Performance of Anti-Biofouling Barriers on Nano-Engineered Metal Surfaces

Abstract

In this work, we apply superhydrophilic, superhydrophobic and lubricant-impregnated wettability on aluminum (A1050), stainless steel (SUS-430) and Titanium (Ti) substrates, and investigate the anti-biofouling behaviors of such surface treatment.We fabricated nanostructures on three different metal surfaces using oxidation process, which can turn the surface into superhydrophilic (SHPi). Figure 1 shows the FESEM images of the investigated surfaces including oxide structure of A1050, SUS-430, and Ti. Then a silane (1H,-1H,2H,2H Perfluorodecyltrimethoxysilane) was vapor-deposition on the surface to induce superhydrophobicity (SHPo). In addition, silicone 100cst oil was infused on superhydrophobic surface to obtain the lubricant-impregnated slippery surface (LIS). Figure 2 shows the static and dynamic contact angles of the each investigated surfaces. The static contact angle of SHPi is <5° by the formation of thin water layer into nanostructures. Meanwhile, SHPo has stable air layer into nanostructures and it enables large contact angle (>150°) on the surface. In case of LIS, the thin lubricant layer covers nanostructures and it makes extremely small contact angle hysteresis (<5°) by its water repellency. Such three surfaces have different anti-biofouling barrier (SHPi, SHPo and LIS have the thin water layer, the air layer, and the lubricant layer, respectively). Pseudomonas aeruginosa (P.aeruginosa) attachment under static condition. For fluorescence imaging of attached bacterial cells, the substrates were stained with SYTOX green nucleic acid stain as shown Figure 3. Using the Image J analysis, covered area was extracted from the samples with different wetting characterestics, and their anti-fouling performance was quantitatively compared with that of Bare sample (Figure 4-6). The measured covered area shows that the biofouling behaviors are different depending on the substrates.