Guest-binding behavior of peptide nanocapsules self-assembled from viral peptide fragments

The binding behavior of guests (dyes and DNA) into peptide nanocapsules formed via self-assembly of a 24-mer beta-annulus peptide fragment obtained from the capsid protein of the tomato bushy stunt virus is reported. The pH dependence of the zeta potential of the peptide nanocapsules indicates that the C- and N-termini are directed to the exterior and interior of the nanocapsules, respectively. Equilibrium dialysis experiments with dyes and the peptide nanocapsules at pH 7 showed that the peptide nanocapsules tend to bind anionic dyes. Binding of sodium 8-anilinonaphthalene-1-sulfonate and uranine into the peptide nanocapsules minimally affected the size of the nanocapsules, whereas binding of other anionic dyes resulted in the formation of precipitates. In addition, binding of Thioflavin T to the beta-annulus peptide promoted disassembly of the nanocapsules. Complexation of the beta-annulus peptide with M13 phage DNA formed a core-shell nanosphere in which the DNA was encapsulated in the peptide assembly.