Towards An In Vitro Model of Testing Osteoblast Cellular Function In Contact With Various Surfaces

Past studies have shown that the success of total joint replacements depends on the biocompatibility of orthopaedic materials, which can be improved by modifying the implant surface. However, the exact roles of these modifications and their effective mechanisms are poorly understood. The objective of this study was to develop and evaluate a model system to investigate the impact of nano-structured surfaces, produced by the ion beam-assisted deposition (IBAD) technique, on biomarkers of osteointegration using an in vitro model. The IBAD technique was employed to deposit zirconium oxide (ZrO2), Titanium oxide (TiO2), and Titanium (Ti) nano-films on glass or Ti substrates. Essential cellular functions including adhesion, proliferation, differentiation, and apoptosis of a human osteosarcoma cell line (SAOS-2) were compared on coated vs. uncoated surfaces at both molecular and gene levels. Our studies have resulted in several novel observations, including enhanced cell adhesion on nano-coated surfaces assessed by the number of DAPI-stained cells along with monitoring cell morphology (actin stress fiber remodeling at focal adhesion sites) on the surfaces using immunofluorescence techniques. Similarly, we reported that IBAD nano-modifications increased cell proliferation on nano-surfaces measured by mitochondrial dehydrogenase activity and a nuclear cell proliferation-associated antigen. Moreover, enhanced cell differentiation on IBAD-produced surfaces was determined by ALP activity and the rate of calcium deposition in alizarin red assays that are in vitro indicators of the successful bone formation. In addition, programmed cell death and necrosis assessed by annexin V staining and flow cytometry observed to be higher on uncoated surfaces compared to nano-surfaces. Finally, there was a correlation between IBAD-modifications and enhanced bone-associated gene expression at cell adhesion, proliferation, and differentiation as assessed by polymerase chain reaction (PCR) techniques. In summary, our studies using an in vitro model system showed that nano-coated surfaces produced by the IBAD technique are superior to uncoated surfaces in supporting bone-cell adhesion, proliferation, differentiation, and reducing apoptosis at both molecular and gene levels. Therefore, increased osteoblast cellular functions and enhanced bone formation with stronger attachments would be expected from these surfaces in bone-cell applications. In contrast, as anticipated by design, polish uncoated metallic surfaces, e.g., cobalt-chromium inhibited such interactions

Comparing biocompatibility of IBAD-produced nano-films of titanium oxide with orthopaedic grade titanium

Titanium (Ti) is the material of choice for orthopaedic applications because it is biocompatible and encourages osteoblast growth. The present study was devised to compare the osteoblast functions on nano-crystalline titanium oxide films produced by an ion beam assisted deposition (IBAD) technique with the osteoblast functions on micro-crystalline orthopaedic-grade titanium. To characterize the biocompatibility of these surfaces, we have studied cell adhesion, growth, and differentiation on different samples. Cell responses to surfaces were examined using the human osteosarcoma cell line (SAOS-2) with osteoblastic properties. To compare cell adhesion and growth, DAPI-stained nuclei were counted using ImageJ and Metamorph software. Immunofluorescence staining was also applied to monitor actin stress fiber shapes in order to compare cell morphology and actin remodeling at focal adhesion sites on the surfaces. Then, alizarin red assay was used to detect calcium compounds on surfaces which is an indication of successful in-vitro bone formation. Our experimental results indicated that nan-crystalline TiO2 is superior to micro-crystalline Ti in supporting growth, adhesion, and proliferation. Also, significantly more calcium deposition was observed on the nano-surfaces

Strategic management of foreign vassals in Iran regarding world recession period

AbstractThis paper which introduces strategic planning for foreign vassals during recession period is the result of a research project. This project has been done for Yazd Government, therefore due to security issues; statement whole of this project is not possible and therefore only some of permitted information could be mentioned. As a basic model Bryson's model was selected and the research group did its stages after each other. During this process, the group used observations, questionnaires, interviews and official national and international documents, analyzed internal and external different stakeholders, defined strategic issues and finally proposed possible strategies for the Yazd government. The procedure of strategy planning is illustrated briefly in this paper. In the end of project, the research group presents its findings and results to the client with a one year operating plan. In the next sections a short report of this project will be depicted

Effect of Treated Time of Hydrothermal Etching Process on Oxide Layer Formation and Its Antibacterial Properties

Inspired by natural materials, we developed an antibacterial surface on titanium (Ti) using hydrothermal etching techniques and examined the effect of treated time on oxide layer formation, its antibacterial properties, and surface defects. Hydrothermal etching was conducted on Grade 2 commercially pure Ti immersed in 5M NaOH at 250 °C during a range of time of 0–12 h. Nanopillars generated on the surface had ~100 nm thickness, which resulted in decreased attachment and rupturing of the attached bacteria. The results also showed that 6 h and 8 h of etching time provided a desirable uniform nanopillar structure with the most effective prevention of bacterial adherence on the surface. Multiscale SEM observations revealed that the longer the etching was conducted, the more cracks propagated, which led to an increase in dissociated fragments of the oxide layer. In the 12 h of etching, a higher density of bacterial adherence was observed than that of the untreated and the shorter time treated samples, indicating that etching took longer than 10 h worsened the antibacterial properties of the nano-patterned surface of Ti. This study demonstrated that the optimal time duration is 6–8 h for the oxide layer formation to maximize antibacterial activity and minimize cracking formation on the surface. For future studies, we suggest exploring many possible conditions to generate a more uniform nanopattern without structural defects to secure the integration between a newly deposited oxide layer and the substrate