Improving the detection limit of Salmonella colorimetry using long ssDNA of asymmetric-PCR and non-functionalized AuNPs

Lijun Wang; Xue Wu; Haixia Hu; Yukun Huang; Xiao Yang; Qin Wang; Xianggui Chen

doi:10.1016/j.ab.2021.114229

Improving the detection limit of Salmonella colorimetry using long ssDNA of asymmetric-PCR and non-functionalized AuNPs

Anal Biochem. 2021 Aug 1:626:114229. doi: 10.1016/j.ab.2021.114229. Epub 2021 Apr 30.

Authors

Lijun Wang¹, Xue Wu¹, Haixia Hu¹, Yukun Huang¹, Xiao Yang¹, Qin Wang², Xianggui Chen³

Affiliations

¹ School of Food and Bioengineering, Xihua University, Chengdu, 610039, China.
² School of Food and Bioengineering, Xihua University, Chengdu, 610039, China; Department of Nutrition and Food Science, University of Maryland, College Park, MD, 20742, United States.
³ School of Food and Bioengineering, Xihua University, Chengdu, 610039, China. Electronic address: chen_xianggui@mail.xhu.edu.cn.

PMID: 33939971
DOI: 10.1016/j.ab.2021.114229

Abstract

A colorimetric sensor based on gold nanoparticles (AuNPs) and single-stranded DNA (ssDNA) is a simple and rapid method for detecting foodborne pathogens. However, the colorimetric method employed in previous studies involved short ssDNA (<100 nucleotides), including the aptamer and PCR products, resulting in the high detection limit of this technique. In this study, a colorimetric sensor was developed based on long ssDNA of asymmetric PCR (aPCR) and non-functionalized AuNPs for detecting Salmonella Typhimurium (S. Typhimurium). In the presence of S. Typhimurium, the long ssDNA (547 nt) amplified by aPCR-protected AuNPs from NaCl-induced aggregation, while the solution retained a red color. After optimizing parameters, the limit of detection (LOD) of the colorimetric sensor was 2.56 CFU/mL with high specificity. Recovery studies showed its feasibility for detecting S. Typhimurium (10² CFU/mL, 10⁴ CFU/mL, and 10⁶ CFU/mL) in spiked lettuce samples. This colorimetric sensor provides new opportunities for the highly sensitive detection of bacteria in real food samples.

Keywords: Asymmetric PCR; Colorimetric sensor; Gold nanoparticles; Long ssDNA; Salmonella spp..

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

DNA, Bacterial / analysis*
DNA, Single-Stranded / analysis*
DNA, Single-Stranded / genetics
Gold / chemistry*
Limit of Detection
Metal Nanoparticles / chemistry*
Polymerase Chain Reaction / methods*
Salmonella typhimurium / genetics*

Substances

DNA, Bacterial
DNA, Single-Stranded
Gold