Photothermal therapy (PTT) is a promising biomedical strategy for combating cancer, thanks to its non-invasive nature and exceptional targeting and precision capabilities [1]. AuNPs are commonly used in PTT as therapeutic agents, due to their unique properties, notably their high photothermal potency and small size, which favor targeted penetration into cancer cells [2]. Advances in AuNP synthesis methods enable their structure, shape and size to be tailored to the desired photothermal effect [3]. AuNPs feature a special surface plasmon resonance (SPR) phenomenon [4] that enhances their absorption properties and enables them to generate heat when irradiated at a specific wavelength. Furthermore, their excellent biocompatibility and ease of conjugation with other biomedical entities via gold-thiol bioconjugation chemistry opens up the possibility of their use as high-safety therapeutic mediators [5,6]. Thanks to recent advances in nanomaterial synthesis and fabrication methods, a diverse range of AuNP forms can be created, including nanorods, nanoshells, nanospheres, nanocages and nanostars [7]. All these forms offer SPR and enhanced radioactive properties. In addition, gold can be combined in core/shell nanostructures with other inorganic or organic materials such as silica/gold, iron oxide/gold [8]. These various AuNPs morphologies possess unique characteristics that could be exploited for different photothermal therapy approaches in the treatment of cancer. A number of therapeutic approaches have been identified that make use of AuNPs, such as cancer drug delivery, molecular diagnostics for pathology detection, and nanoscale immunotherapy. These fields offer significant potential for future clinical applications [9]. Recent advances in nanoparticle research have enhanced our comprehension of how to create novel targeted therapies and systemic cancer treatments, and have also facilitated the discovery of new oncogenic targets [10]. Consequently, multiple nanoparticles have been assessed for their potential in precise drug delivery, aiming to enhance effectiveness while mitigating unwanted side effects [11,12]. To maximize their effectiveness, the majority of these therapeutic agents must either accumulate within cells or target specific cellular organelles to exert their effects. In this context, it is crucial that the AuNPs can efficiently reach their intended intracellular destinations upon cell entry to successfully carry out their intended tasks. As our knowledge of cellular uptake mechanisms and the intracellular pathway of AuNPs deepens, approaches have been developed to direct the delivery of these AuNPs to specific subcellular locations [13,14]. In this context, multiple investigations have emphasized the use of diverse ligands affixed to nanoparticles for targeting the surfaces of cancer cells. These studies have additionally scrutinized what happens to these nanoparticles after they've fulfilled their functions, with a specific focus on the fundamental mechanisms governing their movement and transfer during the internalization process. Furthermore, as research advances, a few reports have delved into specific ligands that possess the capability to target distinct cellular organelles and understand their precise action pathways [15,16]. Overall, larger particles (>1μm) are generally capable of being taken up by cells via a process of micropinocytosis. In contrast, nanoparticles are more frequently internalized via endocytosis, a dynamic, efficient and carefully regulated internalization pathway for various nanoparticle types and sizes [17]. In the majority of situations, once they have interacted with specific organelles and performed their predefined functions, such as the release of therapeutic agents or the generation of photothermal heat, AuNPs have the capacity to be taken up by the lymphatic system and, subsequently, to be eliminated after circulating for some time in the surrounding physiological milieu [18]. A thorough understanding of the mechanisms of cell death in PTT is crucial to improving treatment efficacy and minimizing undesirable side effects. apoptosis and necrosis are the two fundamental mechanisms leading to cell death. Apoptosis is a complex and highly regulated mechanism that helps eliminate damaged or unwanted cells, including cancer cells. This mechanism is based on the rupture of the cytoplasmic membrane and the delivery of physiological or pathological stimuli to the cell [19]. In contrast, necrosis is the premature and unscheduled death of one or more cancer cells. Necrosis occurs when the cell undergoes structural or chemical stress from which it cannot recover: ischemia (lack of oxygen), extreme temperature, physical trauma [20]. Unlike chemotherapy, which can only induce necrosis in cancer cells, PTT treatments based on AuNPs can engage both mechanisms [21,22]. Studies have shown that the initiation of both mechanisms depends on factors such as AuNPs localization, irradiation