## 3 Results
### Multifunctional Nanoparticles for Therapy and Imaging
#### 3.1.1 Nanoparticle Drug Carriers
These nanostructured systems are formed through the spontaneous self-assembly of amphiphilic polymers in aqueous environments, resulting in a hydrophobic core capable of encapsulating lipophilic drugs and a hydrophilic shell that provides colloidal stability and prolonged blood circulation time. Their ability to co-encapsulate multiple therapeutic agents within a single carrier offers the potential for synergistic therapeutic effects, which is particularly valuable in oncological treatments. Moreover, polymeric micelles--especially those based on prodrug strategies--are considered a promising platform for combination drug delivery, offering enhanced anticancer efficacy and reduced systemic toxicity [22]. Polymeric micellar drug delivery technology is actively studied as a promising nanocarrier for multi-drug delivery. * Carbon Nanotubes  
Carbon nanotubes (CNTs) are notable for their unique characteristics that distinguish them from other potential drug carriers. They consist of cylindrical tubes formed by rolled graphene sheets, made entirely of carbon, featuring high aspect ratios in both length and width. Depending on the number of concentric walls, CNTs exhibit exceptional mechanical strength, high electrical conductivity, and remarkable chemical stability. Based on their layered structure and diameter, researchers classify CNTs into three types: single-walled nanotubes (SWCNTs), double-walled nanotubes (DWCNTs), and multi-walled nanotubes (MWCNTs) [23]. Due to their distinct chemical composition, shape, ultra-small size, and targeting capabilities, carbon nanotubes can function effectively at the biomolecular level. They can carry various therapeutic agents, enabling site-specific delivery and prolonged accumulation in targeted tumor tissues, thereby reducing potential systemic toxicities. However, the toxicity of CNTs remains a concern, as factors such as concentration, size, degree of functionalization, and the presence of catalytic residues can influence it. Recent studies indicate that CNTs can induce oxidative stress or exhibit asbestos-like behavior under certain conditions. Therefore, researchers need to conduct further studies to fully assess their biocompatibility and safety profiles [24]. * Gold Nanoparticles  
Gold nanoparticles (AuNPs) have been widely utilized in both therapeutic applications and diagnostics. Due to their small size, they have a large surface-area-to-volume ratio, which gives them unique physicochemical and optoelectronic properties, including controllable sizes below 100 nm, high chemical stability, strong absorption in the near-infrared (NIR) spectrum, and the presence of localized surface plasmons. These features make them excellent candidates for drug delivery and cancer therapy [25]. Technological advances have allowed scientists to synthesize AuNPs in various shapes and sizes--spheres, rods, nanocages, and nanocavities. Surface functionalization with ligands such as polyethylene glycol (PEG), peptides, nucleic acids, or antibodies enhancestheir biocompatibility and cellular specificity, while simultaneously reducing phagocytosis and degradation during systemic circulation. Their favorable interaction with biological systems, combined with the ease of tailoring their surfaces and targeting therapeutic agents to specific sites, positions them as valuable platforms for precise and controlled cancer drug delivery [26]. Although AuNPs are generally considered biocompatible, their unmodified forms may accumulate in reticuloendothelial organs such as the liver and spleen. This raises concerns regarding potential toxicity, particularly with repeated administrations. Consequently, further studies are warranted to comprehensively validate their safety profile [27].