In vitro study of the SBF and osteoblast-like cells on hydroxyapatite/chitosan–silica nanocomposite

Hydroxyapatite/chitosan–silica (HApCSi) nanocomposites were synthesized by co-precipitated method and their potential application as filler materials for bone regeneration were investigated in simulated body fluid (SBF). To study their biocompatibility, they were cultured with rat osteoblast-like UMR-106 cells for 3, 7, 14, and 21 days. Studies of the silica contents in chitosan matrix showed the presence of silinol (Si–OH) groups in CSi hybrid and their decrease after being composited with calcium phosphate (CaP) which is desirable for the formation of the apatite. XRD and TEM studies showed that the HAp formed in the CSi matrix were nanometer (20–40 nm) in size. Nanocomposites of HApCSi20 processed with 20%v/v silica whisker showed a micro hardness of 84.7 ± 3.3 MPa. Mineralization study in SBF showed the formation of apatite crystals on the HApCSi surface after being incubated for 7 days. In vitro biocompatibility, cell morphology, proliferation, and cell adhesion tests confirmed the osteoblast attachment and growth on the HApCSi20 surface. The density of cells and the production of calcium nodules on the substrate were seen to increase with increasing cultured time. The mechanical evaluation and in vitro experiment suggested that the use of HApCSi composite will lead to the formation of new apatite particles and thus be a potential implant material.     

In vitro study of vancomycin release and osteoblast-like cell growth on structured calcium phosphate-collagen

A drug delivery vehicle consisting of spherical calcium phosphate-collagen particles covered by flower-like (SFCaPCol) blossoms composed of nanorod building blocks and their cellular response is studied. The spherical structure was achieved by a combination of sonication and freeze-drying. The SFCaPCol blossoms have a high surface area of approximately 280 m²g^? 1. The blossom-like formation having a high surface area allows a drug loading efficiency of 77.82%. The release profile for one drug, vancomycin (VCM), shows long term sustained release in simulated body fluid (SBF), in a phosphate buffer saline (PBS, pH 7.4) solution and in culture media over 2 weeks with a cumulative release ~ 53%, 75% and 50%, respectively, over the first 7 days. The biocompatibility of the VCM-loaded SFCaPCol scaffold was determined by in vitro cell adhesion and proliferation tests of rat osteoblast-like UMR-106 cells. MTT tests indicated that UMR-106 cells were viable after exposure to the VCM loaded SFCaPCol, meaning that the scaffold (the flower-like blossoms) did not impair the cell's viability. The density of cells on the substrate was seen to increase with increasing cultured time.     

Biocomposite of hydroxyapatite-titania rods (HApTiR): Physical properties and in vitro study

The aim in this research is to study the physical and biocompatible properties of hydroxyapatite (HAp) composites (HApTiR) having different amounts of titania rod (TiR) in them (10–90 wt.%). The HAp and TiR were produced using hydrothermal and co-precipitation under reflux methods, respectively. The physical properties and the in vitro biocompatibility of the composites to simulated body fluid (SBF) were investigated. They were also cultured with rat osteoblast-like UMR-106 cells. The synthesized powder showed a core-shell structure with the titania rod as the core and the apatite as the shell. The hardness of the composites of HApTiR's whisker increased from 74.8 to 92.9 MPa as the TiR content was increased from 10 to 90 wt.%. Mineralization study in SBF showed the formation of apatite crystals on the HApTiR's surface after 7 days of incubation. In vitro cell adhesion tests confirmed the osteoblast attachment and growth on the HApTiR's surface. The density of cells, spread and the production of calcium nodules on the substrate were seen to increase with increasing TiR contents except for HApTiR90 (TiR = 90 wt.%) which exhibited lesser growth. MTT tests on HApTiR70 indicated that UMR-106 cells were viable and the density of cells on the substrate was seen to increase with increasing culturing time.     

High Dietary Cholesterol Masks Type 2 Diabetes-Induced Osteopenia and Changes in Bone Microstructure in Rats

Type 2 diabetes mellitus (T2DM) often occurs concurrently with high blood cholesterol or dyslipidemia. Although T2DM has been hypothesized to impair bone microstructure, several investigations showed that, when compared to age-matched healthy individuals, T2DM patients had normal or relatively high bone mineral density (BMD). Since cholesterol and lipids profoundly affect the function of osteoblasts and osteoclasts, it might be cholesterol that obscured the changes in BMD and bone microstructure in T2DM. The present study, therefore, aimed to determine bone elongation, epiphyseal histology, and bone microstructure in non-obese T2DM Goto-Kakizaki rats treated with normal (GK-ND) and high cholesterol diet. We found that volumetric BMD was lower in GK-ND rats than the age-matched wild-type controls. In histomorphometric study of tibial metaphysis, T2DM evidently suppressed osteoblast function as indicated by decreases in osteoblast surface, mineral apposition rate, and bone formation rate in GK-ND rats. Meanwhile, the osteoclast surface and eroded surface were increased in GK-ND rats, thus suggesting an activation of bone resorption. T2DM also impaired bone elongation, presumably by retaining the chondrogenic precursor cells in the epiphyseal resting zone. Interestingly, several bone changes in GK rats (e.g., increased osteoclast surface) disappeared after high cholesterol treatment as compared to wild-type rats fed high cholesterol diet. In conclusion, high cholesterol diet was capable of masking the T2DM-induced osteopenia and changes in several histomorphometric parameters that indicated bone microstructural defect. Cholesterol thus explained, in part, why a decrease in BMD was not observed in T2DM, and hence delayed diagnosis of the T2DM-associated bone disease.     

Biomagnetic of Apatite-Coated Cobalt Ferrite: A Core–Shell Particle for Protein Adsorption and pH-Controlled Release

Magnetic nanoparticle composite with a cobalt ferrite (CoFe₂O₄, (CF)) core and an apatite (Ap) coating was synthesized using a biomineralization process in which a modified simulated body fluid (1.5SBF) solution is the source of the calcium phosphate for the apatite formation. The core–shell structure formed after the citric acid–stabilized cobalt ferrite (CFCA) particles were incubated in the 1.5 SBF solution for 1 week. The mean particle size of CFCA-Ap is about 750 nm. A saturation magnetization of 15.56 emug^-1 and a coercivity of 1808.5 Oe were observed for the CFCA-Ap obtained. Bovine serum albumin (BSA) was used as the model protein to study the adsorption and release of the proteins by the CFCA-Ap particles. The protein adsorption by the CFCA-Ap particles followed a more typical Freundlich than Langmuir adsorption isotherm. The BSA release as a function of time became less rapid as the CFCA-Ap particles were immersed in higher pH solution, thus indicating that the BSA release is dependent on the local pH.