Effect of Spontaneous and Water-Based Passivation on Components and Parameters of Ti6Al4V (ELI Grade) Surface Tension and Its Wettability by an Aqueous Solution of Sucrose Ester Surfactants

Joanna Krawczyk,Amparo María Gallardo-Moreno,María Luisa González-Martín

doi:10.3390/molecules27010179

Abstract

Solid wettability is especially important for biomaterials and implants in the context of microbial adhesion to their surfaces. This adhesion can be inhibited by changes in biomaterial surface roughness and/or its hydrophilic–hydrophobic balance. The surface hydrophilic–hydrophobic balance can be changed by the specifics of the surface treatment (proper conditions of surface preparation) or adsorption of different substances. From the practical point of view, in systems that include biomaterials and implants, the adsorption of compounds characterized by bacteriostatic or bactericidal properties is especially desirable. Substances that are able to change the surface properties of a given solid as a result of their adsorption and possess at least bacteriostatic properties include sucrose ester surfactants. Thus, in our studies the analysis of a specific surface treatment effect (proper passivation conditions) on a biomaterial alloy’s (Ti6Al4V ELI, Grade 23) properties was performed based on measurements of the contact angles of water, formamide and diiodomethane. In addition, the changes in the studied solid surface’s properties resulting from the sucrose monodecanoate (SMD) and sucrose monolaurate (SML) molecules’ adsorption at the solid–water interface were also analyzed. For the analysis, the values of the contact angles of aqueous solutions of SMD and SML were measured at 293 K, and the surface tensions of the aqueous solutions of studied surfactants measured earlier were tested. From the above-mentioned tests, it was found that water environment significantly influences the components and parameters of Ti6Al4V ELI’s surface tension. It also occurred that the addition of both SMD and SML to water (separately) caused a drop in the water contact angle on Ti6Al4V ELI’s surface. However, the sucrose monolaurate surfactant is characterized by a slightly better tendency towards adsorption at the solid–water interface in the studied system compared to sucrose monodecanoate. Additionally, based on the components and parameters of Ti6Al4V ELI’s surface tension calculated from the proper values of components and parameters of model liquids, it was possible to predict the wettability of Ti6Al4V ELI using the aqueous solutions of SMD and SML at various concentrations in the solution.

Highlights

Metallic implants are widely used for biomedical applications
The surface properties of a given solid play a crucial role in many processes occurring at different interfaces and in different fields
The dependence can be expressed by the Young equation [16]: γS − γSL = γL cos θ where γS is the solid surface tension, γL is the liquid surface tension and γSL is the solid– liquid interface tension

Summary

Introduction

Metallic implants are widely used for biomedical applications. The most common are used in orthopedic surgery or dental applications, where they serve as temporary or permanent implants in the body. Metals possess many properties which make them desirable for bone repair, their corrosion stability and biocompatibility can be problems. The body contains many compounds, for example, water, sodium chloride and proteins, which are very reactive to metals. Since metals possess the ability to alloy, metals can be modified by using elements that do not exert adverse effects in the body. Titanium alloys are able to tolerate the corrosive environment of the body to a great extent [1,2]

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