Photothermal ATP detection by competitive displacement of ZIF-67 adsorbed G4-dHemin DNAzyme

Abstract

Adenosine triphosphate (ATP) is the primary energy currency in biological system. Abnormal ATP levels are closely related to physical disease. There are series of shortcomings of traditional ATP detection methods, such as complex sample preparation, expensive analysis cost, lack of specificity. Therefore, it is extremely important to establish a convenient and simple ATP monitoring method. Herein, we propose a photothermal biosensing strategy utilizing zeolitic imidazolate framework-67 (ZIF-67) and G4-dHemin DNAzyme for both precise and selective ATP quantification. This platform enables the detection of ATP through a novel competitive displacement mechanism, and achieves higher specificity and lower costs than the traditional method without relying on the aptamer. ZIF-67 has ultrahigh selectivity for recognizing ATP, and G4-dHemin DNAzyme exhibits oxidase-like activity which can effectively oxidize TMB. In this work, G4-dHemin DNAzyme was adsorbed by ZIF-67 due to the electrostatic effect. As a result, the oxidase-like activity of G4-dHemin DNAzyme was greatly reduced. The presence of ATP released the G4-dHemin DNAzyme from ZIF-67, allowing the restore of oxidase-like activity of G4-dHemin DNAzyme. Thus, the colorless TMB could be effectively oxidized to blue substrates (ox TMB). ox TMB, as an excellent photothermal agent, converted the optical signal into a thermal signal (temperature increasing) driven by an 808 nm laser (2.45 W). Then, the photothermal and color signal variations were easily monitored by a portable thermometer and a smartphone. The minimum detection limit of this method was calculated to be 0.41 μM, which could meet the detection of ATP in real samples.