An aptasensor for detection of potassium ions based on RecJf exonuclease mediated signal amplification

Abstract

An electrochemical biosensor for potassium has been developed combining specific potassium–aptamer binding and RecJ_f exonuclease mediated signal amplification. Generally, the DNA probe with a stem-loop structure containing an anti-K⁺ aptamer sequence is designed and modified on a gold electrode. K⁺ can specifically bind to the aptamer and a G-quadruplex structure forms, which breaks the original stem-loop structure. The induced single-stranded 5′ end can be further digested by RecJ_f exonuclease, releasing K⁺ which can bind to another DNA probe on the electrode. After cycles of RecJ_f exonuclease cleavage initiated by K⁺, the electrochemical signal intensity is significantly decreased, and can be used to determine the concentration of K⁺. This aptasensor shows high sensitivity, selectivity as well as excellent stability and accuracy, which provides possibilities for further applications of K⁺ assay in clinical diagnosis.