Ceramic coatings may be applied onto metallic components of joint replacements for improved wear and corrosion resistance as well as enhanced biocompatibility, especially for metal-sensitive patients. Silicon nitride (SiN_x) coatings have recently been developed for this purpose. To achieve a high coating density, necessary to secure a long-term performance, is however challenging, especially for sputter deposited SiN_x coatings, since these coatings are insulating. This study investigates the time-dependent performance of sputter-deposited SiN_x based coatings for joint applications. SiN_x coatings with a thickness in the range of 4.3–6.0 µm were deposited by reactive high power impulse magnetron sputtering onto flat discs as well as hip heads made of CoCrMo. SiN_x compositional analysis by X-ray photoelectron spectroscopy showed N/Si ratios between 0.8 and 1.0. Immersion of the flat disks in fetal bovine serum solution over time as well as short-term wear tests against ultra-high molecular weight polyethylene (UHMWPE) discs showed that a high coating density is required to inhibit tribocorrosion. Coatings that performed best in terms of chemical stability were deposited using a higher target power and process heating.

A deteriorating nail standard is a growing problem as the global prevalence of diabetes is increasing. Systemic treatment with mineral supplements may not be recommended, mainly due to the high doses required to deliver optimal therapeutic concentrations. In this work, we evaluate nail polish formulations for the local delivery of strengthening elements to the nail plate. Specifically, we assess calcium and silicon release from nail polish base coat formulations containing three different concentrations of White Portland Cement to water, as well as to artificial and human nails. The delivery of calcium and silicon to the dorsal nail plate was determined by inductively coupled plasma optical emission spectrometry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. To the best of our knowledge, this is the first study showing that such dual elemental delivery to human nails can be achieved from nail polish formulations. Hence, this work may form the basis for new inventions where therapeutic functionalities can be integrated with the mechanical and cosmetic properties of a base coat nail polish. Future permeability studies are required to verify long-term effects on the nail standard, induced by the formulations under study.