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In this paper, CoCrMo alloy surface was implanted with 100 keV nitrogen ions to modify it. Bovine serum albumin (BSA) adsorption and the initial behavior of tribo-corrosion in the simulated system were studied. Nitrogen ion implantation can promote BSA dynamic adsorption due to the change of friction and wear mechanisms. From the tribo-corrosion test results, the open circuit potential (OCP) increased to about 0.6 V and the coefficient of friction (COF) decreased to about 0.2 for the nitrogen ion-implanted CoCrMo compared with the untreated sample before the modified layer failure. The point when the open circuit potential and the coefficient of friction changed during long wear time (1, 2 and 4 h) is considered the sign of the worn through modified layer. Then, the OCP of the implanted sample rose by 0.3 V compared with the untreated sample, and the COF remained at around 0.3, which is lower compared with the COF of untreated sample after the modified layer has been worn through. Thus, nitrogen ion implantation not only improved wear and corrosion resistance of the CoCrMo alloy, but also promoted BSA adsorption on the CoCrMo alloy surface, which effectively reduced the wear volume and metal ions release. [ABSTRACT FROM AUTHOR]

As more researchers have acknowledged that the aggregation of amyloid β (Aβ) peptides might only be a pathological phenomenon that appears during the course of Alzheimer's disease (AD), it is therefore of great significance to have a preclinical or an early clinical diagnosis. Cu 2+ dyshomeostasis and oxidative stress, such as hydroxyl radical ( • OH), are found to be associated with peptide aggregations. However, we still do not know how the levels of Cu 2+ and • OH are altered in the brain before massive Aβ plaques appear. Herein, we demonstrated the design and application of a sensitive electrochemical sensor to monitor Cu 2+ and • OH simultaneously in one system without obvious cross-talk. The electrode was fabricated using black phosphorus-loaded Au (BP-Au) nanoparticles, which were then sequentially linked with DNA1, DNA2-labeled Au (Au-DNA2) nanoparticles, and methylene blue (MB). Cu 2+ was first recognized and captured onto the sensor by BP with high selectivity and then produced a reduction current at around -0.01 V. The • OH quantification was established on the cleavage of the hybrid structure between DNA1 and BP-Au upon the appearance of • OH in the phosphate-buffered saline (PBS), leading to the depletion of the voltammetric response of MB around -0.25 V. Good linear correlations were obtained over concentrations of 0.5-127.5 μM for Cu 2+ and 0.5-96.0 μM for • OH. Most importantly, the developed sensor was successfully applied to track the variations of the two species in brain tissues from APP/PS1 transgenic AD mice at the early stages before massive Aβ plaques appeared.