Cancer ranks among the top causes of illness and death globally. Nanotechnology holds considerable promise for enhancing the effectiveness of therapeutic and diagnostic approaches in cancer treatment. Our study presents a promising strategy for applying thiocompound nanomedicine in cancer therapy. Our first study aimed to investigate the biological properties of a new compound thiodiosgenin (TDG)-a new derivative of diosgenin-a natural compound with known antioxidant and anticancer properties. Our current second study aimed to compare the therapeutic efficacy of a new diosgenin-functionalized gold nanoparticles-with its precursor on prostate cancer (DU-145) cell lines. Moreover, the safety of the new thio-derivative and new conjugates was tested against the human epithelial line PNT-2. New advanced analytical techniques were developed for the characterization of nanomaterials using methods such as SP-ICP-MS, UV-Vis, TEM, NMR, FT-IR ELS, and TGA. Our synthetic approach was based, on the one hand, on the ligand exchange of citrates to thiodiosgenin (TDG) on gold nanoparticles, and on the other hand, on the attachment of DG through an ester bond to the linker, which was 3-mercaptopropionic acid (MPA) on gold nanoparticles. Initial in vitro studies indicate that TDG shows greater cytotoxic effects on cancer cells but poses risks to normal prostate epithelial cells (PNT-2). It was demonstrated that all the conjugates produced exhibited significant cytotoxic effects against cancer cells while being less harmful to normal prostate epithelial cells (PNT-2) compared to TDG itself. All the obtained conjugates showed antitumor properties; however, for targeted transport, the system referred to as AuNPs-MPAm1-DG is promising, due to the size of the nanoparticles of 53 nm, zeta potential of -30 mV, and loading content of 27.6%. New methods for synthesizing conjugates with diosgenin were developed and optimized for medical applications. Advanced new analytical methodologies were developed to characterize new conjugates, particularly the use of SP-ICP-MS, to solve existing differences in the shape and morphology of the surface of new conjugates.