This proposal aims to generate hollow, porous Nano-Delivery Vehicles (NDVs) that are functionalized with a stealth coating to allow for long circulation times and with surface bound antibodies for tumor targeting. The NDVs are sufficiently small to leave the vasculature at tumor sites, can controllably deliver a wide variety of chemotherapeutic drugs at a predetermined rate, and can be detected using fluorescence or elemental analysis. The efficacy of NDVs functionalized with HER2 targeting Fab'fragments and containing two different types of chemotherapeutic drugs will be tested in cell culture and in a mouse breast cancer model.