Femtosecond Laser Nano/Micro Textured Ti6Al4V Surfaces—Effect on Wetting and MG-63 Cell Adhesion

Abstract

Nano- and microstructured titanium surfaces have recently attracted attention in the field of regenerative medicine because of the influence which surface characteristics such as roughness and wettability can have on cellular processes. This study focuses on the correlation of surface properties (wettability and nano/micro texture) of laser-structured Ti6Al4V samples with pronounced cell adhesion. Samples were structured with multiple laser parameters in order to create a range of surface properties. Surface characterization was performed by contact angle measurements 1 and 7 days after laser processing. The arithmetic mean roughness of the material surface in an area (Sa) was determined by means of confocal laser scanning microscopy (CLSM). Immediately after wettability tests of the laser-structured surfaces, in vitro experiments with human MG-63 osteoblasts were carried out. For this purpose, the cell morphology and actin cytoskeleton organization were analyzed using CLSM and scanning electron microscopy. On rough microstructures with deep cavities, the cell growth and spreading were inhibited. An improved cellular adhesion and growth on nanostructured and sinusoidal microstructured surfaces could be demonstrated, regardless of hydrophilicity of the surfaces.

Time-Dependent Anisotropic Wetting Behavior of Deterministic Structures of Different Strut Widths on Ti6Al4V

“…The change in wetting behavior of laser irradiated areas on metals is consistent with findings of other research groups and is related to a change in the chemical composition of the surface over time [18,21,23,24]. Several studies have been published with explanatory approaches for the changes.…”

“…The influence of femtosecond laser radiation on groove and lattice structures was presented in a work for a few strut widths [15], but no anisotropic droplet formation was displayed. Moreover, it is known that laser structured metallic surfaces show a strong dependency on the wetting behavior with regard to time and ambient atmosphere [16][17][18].…”

Effect of Laser Pulse Overlap and Scanning Line Overlap on Femtosecond Laser-Structured Ti6Al4V Surfaces

“…Several studies have already shown that laser induced periodic surface structures (FLIPSS, LIPSS) provide favorable conditions for cell attachment [15,17,58,59]. The impact of two selected micro and two selected FLIPSS structures presented in the current study on the cell adhesion of MG-63 cells have already been investigated [15]. It could be demonstrated, that the osteoblasts adhered tightly, especially to the two investigated FLIPSS-structured surfaces, and it was found that the spreading was superior on these surfaces.…”

“…An appropriate or relatively higher scanning line overlap leads to a homogenous distribution of nanostructures and helps avoid strong waviness of the laser treated surface. Several studies have already shown that laser induced periodic surface structures (FLIPSS, LIPSS) provide favorable conditions for cell attachment [15,17,58,59]. The impact of two selected micro and two selected FLIPSS structures presented in the current study on the cell adhesion of MG-63 cells have already been investigated [15].…”

“…Laser treatment of titanium has been found to be particularly advantageous compared to conventional surface structuring methods because it leads to less contamination of the surfaces [12] and offers the possibility of creating stochastic as well as precise deterministic structures in the microand nanometer range [5,13,14]. In particular, the potential of femtosecond (fs) laser structuring of titanium for use in biomedical implants has been shown in several studies [15][16][17][18]. This technique is superior to nanosecond laser treatments due to opportunity of creating surface topographies with a greater variety of patterns [19].…”