New colloidal materials that can generate heat upon irradiation are being explored for photothermal therapy as a minimally invasive approach to cancer treatment The near-infrared dye indocyanine green (ICG) could serve as a basis for such a material, but its encapsulation and subsequent use are difficult to carry out. We report the three-step room-temperature synthesis of similar to 120-nm capsules loaded with ICG within salt-cross-linked polyallylamine aggregates, and coated with antiepidermal growth factor receptor (anti-EGFR) antibodies for tumor cell targeting capability We studied the synthesis conditions such as temperature and water dilution to control the capsule size and characterized the size distribution via dynamic light scattering and scanning electron microscopy. We further studied the specificity of tumor cell targeting using three carcinoma cell lines with different levels of EGFR expression and investigated the photothermal effects of ICG containing nanocapsules on EGFR-rich tumor cells. Significant thermal toxicity was observed for encapsulated ICG as compared to free ICG at 808 nm laser irradiation with radiant exposure of 6 W/cm(2) These results illustrate the ability to design a colloidal material with cell targeting and heat generating capabilities using noncovalent chemistry.