The interaction between the osteosarcoma cell and stainless steel surface, modified by high-fluence, nanosecond laser pulses

Matej Hočevar,Barbara Šetina Batič,Matjaž Godec,Veno Kononenko,Damjana Drobne,Peter Gregorčič

doi:10.1016/j.surfcoat.2020.125878

Matej Hočevar, Barbara Šetina Batič + Show 4 more

Open Access

https://doi.org/10.1016/j.surfcoat.2020.125878

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Abstract

The irradiation of metallic surfaces by high-fluence laser pulses in an oxygen-containing atmosphere inevitably modifies the surface topography, chemistry, and wettability. These modifications significantly influence cell-surface interactions and, consequently, surface biocompatibility. We investigate how surface texturing by high-fluence nanosecond laser pulses from a Nd:YAG laser (wavelength of 1064 nm) influences cell adhesion and morphology with the aim of assessing its impact on initial cell behaviour. Quantitative and qualitative analysis of osteosarcoma cell adhesion, viability, and cell morphology were evaluated after 24-hour exposure to non-treated and laser-textured stainless-steel (AISI 316L) surfaces by fluorescent and scanning electron microscopy. The results reveal that this, initial interaction between the cells and the laser-textured surfaces leads to round shaped cells with a smaller footprint. Contrarily, on the non-processed stainless-steel and control-glass surfaces the polygonal, highly elongated, and flattened cells are observed. The cells on the laser-textured surfaces are less dendritic, with short tubular protrusions and an overexpression of extracellular vesicles, which are rarely found on non-treated and control samples. This likely happens due to the formation of nanostructured, high-temperature oxides that are induced by laser ablation. The analysis by X-ray photoelectron spectroscopy reveals that the laser-textured stainless-steel surfaces contain Cr hexavalent oxide, which is more toxic than the native oxide layer on the non-processed samples.

Highlights

As explained in the main manuscript, surface morphology, topography, and roughness of the nontreated and laser-textured 316L samples were examined by using SEM and IFM (3D surface roughness measurements)
No differences in surface roughness are observed on the non-treated sample at different directions of measurement
Fluorescence microscopy imaging was followed by SEM observations of the attachment pattern and morphology of MG63 cells on the non-treated and laser-textured surfaces and compared to the control glass surface

Summary

Surface morphology and topography measurements

As explained in the main manuscript, surface morphology, topography, and roughness of the nontreated and laser-textured 316L samples were examined by using SEM (surface morphology imaging) and IFM (3D surface roughness measurements). Surface area roughness (Sa) reveals that the laser-textured sample is much rougher due to the laserinduced morphology. On the non-treated surface, without any preferential topography, Ra was measured perpendicular (Rap) and parallel (Ral) with respect to the sample (Figures S3-S4), while on the laser-textured sample Ra was measured perpendicular (Rap) and parallel (Ral) to the direction of the laser-texturing. No differences in surface roughness are observed on the non-treated sample at different directions of measurement. A cross-section of both samples is shown in Figure S5 for better visual comparison of the surface profiles on the non-treated and the laser-textured samples

Measurement point

SEM of cell adhesion pattern and cell gross morphology