Bioinspired superhydrophobic surfaces, inhibiting or promoting microbial contamination?

Bioinspired superhydrophobic surfaces have offered unique advantages in combating microbial contaminations involving fungi, bacteria, and viruses, especially during the global COVID-19 pandemic. It has been widely accepted that the biofouling-resistant capability of the superhydrophobic substrates principally arises from the entrapped air-layer. With this principle, substantial consideration is devoted to designing superhydrophobic surfaces with an emphasis on stabilizing the air-layer. However, some superhydrophobic surfaces were proven to promote the attachment of microorganisms in certain cases, implying that the mechanisms governing the capacity of superhydrophobic surfaces to mediate microbial adhesion still need to be better understood. Here, we review recent efforts in elucidating the inter-relationship between surface superhydrophobicity and microbial adhesion to make a generalizable consensus on why some superhydrophobic surfaces can repel microbes while others may be incapable. In this context, we shed light on the fact that surface topography and low surface energy are not only the requirements to develop superhydrophobic surfaces but also play a decisive role in endowing surfaces with improved anti-adhesive properties. The obtained viewpoints ideally pave the way for engineering functional superhydrophobic surfaces that effectively reduce microbial contamination on a predetermined basis and can potentially be applied to high-touch surfaces, biomaterial surfaces, personal protective equipment (PPE), and other medical equipment.