Novel FRET-Based Radiosensitization Using Quantum Dot-Photosensitizer Conjugates

A novel radiosensitizer was synthesized by covalently conjugating quantum dots (QDs) to a photosensitizer. We hypothesized that QDs excited by 6-MV X-rays would serve as an energy donor to activate the photosensitizer. Photon emission from QDs was linearly proportional to radiation dose rate. Donor quenching in conjugates indicated that activation of photosensitizer occurred by Forster resonance energy transfer. Radiation treatment of lung carcinoma cells with conjugate increased cell killing by 34% compared to radiation alone. Cell toxicity in non-irradiated controls was negligible. Thus, this conjugate acts via a novel mechanism of radiosensitization that will improve treatment of deeply seated tumors.