Label-free detection of T4 DNA ligase and polynucleotide kinase activity based on toehold-mediated strand displacement and split G-quadruplex probes

Herein, an efficient pair of split G-quadruplex probes was selected (S/N = 21) to construct a simple, rapid and label-free technique for the detections of T4 DNA ligase and PNK activity. DNA ligase and PNK are engaged in DNA replication and repair, ensuring the genetic stability. The detections of T4 ligase and PNK activity are of great significance in biology and biomedicine. Split G-quadruplex probes are robust label-free biosensing tools with turn-on signal readout. The selected pair of split G-quadruplex probes combined with toehold-mediated strand displacement in this work demonstrated an efficient strategy for monitoring the activities of T4 DNA ligase and PNK with good sensitivity.