U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Main content area

A rapid method for the detection of foodborne pathogens by extraction of a trace amount of DNA from raw milk based on amino-modified silica-coated magnetic nanoparticles and polymerase chain reaction

Yalong Bai, Minghui Song, Yan Cui, Chunlei Shi, Dapeng Wang, George C. Paoli, Xianming Shi
Analytica chimica acta 2013 v.787 pp. 93-101
temperature, bacterial contamination, raw milk, Salmonella Enteritidis, DNA, food contamination, food matrix, polymerase chain reaction, rapid methods, food pathogens, magnetic separation, microbial detection, pH, Listeria monocytogenes, nanoparticles
A method based on amino-modified silica-coated magnetic nanoparticles (ASMNPs) and polymerase chain reaction (PCR) was developed to rapidly and sensitively detect foodborne pathogens in raw milk. After optimizing parameters such as pH, temperature, and time, a trace amount of genomic DNA of pathogens could be extracted directly from complex matrices such as raw milk using ASMNPs. The magnetically separated complexes of genomic DNA and ASMNPs were directly subjected to single PCR (S-PCR)or multiplex PCR (M-PCR) to detect single or multiple pathogens from raw milk samples. Salmonella Enteritidis (Gram-negative) and Listeria monocytogenes (Gram-positive) were used as model organisms to artificially contaminate raw milk samples. After magnetic separation and S-PCR, the detection sensitivities were 8 CFU mL−1 and 13 CFU mL−1 respectively for these two types of pathogens. Furthermore, this method was successfully used to detect multiple pathogens (S. Enteritidis and L. monocytogenes) from artificially contaminated raw milk using M-PCR at sensitivities of 15 CFU mL−1 and 25 CFU mL−1, respectively. This method has great potential to rapidly and sensitively detect pathogens in raw milk or other complex food matrices.