidized pullulan and free amino groups of chitosan, and by physical bonds formed during freeze-thaw cycles and lyophilization. The deposition of calcium phosphates was performed by alternate soaking of the porous hydrogels into solutions with calcium and phosphate ions, assuring a basic pH required for hydroxyapatite formation. The mineralized hydrogels were characterized using FTIR spectroscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis, showing that inorganic particles containing between 80 and 92% hydroxyapatite were deposited in a high amount on the pore walls of the polymeric matrix. The composition of the organic matrix influenced the crystallization of calcium phosphates and the mechanical properties of the composite hydrogels. In vitro biological tests showed that mineralized hydrogels support the proliferation of MG-63 osteoblast-like cells to a greater extent compared to pristine hydrogels.

Synthesis, characterization, in vitro biocompatibility and antibacterial properties study of nanocomposite materials based on hydroxyapatite-biphasic ZnO micro- and nanoparticles embedded in Alginate matrix

The paper presents the results of studies of biocompatibility and antibacterial properties of multiphase nanocomposite materials based on HA-Alg-ZnO (hydroxyapatite‑sodium alginate-biphasic zinc oxide) and HA-ZnO (hydroxyapatite‑zinc oxide), which were synthesized from the analytically pure calcium nitrate tetrahydrate, ammonium hydrophosphate, hydrous ammonia, zinc nitrate hexahydrate and calcium chloride. The samples' antimicrobial activity assessment was carried out on Gram-negative (E. coli, P. aeruginosa) and Gram-positive bacteria (S. aureus and S. epidermidis) test cultures by the co-incubation and modified "agar diffusion" methods. The murine fibroblast cells were used for the biocompatibility tests and cytotoxicity evaluation. It was shown that synthesized nanocomposite material has a multiphase nanoscale architecture, where ZnO nanocrystals are represented by two lattices: cubic and hexagonal. The possible explanation of ZnO nanocrystals' phase transition is given. At the same time, a partial replacement of Ca²⁺ ions by Zn²⁺ ions in the HA lattice possibly occurs due to processing of composite by US radiation. The replacement was evidenced by the non-stoichiometric Ca/P ratio < 2.16, OPO lines' shifting on FTIR spectrum and TEM analysis. The studied composite demonstrate a pronounced antibacterial activity due to the incorporation of ZnO particles into sodium alginate and moistened powder of hydroxyapatite. Both forms of HA-ZnO (suspension) and HA-Alg-ZnO (beads) are biocompatible. An interpretation of the process of Zn ions' embedding into hydroxyapatite and alginate matrix is given, as well as their influence on the biomimetic composite properties is discussed in details. STATEMENT OF SIGNIFICANCE: A number of studies have shown that Zn effectively inhibits the growth and development of bacteria and yeast fungi. Zinc plays an important role in the creation of new antimicrobial agents, and zinc-doped hydroxyapatite will find further application in biomedicine. In this regard, the phase states of zinc oxide, as well as the processes of calcium replacement by zinc in calcium apatite and in alginate should be explored fully. Nowadays we have lack of information and the study's results about those interactions. The present study provides data of the multiphase morphology, antimicrobial activity, biocompatibility and cytotoxicity of the biomimetic nanostructured composite materials, such as sodium alginate/hydroxyapatite/ZnO based granules and hydroxyapatite/ZnO based hydrogel, and the establishing Zn ions' behavior patterns with another composite components.

