Antireflective and Superhydrophobic Coating for Boosting Cyanobacterial Photobioreactor Performance

Biofouling poses a notorious challenge during photosynthetic microorganism cultivation in photobioreactors (PBRs) by hindering light penetration, degrading the cultivation environment and eventually diminishing bioproductivity. To solve this problem, we developed a superhydrophobic SiO₂ coating with antireflective properties using sol–gel technology. The coating is cost-effective due to its simple, fluorine-free, and heat-free fabrication process, showing excellent performance in both preventing cyanobacterial adhesion and enhancing light transmission. Compared to uncoated substrates, the transmittance increases by 5.8 to 7.0%, depending on the substrate material (glass, polystyrene, poly(vinyl chloride) and polycarbonate). When applied to glass tube PBRs, this coating significantly promotes cyanobacterial proliferation and chlorophyll-a content compared to uncoated PBRs and those with rough superhydrophobic coatings that compromise transparency. These results underscore the critical roles of both antifouling and antireflective properties in optimizing the cultivation of photosynthetic microorganisms, and suggest the potential applications of the proposed coating in the cyanobacterial industry and other bioculture domains.