Gas-Phase Produced Cu@CuO Nanoparticles on Microarc Oxidized TiO 2 : Effect of Size on Antibacterial Efficiency and Osteoblast Viability Sitki Aktas,* Salih Durdu,* Toby W. Bird, Kadriye Ozcan, Gurkan Yigitturk, Salim Levent Aktug, Maha Alotaibi, Metin Usta, and Andrew Pratt* Cite This: ACS Appl. Nano Mater. 2023, 6, 22253−22264 Read Online ACCESS Metrics & More Article Recommendations ABSTRACT: In this work, highly porous and rough TiO 2 surfaces coated with Cu@CuO core−shell nanoparticles were fabricated on a Ti6Al4V alloy by microarc oxidation (MAO) and gas-phase synthesis. The phase structure, binding energy, surface morphology, elemental distribution, and wettability were investigated by XRD, XPS, SEM, EDX-mapping, and contact angle goniometery, respectively. Cu@CuO core−shell nanoparticles with mean particlesizesof8.1 ± 0.2,15.2 ± 0.3,and17.2 ± 0.2nmweredepositedonto anatase- and rutile-based MAO surfaces. Cu, Ti, and O were all found to be homogeneously distributed across the entire sample surface. MAO surfaces decorated with Cu@CuO nanoparticles exhibited hydrophobic behavior compared to bare Ti6Al4 V and bare MAO surfaces, leading to the demonstration of antimicrobial activity. For Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa,and Escherichia coli,the antimicrobialactivityoftheCu@CuO-nanoparticle-treatedMAOsurfaceswassignificantlyimprovedwithrespecttoabaresubstrate andbareMAOsurfaces.Inaddition,cellviabilityincreasedproportionallywithincreasingCu@CuOnanoparticlesizecomparedto the MAO surface. KEYWORDS: Cu@CuO core−shell nanoparticles, wettability, antimicrobial properties, gas-phase synthesis, microarc oxidation (MAO) 1. INTRODUCTION Titanium alloys that have low density, high strength, superior corrosion resistance, and biocompatibility are widely used for orthopedic implants. 1,2 However, titanium alloys are bioinert, cannot bond to bone tissue, and do not possess any antibacterial ability. 3 Titanium dioxide (TiO 2 )-based nano- tube/microporous bioceramic coatings on titanium alloys can be produced by anodic oxidation (AO) 4−6 and microarc oxidation (MAO) 7,8 allowing well-ordered TiO 2 nanotube arrays to be produced on Ti and its alloys. 4−6 However, compared to TiO 2 nanotubes produced by AO. However, compared to AO-synthesized TiO 2 nanotubes, TiO 2 -based bioceramiccoatingspreparedbyMAOhavereceivedincreased attention recently due to their high adhesion strength, improved wear resistance, corrosion protection, biocompati- bility,andbioactivityforcontrolledandrapidhealing. 7,8 MAO, which is an electrochemical oxidation process, can be applied totitanium,aluminum,magnesium,zirconium,etc.formedical implant, automotive, defense, and space applications. 9−11 The bioceramic surfaces produced by the MAO process are porous and this is beneficial for cell attachment. 12 In addition, it is well-known that the MAO-modified titanium surface possesses high adhesion strength and wear resistance compared to other commercially used plasma spray techni- ques. 13 The antibacterial activity of TiO 2 is relatively weak compared to those of antibacterial agents such as Cu, Ag, Zn, etc. Thus, a crucial obstacle faced after implementation is bacterial colonization under body conditions resulting in destructive complications that can potentially lead to implant loss. 14 It is well-known that copper (Cu) possesses superior antibacterialpropertiesversuswide-spectrumbacteria.Interms of antibacterial efficiency and cytotoxicity, Cu delivers by far the best compromise compared to other antibacterial structures such as Ag and Zn. 15 Moreover, Cu can induce osteoblast proliferation, differentiation, and migration. 16 Thus, in view of the many advantages compared to Ag and Zn, Cu- based NPs are preferred on the MAO surfaces in this work. Nanoparticleswithuniquepropertiesinthesizerangeof1− 100 nm are widely explored and used in the field of medical Received: September 19, 2023 Revised: November 10, 2023 Accepted: November 15, 2023 Published: November 29, 2023 Article www.acsanm.org © 2023 American Chemical Society 22253 https://doi.org/10.1021/acsanm.3c04481 ACS Appl. Nano Mater. 2023, 6, 22253−22264 Downloaded via UNIV OF YORK on July 3, 2025 at 16:56:20 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.