## 1 Introduction  
Recently, skin cancer incidence is rising due to the increase in UV exposure. Skin cancer is largely divided into three types such as basal cell carcinoma, squamous cell carcinoma and malignant melanoma. Among them, malignant melanoma, which is known to be the most dangerous, is caused by malignant changes in melanocytes in the skin or mucous membrane. Over time, melanoma metastases to surrounding tissues through lymphatic vessels or blood vessels, and the probability of recurrence is high even if treated with the excision of the affected area. Treatment through excision causes bleeding in the affected area and surrounding tissues, and there is a risk of secondary infection in the incision [1; 2; 3; 4]. To overcome this, photothermal therapy is drawing attention as an alternative treatment to conventional surgical methods [5; 6]. Photothermal therapy is a treatment technique that kills tumor tissue through heat using the photothermal effect. Being non-invasive, it has the advantage of less risk of secondary infection and faster recovery after treatment compared to conventional surgical methods [7; 8]. However, photothermal therapy has the limitation that penetration depth of the optical excitation radiation required for sub-tissue heat generation is relatively short (up to about 5 mm) due to light absorption and scattering of biological tissues [9]. Photothermal therapy uses the heat energy generated through various methods such as microwave, electromagnetic pulse, and so on. Among them, the lasers in the near-infrared spectral range are widely used because of their ease in controlling the heating intensity and heating range [10; 11; 12]. However, in general tissues, as shown in Figure 1, light absorption occurs less in the near-infrared range than in the visible range. Therefore, by injecting a light absorption enhancer into the tumor tissue, the light absorption coefficient is increased only in the tumor tissues, thereby causing the death of the tumor cells due to temperature elevation [13]. Among various light absorption enhancers, gold nanoparticles (GNPs) are widely used because of their harmlessness to the human body and their facile synthesis and surface modification, as well as their strongly enhanced and tunable optical properties [14; 15; 16; 17]. Depending on the temperature, various types of cell death exist in tissues including cancer cells [19; 20; 21]. If a cancer cell death happens in the form of necrosis, there is a possibility of cancer recurrence and metastasis by affecting surrounding tissues; thus, inducing cancer cell deaths by apoptosis is critical. Generally, a cell undergoes necrosis if the temperature of the cell is higher than 50 \({}^{\circ}\)C and apoptosis if it is between 43 and 50 \({}^{\circ}\)C [19; 20; 21]. In photothermal therapy, when the intensity of laser irradiation on the tissue increases and the amount of GNPs in tumor tissues increases, this leads to the excessive temperature rise of tumor tissues, thereby causing thermal damage to surrounding tissues and necrosis of the tumor tissue. Conversely, when the intensity of laser irradiation on the tumor is too low or the amount of GNPs input into tumor cells is too little, temperature elevation in tumor cells is not sufficient, thereby causing incomplete removal of tumor cells. Therefore, in photothermal therapy, it is critical to maintain the therapeutic temperature range in which apoptosis incurs but does not cause excessive heating and damage to the surrounding tissues [22]. Based on these conditions, various studies on photothermal therapy are being conducted. [PERSON] et al. [23] studied LiposAu nanoparticles, which can kill cancer cells by photothermal therapy. Through in situ experiments performed on small animals, they confirmed that hepatocytes were degraded, and particles were removed through the hepatobiliary and kidney pathways. Additionally, a 750 nm wavelength NIR laser was used to completely remove the tumor implanted in the mouse, thereby confirming the possibility of photothermal therapy.