In Vitro Studies on Nanoporous, Nanotubular and Nanosponge-Like Titania Coatings, with the Use of Adipose-Derived Stem Cells

Abstract

In vitro biological research on a group of amorphous titania coatings of different nanoarchitectures (nanoporous, nanotubular, and nanosponge-like) produced on the surface of Ti6Al4V alloy samples have been carried out, aimed at assessing their ability to interact with adipose-derived mesenchymal stem cells (ADSCs) and affect their activity. The attention has been drawn to the influence of surface coating architecture and its physicochemical properties on the ADSCs proliferation. Moreover, in vitro co-cultures: (1) fibroblasts cell line L929/ADSCs and (2) osteoblasts cell line MG-63/ADSCs on nanoporous, nanotubular and nanosponge-like TiO2 coatings have been studied. This allowed for evaluating the impact of the surface properties, especially roughness and wettability, on the creation of the beneficial microenvironment for co-cultures and/or enhancing differentiation potential of stem cells. Obtained results showed that the nanoporous surface is favorable for ADSCs, has great biointegrative properties, and supports the growth of co-cultures with MG-63 osteoblasts and L929 fibroblasts. Additionally, the number of osteoblasts seeded and cultured with ADSCs on TNT5 surface raised after 72-h culture almost twice when compared with the unmodified scaffold and by 30% when compared with MG-63 cells growing alone. The alkaline phosphatase activity of MG-63 osteoblasts co-cultured with ADSCs increased, that indirectly confirmed our assumptions that TNT-modified scaffolds create the osteogenic niche and enhance osteogenic potential of ADSCs.

The Photocatalytic Activity of Titania Coatings Produced by Electrochemical and Chemical Oxidation of Ti6Al4V Substrate, Estimated According to ISO 10678:2010

“…5.8 M HCl solution led to the production of fibrous coatings and uniformLy coated substrate surfaces without cracks or gaps (Figure 2a-c Analysis of the SEM images proved the formation of uniform coatings of the same tube length (approximately 140-190 nm), without cracks or gaps. The XRD and Raman scattering investigations confirmed the amorphousness of all of the produced TNT coatings, which is in agreement with the results of our previous widely run studies of these systems [35,36]. It should be noted that the studied TNT coatings preserved amorphousness up to 553 K, which was confirmed by the results of our earlier investigations [45].…”

“…Due to the fact that, for several years, we have been conducting intensive research on amorphous titania systems with high biocompatibility and application possibilities for the needs of medical devices [34][35][36][37][38], it was important to take a closer look at these systems in terms of checking their photocatalytic activity. Such activity could be used in medical device sterilization processes involving UVA light.…”

“…The synthesis, and structural and morphological characterization of titania nanotubes (TNT) and nanofiber (TNF) samples, were carried out considering results of our earlier reports [35][36][37].…”

“…The anodic oxidation method allowed the production of titania nanoporous coatings (TNT10), nanotubular coatings (TNT20) and nanosponge-like coatings (TNT40) dependent on the used potential [35,36]. The morphology and cross-section differences between these three types of TNT systems are presented in Figure 1a was stirred every 20 min.…”

“…Our previous works were mainly focused on the estimation of the bioactivity of titania-based materials produced on the surface of titanium or its alloys' substrates and differing in architecture and structure [34][35][36][37][38]. These materials were synthesized mainly by electrochemical oxidation (titania nanoporous, nanotubular and nanosonge-like coatings (TNT)), and also by direct chemical oxidation (titania nanofibrous coatings (TNF)), without further annealing.…”