Proximity recognition and polymerase-powered DNA walker for one-step and amplified electrochemical protein analysis

The development of simple, flexible, cost-effective and sensitive electrochemical methods for protein analysis is of very importance for its potential application in disease diagnosis and biomedicine research. Herein, a new protein binding-induced proximity recognition and polymerase-powered DNA walker strategy was proposed for one-step and sensitive electrochemical quantification of proteins. Two DNA probes were designed with a hairpin-like one immobilized on the electrode and another one used as a DNA walker strand. The protein binding with the recognition elements labeled on these two probes brought their proximity hybridization, accompanied with the annealing of a redox probe-labeled primer strand on the opened immobilization probe. The DNA polymerization of primer strand in the presence of DNA polymerase induced the release of the DNA walker strand, which then walked to the adjacent immobilization probe for the proximity hybridization and progressive polymerase-powered DNA walker operation again. This induced the electrochemical signal reporting and amplifying toward protein quantification. The sensitive and selective detection toward proteins was achieved with the detection limits toward anti-dig antibody and streptavidin as 80 and 16 pM, respectively. Thus, the current study offers a simple, generic, one-step and amplified detection strategy for electrochemical protein quantification.