The unique size- and shape-dependent optical and thermal properties of gold nanoparticles (AuNPs), as well as versatility of their functionalization and targeting, make them valuable tools in a variety of scientific and technological fields for a wide range of applications, including diagnostics, drug delivery, imaging, sensors development, and synthesis of organic compounds [1-3].

Among AuNPs, gold nanorods (AuNRs) are in high demand due to the tunability and sensitivity of their longitudinal surface plasmon resonance [4, 5]. The anisotropic AuNRs structure displays two surface plasmon bands, corresponding to surface electron oscillation on transverse and longitudinal sides [6]. Typically, a two-step synthesis process using surfactants and seed particles, where gold seeds are prepared and then added to the growth solution, is used. Researchers continue to explore new applications for these nanomaterials, making them an active area of research and development [7].

The main aim of this study was to synthesize AuNRs of different lengths using different methods. The obtained AuNRs were characterized using the techniques SEM, DLS, and UV-VIS. These techniques allowed a detailed study of the structural and optical properties of the AuNRs and provided valuable insight into the synthesis. The characterization results were crucial to guide the synthesis and to further understand the potential applications of AuNRs.