Photoacoustic tomography (PAT) has emerged as a hybrid, nonionizing imaging modality because of its satisfactory spatial resolution and high soft tissue contrast. Here, we demonstrate the application of a novel organic PAT contrast agent based on polypyrrole nanoparticles (PPy NPs). Monodisperse PPy NPs are ∼46 nm in diameter with strong absorption in the near-infrared (NIR) range, which allowed visualization of PPy NP-containing agar gel embedded in chicken breast muscle at a depth of ∼4.3 cm. Compared with PAT images based on the intrinsic optical contrast in mice, the PAT images acquired within 1 h after intravenous administration of PPy NPs showed the brain vasculature with greater clarity than hemoglobin in blood. Preliminary results showed no acute toxicity to the vital organs (heart, liver, spleen, lungs and kidneys) in mice following a single imaging dose of PPy NPs. Our results indicate that PPy NPs are promising contrast agents for PAT with good biocompatibility, high spatial resolution and enhanced sensitivity.

This review focus on the recent developments in inorganic nanomaterials for tumor SDT.

Novel “soft” microbubbles have been fabricated to show outstanding ultrasound imaging capability, and triggered CuS nanoparticles delivery through ultrasound-targeted microbubble destruction for efficient photothermal ablation of cancer cells.

Triple-negative breast cancer (TNBC), which is a kind of aggressive breast cancer, has a much higher recurrence rate and a shorter overall survival rate than other breast cancer subtypes owing to its lack of expression of the progesterone receptor (PR), estrogen receptor (ER) and HER2. For improving the therapeutic efficacy of TNBC, we developed a new kind of multifunctional cationic porphyrin-grafted lipid (CPGL) microbubble loaded with HIF 1α siRNA (siHIF@CpMB). Owing to the amphiphilic structure of CPGL, it can be self-assembled into microbubbles (MBs) with conventional lipids and the porphyrin group could be used as a photosensitizer for photodynamic therapy (PDT), while the amino group could adsorb HIF 1α siRNA (siHIF) through electrostatic adsorption. Such MBs possess a remarkably high drug loading content and less premature drug release. Distribution of MBs could be easily monitored by real-time US imaging (3–12 MHz). Furthermore, with the assistance of ultrasound targeted microbubble destruction (UTMD), siHIF@CpMBs could be efficiently converted into nanoparticles in situ, facilitating the accumulation of porphyrin and siRNA at the tumor site through the cavitation effect. HIF 1α siRNA down-regulated the HIF 1α level, which was induced by the common hypoxic tumor environment or the ROS (generated by PDT), enhanced the PDT efficacy and partly inhibited the tumor progression. Therefore, UTMD assisted combination of PDT and gene therapy was believed to be an effective therapeutic strategy for TNBC.