Talanta. 2026 Feb 28;305:129602. doi: 10.1016/j.talanta.2026.129602. Online ahead of print.

ABSTRACT

While the precise identification of cancer cells holds significant importance for early diagnosis, prediction of prognosis in patients and evaluating the risk of recurrence after surgery, the intracellular imaging of low abundance of miRNA biomarkers is essential for recognizing tumor cells but remains highly challenging due to the limitation of ‘one-to-one’ signal transduction mechanism and fragility of sensing probes (especially a multiple-components-based probe) in complex biological environments. Herein, we demonstrate AHP-AuNP nanoprobe (essentially spherical nucleic acid, SNA) for the sensitive amplification imaging of intracellular miRNA-21 biomarker, where a gold nanoparticle (AuNP) surrounded by a layer of DNA AHPs capable of identifying target miRNA-21 with the apurinic/apyrimidinic (AP) site available for the cleavage by endonuclease APE1. The cancer-related miRNA-21 can specifically open the loop-stem structure of AHP-AuNP nanoprobe and trigger the ERDN amplification reaction, during which endogenous enzyme (E), target recycle (R), scissile AP site-contained DNA probe (D), and gold nanoparticle substrate (N) are integrated into an assay system, finally leading to the unarming of SNA in a divide-and-conquer pattern and generating a sensitive fluorescence signal. Even if only one DNA strand is involved in the signaling process, miRNA-21 can be detected down to 27.1 pM, achieving a 90 times improved limit of detection. Moreover, no obvious interference from exogenous enzymes and miRNA family members, and even a single-base mismatch can be easily sensed. Additionally, without the requirement of transfection agents, AHP-AuNP nanoprobe can enter living cells and accomplish the sensitive fluorescence imaging of intracellular miRNA-21, enabling the identification of cancerous cells from healthy cells. AHP-AuNP nanoprobe is expected to become a powerful diagnostic tool for specifically screening tumor cells in patients and holds exceptional promise for the early diagnosis of cancers, prediction of surgical tumor recurrence, and evaluation of metastasis.

PMID:41764800 | DOI:10.1016/j.talanta.2026.129602