Effect of Surface Roughness Ti6Al4V Modified by Hydroxyapatite Coating

Several studies have described the use of HAp layers on titanium alloys in the recent years. Among the methods of strengthening the adherence of such layers, which call the researchers’ attention, there is the development of coating by sol-gel type techniques. Coatings of HAp on the alloy of Ti6Al4V allow the formation of uniform layers, with controlled porosity and better adhesion and with properties required for its use as orthopaedic implants. In this paper, samples of Ti6Al4V alloy were used as substrates with different surface roughness, coated with HAp layers that were deposited by a spin-coating technique, using a solution obtained by the sol-gel method. The layers have good homogeneity and good adhesion to the substrate, where stability and uniformity observes for Hap_250 and Hap_110 compared with Hap_29 and Hap_45, that indicate to the importance of surface roughness. Therefore, the biological characterization was investigated, including the film stability in the Simulated Body Fluid (SBF) and the antimicrobial activity of Ti6Al4V alloys coated with hydroxyapatite. Also, the biofilm formation by P. aeruginosa species was evaluated. The morphology and structure of the films were performed by scanning electron microscopy (SEM) and X-ray diffraction (XRD)

Macrophage-like cells are responsive to titania nanotube intertube spacing—an in vitro study

The authors gratefully acknowledge support from Ministry of Research, Innovation and Digitalization through project 41PFE/30.12.3021.With the introduction of a new interdisciplinary field, osteoimmunology, today, it is well acknowledged that biomaterial-induced inflammation is modulated by immune cells, primarily macrophages, and can be controlled by nanotopographical cues. Recent studies have investigated the effect of surface properties in modulating the immune reaction, and literature data indicate that various surface cues can dictate both the immune response and bone tissue repair. In this context, the purpose of the present study was to investigate the effects of titanium dioxide nanotube (TNT) interspacing on the response of the macrophage-like cell line RAW 264.7. The cells were maintained in contact with the surfaces of flat titanium (Ti) and anodic TNTs with an intertube spacing of 20 nm (TNT20) and 80 nm (TNT80), under standard or pro-inflammatory conditions. The results revealed that nanotube interspacing can influence macrophage response in terms of cell survival and proliferation, cellular morphology and polarization, cytokine/chemokine expression, and foreign body reaction. While the nanostructured topography did not tune the macrophages’ differentiation into osteoclasts, this behavior was significantly reduced as compared to flat Ti surface. Overall, this study provides a new insight into how nanotubes’ morphological features, particularly intertube spacing, could affect macrophage behavior.Publisher PDFPeer reviewe

Poly(2-isopropenyl-2-oxazoline) hydrogels for biomedical applications

Synthetic polymers have had a major impact on the biomedical field. However, all polymers have their advantages and disadvantages, so that the selection of a certain polymeric material always is a compromise with regard to many properties, such as synthetic accessibility, solubility, thermal properties, biocompatibility, and degradability. The development of novel polymers with superior properties for medical applications is the focus of many research groups. The present study highlights the use of poly(2-isopropenyl-2-oxazoline) (PiPOx), as biocompatible functional polymer to develop synthetic hydrogel materials using a simple straightforward synthesis protocol. A library of hydrogels was obtained by chemical cross-linking of PiPO(x), using eight different nontoxic and bio-based dicarboxylic acids. The equilibrium swelling degree of the final material can be modulated by simple modification of the composition of the reaction mixture, including the polymer concentration in the feed ratio between the 2-oxazoline pendent groups and the carboxylic acid groups as well as the cross-linker length. The hydrogels with the highest water uptake were selected for further investigations regarding their potential use as biomaterials. We evaluated the thermoresponsiveness, the pH degradability under physiological conditions, and demonstrated proof-of-concept drug delivery experiments. The in vitro cellular studies demonstrated the noncytotoxic character of the PiPOx hydrogels, and their protein repellent properties, while mineralization studies revealed that such scaffolds do not promote mineralization/calcification phenomena. In view of these results, these hydrogels show potential use as ophthalmologic materials or in drug delivery applications

Controlling the Melt Resistance to Flow as a Possibility of Improving the Miscibility and the Time Behavior of Some Blends Based on Starch

The paper proves that the miscibility of some blends based on starch can be improved by finding for each of them the melt resistance to flow at which the nonstationary flow and the melt degradation are avoided and the developed shear rate homogenizes optimally the material composition. The obtained results show that, for process sensitive materials like starches, the border between good and less miscibility is so narrow that the window of melt processing conditions and the best formulation must be found for each of them. The improving of miscibility by controlling the melt resistance to flow proves to be a good method to prevent retrogradation and plasticizer leaching and so to handle the new compounds behavior during usage

