Numerical Simulation on Thermal Response of Laser-Irradiated Biological Tissues Embedded with Liquid Metal Nanoparticles

Photothermal therapy is emerging as a very promising way for minimally invasive cancer treatment. To enhance thermal energy deposition of laser in target malignant tissues, liquid metal nanoparticles (LMNPs) have been recently identified as completely unprecedented photothermal sensitizers due to their unique physicochemical properties and superior photothermal conversion rate under near-infrared (NIR) laser irradiation. However, there is currently a strong lack of understanding of the laser energy distribution and the transient temperature field within the biological tissues, which would seriously hinder the development of LMNPs assisted photothermal therapy. Therefore, this paper focused on the distinctive photothermal effect of LMNPs embedded in biological tissues under NIR laser irradiation. The mathematical model coupling the Monte-Carlo photon transport model with Penne's bioheat transfer model has been established. Simulation studies have shown that LMNPs play an important role in enhancing the absorption of NIR laser, which contributes to local temperature rise and improves the temperature distribution. Comparing with the control case without LMNPs, the maximum temperature increases by nearly 1.0 time, the local temperature rise reaches 30 degrees C in 1.0 second. When the diameter and concentration of LMNPs are 40 nm and 10(12)/mm(3), the resulting temperature variation and distribution is best for the effective killing of tumors without damaging normal tissues. In addition, the simulation results are meaningful for guiding the selection of laser irradiation time in conjunction with the cooling time, ensuring the controllable accuracy of treatment. To the best of our knowledge, the present study is one of the first attempts to quantify the influence of transformable LMNPs on the temperature distributions inside the biological tissues, showing important academic significance for guiding LMNPs assisted photothermal treatment.