¹Department of Analytical Chemistry, Faculty of Pharmacy, Ankara University, 06560 Ankara, Turkey DOI : 10.29228/jrp.167 An overdose of an anticancer agent in the human body not only leads the high cytotoxicity on the neoplastic cells but also causes serious side effects. The regular detection of an anticancer agent level in biological fluids using an alternative technique is crucial in terms of assessment of therapeutic efficiency in chemotherapy process. In this work, we developed a micelle-enhanced spectrofluorimetric approach for the determination of topotecan (TPC), which is an effective anticancer agent used in the treatment of certain types of cancer, in human serum and binding mechanism of TPC-DNA. The proposed method exhibited a strong pH-dependent emission signal at 535 nm after excitation of 380 nm towards the TPC in the presence of surfactants. The relative fluorescence signal for TPC was found to be linear in the wide concentration range of 0.01 – 1.8 μM (R2 = 0.9981) with a challenging detection limit of 3.3 nM. The developed spectrofluorimetric method was successfully applied to the analysis of TPC in spiked human serum samples with the good recovery results. Moreover, for the first time, the interaction mechanism between TPC and double-stranded DNA (ds-DNA) was studied by developed spectrofluorimetric method. The binding constant value of 8.5 x 10-3 M-1 calculated by Stern-Volmer method indicated the strong intercalation-based binding of TPC into the base pair of ds-DNA. The developed spectrofluorimetric method can provide new insight for the design of DNA-targeted drugs, and lead an alternative approach for the detection of anticancer drugs such as TPC in biological samples. Keywords : Spectrofluorimetry; Drug–DNA interaction; Fluorescence; Intercalation; Determination