A single weak-binding event is multiplied into an efficient receptor site for protein surfaces (106 M-1 in buffered aq. soln.) in a biomimetic fashion. This has hitherto been done with natural host/guest pairs, but not with artificial receptors. The org. reaction presented is one of very few that enable chemists to fuse multiple ionic building blocks covalently in highly polar soln.; this 1-pot reaction proceeds with virtually quant. yield. According to this concept, other building blocks with aldehyde groups can likewise be multiplied into monodisperse functional dendrimers. Small basic proteins are bound by octameric dendrimers in 1:1 or 1:2 complexes with millimolar to submicromolar affinities. The complexation event is studied independently in buffered aq. soln. by three different spectroscopic methods (PFG-LED, UV/Vis, and fluorescence). Potential new applications include recombinant protein purifn. through Arg tags on immobilized dendrimers and on/off switching of protein function by reversible active-site capping of enzymes.