Advanced Nanostructured Surfaces for the Control of Biofouling: Cell Adhesions to Three-Dimensional Nanostructures

In marine environments or industrial water systems, microorganisms are likely to adhere onto surfaces and form biofilms. Such biofouling creates significant adverse effects, e.g., increases flow friction by roughening surfaces. Previous studies demonstrated the effectiveness of surface microstructures on the prevention of biofouling, which is also closely associated with the surface energy and wettability. Unfortunately, the study of the anti-biofouling property of the micro- and nanostructured surfaces with regulated surface wettability is underperformed at present. In this paper, we report on the bio-adhesions of various cell types on nanoengineered surfaces with dense-array nanostructures whose physical and chemical properties are systematically controlled for the prevention of biofouling. Two nanopatterns (pillar and grating) with varying three-dimensionalities (e.g., structural heights are varied from 50 to 500 nm while the pattern periodicity is fixed at 230 nm) are tested in both hydrophilic and hydrophobic surface conditions. The structural tips are especially sharpened (<10 nm in tip radius) to minimize the cell contact to the substrate and potentially biofouling. The experimental results show that cells were much smaller and their proliferation significantly lower on taller nanostructures in both hydrophilic and hydrophobic surface conditions. Cells were found levitated by sharp tips and easily peeled off, i.e., their adherence to the sharp-tip tall nanostructures was relatively weak regardless of the surface wettability. The ability to control adherence and growth of cells by nanoscale surface topographies can empower the micro- and nanotechnology-based materials, devices, and systems for anti-biofouling and anti-microbial applications. The knowledge obtained through this investigation will also be useful in engineering problems that involve contact with biological substances and in the development of energy efficient surfaces for green tribology.