Novel small molecular dye-loaded lipid nanoparticles with efficient near-infrared-II absorption for photoacoustic imaging and photothermal therapy of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant cancers worldwide and is the second leading cause of mortality in cancer patients. Thus, accurate diagnosis and effective treatment of the malignancy is very critical for HCC patients. The photoacoustic (PA) nanoparticle with ultra-sensitive imaging signals and high photothermal conversion efficacy is a new and promising method for achieving the desired goals. In this study, we have synthesized a novel lipid nanoparticle based on IR-1061 dyes by encapsulating the dye into a liposome which was modified by DSPE-PEG₂₀₀₀. We conducted serial experiments to investigate the PA diagnosis performance, the surgical navigation, and the photothermal therapy (PTT) capability of the novel nanoparticle (Polipo-IR NP) in nude mice bearing HCC. The results showed that our novel nanoparticles exhibited strong laser energy absorption at 1064 nm wavelength, high photothermal conversion efficacy (45.25%) and ultra-sensitive PA signals. The in vivo PA studies demonstrated that the proposed nanoparticles could diagnose tumors non-invasively and accurately with a strong signal-to-noise ratio of 5.98 ± 0.23 at 3 h post-injection and could successfully achieve radical resection of tumors intraoperatively. Furthermore, the PTT test demonstrated a remarkable cancer cell killing ability because of its high photothermal conversion efficacy. The excellent photostability and high biocompatibility were also validated by in vitro and in vivo experiments. Thus, our proposed NIR-II PA and PTT nanoparticles based on the IR-1061 dye would potentially provide novel insights into understanding polymethine dyes in nanomedicine and would greatly benefit early diagnosis and treatment of HCC patients.