Characteristics of temperature changes in photothermal therapy induced by combined application of indocyanine green and laser

Abstract

Photothermal therapy, a type of laser application, has the ability to eradicate tumor cells by a local thermal effect and elicit a tumor specific immune response. Indocyanine green (ICG), a photosensitizer, can effectively elevate the local temperature by absorbing energy from the laser. The present study aimed to investigate the characteristics of temperature changes during photothermal therapy with an infrared thermometer in an ICG solution and in tumor-bearing mice treated with a combination of laser and ICG. Additionally, the present study observed the morphological changes of tumor tissue by hematoxylin-eosin staining following photothermal therapy. In the solution experiment, when the laser power density was 1 W/cm 2 and the concentration of ICG was 0 or 0.0187 mg/ml, the temperature of the water was elevated by 3 and 28˚C, respectively. In the tumor-bearing mice experiment, when the laser power density was 1 W/cm 2 and the concentration of ICG was 0 and 0.1 mg/ml, the temperature of the tumor-bearing mice was elevated by 6.9 and 28.5˚C, respectively. With an increase in laser power density, including 0.6, 0.8 and 1.0 W/cm 2 , the temperature was 23.3, 26.7 and 28.5˚C, respectively. Pathological tissue sections demonstrated that a large number of tumor cells experienced necrosis, and the envelope of the tumor was destroyed. Numerous inflammatory cells, in particular lymphocytes, infiltrated into the tumor tissue following tumor tissue treatment with a combination of laser and ICG. These results indicated that a combination treatment with laser and ICG may significantly increase the temperature of the water solutions and in the tumor-bearing mice. The concentration of ICG and laser power density contributed to the temperature elevation, in particular to the concentration of ICG.

Development of hyperthermia measurable fiber radiometric thermometer for thermotherapy

“…We have demonstrated that the hmFRT can detect BBR emitted from a tissue at temperatures down to 35°C using a 2 m silica fiber as the transmission media. After calibration, the hmFRT can accurately track tissue temperature change at a rate of 10°C/minute, which is a response time comparable to other studies for hyperthermia treatment . Such sensitivity and tracking ability show that hmFRT is promising for detecting two important hyperthermia temperature ranges, 40 to 45°C and 50 to 80°C, during thermotherapy.…”

Novel Multifunctional Nanoagent for Visual Chemo/Photothermal Therapy of Metastatic Lymph Nodes via Lymphatic Delivery

“…However, the maximum temperatures were not the same, and according to the concentration from high to low, the temperatures were 45.0, 42.8, 39.0, 36.8 °C (Figure b 1 ). Many studies have confirmed that the key to hyperthermia is temperature control, and 40–45 °C is the proper temperature for killing tumors, while the normal tissues are not or minimally damaged . In this study, the two higher-concentration groups (15 and 20 mg/mL) quickly obtained the required temperature after laser irradiation.…”

Valproic Acid Thermally Destabilizes and Inhibits SpyCas9 Activity

“…After irradiation with a near-infrared (NIR) laser, ICG can complete photothermal energy transfer to readily increase the local environmental temperature to above 10 C within minutes. 24,25 In this case, the degradation of SpyCas9 was achieved by co-incubating VPA with ICG after NIR irradiation for 180 s, while the reduction could not be confirmed at a single treatment with other VPA or ICG (Figure 3A; Figure S3A). Interestingly, warming with an external heat bag resulted in a mild reduction of SpyCas9 (Figure 3B; Figure S3B).…”