Rapid, highly-sensitive, and highly-specific nucleic acid detection

A method for detecting a target nucleic acid, comprising:

• providing an on-chip isotachophoresis (ITP) device, which has a first reservoir containing a leading electrolyte (LE), a second reservoir containing a trailing electrolyte (TE), and a microfluidic channel connecting the first and second reservoirs, wherein a region of the microfluidic channel is provided with a sieving matrix for separating double-strand and single-strand nucleic acids, wherein the first or second reservoirs further containing a spacer ion having a mobility between that of the LE and the TE;
• providing a probe which is a double-strand nucleic acid formed of a protector strand nucleic acid modified with an enzyme and a complement strand nucleic acid, wherein the protector strand nucleic acid is released in the presence of the target nucleic acid;
• adding the probe and a sample to the first reservoir;
• applying a voltage between the first and second reservoirs;
• adding a single strand nucleic acid modified with a substrate of the enzyme to the second reservoir or another reservoir located more downstream than the sieving matrix, the substrate being one that is capable of being converted by the enzyme into a luminescent and/or chromogenic form;
• and
• detecting a luminescent and/or chromogenic signal in the microfluidic channel at an interface between the LE and the spacer ion.