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[Display omitted] • Deposited HEFs showed a higher capacity for HAp formation and bioactivity. • Low working pressure yielded a dense and compact structure with no cracks. • Ti content disparity occurred due to its lower atomic weight during sputtering. • In the dense microstructure, oxygen diffusion through the depth has been minimized. • HEA-1500-Ar25-P0.5 caused robust protection lowering Ni ion release in AS and SBF. This paper presents the experimental findings on the effect of deposition conditions on the microstructure of the corrosion-resistant TiTaNbZrMo high entropy alloy (HEA) thin films deposited on NiTi substrates with the purpose of enhancing biocompatibility of the NiTi shape memory alloy (SMA). For this purpose, RF magnetron sputtering was employed to fabricate TiTaNbZrMo HEA films with 750 nm and 1500 nm thicknesses. Static immersion experiments were conducted in simulated body fluid (SBF) and artificial saliva (AS) solutions for 1, 14, and 28 days to establish the relationship between Ni ion release and deposition parameters. The results revealed that thin films grown under low working pressure exhibited crystalline body-centered cubic (BCC) microstructure with a highly dense, compact, and crack-free structure, while those deposited under high-pressure conditions exhibited an amorphous structure with inherent cracks. The biocorrosion test results indicated that the dense and compact thin film fulfilled the expected corrosion resistance requirements for prolonged utility in human body. Moreover, the HEA films revealed an outstanding amount of hydroxyapatite (HAp) formation, indicating remarkable bioactivity and favorable bone-bonding capabilities. The findings suggest that the HEA films deposited under low working pressures could constitute promising alternatives to conventional coatings on NiTi SMAs. [ABSTRACT FROM AUTHOR]

In this paper, parylene C coating with the thickness of 2 μm was deposited on different magnesium alloy substrates (AZ31, WE43 and AZ91). The structure and phase composition of parylene C coating was analysed by Fourier transformed infrared (FTIR) spectroscopy and X-ray diffraction (XRD). In addition, extensive surface characterization was done using atomic force microscopy. The corrosion performance of polymer-coated magnesium alloys was investigated by electrochemical measurements in Hanks’ balanced salts solution that simulates bodily fluids at 37 ± 0.5 °C. The depth-dependent mechanical properties including Young’s modulus and nanohardness of parylene C films were investigated using nanoindentation technique. The effect of the penetration depth on the properties on nano- and microscale level have been described in detail. The percentage of elastic recovery was used to characterize the elastic properties of the polymeric coatings. The results of XRD showed (020) preferred orientation of the monoclinic unit cell of the alpha phase of parylene C. The parylene C revealed a semicrystalline structure with nanocrystalline blocks of 4.9 nm. The parylene C film shows a uniform surface morphology with a higher roughness level at micro and nanoscales compared to magnesium alloy surfaces. All of the uncoated substrates exhibited a low corrosion resistance compared to the coated samples, indicating that the corrosion resistance of the magnesium alloys could be improved by parylene C coating. The resulting average nanohardness and Young’s modulus of the parylene C coatings deposited onto different substrates were in the range of 0.18–0.25 GPa and 4.19–5.14 GPa, respectively. Furthermore, a higher percentage of elastic recovery of the polymer coating indicated a higher elasticity as compared to the magnesium alloy surface. The polymer coating has revealed the ability to recover elastically. Therefore, parylene C coating can not only improve corrosion resistance, but also provide the ability to recover elastically, expanding the potential applications of this material to include various biointerface platforms. [ABSTRACT FROM AUTHOR]

The paper presents a novel method for quantification of the modifications that occur on the surface of different types of gel-coated glass fibre-reinforced polyester composites under artificial UV-ageing at 254 nm. The method implies the adsorption of an ionic dye, namely methylene blue, on the UV-aged composite, and computing the CIELab colour space parameters from the photographic image of the coloured composite's surface. The method significantly enhances the colour differences between the irradiated composites and the reference, in contrast with the non-coloured ones. The colour modifications that occur represent a good indicative of the surface degradation, alteration of surface hydrophily and roughness of the composite and are in good correlation with the ATR-FTIR spectroscopy and optical microscopy results. The proposed method is easier, faster and cheaper than the traditional ones. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we present the first report about constructing a scaffold-like delivery system with poly (lactic-co-glycolic) (PLGA) microspheres on micro-arc oxidation titanium (MAO-Ti). The results show that this system could be stable on the porous MAO-Ti surface up for 6 weeks. Not only the system could control the release of model protein BSA, but also the MAO film could regulate the pH value of the solution which would decrease by the degradation of PLGA microspheres. In addition, compared to MAO-Ti, this system loaded with BSA could improve the proliferation of HBMSCs after 3 or 7 days culture. [Copyright &y& Elsevier]

