Sensitive and Label-free Detection of Bacteria in Osteomyelitis through Exo III-Assisted Cascade Signal Amplification

[Image: see text] Rapid and sensitive pathogenic bacterial identification and isolation from complicated clinical specimens are of great importance for the early diagnosis and prevention of osteomyelitis. Herein, we proposed a novel methicillin-resistant Staphylococcus aureus (MRSA) detection strategy through two specially designed streptavidin magnetic bead-based probes, including a capture probe and a report probe. In detail, the capture probe takes the responsibility to specially bind with the surface protein of MRSA and leads to the liberation of the promoter which could subsequently initiate report probe-based signal amplification. Afterward, the hybridization of the promoter probe with the report probe could then transform the protruding 3′ terminus of template DNA in the report probe into a blunt end. With the assistance of Exo III, the template could be digested to liberate the promoter to form a recycle and to liberate the biprobe to induce the following rolling circle amplification (RCA)-based signal amplification. Through the integration of the Exo III-assisted recycle and RCA-based signal amplification, the proposed method exhibited a favorable detection performance.