Colorimetric Aptasensor Based on Fe3O4–Cu2+ Nanozyme with Intrinsic Peroxidase-Like Activity in the Detection of Breast Cancer Exosomes

Because breast cancer cells such as MCF-7, exhibit vital and developmental signs by exosome secretion, diagnosing them in the blood can provide a good index of the presence of breast cancer. However, accurate and inexpensive detection of exosomes in clinical practice faces challenges. Therefore, in the presents study, an aptasensor based on CD63 aptameriron oxide-copper ion nanozymes (Fe₃O₄-Cu2+-NZs) was designed with the ability of the CD63 aptamer to interact with the exosome and the release of the Fe₃O₄-Cu2+-NZs for peroxidase-like activity on the tetramethylbenzidine (TMB). After fabrication of CD63 aptamer-Fe₃O₄-Cu2+-NZs based on hydrothermal method, their physicochemical properties were investigated with the SEM, TEM, DLS, Zeta, XRD and magnetization. To investigate the interaction of CD63 aptamer-Fe₃O₄-Cu2+-NZs with exosomes, the required exosomes were extracted from cultured MCF-7 cells. The performance of CD63 aptamer-Fe₃O₄-Cu2+-NZs on TMB degradation in the presence and absence of exosomes was investigated through UV-vis adsorption and ocular observations based on colour changes on laboratory and real samples. The results show that the absence of exosomes significantly inhibited the peroxidase-like activity of CD63 aptamer-Fe₃O₄-Cu2+-NZs due to the aptamer coating. Under optimal conditions, the designed CD63 aptamer-Fe₃O₄-Cu2+-NZs is capable of detecting exosomes in the range of 1.4 × 10⁴-5.6 × 105 particles/μL with a detection limit of 5.91 × 10³ particles/μL. Also, this method showed a satisfactory outcome in detection of cancer cells in real samples. Overall, this colorimetric aptasensor can be used to diagnose breast cancer cells based on a simple and inexpensive approach.