Novel protein-inorganic nanoparticles prepared by inorganic replication of self-assembled clathrin cages and triskelia

Clathrin nanocages are constructed through spatially extended contacts that arise between helix hairpin motifs of overlapping triskelia, and as such represent an unusual protein nanostructure for the structural templating of novel types of bioinorganic constructs. Solid hybrid nanoparticles comprising a single gel-embedded polyhedral protein (clathrin) cage were produced by template-directed condensation of polycationic clusters of aminopropyl-functionalized magnesium phyllosilicate or oligomers of aminopropyl-functionalized silica. Alternatively, tripodal or hollow spheroidal clathrin-CdS constructs decorated with arrays of semiconductor nanoparticles were obtained by binding Cd(II) ions to individual triskelia or preformed cages, respectively, followed by reaction with sodium sulfide. Replication of the protein superstructures is facilitated by electrostatic interactions, and is accomplished without loss of secondary structure.