Biomimicking Hydrophobicity Using Microscale Structures for Biomedical Applications

Abstract

Hydrophobic surfaces provide special characteristics for biomedical applications ranging from tunable protein adsorption, cellular interactions, and hemocompatibility to antibacterial coatings. In this research, we biomimic the hair-like micro-whisker structures of magnolia leaf using a synthetic polymeric formulation. Optical and scanning electron microscopy images revealed the presence of micro-whiskers resulting in higher water contact angles. The top layer of the magnolia leaf had a contact angle of 50º as compared to the hydrophobic bottom layer at 98º. A synthetic polymeric formulation was coated on different materials to study its effect on hydrophobicity. The coating was replicated (n=3) on each of the materials used such as glass, polymer, fabric, wood, and stainless steel. A surface tensiometer was used to measure the transition from hydrophilic to hydrophobic interactions between water and the substrate materials. Contact angle measurements revealed an increase in hydrophobicity for all the materials from their original uncoated surface. Glass displayed the highest increase in contact angle from 37º to 90º. Phase analysis of the coated region was performed to characterize the surface exposure of glass substrate to the synthetic polymeric formulation. An increase in the coated region showed a significant increase in contact angle from 50º to 95º. This research lays the foundation to develop and understand hydrophobic coatings for several biomedical applications including non-fouling implant surfaces, lab-on-chip devices, and other diagnostic tools.