In recent years, a wide range of near-infrared (NIR) light absorbing nanomaterials, mostly inorganic ones, have been developed for
photothermal therapy (PTT) of
cancer. In this work, we develop a novel organic PTT agent based on poly-(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (
PEDOT:PSS), a conductive
polymer mixture with strong NIR absorbance, for in vivo photothermal treatment of
cancer. After being layer-by-layer coated with charged
polymers and then conjugated with branched
polyethylene glycol (PEG), the obtained
PEDOT:PSS-PEG nanoparticles are highly stable in the physiological environment and exhibit a stealth-like behavior after
intravenous injection with a long blood circulation half-life. As a result, an extremely high in vivo
tumor uptake of
PEDOT:PSS-PEG attributed to the
tumor-enhanced permeability and retention effect is observed. We further use
PEDOT:PSS-PEG as a PTT agent for in vivo
cancer treatment and realize excellent therapeutic efficacy in a mouse
tumor model under NIR light irradiation at a low
laser power density. Comprehensive blood tests and careful histological examination reveal no apparent toxicity of
PEDOT:PSS-PEG to mice at our treated dose within 40 days. To our best knowledge, this work is the first to use systemically administrated conductive
polymer nanoparticles for highly effective in vivo PTT treatment in animals and encourages further explorations of those organic nanomaterials for
cancer theranostic applications.