Bioassisted selective-capture and release of nanoparticles toward application on microfluidic devices

Peptides with affinity for inorganic materials hold promise for immobilizing functional nanostructures on a solid surface. In this study, a peptide with strict selective affinity for ZnO surfaces was utilized. We functionalized cadmium selenide (CdSe) nanoparticles by conjugating ZnO-binding peptides (ZnOBPs) on the surface of the nanoparticles and performed spontaneous and reversible patterning of ZnOBP-displayed nanoparticles on lithographed ZnO films. Conjugation of ZnOBPs on CdSe nanoparticles caused spontaneous adsorption of the nanoparticles on a ZnO film, and fluorescence and cathodoluminescence images clearly showed specific adsorption of nanoparticles on nano- and micrometer scales. The selectively-bound nanoparticles on ZnO films were completely released by changing the phosphate concentration in solution; such release did not require heat or mechanical applications. Our results show the potential of material-binding peptides for nanopatterning and dynamic microarray applications.