Dimethylamino-Functionalized BODIPY Nanoparticle Enhances Near-Infrared Fluorescence Imaging and Photothermal Therapy

Organic dyes have been widely used in bioimaging, molecular probes, imaging in vivo, and phototherapy. However, it is still a major challenge to improve the imaging and therapeutic properties of organic dyes. In this work, boron dipyrromethene (BODIPY) nanoparticles (NPs) were synthesized with poly(ethylene glycol)2k-block-poly(d,l-lactide)2k (PEG–PLA) NPs for tumor microenvironment response, near-infrared fluorescence (NIRF) imaging with a high signal-to-noise ratio (SNR), and photothermal therapy (PTT). The absorption and fluorescence spectra of the obtained BDP changed as the pH decreased. The introduction of a dimethylamino group enhanced the photothermal conversion efficiency and imaging capability of BODIPY-loaded PEG–PLA NPs (BDP NPs). After injection into mice, these NPs showed excellent photothermal efficacy toward hepatoma and papillary thyroid cancer. Additionally, BDP NPs could be used for NIRF imaging with a high SNR after BODIPY was modified with a dimethylamino group. This work highlights that molecular engineering can enhance the luminescence and photothermal properties of dyes and that BDP NPs are excellent theranostic agents.