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(A) Schematic of the mechanical test designed to measure the interfacial bond strength between different CoCr samples and PMMA. (B) Tensile bond strength between PMMA and bare CoCr (black), PAP-treated CoCrOCP (grey) and PAP-treated CoCr−0.5 V (orange). Brackets indicate statistically significant differences between groups (p < 0.05)
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Tailoring the surface chemistry of CoCr alloys is of tremendous interest in many biomedical applications. In this work, we show that CoCr can be modified by diazonium electrografting provided the surface is not homogeneously covered with an oxide layer. Cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) show the electrografting of a...
Citations
... For alloys with a higher Co content (68-70 at.%), regardless of the concentration of Cr and Mo, no significant passive behavior was observed [32]. Alloys of cobalt with chromium in the Ringer's solution showed a tendency toward passivation due to the formation of mixed protective layers of Cr 2 O 3 -CoO with a high stability on their surfaces [33]. Figure 4 shows the impedance spectra of the samples under study in a sodium sulfate solution (Hodograph 2-S and 3-S) and in the Ringer's solution (Hodograph 1-R and 3-R). ...
In this work, an attempt was made to reveal and explain the influence of the process of formation of 2D nanostructures at the surface of an amorphous alloy (an alloy with the composition Co75Si15Fe5Cr4.5Al0.5 (in at.%) was used for this purpose) on the corrosion and magnetic properties of such an alloy. Two-dimensional nanostructures (nanocells of 100–150 nm in size, which were obtained by anodizing the initial sample in an ionic liquid) are essentially a pattern on the surface of the sample, and they cannot completely cover and block the surface from external effects. It was postulated that the presence of these nanostructures during corrosion and magnetic tests has no significant effect. However, a noticeable inhibition effect was observed during corrosion tests and a less noticeable (but still detectable) effect was observed during magnetic tests. The authors believe that the effect obtained, with a detailed study, can be used to increase the corrosion resistance and to improve the properties of traditional magnetic materials.
... Without a history of the use of the Co-Cr alloy in dental works, it worth mentioning in short some of their merits and demerits to understand their success and, simultaneously, the necessity of developing new strategies for their use [8][9][10]. The main strategies have introduced new extended procedures for Co-Cr surface modifications [11][12][13][14][15][16] or have changed their composition [17][18][19]. The use of CoCrMo dental alloys on a mass scale has led sometimes to certain pigment metallic lesions that are even more aggressive due to their ion release [20,21]. ...
The aim of the paper is based on a combined approach to improve dental alloy performance using a new Ni-free Co–Cr composition with Mo, Nb and Zr and coated with an anodic oxidation film. The coated and uncoated samples were surface characterized by performing SEM (scanning electronic microscopy), XRD (X-rays diffraction) contact angle measurements and corrosion studies with open circuit potential, potentiodynamic polarization and EIS (impedance electrochemical spectroscopy) procedures. The SEM equipment with an EDX (Energy-dispersive X-ray spectroscopy) module indicated the sample morphology and the XRD investigations established the formation of the oxides. The electrochemical procedures were performed in Ericsson artificial saliva for coated samples in various conditions. Based on all the experiments, including the decrease in the hydrophobic character of the uncoated samples and the decrease in the hydrophilic values of the anodized alloys, the improved performance of the coated samples was established as a conclusion.
In industries as diverse as automotive, aerospace, medical, energy, construction, electronics, and food, the engineering technology known as 3D printing or additive manufacturing facilitates the fabrication of rapid prototypes and the delivery of customized parts. This article explores recent advancements and emerging trends in 3D printing from a novel multidisciplinary perspective. It also provides a clear overview of the various 3D printing techniques used for producing parts and components in three dimensions. The application of these techniques in bioprinting and an up-to-date comprehensive review of their positive and negative aspects are covered, as well as the variety of materials used, with an emphasis on composites, hybrids, and smart materials. This article also provides an updated overview of 4D bioprinting technology, including biomaterial functions, bioprinting materials, and a targeted approach to various tissue engineering and regenerative medicine (TERM) applications. As a foundation for anticipated developments for TERM applications that could be useful for their successful usage in clinical settings, this article also examines present challenges and obstacles in 4D bioprinting technology. Finally, the article also outlines future regulations that will assist researchers in the manufacture of complex products and in the exploration of potential solutions to technological issues.
