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In vitro cytotoxicity assessment is indispensable in developing new biodegradable implant materials. Zn, which demonstrates an ideal corrosion rate between Mg-and Fe-based alloys, has been reported to have excellent in vivo biocompatibility. Therefore, modifications aimed at improving Zn's mechanical properties should not degrade its biological response. As sufficient strength, ductility and corrosion behavior required of load-bearing implants has been obtained in plastically deformed Zn-3Ag-0.5Mg, the effect of simultaneous Ag and Mg additions on in vitro cytocompatibility and antibacterial properties was studied, in relation to Zn and Zn-3Ag. Direct cell culture on samples and indirect extract-based tests showed almost no significant differences between the tested Zn-based materials. The diluted extracts of Zn, Zn-3Ag, and Zn-3Ag-0.5Mg showed no cytotoxicity toward MG-63 cells at a concentration of ≤12.5%. The cytotoxic effect was observed only at high Zn 2+ ion concentrations and when in direct contact with metallic samples. The highest LD 50 (lethal dose killing 50% of cells) of 13.4 mg/L of Zn 2+ ions were determined for the Zn-3Ag-0.5Mg. Similar antibacterial activity against Escherichia coli and Staphylococcus aureus was observed for Zn and Zn alloys, so the effect is attributed mainly to the released Zn 2+ ions exhibiting bactericidal properties. Most importantly, our experiments indicated the limitations of water-soluble tetrazolium salt-based cytotoxicity assays for direct

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Resist-based lithographic tools, such as electron beam (e-beam) and photolithography, drive today’s state-of-the-art nanoscale fabrication. However, the multistep nature of these processes, expensive resists, and multiple other consumables limit their potential for cost-effective nanotechnology. Here, we report a one-step, resist-free, and scalable methodology for directly structuring thin metallic films on flexible polymeric substrates via e-beam patterning. Controlling e-beam dose results in nanostructures as small as 5 nm in height with a sub-micrometer lateral resolution. We structure nanoscale thick films (100 nm) of Al, TiN, and Au on standard Kapton tape to highlight the universal use of our nanopatterning methodology. Further, we utilize direct e-beam writing to create various high-resolution biomimetic surfaces directly onto ceramic thin films. In addition, we assemble architectured mechanical metamaterials comprising crack “traps”, which confine cracks and prevent overall material/device failure. Such a resist-free lithographic tool can reduce fabrication cost dramatically and may be used for different applications varying from biomimetic and architectured metamaterials to strain-resilient flexible electronics and wearable devices.