Molecular beacon-based DNA tetrahedrons for APE 1 activity detection in living cells

Human apurine/apyrimidine endonuclease (APE) is a multifunctional enzyme that affects the occurrence and development of cancer through DNA repair and redox regulation. It has been identified as a tumor marker for detection and prognosis and drug target due to its overexpression in a variety of cancers. However, the accurate detection of APE 1 activity is still a huge challenge. Traditional approaches exist some disadvantages, including low sensitivity, complex operation and professional equipment requirements. Therefore, it is necessary to develop a fast, sensitive and simple biosensor to detect APE 1 activity in vivo and in vitro. In this report, a new tetrahedral molecular beacon (TMB) probe is designed for the detection of APE 1 activity. This probe not only has the advantage that the tetrahedron can enter the cells without a transfection agent, but also has the advantages of simple operation and low cost. The extracellular detection limit of TMB is as low as 0.0026 U/mL, and this program has successfully achieved APE 1 intracellular imaging to distinguish cancer cells overexpressing APE 1 from normal cells. In addition, the probe which is an effective mean for screening APE 1 inhibitor can also monitor the response of APE 1 to different drugs. All in all, our probe can be successfully applied to detect APE 1 activity in vivo and vitro, and can achieve living cells drug screening. And this probe also provides a general method for the detection of other endogenous biological targets in living cells.