Polymers are commonly used as materials in biomedical applications. The surface properties of the materials need to be tailored to meet the requirements set by the application. One common approach in biomedical devices is to prevent biofouling as the attachment of microorganisms may result in the infection of the patient. Anti-biofouling of polymers is attractive as they can avoid the introduction of drugs which is one approach to prevent biofouling.
Wetting strategies for anti-biofouling surfaces
Several different anti-fouling strategies have been studied which are based on tailored surface wettability of the polymer surface. In general wettability of the surface is divided into four categories depending on the water contact angle (WCA). If WCA on the surface is
• < 10° the surface is superhydrophilic
• 10 ° - 90° the surface is hydrophilic
• 90° - 150° the surface is hydrophobic
• > 150° angles are superhydrophobic.
Superhydrophilic surfaces are completely wetted with water, forming a water layer on the surface which will prevent the adhesion of proteins, cells, and bacteria. Several hydrophilic polymers follow this wetting strategy for anti-fouling. The most investigated hydrophilic polymers for biomedical applications are PEG-based polymers. The anti-biofouling action of PEG-based polymers is the result of both steric and hydration effects and is dependent on the size, branching, and surface-packing density of the specific PEG molecule. Hydrophobic surfaces are rarely able to work as anti-biofouling surfaces although some examples can be found in the literature. Superhydrophobic surfaces, on the other hand, can offer anti-biofouling characteristics due to reduced contact between the water and the surface which leads to reduced adsorption of the proteins on the surface.
Durability of the anti-biofouling materials
One additional aspect of the anti-biofouling surfaces that needs attention is their durability. As anti-biofouling surfaces are often a combination of chemistry and surface roughness, they are typically easily damaged by scratching, degradation, and rough handling. Enhancing durability is a significant challenge that needs to be addressed for widespread industrial use.
If you would like to learn more about different contact angle measurements used within biomedical applications, please download the white paper through the link below.
