Contribution of potassium ion and split modes of G-quadruplex to the sensitivity and selectivity of label-free sensor toward DNA detection using fluorescence

► Three split probe designs of G-quadruplex using fluorescence were studied. ► Potassium ion is critical in the stability of hybrids of split probes and target DNA. ► The stability of hybrid decides the sensitivity and selectivity of each design. ► Symmetrically split G-quadruplex is more favorable for single mismatch discrimination.