**4. Novel technologies for detecting the pathogens**

In recent years, the rapid detection of foodborne pathogens has developed rapidly. Molecular biology, nucleic acid hybridization, and other technologies have been highly valued and widely used in laboratory or factory production.

#### **4.1 Nanoparticles in pathogen detection**

Substances are manipulated at atomic, molecular, and supramolecular scales through nanotechnology ("nanotech"). Advances in manipulating these nanomaterials allow specific or non-specific binding of different biomolecules. The large specific surface area allows more biomolecules to be immobilized, thereby increasing the number of reaction sites that can be used to interact with the target species, which is one of the main advantages of biosensing using nanomaterials. In addition, nanomaterials have been widely used in 'label-free 'detection due to their excellent electronic and optical properties, and biosensors with enhanced sensitivity and improved response time have been developed [34].

Metal nanoparticles, especially gold and silver (5–110 nm in size) exhibit excellent properties, such as signal amplification, have potential application in various areas such as variable optical and electrical determinations. Gold nanoparticles (AuNPs) change the color aggregation from blue to red with the ability to scatter light, showing excellent chemical stability and electrical conductivity. AuNPs were used to detect Salmonella and *E. coli* O157: H7 organisms at 98.9 CFU/mL and 1–10 CFU/mL, respectively. Magnetic nanoparticles such as iron, nickel, and cobalt (size range of 1–100 nm) with electrical conductivity properties for utilization as a detection mean. Quantum dots (2–10 nm) were detected in *E. coli* O157:H7 103 CFU/mL through a semiconductor material consisting of semiconductor fluorescent nanonuclei (typically cadmium mixed with selenium or tellurium). Carbon nanotubes are formed by anisotropies of carboncontaining cylindrical graphene sheets. Multiwalled nanotubes (MWNTs, 2–100 nm) with photoluminescence and excellent electrical properties are composed of many concentrated single-walled nanotubes (SWNTs, 0.4–3 nm). A half conductance apparatus was used to monitor *E. coli* o157:h7 at 1 cell/mL restriction [35]. Thiol modified oligonucleotides covalently bound-based methods to gold nanoparticles are used as probes in various rapid detection ways. Due to its cost, functional chemistry is not so widespread. This method employs nonfunctional AuNPs to detect dsDNA and ssDNA [36].

#### **4.2 Polymerase chain reaction (PCR)**

Polymerase chain reaction (PCR) plays an important role in molecular methods in detecting foodborne pathogens. As early as 30 years ago, PCR, which was invented

## *Foodborne Pathogens of Enterobacteriaceae, Their Detection and Control DOI: http://dx.doi.org/10.5772/intechopen.102086*

for the detection of single bacterial pathogens present in food by identifying specific target DNA sequences [37]. PCR works by amplifying specific target DNA sequences in a three-step cycle [38]. Firstly, single-stranded DNA was obtained from target double-stranded DNA by high-temperature denaturation. Then, deoxyribonucleic acid was lead on the backbone of DNA by adding specific primers and heat-resistant DNA polymerase in the polymerization process of DNA, so a new double-stranded DNA was synthesized. The amplified products of PCR were stained by ethidium bromide on electrophoretic gels [39]. PCR such as loop-mediated isothermal amplification (LAMP), multiplex PCR (mPCR) and RT-PCR, etc. is used to detect foodborne pathogens, including *E. coli* 157: H7, *S. aureus*, *Campylobacter jejuni*, *Salmonella* and *Shigella* [40]. Because of the advantage of high specificity, efficiency and easy operation, LAMP and mPCR are used quite frequently [41–47].
