Abstract: Nanoparticulate carrier formulations are useful to solubilize, deliver, and target hydrophobic drugs for treating diseases including cancer and bacterial infections. The formulations contain amphiphilic peptides having a hydrophobic portion and a positively charged hydrophilic portion. The peptides self-associate at nonacidic pH to form mi-celles with a spherical nanoparticle morphology. The hydrophobic core of the nano-particles encapsulates hydrophobic drugs, including antitumor agents, increasing their solubility in water and allowing them to be targeted, for example, to cancer cells. The positively charged surface of the nanoparticles, together with an optional targeting moiety such as an RGD peptide, allows the nanoparticles to bind selectively to mammalian cells and bacterial cells, including cancer cells that overexpress integrin receptors.