DNAzyme-based and smartphone-assisted colorimetric biosensor for ultrasensitive and highly selective detection of...

Herein, a colorimetric biosensor for histamine detection in meat is first established based on the enhancement of DNAzyme with peroxidase-mimic activity. Histamine can boost the generation of G-quadruplex sequences, and make them more easily bond with hemin to produce many DNAzyme molecules. In addition, histamine increases the affinity of DNAzyme to the substrate 3,3',5,5'-tetramethylbenzidine (TMB). Therefore, the obtained DNAzyme can catalyze H₂O₂ and dissolved oxygen to produce many reactive oxygen species (ROS), which cause the TMB molecule to lose two electrons and generate yellow products, exhibiting a clear absorption peak at 450 nm. The colorimetric biosensor has excellent sensitivity, and the detection limit is as low as 38 μg·L^-1 for histamine. Moreover, the biosensor has high selectivity and anti-interference ability, and exhibits a good recovery rate in actual meats. The above results show that the strategy has potential for application in the detection of trace histamine in meats.