Structure and Surface Morphology Effect on the Cytotoxicity of [Al2O3/ZnO]n/316L SS Nanolaminates Growth by Atomic Layer Deposition (ALD)

Abstract

Recently, different biomedical applications of aluminum oxide (Al2O3) and zinc oxide (ZnO) have been studied, and they have displayed good biocompatible behavior. For this reason, this study explores nanolaminates of [Al2O3/ZnO]n obtained by atomic layer deposition (ALD) on silicon (100) and 316L stainless steel substrates with different bilayer periods: n = 1, 2, 5, and 10. The intention is to correlate the structure, chemical bonds, morphology, and electrochemical properties of ZnO and Al2O3 single layers and [Al2O3/ZnO]n nanolaminates with their cytotoxic and biocompatibility behavior, to establish their viability for biomedical applications in implants based on the 316L SS substrate. These nanolaminates have been characterized by grazing incident X-ray diffraction (XRD), finding diffraction planes for wurtzite type structure from zincite. The chemical bonding and composition for both single layers were identified through X-ray photoelectron spectroscopy (XPS). The morphology and roughness were tested with atomic force microscopy (AFM), which showed a reduction in roughness and grain size with a bilayer period increase. The thickness of the samples was measured with scanning electron microscopy, and the results confirmed the value of ~210 nm for the nanolaminate samples. The electrochemical impedance spectroscopy analysis with Hank’s balanced salt solution (HBSS) evidenced an evolution of [Al2O3/ZnO]n/316L system corrosion resistance of around 95% in relation with the uncoated steel substrate as function of the increase in the bilayers number. To identify the biocompatibility behavior of these nanolaminate systems, the lactate dehydrogenase test was performed with Chinese hamster ovary (CHO) cells for a short system of life cell evaluation. This test shows the cytotoxicity of the multilayer compared to the single layers of Al2O3, ZnO, and 316L stainless steel. The lowest cytotoxicity was found in the single layers of ZnO, which leads to cell proliferation easier than Al2O3, obtaining better adhesion and anchoring to its surface.

Al2O3-ZnO atomic layer deposited nanolaminates for improving mechanical and corrosion properties of sputtered CrN coatings

“…The Al2O3 / ZnO nanolaminates exhibited a modulus of 140 to 145 GPa, which lies in between the value for the two films, and a hardness of 8 GPa, which is similar to that of Al2O3. Osorio et al [41] examined the electrochemical behavior of these nanolaminates on 316L SS. Their results showed that the corrosion resistance of [Al2O3/ZnO]n nanolaminates was higher in comparison with single layered 316L SS surface.…”

Enhancing Internal and External Stability of Perovskite Solar Cells Through Polystyrene Modification of the Perovskite and Rapid Open‐Air Deposition of ZnO/AlOx Nanolaminate Encapsulation

“…In contrast, ZnO, in both the single‐layer and NL TFEs, crystallizes in a wurtzite‐type structure. [ 31 ] The single‐layer ZnO is polycrystalline with peaks at 31.3°, 34.75°, 37°, and 47.30°, corresponding to the (100), (002), (101), and (102) planes, respectively. [ 32 ] For the 2‐layer NL TFE, the intensity of the ZnO peaks decreased slightly compared to the single‐layer ZnO, as the ZnO layer is thinner.…”

Release Rate Studies of 5-Aminosalacylic Acid Coated with Atomic Layer-Deposited Al2O3 and ZnO in an Acidic Environment

“…First, the use of ALD-based metal oxide chemistries such as Al 2 O 3 , ZnO, and TiO 2 are well established. − A key advantage being that ALD occurs at relatively low temperatures (≤150 °C) to maintain the API’s viability. Second, the metal oxide candidates presented above are considered biocompatible and present no known toxicity. − Third, ALD provides non-line-of-sight and self-limiting deposition characteristics that result in highly conformal and pin-hole free films that act as diffusion barriers around particles . Fourth, the use of nanoscale films to coat API powders provides flexibility in terms of adding multifunctionality to pills without adding to its bulk and thus can result in maintaining high dosage levels.…”