Fouling is the undesirable accumulation of a material on a variety of objects and has become a widespread global problem. Since chemical modifications of materials’ surfaces for killing adherent bacteria have poor long-term performance, surface topology is of great interest to develop bactericidal surfaces in place of traditional chemical-based approaches that are often toxic to human beings and environments. In this talk, we use nanopatterned surfaces fabricated by polystyrene-block-poly(methyl methacrylate) (PS-<i>block</i>-PMMA) diblock copolymers as rational models. PS-block-PMMA along with neutral air/substrate wetting conditions allows us to fabricate vertically oriented cylindrical or lamellar microdomain structures on silicon substrates. Vertically oriented PS cylinders are then cross-linked by UV and the PMMA component can be removed by acetic acid, creating PS “nanopillars”. Our results with PS nanopillars (the height of 25 nm and domain spacing of 60 nm) showed antibiofouling, bactericidal, and self-cleaning properties against Escherichia coli (E coli), while the bacteria remain rod-shaped on “flat” PS control surfaces. Moreover, we have identified that these multifunctional properties are significantly enhanced by coating the PS nanopillars with a very thin layer of titanium oxide that are often utilized in biomedical devices and biomaterials due to their positive characteristics including antimicrobial activity, biocompatibility, good mechanical strength. We will further discuss the roles of geometric parameters of nanopatterned surfaces in these multifunctional properties against the model bacterium.

Antimicrobial surface modification via self-assembled nanopatterns of block copolymer films

ACS Spring 2022

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