This work compares the degradation of Mg and Mg-Ca0.3 alloy when they are exposed for 14 days to Hank’s solution at 37 °C. A combination of immersion test, electrochemical techniques (PDP, EIS, EN), and surface characterization methods (SEM-EDS, XRD, and XPS) were carried out. The pH change over time, the lower mass loss (≈20%), and the lower concentration of the released Mg2+ ions (≈3.6 times), as well as the lower level of the surface degradation, allowed to consider the positive effect of Ca, presenting Mg-Ca0.3 alloy with lower electrochemical activity than that of Mg. The positive effect of Ca may be due to the formed layer characteristics on the alloy surface, which impedes the cathodic hydrogen evolution and Mg-ions release. The electroless deposited Ag-nano-particles (Ag-NPs) on Mg-Ca0.3 surface were characterized by SEM-EDS, XRD, UV-Vis, and contact angle. The agar-diffusion test was used to compare the growth of Staphylococcus aureus and Escherichia coli bacteria on Mg-Ca0.3 in the presence of Ag-NPs deposits in different size. Zeta-potential of the bacteria was negative, with respect to pH of the Mueller-Hinton culture broth. The greater antibacterial effect of S. aureus was attributed to its more negative zeta-potential, attracting more released Ag+ ions.

ZnO and hybrid of ZnO/Ag structures in the nanometer size were electroless deposited on the Mg-Ca0.3 alloy surface, achieved from aqueous solutions (10−3 M at 21 °C) of ZnO (suspension), Zn(NO3)2 and AgNO3. The surface characterization of the deposits was carried out by Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), X-Ray Photoelectron Spectroscopy (XPS), Fourier transform infrared (FTIR), UV-Visible and Raman spectroscopy. The nanoparticles (NPs) area size distribution analysis revealed that the average of ZnO-NPs was ~85 nm. Likewise, the Ag-NPs of electroless deposits had an average area size of ~100 nm and nucleated in the vicinity of ZnO-NPs as Ag+ ions have been attracted by the negatively charged O2− atoms of the Zn-O dipole. The ZnO-NPs had the wurtzite structure, as indicated by Raman spectroscopy analysis and XRD complementary analysis. The UV-Visible spectroscopy analysis gave a peak at ~320 nm associated with the decrease in the imaginary part (k) of the refractive index of Ag-NPs. On the Mg-Ca0.3 surface, MgO, Mg(OH)2 and MgCO3 are present due to the Mg-matrix. XRD spectra of Ag-NPs indicated the presence of planes arranged with the FCC hexagonal structure. The reported hybrid ZnO/Ag electroless deposits of NPs are of interest for temporary implant devices, providing antibacterial properties to Mg-Ca0.3 surface, a widely used biodegradable material.