Luminescent DNAzyme and universal blocking linker Super Polymerase Chain Reaction visual biosensor for the detection of Salmonella.

Here, we constructed a fast, universal, "turn-on" biosensor for the highly sensitive visual detection of Salmonella based on luminescent DNAzyme and a universal blocking linker Super Polymerase Chain Reaction (S-PCR). The primer in this biosensor was specially designed. The G-quadruplex sequence is attached to the 5' end of the primer by a blocking linker and is blocked in the stem part. The S-PCR amplification releases the G-quadruplex, which is incubated with hemin to form DNAzyme to exert peroxide-like activity. The visible colored products are generated by the addition of 3,3',5,5'-Tetramethylbenzidine. Detection sensitivity is high and, even when the concentration of the Salmonella genome in a sample is as low as 1.5 copies/µL, this color change can be seen with the naked eyes. Moreover, this method is simple and fast, as the S-PCR can be completed in less than 10 min using the newly built equipment and without the need for large instruments.