In situ growth of tendril-like Ni-NCNTs on carbon fabric for ultrasensitive determination of breast cancer exosomal miRNA-135a

MicroRNA-135a (miRNA-135a) is a crucial biomarker for the early diagnosis of breast cancer (BC), the leading malignancy among women. However, its sensitive and efficient detection remains challenging due to the time-consuming nature of conventional techniques and the extremely low abundance of miRNA-135a in biological samples. In this work, we developed an ultrasensitive electrochemical aptasensor based on nickel‑embedded nitrogen‑doped carbon nanotubes (Ni‑NCNTs) wrapped carbon fiber (CF) for the rapid detection of miRNA‑135a within only 15 min. The tendril‑like Ni‑NCNTs were grown in situ and uniformly around the CF surface via a Ni 2 + ‑induced controlled chemical vapor deposition process, serving as an effective nanoscale signal amplifier. This unique hierarchical architecture exhibits excellent electrocatalytic activity, rapid electron‑transfer capability, and abundant active sites for immobilizing capture DNA (cDNA), thereby enhancing the recognition and signal response to reverse‑transcribed DNA (rtDNA) corresponding to miRNA‑135a. Under optimized conditions, the aptasensor achieved an ultralow detection limit of 3.24 aM (3.24 ×10 −9 nM) with high reliability, excellent selectivity, and efficient performance in real‑sample analysis. The CF@Ni‑NCNTs based aptasensor demonstrates considerable potential to facilitate rapid, ultrasensitive early detection screening and warning of various cancers, offering a powerful analytical platform to support clinical diagnostics in diverse scenarios.