duration and laser intensity [23]. When passively targeted by AuNPs, the majority tends to concentrate in the extracellular matrix rather than crossing the cell membrane or nucleus. In this case, most nanoparticles generate heat through PTT outside the cell, leading to an increase in the temperature of the cellular environment, rather than generating heat inside the cell. On the other hand, active targeting causes AuNPs to enter into cell organelles after receptor-mediated endocytosis, resulting in sub-cellular heating inside target cells. In short, heating cell organelles is likely to trigger cell death mechanisms more effectively than extracellular heating. It should be noted that, regardless of the type of targeting, the PTT process by AuNPs originates from the surface plasmon resonance (SPR). This phenomenon is highly dependent on the shape, size, and nature of the surrounding medium, meaning the location of the AuNPs in the cell tissue. Consequently, the amount of heat generated by resonating AuNPs is dependent on the specific location within the cell where they are localized. For this reason, it is crucial to study the thermoplasmonic properties of AuNPs when embedded in different cellular organelles. In this perspective, numerical simulation is proving to be a valuable tool for understanding the optical behavior of AuNPs embedded in biological tissues, as well as for the design of medical devices interacting with the human body. However, to ensure that numerical simulations accurately reflect the actual interaction between AuNPs and light within biological cells, accurate modeling of the optical properties of subcellular elements and the behavior of metal nanoparticles is essential. The association of AuNPs with biological tissues can be considered as a physical nanocomposite system composed of a matrix and inclusions. Namely, Nanocomposites are materials composed of nanoparticles dispersed in a matrix, and their optical properties depend on factors such as size, shape, concentration and properties of the individual components. Modeling the optical properties of nanocomposites calls on various numerical methods to predict their behavior and characteristics. These include: (i) The Finite Element Method (FEM) [[24], [25], [26]], which is based on the discretization of the finite element domain to solve Maxwell's equations. This method is useful for modeling light-matter interactions in complex structures. (ii) The Finite Difference Method (FDM) [27] in which the differential equations of electromagnetic fields are discretized in finite differences. This makes it possible to simulate light propagation in nanostructures. (iii) Transfer matrix methods [28], which are used to model light propagation through thin films and multilayer structures. They are useful for nanocomposites with well-defined interfaces. Monte Carlo methods are stochastic methods that simulate the path of individual photons through a material. They are often used to model light scattering in turbid or disordered materials [29]. In this study, we used the FEM to examine the optical and thermoplasmonic characteristics of spherical gold nanoparticles (SAuNPs) and hollow gold nanoparticles (HAuNPs) incorporated into various subcellular structures. Following the internalization process, AuNPs of various shapes can localize in different subcellular entities such as the lysosome, cell membrane, mitochondria, nucleus and cytoplasm, or be trapped outside the cell by placing themselves in the extracellular fluid. The optical properties of the nanocomposite made up of AuNPs embedded in cell matrices are determined from the effective dielectric permittivity, a complex quantity denoted εeff=εeff′+iεeff″. First, the real εeff′ and imaginary εeff″ parts of the effective permittivity are obtained from the electric potential distribution. Next, the absorption cross sections of AuNPs and the enhanced electric field in the vicinity of AuNPs embedded in different subcellular structures are calculated and compared. Once the absorption of AuNPs is determined at surface plasmon resonance (SPR), these nanostructures are considered as nanoscale heat sources, capable of heating the subcellular sites where they are localized. We have studied in detail the thermoplasmonic properties of these nanoparticles, in particular by calculating the thermal power generated and the temperature distribution around the plasmonic structures at SPR. We have also discussed the effect of cavity size in HAuNPs on their thermoplasmonic properties. The rest of this paper is structured as follows: The second section deals with the physical system modeling the AuNPs/biological medium composite and the calculation numerical method. In the third section, we present the various simulation results obtained and discuss the optical and thermoplasmonic effects of SGNPs and HGNPs embedded in different cellular organelles structures. The final section is devoted to conclusions and concluding remarks.