Potential of Superhydrophobic Surface for Blood-Contacting Medical Devices

Abstract

Medical devices are indispensable in the healthcare setting, ranging from diagnostic tools to therapeutic instruments, and even supporting equipment. However, these medical devices may be associated with life-threatening complications when exposed to blood. To date, medical device-related infections have been a major drawback causing high mortality. Device-induced hemolysis, albeit often neglected, results in negative impacts, including thrombotic events. Various strategies have been approached to overcome these issues, but the outcomes are yet to be considered as successful. Recently, superhydrophobic materials or coatings have been brought to attention in various fields. Superhydrophobic surfaces are proposed to be ideal blood-compatible biomaterials attributed to their beneficial characteristics. Reports have substantiated the blood repellence of a superhydrophobic surface, which helps to prevent damage on blood cells upon cell-surface interaction, thereby alleviating subsequent complications. The anti-biofouling effect of superhydrophobic surfaces is also desired in medical devices as it resists the adhesion of organic substances, such as blood cells and microorganisms. In this review, we will focus on the discussion about the potential contribution of superhydrophobic surfaces on enhancing the hemocompatibility of blood-contacting medical devices.

Keywords: anti-biofouling; antibacterial; antihemolytic; antithrombotic; blood compatible; medical device; superhydrophobic.

Figure 1

Wetting states of surface based on (A) Wenzel’s model and (B) Cassie–Baxter’s model. (C) Schematic of a water droplet slides off a tilted surface. θ represents the apparent contact angle, which measures the wettability of the surface by a liquid droplet. θa, θr, and θs represent advancing contact angle, receding contact angle, and sliding angle, respectively.

Figure 2

Comparison between the hemolytic effect of (A) superhydrophobic surface and (B) non-superhydrophobic surface. Superhydrophobic surface repels the red blood cells, leaving the blood cells unharmed due to the structured surface and low surface energy. On the other hand, red blood cells tend to adhere to the non-superhydrophobic surface, denature and promote the adhesion of clotting agents, consequently leading to thrombosis and entrapment of microbial cells.

Figure 3

Structured surface embedded with protrusions. The protrusions increase surface roughness, thus providing resistance to cell adhesion. h and i represent height and interspacing area, respectively. The roughness of the surface depends on the size of protrusions. The anti-adhesion abilities are to be adjusted by altering the height of protrusions and/or interspacing between them.