Disclosed herein, inter alia, are compositions and methods of modulating macrophage activity. Provided is a method of treating a disease (e.g., a macrophage-associated disease, autoimmune disease, inflammatory disease, or a cancer of an organ in the intraperitoneal cavity), the method including intraperitoneally administering to a subject in need thereof a therapeutically effective amount of a nanoparticle composition or pharmaceutical composition. Provided is a silica nanoparticle non-covalently bound to a plurality of nucleic acids, wherein the silica nanoparticle has a net positive charge in the absence of the plurality of nucleic acids. Provided is a pharmaceutical composition including a nanoparticle composition as described herein, and a pharmaceutically acceptable excipient.