Ultrasensitive cloth-based microfluidic chemiluminescence detection of Listeria monocytogenes hlyA gene by hemin/G-quadruplex DNAzyme and hybridization chain reaction signal amplification.

In this work, a cloth-based chemiluminescence (CL) biosensor has been firstly presented for highly sensitive determination of long PCR amplicons. Under the action of a hybridization chain reaction, a good deal of hemin/G-quadruplex DNAzyme molecules are produced, which can effectively enhance the CL signal. Moreover, effective cloth-based DNA biosensors can be fabricated by sequential wax screen-printing and surface-modification processes. Especially, the integration of a desirable hydrophobic barrier and gravity/capillary flow onto the flow channel of the cloth-based device makes the biosensor easy to be fabricated and to be associated with a flow CL. For the luminol/HO-based CL system, the signals are triggered by the hemin/G-quadruplex DNAzyme and are recorded by a low-cost CCD. Under optimized conditions, the determination range of target DNA is 0.002-20,000 pM and its limit of detection is calculated to be 1.1 fM. The results show that the proposed CL biosensor has a good analytical performance, such as high detectability and specificity, wide linear range, and receivable reproducibility and stability. Finally, the proposed biosensor is proven by the fact that this method can successfully detect the target DNA prepared from the Listeria monocytogenes-spiked milk samples. Therefore, it is believed to have the potential application prospects in food safety and environmental monitoring. Graphical abstract.