Use of polyelectrolyte thin films to modulate Osteoblast response to microstructured titanium surfaces

Abstract

The microstructure and wettability of titanium (Ti) surfaces directly impact osteoblast differentiation in vitro and in vivo. These surface properties are important variables that control initial interactions of an implant with the physiological environment, potentially affecting osseointegration. The objective of this study was to use polyelectrolyte thin films to investigate how surface chemistry modulates response of human MG63 osteoblast-like cells to surface microstructure. Three polyelectrolytes, chitosan, poly(l-glutamic acid), and poly(l-lysine), were used to coat Ti substrates with two different microtopographies (PT, Sa = 0.37 µm and SLA, Sa = 2.54 µm). The polyelectrolyte coatings significantly increased wettability of PT and SLA without altering micron-scale roughness or morphology of the surface. Enhanced wettability of all coated PT surfaces was correlated with increased cell numbers whereas cell number was reduced on coated SLA surfaces. Alkaline phosphatase specific activity was increased on coated SLA surfaces than on uncoated SLA whereas no differences in enzyme activity were seen on coated PT compared to uncoated PT. Culture on chitosan-coated SLA enhanced osteocalcin and osteoprotegerin production. Integrin expression on smooth surfaces was sensitive to surface chemistry, but microtexture was the dominant variable in modulating integrin expression on SLA. These results suggest that surface wettability achieved using different thin films has a major role in regulating osteoblast response to Ti, but this is dependent on the microtexture of the substrate.

The responses to surface wettability gradients induced by chitosan nanofilms on microtextured titanium mediated by specific integrin receptors

“…The titanium disks were treated by sand-blasting followed by an acid-etch to generate a microtextured surface (SLA, Sa = 3.1 μm), as described previously [4]. …”

“…Titanium surface roughness, energy, chemical composition, and wettability regulate osteoblast response through interaction between the outermost implant surfaces and bone [1–4]. Osteoblasts display a more differentiated phenotype on complex micron-/submicron-scale rough surfaces than on relatively smooth titanium surfaces [3,5].…”

“…We previously demonstrated that surface wettability can be modified by polyelectrolyte coatings applied to sandblasted/acid-etched (SLA) surfaces [4]. This study showed that osteoblasts cultured on chitosan-coated rough surfaces exhibited increased production of osteocalcin, a late marker of osteoblast differentiation, and osteoprotegerin, a local factor produced by osteoblasts to inhibit osteoclast differentiation [22], compared to SLA surfaces without coating or coated with either poly( l -glutamic acid) or poly( l -lysine).…”

“…While each of these surface properties can affect cell response differently, it is difficult to distinguish the effect of individual surface properties on cell response [4] since changing one property often changes others. To address this limitation, the aims of this study were to develop a surface wettability gradient without changing chemistry and micron scale roughness and to investigate the role of surface wettability on osteoblast response.…”

In situ fabrication of silver nanoparticle-filled hydrogen titanate nanotube layer on metallic titanium surface for bacteriostatic and biocompatible implantation

“…37 Therefore, compared with titanium, titanium foil with an H 2 Ti 3 O 7 layer on the surface can enhance the differentiation of preosteoblast cells. As reported by Park et al 38 and Keselowsky et al, 39 hydroxyl (-OH) and amine (-NH 2 ) groups on a material surface can greatly enhance osteoblast differentiation. The existence of rich hydroxyl groups on the surface of H 2 Ti 3 O 7 nanotubes is the main reason for the enhancement of osteoblast differentiation of MC 3T3-E1 cells in this work.…”