Thiolated chitosans (Chit-SH) are biopolymers derived from chitin, found in the exoskeletons of crustaceans, insect cuticles, and algae. These polymers are modified by coupling thiol-functional reagents to their primary amino groups. Chit-SH offers a broad range of beneficial properties for biomedical applications, including biocompatibility, mucoadhesion, and wound healing. Additionally, Chit-SH can be integrated into nanosystems for the selective detection and treatment of tumors. This study focuses on large-scale synthesis of Chit-SH and its application as a capping agent for gold nanorods (GNRs), an optically active class of nanomaterials absorbing light in the so-called “biologicl window”. The system was further functionalized with an anti-integrin α5β1 aptamer, capable of selectively targeting bladder cancer cells smaller than 1 mm. The resulting chitosan-coated gold nanorods functionalized with the aptamer (GNRs@Chit-Apt) were synthesized and characterized. Critical process parameters influencing the synthesis were analyzed, including the degree of functionalization, the amount of Chit-SH used for capping, and the removal of cytotoxic CTAB from the GNRs. Additionally, the scalability and purification methods were optimized for large-scale production. The theranostic potential of GNRs@Chit-Apt was evaluated in preclinical trials, demonstrating its efficacy in targeting bladder cancer cells. These findings highlight the potential of Chit-SH as a versatile material for developing theranostic nanomaterials with applications in cancer detection and therapy .