Focused Ultrasound-Augmented Cancer Phototheranostics Using Albumin-Indocyanine Green Nanoparticles

The purpose of this study was to develop a nanoparticle (NP) drug-loading system that enhances the efficiency of indocyanine green (ICG) entry into the tissue under focused ultrasound optimization and, in turn, enables more efficient identification and photothermal therapy (PTT) of the tumor. The new NPs were prepared by assembling intermolecular disulfide bonds to form human serum albumin (HSA) NPs and then conjugating those with ICG dye. The NP material was used to test the sensitivity of near-infrared fluorescence imaging and photoacoustic tumor imaging in vitro and in vivo. In addition, the combination of HSA-ICG NPs, focused ultrasound, and microbubbles was used to test PTT on the tumor. HSA-ICG NPs had good biocompatibility and were only a little toxic to cells and mice. In addition, they obviously enhanced tumor near-infrared fluorescence and photoacoustic bimodal imaging. Combined with HSA-ICG NPs, the depth of photoacoustic imaging was increased. Moreover, ICG that was absorbed in the HSA NPs promoted optical absorption in the near-infrared region, which greatly enhanced the PTT treatment's efficiency. This new bimodal tumor-imaging agent enhances the therapeutic effect of PTT and improves the detection of tumors in vivo, thus presenting great potential for use in clinical studies.