Ultrasensitive Chemiluminescent Detection of Salmonella with DNA Hybridization and Silver Amplification of Nanogold Labels

Abstract

An ultrasensitive chemiluminescent DNA hybridization assay for Salmonella was developed by using silver amplification of nanogold labels. A sandwich-type DNA hybridization, which involved sequence-specific oligonucleotide probes from Salmonella, was conducted to assemble nanogold onto ELISA microwells. After that, silver was deposited around nanogold, further dissolved as Ag⁺, and then traced by luminol chemiluminescent reaction. The optimized experiments showed that chemiluminescent intensity is proportional to the target oligonucleotide concentration, ranging from 1 to 1000 fM with a detection limit of 0.3 fM. The method has been successfully applied to detect Salmonella in food samples with a detection limit of 5 cfu/mL.

Keywords:

• Chemiluminescence
• DNA hybridization
• Nanogold label
• Salmonella
• Silver amplification

Acknowledgments

This work was partly supported by NSFC (20805019), “863” Project (2008AA10Z419), MOE High School Doctoral Programmes Founding for New Teachers (20070295014), NSF of Jiangsu Province (BK20081603), PCSIRT0627, 111 project-B07029 of China.

Notes

^a the diluted fold is 10 for each diluted grad;

^b the result is the mean of two flat counted values.

^a the official method normally includes the enrichment, selective cultivation, and biochemical assay process to identify and detect Salmonella.