The synthesisSynthesis of aryldiazonium tetrachloroaurate(III) salts [X–4–C6H4N≡N]AuCl4 (X=F, Cl, Br, I, CN, NO2, COOH, bisaniline, triazine-based dendrimers, C8F17, C6H13) is reported by the protonation of anilines with chloroauric acid in acetonitrile followed by one-electron oxidation using nitrosonium salt [NO]X (X=tetrafluoroborate, hexafluorophosphate). X-ray crystal structure of X=CN, NO2, COOH, C8F17, C6H13 from acetonitrile or water (X=COOH) displayed [–N≡N]+ bond distance typical of a triple bond. Electrochemical reduction of the salts showed low or even positive potential values versus silver/silver chloride reference electrode. The robustRobust nanoparticlesgold-aryl nanoparticlesGold-aryl nanoparticles, termed organometallic nanoparticles, were constructed using green and mild chemical reduction routes of the diazonium gold(III) salts for forensic, environmental, and nanomedicine engineeringNanomedicine engineering applications. Specifically, the salts were used in, for example, the development of latent fingerprints on copper and nickel coins, formation of gold-silver alloys, gold-aryl core-tine oxide shell structures, formation of protein and amino acid bioconjugatesProtein bioconjugates, and electrochemical synthesisSynthesisof gold-aryl nanoparticlesGold-aryl nanoparticles stabilized with polyaniline.
Aryldiazonium salt chemistry, as a versatile surface decoration and functionalization method, has been intensively employed in construction of sensing interface. The para-position (–R) of aryldiazonium salt bearing different functional moieties endows the sensing surface with different purposes. Typically, bioreceptor linkage groups (e.g. –COOH, –NH2) are essential, and inert groups (e.g. –H, –CH3)-based spacer and antifouling moieties can be incorporated according to the actual requirement. Introduction of molecular wires, or nanomaterials (e.g. carbon based or noble metal based) can further enhance signal and/or electron transfer helping to increase the sensitivity. This chapter focuses on the design of the sensing interface by applying the aryldiazonium salt surface chemistry with the format of forming single/mixed aryldiazonium salt layers, and their translations into biosensing of different target analytes.
Diazonium chemistry has been widely adopted for numerous biomedical applications such as implant materials, tissue engineering scaffolds, and drug delivery. The versatility of substrate materials that can be modified by diazonium chemistry and the wide range of functional groups that can be introduced on the surface are among the advantages of diazonium chemistry over other surface modification techniques. Indeed, it provides a versatile tool to change the surface properties of biomaterials to control their wettability, biocompatibility, protein adsorption, and immune response. Diazonium chemistry is also useful as a linker to attach biomolecules or polymeric layer on biomaterial surfaces. In this chapter, we provide an up-to-date review of the use of diazonium chemistry in biomaterials used in biomedical applications.
The corrosion of Co–28Cr–6Mo and Co–35Ni–20Cr–10Mo, as biomedical alloys, has been investigated for effects of typical species (albumin and H2O2) in physiological saline, with their coexistence explored for the first time. Electrochemical and long term immersion tests were carried out. It was found that Co alloys were not sensitive to the presence of albumin alone, which slightly promoted anodic dissolution of Co–35Ni–20Cr–10Mo without noticeably affecting Co–28Cr–6Mo and facilitated oxide film dissolution on both alloys. H2O2 led to a clear drop in corrosion resistance, favouring metal release and surface oxide formation and inducing much thicker but less compact oxide films for both alloys. The coexistence of both species resulted in the worst corrosion resistance and most metal release, while the amount and composition of surface oxide remained at a similar level as in the absence of both. The effect of H2O2 inducing low compactness of surface oxides should prevail on deciding the poor corrosion protection ability of passive film, while albumin simultaneously promoted dissolution or inhibited formation of oxides due to H2O2. Corrosion resistance was consistently lower for Co–35Ni–20Cr–10Mo under each condition, the only alloy where the synergistic effect of both species was clearly demonstrated. This work suggests that the complexity of the environment must be considered for corrosion resistance evaluation of biomedical alloys.