Chlorogenic acid- loaded calcium phosphate chitosan nanogel as biofilm degradative materials

This work describes an effort to develop an antimicrobial agent (chlorogenic acid - CGA) loaded porous nanogel based on calcium phosphate-chitosan (CaPNP@Chi) nanogel with biofilm degradative properties and has potential applications in restorative dentistry. The nanogel was prepared by ionic gelation of calcium phosphate nanoparticles and chitosan in the ratio of 1.25: 1. Chlorogenic acid was loaded to the nanoparticles as an ethanolic solution and the encapsulation efficiency determined by chromatographic techniques. The particle size and morphology of CaPNP@Chi and CaPNP@Chi@CGA was determined by dynamic light scattering and scanning electron microscopic techniques. The minimum inhibitory concentration against S. aureus and K. pneumoniae was determined through the well diffusion method. The biofilm formation and biofilm decay were studied through staining assays. The toxicity, if any of the nanogel was assessed by MTT assay against HaCaT cells. All data were statistically analyzed. The composite had a CGA encapsulation efficiency of 70% and was thermally stable up to 124 °C. The zone of inhibition was found to be 18.7 mm ± 0.6 against S. aureus. CaPNP@Chi@CGA showed a 68% increase in biofilm degradation when compared with the untreated group. Results obtained in this study suggest that the positively charged nanogel interacted with the bacterial cell membrane and brought about the disruption of the cell membrane. Also, CaPNP@Chi@CGA was observed to be nontoxic up to 40 μg/mL to HaCaT cells. These results support the potential of CaPNP@Chi@CGA nanogel for biofilm degradation and its application as filling material in restorative dentistry.

Effect of gamma irradiation on carbon dot decorated polyethylene-gold@ hydroxyapatite biocomposite on titanium implanted repair for shoulder joint arthroplasty

High disappointment rate of the ligament to hard tissue mending after the medical procedure has dependably been a testing issue in rotator cuff repair. Considering the elasticity of carbon dot decorated polyethylene (f-CDs-PE) and osteogenic movement of gold substituted hydroxyapatite (Au@HA) bioceramic, f-CDs-PE-Au@HA biocomposite coatings were created by an electrophoretic deposition method (EPD), the in vivo and in vitro bioactivity and cytocompatibility were researched. The physico-chemical properties of f-CDs-PE-Au@HA biocomposite coatings were characterized using fourier transform infra-red (FTIR) and X-Ray diffractometery (XRD). The morphology of the fabricated biocomposites was analyses via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. With a gamma-irradiation of f-CDs-PE-Au@HA biocomposite coating (BC₂), the bond and multiplication of cells on biocomposite coating were improved. The specimen with a f-CDs-PE-Au@HA biocomposite (BC₂) demonstrated a most noteworthy alkaline phosphatase activity articulation. The animal model consequences additionally show that the f-CDs-PE-Au@HA biocomposite (BC₂) had great bioactive and cytocompatibility, which could develop the association of collagen and the arrangement of ligament and hard tissue. Expansion of the gamma-ray irradiation with f-CDs-PE-Au@HA biocomposite coating (BC₂) at the tendon- hard tissue crossing point was exhibited to reinforce the mending entheses, increment hard tissue and tendon development and progress collagen association contrasted and control. The above outcomes have recommended that the progressive, implantable and solid stringy platforms built utilizing EPD extraordinary potential for enlargement of rotator cuff tears-recuperating.

Preparation and Characterization of Biomimetic Hydroxyapatite Nanocrystals by Using Partially Hydrolyzed Keratin as Template Agent

Hydroxyapatite (HA), a typical inorganic component of bone, is a widely utilized biomaterial for bone tissue repair and regeneration due to its excellent properties. Inspired by the recent findings on the important roles of protein in biomineralization and natural structure of fish scales, keratin was chosen as a template for modulating the assembly of HA nanocrystals. A series of HA nanocrystals with different sizes were synthesized by adjusting the concentration of partially hydrolyzed keratin. The structure and compositions of the prepared HA were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectrum, and Transmission electron microscopy (TEM). Results revealed that the size of the synthesized HA nanocrystals can be controlled by adjusting the concentration of partially hydrolyzed keratin. Specifically, the size of synthesized HA decreased from 63 ± 1.5 nm to 27 ± 0.9 nm with the increasing concentration of partially hydrolyzed keratin from 0 to 0.6g. In addition, in vitro cytocompatibility of synthesized HA nanocrystals were evaluated using the MG-63 cells.