Optimization of methyl orange decolorization by bismuth(0)-doped hydroxyapatite/reduced graphene oxide composite using RSM-CCD.

In the current study, the catalyst for the decolorization of methyl orange (MO) was developed HAp-rGO by the aqueous precipitation approach. Then, bismuth(0) nanoparticles (Bi NPs), which expect to show high activity, were reduced on the surface of the support material (HAp-rGO). The obtained catalyst was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. The parameters that remarkably affect the decolorization process (such as time, initial dye concentration, NaBH4 amount, and catalyst amount) have been examined by response surface methodology (RSM), an optimization method that has acquired increasing significance in recent years. In the decolorization of MO, the optimum conditions were identified as 2.91 min, Co: 18.85 mg/L, NaBH4 amount: 18.35 mM, and Bi/HAp-rGO dosage: 2.12 mg/mL with MO decolorization efficiency of 99.60%. The decolorization process of MO with Bi/HAp-rGO was examined in detail kinetically and thermodynamically. Additionally, the possible decolorization mechanism was clarified. The present work provides a new insight into the use of the optimization process for both the effective usage of Bi/HAp-rGO and the catalytic reduction of dyes.

Fabrication and Characterization of a Multifunctional Coating to Promote the Osteogenic Properties of Orthopedic Implants.

Titanium-based alloys are used in orthopedic applications as fixation elements, hard tissue replacements in artificial bones, and dental implants. Despite their wide range of applications, metallic implant defects and failures arise due to inadequate mechanical bonding, postoperative clotting problems, aseptic loosening, and infections. To improve the surface bioactivity and reduce the corrosion rate of the Ti6Al4V alloy, multi-layered coatings (HAp, BG, Cs, and Hep) were applied via electrophoretic deposition (EPD). XRD images showed the presence of HAp within the coating. In vitro investigation: cell line NIH-3T3 fibroblasts were seeded on the non-coated and coated Ti6Al4V substrates, and their cellular behavior was evaluated. The results indicated that the HApBGCsHep coating could enhance the adhesion and proliferation of NIH 3T3 cells. In addition, the potentiodynamic polarization results are compatible with the in vitro outcome.

The effect of theranekron on femur fracture healing in an experimental rat model.

OBJECTIVES: The aim of this study was to investigate the radiological, biomechanical, histopathological and immunohistochemical effects of theranekron on fracture healing in an experimental rat model. MATERIALS AND METHODS: Forty-eight male albino Wistar rats were used. Four groups were formed, with 12 rats in each of theranekron groups 1 and 2, and control groups 1 and 2. After a fracture was created in the right femur of the rats included in the study, fixation was performed with an intramedullary Kirschner wire. Theranekron was administered subcutaneously to theranekron groups 1 and 2 at a dose of 0.3 mg/kg on days 0, 5 and 10. After radiographic analysis of the femurs of theranekron group 1 and control group 1 rats at four weeks of the study was performed, both groups were divided into two equal subgroups (six femurs in each group). Histopathological and immunohistochemical examinations were performed in one subgroup and biomechanical examination in the other subgroup. At the end of six weeks, the rats in theranekron group 2 and control group 2 were evaluated after applying the same procedure as in the fourth week. RESULTS: When the mean radiological scores of the theranekron and control groups were compared, a statistically significant difference was found in favor of the theranekron group at four and six weeks (p=0.028 and p=0.006, respectively). At four weeks, statistically significant higher biomechanical forces were obtained in the theranekron group compared to the control group (p=0.030). In the histopathological evaluation, the inflammation value of the control group at four weeks was statistically significantly higher than the theranekron group (p=0.027). The angiogenesis, osteoblast proliferation, and bone formation values of the theranekron group were significantly higher than the control group (p=0.014, p=0.014, and p=0.005, respectively). At six weeks, the bone formation values of the theranekron group were statistically significantly higher than the control group (p=0.021). The difference between the theranekron group and the control group scores of the immunohistochemical evaluation were statistically significantly different at four and six weeks (p=0.006 and p=0.011, respectively). CONCLUSION: Theranekron may play a role in accelerating fracture healing by reducing acute inflammation process in the early period of fracture union, increasing fracture strength, angiogenesis, osteoblast proliferation, and bone formation.

Investigation of surface structure and biocompatibility of chitosan-coated zirconia and alumina dental abutments.

BACKGROUND: For long-term success of dental implants, it is essential to maintain the health of the surrounding soft tissue barrier, which protects the bone-implant interface from the microorganisms. Although implants based on titanium and its alloys still dominate the dental implant market, alumina (Al2 O3 ) and zirconia (ZrO2 ) implant systems are widely used in the area. However, they provide smooth and bioinert surfaces in the transmucosal region, which poorly integrate with the surrounding tissues. OBJECTIVE: The main aim of this research was to investigate the surface characteristics and biocompatibility of chitosan-coated alumina and zirconia surfaces. MATERIALS AND METHODS: The substrates were coated via solution casting technique. Additionally, an aging process with a thermocycle apparatus was applied on the coated materials to mimic the oral environment. To define the morphology and chemical composition of the surfaces of untreated, chitosan-coated, and chitosan-coated-aged samples, scanning electron microscopy and energy dispersive X-ray spectrometry were used. The phases and bonds characterized by Fourier transform infrared spectroscopy and X-ray diffraction analysis. The human gingival fibroblast cells were used to evaluate cytocompatibility by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium salt assay. RESULTS: It was observed that both substrates were successfully coated with chitosan and the aging process did not significantly affect the integrity of the coating. The attachment and proliferation of human gingival fibroblast cells were shown to be good on both kinds of chitosan-coated surfaces. CONCLUSION: Coating zirconia and alumina surfaces with chitosan is an efficient surface modification for increasing biocompatibility and bioactivity of these materials in vitro.