A highly sensitive method for the detection of alkaline phosphatase based on thioflavin T/G-quadruplex and strand displacement amplification

Abstract

We report the design of a novel sensitive and selective method, for alkaline phosphatase (ALP) detection, based on thioflavin T/G-quadruplex and strand displacement amplification. In the presence of ALP, the primer with 3′-phosphoryl-termini could be dephosphorylated and then hybridize with the corresponding template. After polymerization and cleavage, a mass of G-rich DNA sequences is generated and forms a four-stranded structure, which can combine with thioflavin T, resulting in a strong fluorescence signal. Under optimal conditions, the fluorescence intensity had a linear relation with ALP concentrations in the interval of 0.005–0.1 U/L, and the detection limit was up to 0.00086 U/L. Moreover, this approach was applicable to screen ALP inhibitors, such as Na3VO4, and determine the activity of ALP in human serum.