In this study, NAC-capped CdTe/CdS/ZnS core/double shell QDs were synthesized in an aqueous medium to investigate their utility in distinguishing normal DNA from mutated DNA extracted from biological samples. Following the interaction between the synthesized QDs with DNA extracted from leukemia cases (represents damaged DNA) and that of healthy donors (represents undamaged DNA), differential fluorescent emission maxima and intensities were observed. It was found that damaged DNA from leukemic cells DNA-QDs conjugates at 585 nm while intact DNA (from healthy subjects) DNA–QDs conjugates at 574 nm. The obtained results from the optical analyses indicate that the prepared QDs could be utilized as probe for detecting disrupted DNA that is associated with a number of diseases including malignancies. Additionally, the manufactured NAC-CdTe core with CdS shell and ZnS shell QDs were further characterized by high-resolution transmission using field emission scanning electron microscopy (FESEM), energy dispersive X-ray fluorescence (EDX), X-ray diffraction (XRD), infrared spectrum (IR), UV-vis absorbance, photoluminescence (PL) and absorbency intensity using the fully automatic ELISA. The XRD results revealed the formation of NAC-CdTe/CdS/ZnS QDs with a grain size of 5.7 nm. While EDX assay emphasizes the compound content of Cd, S, Zn and Te elements. Whereas SEM test’s findings propose the spherical size of NAC- CdTe/CdS/ZnS QDs within the range of 10–40 nm. The demonstrated mono-dispersed lattice structure of NAC-CdTe core with CdS shell and ZnS shell QDs has superior PL emission properties at [Formula: see text] of [Formula: see text]600 nm and UV-Vis absorption bands at 350 nm. Overall, this study suggests that the synthesized QDs could be employed in developing optical biosensors for a variety of biomedical applications to improve early detection of diseases marked by damaged DNA profile including cancers.