Osteogenic and bactericidal surfaces from hydrothermal titania nanowires on titanium substrates

Abstract

Nanotopographical cues on Ti have been shown to elicit different cell responses such as cell differentiation and selective growth. Bone remodelling is a constant process requiring specific cues for optimal bone growth and implant fixation. Moreover, biofilm formation and the resulting infection on surgical implants is a major issue. Our aim is to identify nanopatterns on Ti surfaces that would be optimal for both bone remodelling and for reducing risk of bacterial infection. Primary human osteoblast/osteoclast co-cultures were seeded onto Ti substrates with TiO2 nanowires grown under alkaline conditions at 240 °C for different times (2, 2.5 or 3 h). Cell growth and behaviour was assessed by scanning electron microscopy (SEM), immunofluorescence microscopy, histochemistry and quantitative RT-PCR methods. Bacterial colonisation of the nanowire surfaces was also assessed by confocal microscopy and SEM. From the three surfaces tested the 2 h nanowire surface supported osteoblast and to a lesser extent osteoclast growth and differentiation. At the same time bacterial viability was reduced. Hence the 2 h surface provided optimal bone remodeling in vitro conditions while reducing infection risk, making it a favourable candidate for future implant surfaces.

Bioinspired bactericidal surfaces with polymer nanocone arrays

“…These have largely focused on nanopatterning biocompatible materials such as titanium 31,32,33,34 , titania 35 , graphene 36 , diamond 37,38 and polymeric materials 39,40 . Nanopatterning techniques employed have been diverse including plasma etching 38 , laser ablation 41 , nano-imprint lithography 42 , alkaline hydrothermal methods 33,35 and reactive-ion-etching 41 . One promising colloidal technique is mask-assited lithography or colloidal lithography 43 in which polystyrene or silica microspheres are deposited onto a polymeric surface.…”

Multifunctional Coatings and Nanotopographies: Toward Cell Instructive and Antibacterial Implants

“…Most interestingly, these convex high‐aspect‐ratio bactericidal nanotopographies seem capable of directing the differentiation of MSCs into OBs, which could have positive implication to the real‐world applications in orthopaedic or dental implants where both antimicrobial and osseointegrative properties are vital to ensure their long‐term success. Tsimbouri et al investigated osteogenesis of bactericidal TiO 2 nanowires using a mesenchymal BMSC/bone marrow hematopoietic cell coculture model where both osteogenesis and osteoclastogenesis can occur …”

“…Nanotopographies with bactericidal potential and capacity to support bone cells populations would be ideal substrates for developing new medical implants, and the recent literature indicates this is possible (see previous section). However, it is difficult to design cell instructive surfaces with topography alone, i.e., there is typically a reduction in spreading and/or proliferation of bone‐related cell types on high aspect ratio bactericidal topographies compared to control Ti surfaces . A potential solution to achieve this would be the functionalization of such high aspect‐ratio nanotopographies with chemical ligands with integrin‐binding potential.…”

PEA polymer-coated nanotopography delivers solid-state BMP2, enhances mesenchymal stem cell adhesion, prevents bacterial biofilm formation and protects cells from quorum sensing virulence factors

“…One approach has been to mimic the bactericidal, high aspect ratio topographies that are present on insect wings, such as on Clanger cicada (Psaltoda claripennis) 45 and the dragonfly (Diplacodes bipunctata) 46 . Materials such as black silicon 46 and titanium (a widely used orthopaedic material) 47 have been used to mimic this affect by shaping them into topographies that produce high levels of mechanical deformation of pathogen membranes, leading to bacterial cell rupture and death. 45,46,48 However, these very spiky topographies are far from optimal in terms of osteogenesis.…”

“…45,46,48 However, these very spiky topographies are far from optimal in terms of osteogenesis. 47 Use of integrin mimics has been shown to enhance bioactivity, 49 but does not provide robust osseoinduction potentially because only one facet of the extracellular matrix, adhesion, is being considered.…”