Abstract: In this paper, a two-step method was used to synthesize a biodegradable polyurethane (PU) composed of l-lysine ethyl ester diisocyanate (LDI), poly(ɛ-caprolactone) diols (PCL-diol) and 1,4:3,6-dianhydro-d-sorbitol (isosorbide). Amino groups were introduced onto the surface of the PU membrane by an amination reacting with 1,3-propanediamine to produce polycationic substratum. And then, type I collagen (Col) and chondroitin sulfate (CS) were deposited alternately on the polycationic substratum through layer-by-layer (LBL) assembly technology. The FTIR and 1H NMR results showed that the polyurethane was successfully synthesized. Rhodamine B isothiocyanate (RBITC) fluorescence spectrum indicated that amino groups were successfully introduced onto the PU surface. The results of quartz-crystal microbalance (QCM) and RBITC-Col fluorescence spectroscopy monitoring the LBL assemble process presented that the Col/CS deposited alternately on the PU surface. X-ray photoelectron spectroscopy (XPS) results displayed that the CS deposited on the PU surface as well. The surface of the assembled PU became even smoother observed from the surface morphology by atomic force microscopy (AFM) imaging. The hydrophilicity of the PU membrane was greatly enhanced though the modification of LBL assembly. The PU modified with the adsorption of Col/CS may be a potential application for cartilage tissue engineering due to its created mimicking chondrogenic environment. [Copyright &y& Elsevier]

Abstract: Recently, many studies have been conducted on exploitation of natural materials for modern product development and bioengineering applications. Apart from plant-based materials (such as sisal, hemp, jute, bamboo and palm fibre), animal-based fibre is a kind of sustainable natural materials for making novel composites. Silkworm silk fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. However, when producing silk fibre reinforced biodegradable/bioresorbable polymer composites, hydrophilic sericin has been found to cause poor interfacial bonding with most polymers and thus, it results in affecting the resultant properties of the composites. Besides, sericin layers on fibroin surface may also cause an adverse effect towards biocompatibility and hypersensitivity to silk for implant applications. Therefore, a proper pre-treatment should be done for sericin removal. Degumming is a surface modification process which allows a wide control of the silk fibre''s properties, making the silk fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, a cleaner and environmentally friendly surface modification technique for tussah silk in polymer based composites is proposed. The effectiveness of different degumming parameters including degumming time and temperature on tussah silk is discussed through the analyses of their mechanical and morphological properties. Based on results obtained, it was found that the mechanical properties of tussah silk are affected by the degumming time due to the change of the fibre structure and fibroin alignment. [Copyright &y& Elsevier]

Abstract: Magnesium-based biomaterials have been proposed as potential candidates for biodegradable implant materials, such as bone screws, bone plates, intraluminal stents and so on. However, the poor corrosion resistance inhibits their applications in surgery. They collapse before the injured tissues are healed. In this paper, Mg(OH)2 nonstructural film was synthesized on the substrate of AZ31 magnesium alloy by hydrothermal method with NaOH solution as mineralizer to reduce the corrosion rate of magnesium-based materials. The obtained films were characterized by XRD, SEM, and XPS. The results showed that a Mg(OH)2 film with nanostructure surface can be synthesized by hydrothermal method. It was observed that the thickness of film increased with the holding time. Corrosion rates of the films were studied by immersing the samples in Hank''s solution (37°C). Surface deposits of samples with films soaked in Hank''s solution for 31 days were investigated by XRD, SEM, EDS, XPS, and FTIR. It verified that the corrosion rate of the magnesium alloy with grown film was slowed down in the Hank''s solution and the behavior of corrosion was inhibited effectively. Amorphous calcium apatite precursor was observed to deposit on the surface of the film during corrosion experiments in Hank''s solution. And the tape test revealed a strong adhesion between the film and the substrate. [Copyright &y& Elsevier]

Abstract: In this paper, a new bio-cleaning procedure based on the glucose oxidase (GOx) has been applied on the travertine and peperino substrata to remove the biological patina (i.e., biofilm). Glucose oxidase, used as a model enzyme system, is able to produce in situ H2O2 (the cleaning agent having oxidizing properties) by the enzymatic reaction at room temperature. The travertine and peperino samples came from the Villa Torlonia in Rome (Italy), and an analytical diagnosis on them was performed applying several analytical techniques, such as the differential interference contrast microscopy (DIC), the optical microscope (OM), the Fourier transform infrared spectroscopy (FT-IR) and the X-ray fluorescence (XRF) that evidence the presence of biofilms on the substrata. Better results were obtained on the travertine samples in terms of the cleaning efficiency and the absence of the etching effect on the surface, eventually induced by the peroxide molecule. These results could be explained in terms of the different porosities of the two kinds of stone materials, according to the BET data. A comparative study was also performed to validate the new bio-cleaning procedure, using both traditional approaches based on saturated (NH4)2CO3 solution and EDTA in buffer solution and the enzyme lipase treatments. Among all, the cleaning procedure via GOx shows the best result, probably because the enzyme controls the concentration of the H2O2 in situ and also retains the H2O2 preferentially on the surface (where the biological patina is present) depending on the porosity of the substrata. A synergistic effect, with other enzymes such as lipase and protease, combined with the biocompatibility of the enzymatic treatments, could represent a new way for a higher cleaning efficiency to apply on different stone substrata. [Copyright &y& Elsevier]