Self-assembly of methylene violet-conjugated perylene diimide with photodynamic/photothermal properties for DNA photocleavage and cancer treatment.

Near-infrared (NIR) light-activated phototherapy, such as photothermal therapy (PTT) and photodynamic therapy (PDT), has gained considerable attention due to the advantages of high efficiency and minimally invasiveness. However, the development of a single component therapeutic agent with clear structure and molecular weight that achieve photodynamic/photothermal synergistic therapy is still challenging. Herein, we design and synthesize a new smart photosensitizer (PRX) by conjugation of perylene diimide (PDI) and methylene violet (RAX). The typical donor-acceptor (D-A) structure of RAX facilitates the red-shift of absorption to the near-infrared (NIR) region. The amphiphilic PRX could self-assemble into monodispersed nanoparticles (PRX NPs) with enhanced and broadened absorption. Under a single 808 nm laser irradiation, PRX NPs could generate efficient reactive oxygen species (ROS) and heat simultaneously with the photothermal conversion efficiency as high as 59%. PRX NPs displays strong interaction with DNA and can damage plasmid DNA upon light irradiation. The biocompatibility and high phototoxicity of PRX NPs against A549 cells are further confirmed through MTT assay. Therefore, the as-prepared PRX NPs could be served as a promising antitumor nanoagent through photothermal/photodynamic combination manner.