Amphiphilic Bio-molecules/ZnO Interface: Enhancement of Bio-affinity and Dispersibility

The dispersibility of bio-molecules such as lecithins on the surface of ZnO nanowires are investigated for biosensor applications. Lecithins can be absorbed on an as-synthesized ZnO nanowire surface in the form of sub-micro sized clusters, while scattering well on those annealed under oxygen atmosphere. Wettability analysis reveals that the as-synthesized ZnO nanowires bear a super-hydrophobic surface, which convents to superhydrophilic after oxygen annealing. First-principles calculations indicate that the adsorption energy of ZnO with water is about 0.2 eV at a distance of 2 angstrom when it is superhydrophilic, suggesting that lecithin can be absorbed on the hydrophilic surface stably at this distance and the bio-affinity can be enhanced under this condition.