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The present study explores the microstructural characteristics and electrochemical responses of different TiMoZrTa alloys designed for biomedical implantation. The alloys corrosion resistance (potentiodynamic polarization and electrochemical impedance spectroscopy) was determined in acidified Ringer's solution at 37 °C. The pH was adjusted to 3.6 in order to reproduce the pathological state. The new materials formed spontaneously a passivation oxide film on their surface, and they remained stable for polarizations up to +1.0 VSCE. No evidence of localized breakdown of the oxide layers was registered even when higher positive polarizations than those encountered in the human body were applied.

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In this work we studied the main surface characteristics together with the in vivo osseointegration of three Zr-Ti alloys with hydroxyapatite-zirconia-silver (HAP-ZrO 2 -Ag) coating layer. The main purpose was to provide a quantitative evaluation and interpretation from micro to nano scale of the processes involved in the osseointegration of the HAP-ZrO 2 -Ag coated Zr-Ti specimens in a pig model. The surface characteristics were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). After the insertion of the implants into pig tibia, the osseointegration was investigated by means of biochemical analysis as well as bone histomorphometric and computed tomography measurements. The results of this in vivo study sustains that the capacity of the Zr-Ti specimens coated with HAP-ZrO 2 -Ag to promote osteogenesis is significant during the first month after implantation as compared with the control, being influenced by the interactions between bone tissue and HAP-ZrO 2 -Ag surfaces, but also by the chemical composition of the alloys.

Although Cu and Zn are important microelements with well-defined roles in organisms functioning, their presence in toxic concentrations is related to a contamination process. On the other hand, Pb, Cd, and Hg are toxic xenobiotics with cumulative effects on various organisms, and in the case of Ni the reports are contradictory. All of these heavy metals are found as a naturally content in the earth�s crust wherefrom are mobilized through volcanic eruptions or mining activities. Some human activities, such as metals smelting, burning of fossil fuels, cement obtaining, usage of pesticides in agriculture, contribute to the environmental pollution with these heavy metals. The presence of heavy metals is considered a risk factor for all components of the ecosystem due to their geo- and bio accumulative features. In long-term exposure, especially in countries with intensive industrialization and urbanization, toxic and carcinogenic effects based on various mechanisms were reported. However, the extraction and the usage of heavy metals in various industry branches might be considered a necessary evil for the nowadays modern society. In some moments of our evolution there were no alternatives, neither as knowledge, nor as application possibilities. In last decades, alarm signals were pulled by the scientific community and non-governmental organizations, and a legislation of heavy metal residues monitoring was developed and applied in many countries all over the world. Moreover, various ecological alternatives were found for the limitation or even excluding of pollutant materials from many of our life aspects (unleaded petrol, insecticides based on pheromones, green concrete manufactured with less cement quantity etc.) and different ways of soil phytoremediation and heavy metals biosorption from aqueous media were tested. The aim of this paper is to review the most important aspects related to heavy metals (Pb, Cd, Hg, Ni, Cu, Zn) ecotoxicology. Various sources of environmental pollution and different mechanisms for physiological homeostasis disruption for each reviewed elementary xenobiotic are critically discussed.