Layered Composites Based on Recycled PET/Functionalized Woven Flax Fibres

Extended Abstract Plastic waste is generated by a variety of sources including packaging, automotive, consumer goods, electrical and electronics industries, leading to a significant growth in the volume of waste and the impetuous need to reduce it The paper aims at developing new layered composite materials based on recycled thermoplastic polymer (PETpolyethylene terephthalate) from the food industry reinforced with woven flax fiber functionalized with nano (micro) particles of titanium or alumina and testing the composite in terms of physico-mechanical (tensile strength, bending, shock, etc.), morphological (SEM), structural (FTIR), and thermal (Vicat) properties. Based on this technology, the new composite will exhibit improved physical, mechanical and thermal properties, as well as resistance to mold attack. In this regard, in the first stage, the surface of flax fibers were chemically modified using aluminum (AlCl3), and titanium (titanium butoxide) precursors followed by precipitation. The woven flax whose surface was functionalized with nano (micro) alumina or TiO2 particles were subsequently used to obtain layered composite materials. Layered composite materials were obtained by alternating functionalized / not functionalized woven flax fiber with sheets made from recycled PET. The recycled PET sheets and layered composites based on recycled PET and functionalized / not functionalized woven flax fiber were obtained by press molding using an electrical press at the following optimum parameters: plate temperature -254ºC, preheating time -8 min; pressing time -2 min; cooling time -15 min; pressing force -100 kN. Special attention must be paid to the pre-drying process (at 100-110ºC) to remove adsorbed water. In the absence of the pre-drying operation, the resulting sheets exhibit holes, porosity and discontinuities, making them unusable for the development of layered composite materials. Physical, mechanical and thermal analyses results for specimens of layered composite materials based on recycled PET / functionalised woven flax fiber show significantly improved values compared with the control samples obtained from recycled PET / not functionalized flax fiber. Improved mechanical and thermal properties are due to links developed at the woven flax fiber / polymer phase interphase. Results have also been confirmed by SEM, while the degree of adhesion and the interpenetration of polymer phase / woven flax fiber are superior in the case of composites made of functionalized flax fibers in comparison with the unfunctionalized ones

Embedded Target Filler and Natural Fibres as Interface Agents in Controlling the Stretchability of New Starch and PVOH-Based Materials for Rethinked Sustainable Packaging

A structuring solution converting starch into a multiphase polymeric material was obtained through a melt compounding sequence, which can be irreversibly shaped by thermoforming into rethinked, sustainable packaging, based on the physical modification of starch with polyvinyl alcohol (PVOH), target fillers, (CaCO3 and wood flour), and a good plasticizer compatible with the polar components. Polymeric material can be thermoformed if it can be stretched without breaking in the positive temperature range, have functional properties required by the application, and keep its shape and properties after stretching for more than six months. The properties of the selected quaternary starch-based compound, fulfil the requirements for a thermoformable polymeric material due to the chemical compatibility between the components and the compounding in a selected procedure and optimal conditions wich ensure a comfortable miscibility. Most likely, the obtained miscibility can be explained only by the arrangement of the wood flour at the interface, where it acts as compatibilizer with a main role in structuring the new starch-based materials. The compatibilizer role of the wood flour was proved for the quaternary selected blend by the changing of the thermal degradation mechanism, from one with two stages for binary and tertiary blends, to one consisting of a single stage: decreasing till elimination of morphological defects, the reproducibility of the mechanical properties, stretching without breaking, and dimensional stability after stretching. Future studies will aim to achieve rethinked packaging for applications that require higher strength properties

Romanian bentonite and fly ash characterization and their use in heavy metal “in-situ” immobilization in polluted soils

This article presents the characterization of the Romanian bentonite and fly ash, using different techniques: FAAS, XRD, FT-IR, SEM and EDAX and their evaluation as sorbents for heavy metals immobilization in polluted soils coming from mining and metallurgical activities. The applicability of bentonite and fly ash for Pb (II) and Zn (II) immobilization was studied using aqueous solutions of these metals. The influence of the pH and contact time were studied. The results shown that the Romanian bentonite and fly ash could be used for Pb (II) and Zn (II) immobilization in polluted soils from brownfields

Romanian bentonite and fly ash characterization and their use in heavy metal “in-situ” immobilization in polluted soils

This article presents the characterization of the Romanian bentonite and fly ash, using different techniques: FAAS, XRD, FT-IR, SEM and EDAX and their evaluation as sorbents for heavy metals immobilization in polluted soils coming from mining and metallurgical activities. The applicability of bentonite and fly ash for Pb (II) and Zn (II) immobilization was studied using aqueous solutions of these metals. The influence of the pH and contact time were studied. The results shown that the Romanian bentonite and fly ash could be used for Pb (II) and Zn (II) immobilization in polluted soils from brownfields