A Dual Response DNA Probe for Simultaneously Monitoring Enzymatic Activity and Environmental pH by Nanopores.

Both protease overexpression and local pH in tumor environment are key signatures of cancer. However, sensitive detection of protease activities and accurate measurement of pH in a tumor environment remain challenging. Here, we develop a dual response DNA probe that can simultaneously monitor protease activities and measure the local pH by translocation through α-hemolysin (αHL). The DNA probe bears a short peptide containing phenylalanine (F) at a pre-designed position. Enzymatic cleavage of the peptide either exposes or removes N-terminal F which could form complexes with cucurbit[7]uril. Translocation of the DNA hybrid through αHL generates current signatures that can be used for quantifying protease activities. Furthermore, the current signatures possess pH-dependent pattern which can precisely reflect the local pH. Our results demonstrate that the versatile DNA probe may be further explored for simultaneously measuring multiple parameters of a complex system such as single cells in the future.