Surface behaviour of biomaterials: The theta surface for biocompatibility

Abstract

"Biomaterials" are non-living substances selected to have predictable interactions with contacting biological phases, in applications ranging from medical/dental implants to food processing to control of biofouling in the sea. More than 30 years of empirical observations of the surface behaviours of various materials in biological settings, when correlated with the contact-angle-determined Critical Surface Tensions (CST) for these same materials, support the definition of the "theta surface". The "theta surface" is that characteristic expression of outermost atomic features least retentive of depositing proteins, and identified by the bioengineering criterion of having measured CST between 20 and 30 mN/m. Biomaterials applications requiring strong bioadhesion must avoid this range, while those requiring easy release of accumulating biomass should have "theta surface" qualities. Selection of blood-compatible materials is a main example. It is forecast that future biomaterials will be safely and effectively translated directly to clinical use, without requiring animal testing, based on laboratory data for CST, protein denaturation, and cell spreading alone.

Correlations of Materials Surface Properties with Biological Responses

“…The earliest events follow a common pattern. Such interactions result in differing degrees of bioadhesion and can be effectively correlated usually, even controlled by the surface properties, (especially surface energies) of the substrata involved [1].…”

The use of nano-/microlayers, self-healing and slow-release coatings to prevent corrosion and biofouling

“…The same layers could be effective against microbially influenced corrosion by decreasing the surface free energy, hampering the adsorption of the biomolecules and cells (Baier, 2006, Telegdi, 2009). In addition, the compounds in nanolayers could be toxic for many different microorganisms such as bacteria, (Sun, 2002(Sun, , 2003Skrivanova, 2006;Shin, 2007), viruses (Bergsson, 2001) and fungi (Avis, 2001;Wang, 2002), because they interfere with the cell membrane and compromise its integrity, leading to cell death (Fig 2O.4.1a).…”

Surface Treatments to Modulate Bioadhesion: A Critical Review

“…This being said, there is an increasing interest in surface treatment/engineering of materials specifically regarding manipulating tissue engineering [1][2][3][4][5][6][7][8][9] and bacterial adhesion [10][11][12][13][14]. In a generalized sense, the development of technologies for the manipulation of biological and microbiological adhesion can be viewed in Figure 1.…”

“…This could potentially hinder the interaction between the bacterium and the topographical surface, specifically against features with typical dimensions less than the size of the bacterium, limiting the possibility for bacteria to sense them [17]. With regards to tissue engineering, it has been realized that many untreated potential biomaterials possess poor adhesion characteristics and, as such, have poor biomimetic properties leading to them being rejected by the human body [7]. So, in order to optimize their adhesion characteristics for their use in biological environments, a vast number of techniques and methods have been developed.…”