Self-quenched ferrocenyl diketopyrrolopyrrole organic nanoparticles with amplifying photothermal effect for cancer therapy† †Electronic supplementary information (ESI) available: Experimental methods and additional figures. See DOI: 10.1039/c7sc03351f Click here for additional data file.

Organic nanoparticles (NPs) with near-infrared absorbance possess high photothermal conversion (PTC) efficiency and an excellent photoacoustic signal, presenting a great prospect for photoacoustic imaging (PAI)-guided photothermal therapy (PTT). Herein, a novel diketopyrrolopyrrole derivative (DPPCN-Fc) is synthesized for use as a PTT agent with PAI performance. Due to photo-induced electron transfer (PET), the two flanked ferrocene moieties significantly quench the radiative decay and intersystem crossing process, resulting in an enhanced nonradiative transition, and an amplifying photothermal effect is observed. Exposing the DPPCN-Fc NP aqueous dispersion (100 mg mL ) to 730 nm (1.0 W cm ) laser radiation results in a temperature elevation of 33.4 C within 10 min and the PTC efficiency reaches up to 59.1%, which is higher than most reported photothermal therapeutic agents. Furthermore, under irradiation from 730 nm lasers, cancer cells could be completely killed in vivo due to the amplifying photothermal effects. Therefore, the as-prepared DPPCN-Fc NPs are a promising cancer theranostic agent for photoacoustic imaging-guided cancer photothermal therapy.