Hemin/G-quadruplex based electrochemical sensor for highly sensitive detection of ATP in fish

A label-free, sensitive and reliable electrochemical sensor based on hemin/G-quadruplex (G4) DNAzyme was engineered to determine adenosine triphosphate (ATP) in fish. The nucleic acid sequence (DNA1) including the G4 sequence subunit and anti-ATP aptamer segment is anchored on Au electrodes. The nucleic acid sequence (DNA2) is composed of another G4 sequence fragment and anti-ATP aptamer subunit. The probes DNA1 and DNA2 self-assemble into the active hemin/G4 DNAzyme structure on Au electrodes upon exposure to the target ATP. The determination of the target ATP relied on an increase in the catalytic currents occurring on DNAzyme-anchored electrode via the electrochemical reduction of H 2 O 2 . The proposed strategy enables high-performance and specified determination of the target ATP with a detection limit of 0.04 μmol/L. Specifically, the proposed ATP strategy was further implemented to determine ATP in microorganisms in carp samples. Compared with the classical total viable count (TVC) assay, the proposed ATP assay was feasible to assess the freshness of carp, which expands the applications of hemin/G4 DNAzyme and holds promising potential for freshness assessment in food safety.