Electrochemically Triggered Selective Adsorption of Biotemplated Nanoparticles on Self-Assembled Organometallic Diblock Copolymer Thin Films

The controlled adsorption of the iron-containing cage protein ferritin at the nanoscale using stimuli-responsive self-assembled diblock copolymer thin-film templates is reported. The diblock copolymer used study consists of a cylinder-forming polystyrene-block-polyferrocenylsilane (PS-b-PFS), with PFS as the minor block, and shows reversible redox properties. To prevent any spontaneous protein adsorption on either block, the electrolyte pH is selected to leave the ferritin negatively charged, and the protein concentration and solution ionic strength are carefully tuned. Selective adsorption of ferritin on the PFS domains of the self-assembled thin films is then triggered in situ by applying a positive potential, simultaneously oxidizing the PFS and attracting the ferritin electrostatically.