A chemiluminescent aptasensor based on rolling circle amplification and Co2+/N-(aminobutyl)-N-(ethylisoluminol) functional flowerlike gold nanoparticles for Salmonella typhimurium detection

A sensitive steady-state chemiluminescent aptasensor based on rolling circle amplification (RCA) was fabricated for the detection of Salmonella typhimurium. The sensor utilized aptamer modified Fe3O4 magnetic nanoparticles (MNPs) as capture probes, aptamer as recognition molecules, and Co2+ enhanced N‑(aminobutyl)-N-(ethylisoluminol) (ABEI) functional flowerlike gold nanoparticles (AuNFs) and complementary strand (cDNA) complex (Co2+/ABEI-AuNFs-cDNA) as signal probes. And P-Iodophenol (PIP) was also added to form a typical ABEI- AuNFs-PIP-H2O2 steady-state CL system. By virtue of Fe3O4 MNPs based solid-phase RCA strategy, S. typhimurium can be first captured by the aptamer immobilized on the surface of Fe3O4 MNPs then complex with RCA products to form a sandwich complex. Co2+/ABEI-AuNFs-cDNA signal probes were then assembled on the RCA products to produce and enhance CL signals. Under optimal conditions, the logarithmic correlation between the concentration of S. typhimurium and the CL signal was found to be linear within the range of 32 cfu mL−1 to 3.2×106 cfu mL−1 (R2 =0.9921). The limits of detection of the developed method were found to be 10 cfu mL−1 for S. typhimurium. The method was also used to detect S. typhimurium in real pork samples. The results were compared with those obtained from the plate-counting methods and showed good consistency. Therefore, this detection aptasnesor can be a good candidate for sensitive and selective detection of S. typhimurium with simple and effective operations.