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.