Modulating the Surface Properties of Metallic Implants and the Response of Breast Cancer Cells by Surface Relief Induced via Bulk Plastic Deformation

Benay Uzer

doi:10.3389/fmats.2020.00099

Abstract

Micro/nanoscale textured surfaces have presented promising tissue-implant integration via increasing surface roughness, energy and wettability. Recent studies indicate that surface texture imparted on the metallic implants via surface relief induced with simple bulk plastic deformation methods (e.g., tension or compression tests) do result in enhanced cell response. Considering these recent findings, this study presents a thorough investigation of the effects of surface relief on surface properties of implants and cell adhesion. Experiments are conducted on the samples subjected to interrupted tensile tests up to the plastic strains of 5%, 15%, 25%, and 35%. Main findings from these experiments suggest that, as the plastic deformation level increases up to 35% from the undeformed (control) level, (1) average surface roughness (Ra) increases from 17.58 nm to 595.29 nm, (2) water contact angle decreases from 84.28° to 58.07°, (3) surface free energy (SFE) increases from 36.06 mJ/m2 to 48.89 mJ/m2, and (4) breast cancer cells show 2.4 fold increased number of attachment. Increased surface roughness indicates the distorted topography via surface relief and leads to increased wettability, consistent with Wenzel’s theory. The higher levels of SFE observed was related with high-energy regions provided via activation of strengthening mechanisms, which increased in volume fraction concomitant with plastic deformation. Eventually, the displayed improvements in surface properties have increased the number of breast cell attachments. These findings indicate that surface relief induced upon plastic deformation processes could be utilized in the design of implants for therapeutic or diagnostic purposes through capturing breast cancer cells on the material surface.

Highlights

IntroductionMetallic materials constitute approximately 70% of the total production volume in biomedical applications (Peron et al, 2017), which stems from a set of excellent properties, such as mechanical strength, ductility, biocompatibility, and corrosion resistance (Chen and Thouas, 2015; Uzer et al, 2016; Peron et al, 2017; Nune et al, 2018)
Given the established influence of these properties on cell response, this study aims to investigate the role of surface relief on surface wettability, energy, roughness, and cell attachment behavior
Increased surface free energy (SFE) and wettability on the 35% deformed sample would have promoted the deposition of the adhesion proteins, enhancing the attachment of a greater number of cells. These results indicate that enhanced surface properties via surface relief may increase the number of cell attachments on the implant surface, but may not be influential in the morphology or spreading behavior of the breast cancer cells

Summary

Introduction

Metallic materials constitute approximately 70% of the total production volume in biomedical applications (Peron et al, 2017), which stems from a set of excellent properties, such as mechanical strength, ductility, biocompatibility, and corrosion resistance (Chen and Thouas, 2015; Uzer et al, 2016; Peron et al, 2017; Nune et al, 2018). Clinical success of the implantation strongly relies on early tissue–implant integration along with the elimination of fibrous connective tissue formation on the interface (Le Guéhennec et al, 2007; Hanawa, 2019) This integration can be influenced strongly by the implant surface wettability, which is governed by surface free energy (SFE) and roughness of the material (Liu and Jiang, 2011; Latifi et al, 2013). Modification of these aforementioned surface properties can be utilized to trigger specific molecular reactions controlling the adhesion, proliferation, or differentiation behavior of the cells (Ventre et al, 2012; Barthes et al, 2014; Huo et al, 2017; Raines et al, 2019). Surface properties obviously play a crucial role in cell adhesion, and in order to reveal their cumulative effects, more thorough analyses are required

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