Light induced hydrophilicity and osteoblast adhesion promotion on amorphous TiO₂

Abstract

We have studied the effect of the UV induced superhydrophilic wetting of TiO(2) thin films on the osteoblasts cell adhesion and cytoskeletal organization on its surface. To assess any effect of the photo-catalytic removal of adventitious carbon as a factor for the enhancement of the osteoblast development, 100 nm amorphous TiO(2) thin layers were deposited on polyethylene terephthalate (PET), a substrate well known for its poor adhesion and limited wettability and biocompatibility. The TiO(2) /PET materials were characterized by X-ray photoelectron spectroscopy, and atomic force microscopy and their wetting behavior under light illumination studied by the sessile drop method. The amorphous TiO(2) thin films showed a very poor photo-catalytic activity even if becoming superhydrophilic after illumination. The illuminated samples recovered partially its initial hydrophobic state only after their storage in the dark for more than 20 days. Osteoblasts (HOB) were seeded both on bare PET and on TiO(2) /PET samples immediately after illumination and also after four weeks storage in darkness. Cell attachment was much more efficient on the immediately illuminated TiO(2)/PET samples, with development of focal adhesions and cell traction forces. Although we cannot completely discard some photo-catalytic carbon removal as a factor contributing to this cell enhanced attachment, our photodegradation experiments on amorphous TiO(2) are conclusive to dismiss this effect as the major cause for this behavior.

Osteoblasts Interaction with PLGA Membranes Functionalized with Titanium Film Nanolayer by PECVD. In vitro Assessment of Surface Influence on Cell Adhesion during Initial Cell to Material Interaction

“…In this figure it is also apparent the formation of a series of lines attributed to the different agglomeration of the active phase during the preparation of the membrane. In relation with this behavior and in line with a previous work of our group on the osteoblast growth on PET surface modified with TiO 2 [8], it is worh noting that after UV illumination for sterilization, the TiO 2 /PLGA membranes became superhidrophilic. It is believed that this enhanced hydrophilicty plays a very poisitve role in enhancing the deployment of osteoblast on these modified surfaces.…”

“…We have previously described, on UV illuminated amorphous TiO 2 , a positive effect on osteoblasts development that can be attributed to the transformations undergone by the surface of the oxide subjected to irradiation [8]. …”

“…Furthermore, the in vitro study of cell behavior toward different material surface properties represents a necessary prerequisite in assessing the biocompatibility of a material intended to be used in medical devices [3]. Tissue engineering offers a promising solution for development of synthetic and/or natural scaffolds, upon which osteoprogenitor cells can be seeded and cultured under optimal conditions and, ultimately, implanted to promote osteogenesis in vivo [8]. Though recent studies report decisive positive effects on cells, they frequently employ cells other than of human origin or cells not representing oral implant targets.…”

“…As is well known, cell internal organization and orientation are controlled by focal adhesions, that mediate the regulatory effects of extracellular matrix ECM adhesion and the variation of actin- myosin stress fibers distribution in response to surface properties [13,14] and, as we have previously described, associates with an substantial increase in osteoblastic mitocondrial bioenergetics polarized to focal adhesion sites [8,14]. Focal adhesions FAs are formed during initial cell adhesion and thereafter constantly assembled and disassembled during cell movement.…”

Ultraviolet Pretreatment of Titanium Dioxide and Tin-Doped Indium Oxide Surfaces as a Promoter of the Adsorption of Organic Molecules in Dry Deposition Processes: Light Patterning of Organic Nanowires

“…We have associated this "memory effect" with the development of a peculiar hydroxylation state of the illuminated areas. Although further studies are still necessary to provide further proofs of this hypothesis, the MD simulations reported in Section 3.4, and previous results in our laboratory concerning the selective incorporation of Rhodamine molecules [28,50] or the enhancement of the osteoblast growth on illuminated surfaces of TiO 2 , [29] are in line with this hypothesis. Thus, this article opens a way for the light patterning 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 of semiconducting oxides.…”