A multi pathogenic microorganisms determination method is reported using DNA composites encapsulated DNA silver nanocluster (AgNCs)/graphene oxide (GO)-based system through rolling cycle (RCA) amplification. Firstly, two different RCA-based DNA composites are assembled, coupled with thousands of DNA-stabilized AgNCs probe and ssDNA aptamer specific for two pathogen bacteria targets. GO was then introduced into the system to capture ssDNA aptamer of DNA composites and as a selective fluorescence quencher of DNA/AgNCs. Upon recognizing the target bacteria, ssDNA aptamer part would combine with bacteria and release from the surface of GO. Thus, DNA/AgNCs of RCA-based DNA composites can generate strong fluorescence signal. With the fluorescent report of RCADNA-AgNCs/530 and RCADNA-AgNCs/625, the assay successfully detect Escherichia coli and Staphylococcus aureus at concentrations as low as 38 CFU/mL, and a highly selective and efficient sensing platform was achieved. Therefore, this RCA/DNA-AgNCs/GO-based platform shows excellent application in multi pathogenic microorganisms determination and potential clinic therapy.

Graphical abstract