Sensitive and accurate analysis of low‐concentration of tumor‐derived exosomes (Exos) in biofluids is essential for noninvasive cancer diagnosis but is still challenging due to the lack of high‐sensitive methods with low‐cost and easy‐operation. Herein, exploiting target Exos as a three‐dimensional (3D) track for the first time, we developed a self‐serviced‐track DNA walker (STDW) for wash‐free detection of tumor Exos using exosomal glycoprotein, which was enabled by split aptamer‐recognition‐initiated autonomous running powered by a catalytic hairpin assembly (CHA). Benefiting from high selectivity and sensitivity of the STDW assay, direct detection of tumor Exos in cell culture medium and serum could also be realized. Furthermore, this method exhibited high accuracy in clinical sample analysis, offering the potential for early cancer diagnosis and postoperative response prediction.

Sensitive and accurate analysis of low‐concentration of tumor‐derived exosomes (Exos) in biofluids is essential for noninvasive cancer diagnosis but is still challenging due to the lack of high‐sensitive methods with low‐cost and easy‐operation. Herein, exploiting target Exos as a three‐dimensional (3D) track for the first time, we developed a self‐serviced‐track DNA walker (STDW) for wash‐free detection of tumor Exos using exosomal glycoprotein, which was enabled by split aptamer‐recognition‐initiated autonomous running powered by a catalytic hairpin assembly (CHA). Benefiting from high selectivity and sensitivity of the STDW assay, direct detection of tumor Exos in cell culture medium and serum could also be realized. Furthermore, this method exhibited high accuracy in clinical sample analysis, offering the potential for early cancer diagnosis and postoperative response prediction.

Apurinic/apyrimidinic endonuclease 1 (APE1), also known as redox factor-1 (Ref-1), is a multifunctional protein which is widely existing in living organisms. It can specifically recognize and cleave the DNA in apurinic/apyrimidinic (AP) site in the base excision repair (BER) pathway, as well as regulate the expression of genes to activate some transcription factors. The abnormal ex-pression and disruptions in the biological functions of APE1 are linked to a number of diseases, including inflammation, immunodeficiency, and cancer. Hence, it is extremely desired to monitor the activity of APE1, acquiring a thorough understanding of the healing process of damaged DNA and making clinical diagnoses. Thanks to the advent of DNA nanotechnology, some nanodevices are used to image the activity of APE1 with great sensitivity and simplicity. In this review, we will summarize DNA nanotechnology-empowered fluorescence imaging in the past years for APE1 activity according to the types of DNA probe, which are classified into linear DNA probes, composite DNA nanomaterials and three-dimensional (3D) DNA nanostructures. We also highlight the future research directions in the field of APE1 activity imaging.