Polymerized small molecular dyes providing nanoparticles with stable photosensitivity for eradicating cancer cells

To make small molecular photosensitizer-based nanoparticles photostable, we polymerized such photosensitizers via emulsion polymerization, and the resulting nanoparticles exhibited sustained absorption of the excitation wavelength in the near-infrared region, generated stable photothermal and photodynamic effects upon repeated irradiation with an near-infrared laser, and efficiently eradicated cancerous cells even after prior irradiation exposure.