Tantalum possesses remarkable chemical and mechanical properties, and thus it is considered to be one of the next generation implant materials. However, the biological properties of tantalum remain to be improved for its use in tissue engineering applications. To enhance its cellular interactions, implants made of tantalum could be modified to obtain nanofeatured surfaces via the electrochemical anodization process. In this study, anodization parameters were adjusted to obtain a nanoporous surface morphology on tantalum surfaces and systematically altered to control the pore sizes from 25 to 65 nm using an aqueous HF:H2SO4 electrolyte. Results indicated the formation of Ta2O5‐based nanoporous surface layers, which had up to 28% more surface area and increased nanophase roughness (more than twofolds) compared to nonporous tantalum upon the anodization. It was observed that the nanoporous tantalum oxide surfaces promoted nearly 25% more fibroblast proliferation at 5 days in vitro and 15.5% more cellular spreading. Thus, nanoporous tantalum oxide surfaces can be used to increase biological interactions of the cells and provide a means of improving bioactivity of tantalum for biomaterial applications.

Tantalum is one of the most corrosion-resistant materials and has mechanical properties that are suitable for orthopedic applications. However, tantalum exhibits bioinert characteristics and cannot promote the desired level of osseointegration with juxtaposed bone tissues. To enhance the bioactivity of tantalum, nanoscale surface modifications via anodization could be a potential approach. In this study, surface features having nanotubular, nanodimple, and nanocoral morphologies were fabricated onto tantalum by controlling anodization parameters. Aside from altering the surface morphology, nanotubular, nanodimple, and nanocoral feature sizes were precisely fine-tuned between the 20 and 140 nm range. The results indicated that anodized surfaces consisted of Ta2O5 and non-stoichiometric tantalum suboxide chemistry. Upon the anodization, surface area of the tantalum samples increased up to 2-fold, which was accompanied by up to a 3.5-folds increase in the nanophase surface roughness. Biological studies showed that anodized tantalum surfaces significantly enhanced protein adsorption and improved bone cell proliferation and spreading independently of the anodized surface morphology and feature size. Nanodimple surfaces having a 90 nm feature size promoted 50% more bone cell proliferation and 23% more cellular spreading compared to non-anodized tantalum. Nanodimple surfaces also enhanced alkaline phosphatase activity and increased Ca mineral deposition up to 5 weeks compared to non-anodized tantalum, indicating higher bioactivity. In this study, biological interactions of anodized tantalum surfaces having different morphologies and feature sizes were examined, for the first time, and the potential use of nanostructured tantalum was highlighted for orthopedic applications.

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Tracheomalacia (TM) is a condition in which the anterior part of the trachea consisting of cartilage and/or the posterior part consisting muscle are too soft to ensure its mechanical support. This situation may result in an excessive and potentially lethal collapse of the airway in the newborns. Current treatment techniques include tracheal reconstruction, tracheoplasty, endo- and extra-luminal stents, but are all facing important limitations. To reduce the shortcomings of actual TM treatments, this work proposes a new strategy by wrapping an adhesive hydrogel patch extraluminally around a malacic trachea. To validate this approach, first a numerical model revealed that a hydrogel patch with sufficient mechanical and adhesion strength can potentially preserve the trachea's physiological shape. Accordingly, a new hydrogel formulation was synthesized employing the hydroxyethyl acrylamide (HEAam) and polyethylene glycol methacrylate (PEGDMA) as main polymer network and crosslinker, respectively. These hydrogels provide excellent adhesion on wet tracheal surfaces, thanks to a two-step photo-polymerization approach. Ex vivo experiments revealed that the developed adhesive hydrogel patches can restrain the collapsing of malacic trachea under applied negative pressure. This study, to be confirmed by in vivo studies, is open to the possibility of a new treatment in the difficult clinical situation of tracheomalacia in newborns.