Proteases are crucial for multiple processes during tumor initiation and malignant progression. Several types of protease have been used as new biomarkers for early cancer diagnosis and prognosis. Therefore, sensitive detection of protease concentrations and activities would provide valuable information for evaluating malignant progression of tumors and predicting their metastasis. Further to protease overexpression in tumors, the pH value in the tumor microenvironment is another key signature of cancer. However, there are very few literature reports describing simultaneous determination of protease activities and local pH.
Recently, a team led by Professor WU Hai-Chen from Institute of Chemistry, Chinese Academy of Sciences reported a dual-response DNA probe that can be used to simultaneously monitor enzymatic activity and environmental pH using a nanopore sensor. They found that when the substrate peptides containing N-terminal phenylalanine were attached to the 5’-end of a DNA strand through click reaction, the resulted DNA-peptide hybrid could bind with cucurbit[7]uril (CB[7]) to form a host-guest DNA probe (HGDP). Translocation of HGDP through ?HL produces two types of characteristic current signals which could be used to quantify protease activities. The turn-on mode sensing of leucine aminopeptidase (LAP) affords the limit of detection (LOD) as low as 3.1 fM and the turn-off mode sensing of cathepsin B (cat. B) affords the LOD as 7.2 pM. In addition, the current signatures possess a pH-dependent pattern that precisely reflects the local pH.

A dual-response DNA probe for simultaneously monitoring protease activities and measuring environmental pH

The DNA probe developed here incorporates both target recognition function and signal transduction function, which endows the method with extraordinarily high sensitivity. The potential of the DNA probes may be further explored for simultaneously measuring multiple parameters of a complex system, such as a single cell, in the near future.
Their work entitled “A Dual Response DNA Probe for Simultaneously Monitoring Enzymatic Activity and Environmental pH by Nanopores” has been published in Angew. Chem. Int. Ed. 2019, 58, DOI: 10.1002/anie.201907816. 

Contact:
Prof. WU Hai-Chen
Institute of Chemistry, Chinese Academy of Sciences
Email: haichenwu@iccas.ac.cn