Search

TiN and (Ti,Mg)N thin film coatings were deposited on titanium substrates by using cathodic arc physical vapor deposition (arc-PVD) technique with magnesium contents of 0, 4.24 at% (low Mg) and 10.42 at% (high Mg). The presence of magnesium on both normal (hFOB) and cancer (SaOS-2) osteoblast cell behavior was investigated in (Ti, Mg) N surfaces with or without prior hydroxyapatite (HA) deposition (in simulated body fluid, SBF). Mg incorporation on TiN films was found to have no apparent effect on the cell proliferation in bare surfaces but cell spreading was better on low Mg content surface for hFOB cells. SaOS-2 cells, on the other hand, showed an increased extra cellular matrix (ECM) deposition on low Mg surfaces but ECM deposition almost disappeared when Mg content was increased above 10 at%. HA deposited surfaces with high Mg content was shown to cause a significant decrease in cell viability. While the cells were flattened, elongated and spread over the surface in contact with each other via cellular extensions on unmodified and low Mg doped surfaces, unhealthy morphologies of cells with round shape with a limited number of extended arms was visualized on high Mg containing samples. In summary, Mg incorporation into the TiN coatings by arc-PVD technique and successive HA deposition led to promising cell responses on low Mg content surfaces for a better osteointegration performance. 16th European Congress on Biotechnology -- JUL 13-16, 2014 -- Edinburgh, SCOTLAND 25556119 The Scientific and Research Council of Turkey'' (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [112M339]; ITU Graduate School of Science, Engineering and TechnologyIstanbul Technical University [34525] This study was supported by The Scientific and Research Council of Turkey'' (TUBITAK - Project #112M339). The authors also gratefully thank to ITU Graduate School of Science, Engineering and Technology for ITU-BAP Graduate Student Grant #34525.

Our attempts for cathodic arc physical vapor deposition (CA-PVD) of TiAlN coatings with high voltage pulse bias in order to tune their structural properties were not successful. Resulted coatings had an unacceptable rough surface with a large number of macroparticles (MPs). For solving this problem and benefiting from high voltage pulse bias-induced effects on the coatings structure we superimposed high voltage pulse on DC bias. For this purpose, Ti0.5Al0.5N coatings were deposited on HSS substrates using a DC bias voltage of 40 V and superimposed pulse bias voltages of 500, 1000 and 1500 V with a duty cycle of 14%. Structure, chemistry, morphology and mechanical properties of the coatings were determined in order to investigate the differences induced by the application of superimposed bias. Additionally, corrosion protection properties of the coatings were also investigated. According to the obtained results, this mode of application not only produced coatings with a denser and finer columnar structure but also resulted in a substantial reduction in the number of MPs. A decrease (maximum 3 at.%) in the Al content of the coatings was observed with increasing pulse bias magnitude when compared to their DC bias deposited counterpart. Substrate temperature also increased with increasing pulse bias magnitude, however, it did not increase above 460 degrees C. As a result of the decrease of MP attachment and denser structure of the coatings the corrosion protection properties of the coatings substantially improved. This effect became more pronounced with increasing superimposed voltage magnitude.

Successful nanobiotechnology implementation largely depends on control over the interfaces between inorganic materials and biological molecules. Controlling the orientations of biomolecules and their spatial arrangements on the surface may transform many technologies, including sensors, to energy. Here, we demonstrate the self-organization of L-lactate dehydrogenase (LDH), which exhibits enhanced enzymatic activity and stability on a variety of gold surfaces ranging from nanoparticles to electrodes, by incorporating a gold-binding peptide tag (AuBP2) as the fusion partner for Bacillus stearothermophilus LDH (bsLDH). Binding kinetics and enzymatic assays verified orientation control of the enzyme on the gold surface through the genetically incorporated peptide tag. Finally, redox catalysis efficiency of the immobilized enzyme was detected using cyclic voltammetry analysis in enzyme-based biosensors for lactate detection as well as in biofuel cell energy systems as the anodic counterpart. Our results demonstrate that the LDH enzyme can be self-immobilized onto different gold substrates using the short peptide tag under a biologically friendly environment. Depending on the desired inorganic surface, the proposed peptide-mediated path could be extended to any surface to achieve single-step oriented enzyme immobilization for a wide range of applications.

Realizing that certain industrial applications may require diamond films to be deposited over a surface that has the hardness of titanium but has a much higher melting point, the deposition of diamond films over titanium with a pre-deposited thin film of molybdenum is investigated for the first time. Scanning electron microscopy (SEM) observations show that diamond films synthesized over silicon and metallic substrates exhibit identical morphologies. Raman spectra show that films deposited over a metallic substrate exhibit much higher stress than that of films deposited over silicon. X-ray diffraction (XRD) patterns reveal that carbon and metallic elements diffuse at or near the interface but do not affect the final texture of film.