The invention provides a method of handling a hydrophobic agent, which
method comprises (a) combining in an aqueous solution (i) a hydrophobic
agent and (ii) an isolated peptide that is a structural analog of a
transmembrane domain of an integral membrane protein, wherein one
terminus of the peptide has one or more negatively charged residues, and
(b) allowing the peptide to self-assemble into nanoparticles, wherein the
nanoparticles comprise the hydrophobic agent.