title: Effects of anodizing parameters and heat treatment on nanotopographical features, bioactivity, and cell culture response of additively manufactured porous titanium.
abstract: Anodizing could be used for bio-functionalization of the surfaces of titanium alloys. In this study, we use anodizing for creating nanotubes on the surface of porous titanium alloy bone substitutes manufactured using selective laser melting. Different sets of anodizing parameters (voltage: 10 or 20V anodizing time: 30min to 3h) are used for anodizing porous titanium structures that were later heat treated at 500°C. The nanotopographical features are examined using electron microscopy while the bioactivity of anodized surfaces is measured using immersion tests in the simulated body fluid (SBF). Moreover, the effects of anodizing and heat treatment on the performance of one representative anodized porous titanium structures are evaluated using in vitro cell culture assays using human periosteum-derived cells (hPDCs). It has been shown that while anodizing with different anodizing parameters results in very different nanotopographical features, i.e. nanotubes in the range of 20 to 55nm, anodized surfaces have limited apatite-forming ability regardless of the applied anodizing parameters. The results of in vitro cell culture show that both anodizing, and thus generation of regular nanotopographical feature, and heat treatment improve the cell culture response of porous titanium. In particular, cell proliferation measured using metabolic activity and DNA content was improved for anodized and heat treated as well as for anodized but not heat-treated specimens. Heat treatment additionally improved the cell attachment of porous titanium surfaces and upregulated expression of osteogenic markers. Anodized but not heat-treated specimens showed some limited signs of upregulated expression of osteogenic markers. In conclusion, while varying the anodizing parameters creates different nanotube structure, it does not improve apatite-forming ability of porous titanium. However, both anodizing and heat treatment at 500°C improve the cell culture response of porous titanium.
authors.affiliation: Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft, The Netherlands. Electronic address: s.aminyavari@tudelft.nl.
authors.forename: S
authors.initials: S
authors.lastname: Amin Yavari
authors.affiliation: Prometheus, Division of Skeletal Tissue Engineering, Bus 813, O&N1, Herestraat 49, KU Leuven, 3000 Leuven, Belgium; Tissue Engineering Laboratory, Skeletal Biology and Engineering Research Center, Bus 813, O&N1, Herestraat 49, KU Leuven, 3000 Leuven, Belgium; Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia.
authors.forename: Y C
authors.initials: YC
authors.lastname: Chai
authors.affiliation: Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft, The Netherlands.
authors.forename: A J
authors.initials: AJ
authors.lastname: Böttger
authors.affiliation: KU Leuven, Department of Mechanical Engineering, Section Production Engineering, Machine Design and Automation (PMA), Celestijnenlaan 300B, 3001 Leuven, Belgium; 3D Systems - LayerWise NV, Grauwmeer 14, 3001 Leuven, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Wauthle
authors.affiliation: Department of Metallurgy and Materials Engineering, KU Leuven, Kasteelpark Arenberg 44 - PB2450, B-3001 Heverlee, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Schrooten
authors.affiliation: Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft, The Netherlands; Department of Orthopedics and Dept. Rheumatology, UMC Utrecht, Heidelberglaan100, 3584CX Utrecht, The Netherlands.
authors.forename: H
authors.initials: H
authors.lastname: Weinans
authors.affiliation: Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology (TU Delft), Mekelweg 2, 2628 CD Delft, The Netherlands.
authors.forename: A A
authors.initials: AA
authors.lastname: Zadpoor
mesh_terms: D001672:Biocompatible Materials / Q000138:chemical synthesis* / Q000494:pharmacology; D001826:Body Fluids / Q000737:chemistry; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004566:Electrodes; D004595:Electroplating / Q000379:methods*; D006244:Hardness; D006361:Heating / Q000379:methods; D006801:Humans; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000008:administration & dosage / Q000737:chemistry / Q000648:ultrastructure; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D010087:Oxides / Q000737:chemistry; D010521:Periosteum / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D016062:Porosity; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D001672:Biocompatible Materials; D010087:Oxides; D014025:Titanium
keywords: Anodizing; Bone regeneration; Heat treatment; Nano-texturing; Porous biomaterials