Monitoring a tumor-targeting BODIPY-based theranostic nanomaterial with photoacoustic imaging

Abstract

Photoacoustic imaging has begun to be widely used to observe drug delivery and accumulation in the body. Theranostic, which includes both diagnosis and therapy, is an attractive approach for treating cancer. In this study, we synthesized nanomaterials and verified the theranostic effect through fluorescence and photoacoustic imaging. Selectively transporting a drug to the tumor site is essential to increase the therapeutic effect while reducing side effects. BODIPY has the advantages of being able to change its structure more easily, good photostability, good biocompatibility and high absorption coefficient than cyanine or porphyrin dyes, however they are limited to in vivo experiment due to their poor water solubility. We overcome the limitations of BODIPY-based materials by encapsulating in micellar nanoparticles with Hexa BODIPY cyclophosphazene (HBCP) and DSPE-PEG2000 polymer. HBCP NPs also have a property of selectively accumulating in tumors with enhanced permeability and retention effect due to their bulky nano-size molecular structure. We checked the tumor targeting and retention time of HBCP NPs by monitoring them with fluorescence imaging. In addition, the high heat conversion efficiency of HBCP NPs enables photoacoustic imaging and Photothermal therapy. We also conducted whole body scanning of tail-vein injected tumor-bearing mice with acoustic resolution photoacoustic microscopy system to provide tumor accumulation information of HBCP NP with vascular structure. The result suggests that HBCP NP has a potential to be used as a material for image guided phototherapy.