**3. Nanobiosensor**

Biosensors are synthesized using nanomaterial is called nanobiosensor. This type of biosensor can able to detect the changes happen in the atomic level with more accuracy. In normal biosensor s receptor and transducer materials are made up of normal micro and macro sized material, but in nanobiosensor either receptor or transducer or both are made up of nano material i.e. at least any one dimension is less than 100 nm [30, 31]. Nanomaterials are very small size, so it is having unique physical, mechanical, optical, electrical and magnetic characters when compared to the conventional material. This is the added advantage of the nanobiosensor and reason for all the superior sensing qualities. Researchers have used various nanomaterials and nanocomposites to enhance the sensitivity, shelf life and get the precision in the biosensing results [32, 33]. Mostly four types of nanomaterials i.e., carbon based, metal based, polymer based and nanocomposites are used for various field application [34]. Perhaps among four, dendrimer is not used that much as frequently as other nanomaterial in the bio sensing field. Carbon nanotubes (CNTs), quantum dots (QDs), gold (Au), silica, silver (Ag), graphene and other nanocomposites are synthesized in such a way having large surface area to volume ratio to improve electrochemical parameters (**Figure 2**). The molecular binding is a subject of the biological surface science, which is strongly related to the research on modification of nanostructures properties by controlling their structure and surface

#### **Figure 2.**

*Commonly used nanomaterials in various kind of sensors fabrication with their sizes. L: length; D: Diameter [35].*

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*Perspectives of Nano-Materials and Nanobiosensors in Food Safety and Agriculture*

at a nanoscale level [36, 37]. Recent technological advancement in nanotechnology enable to synthesize nanomaterials with extraordinary optical and electronic properties for electronics and sensing applications [38]. The efficiency of biosensor can be improved by increase the detection limit and the overall performance through using nanomaterials. Nanomaterials provide friendly platform for the assembly of bio-recognition element, the high surface area, high electronic conductivity that

Harmful microorganisms such as pathogenic bacteria, viruses, or parasites and its toxin and excessive use of agrochemicals (pesticides, herbicides and food preservative) are the common causes of food contamination. The primary contaminants leading to foodborne illness are pathogenic microorganisms including: *Bacillus cereus, Clostridium botulinum, Escherichia coli (E. coli), Listeria monocytogenes, Salmonella* and *Staphylococus aureus* [40]. Currently, there are limited methods for field detection of toxins and foodborne pathogens, making early identification of a possible contamination is much difficult because of the low efficient conventional methods. The biosensors integration with various nanostructures like thin films, nanorods, nanoparticles and nanofibers, in the analysis methods for detection of food contaminants has improved the detection sensitivity and increased portability. In food microbiology, nanosensors or nanobiosensors are used for the detection of pathogens in processing plants or in food material, quantification of available food constituents, alerting consumers and distributors

The conventional method for food pathogen detection is colony counting (CFU) on an agar plate which takes 2–3 days for initial results, and up to 1 week for confirming pathogen specificity [42]. These conventional method is not suitable for highly perishable food products. Polymerase chain reaction (PCR) and enzymelinked immunosorbent assay-based (ELISA) can be used as alternative to traditional CFU methods [43]. But these methods are labour-intensive and costly. So using nanobiosensor, that can be adapted on portable platforms to enable rapid testing of wide range of pathogens with potential for on-site analysis [44]. A dimethylsiloxane microfluidic immunosensor integrated with specific antibody immobilized on an alumina nanoporous membrane was developed for rapid detection of foodborne pathogens *Escherichia coli O157:H7* and *Staphylococcus aureus* with electrochemical impedance spectrum [45]. Due to good electrical conductivity and ample functional groups present on surface area carbon nanotubes have been used to develop biosensors for detection of foodborne pathogenic bacteria (*Staphylococcus aureus*) in fresh meat [46]. Miranda et al. developed a hybrid colorimetric enzymatic nanocomposite biosensor for the detection of *E. coli* in aqueous solutions based on enzyme amplification. The efficiency of the method was demonstrated in both solution and test strip format [47]. β-galactosidase an anionic enzyme is electrostatically attached to the cationic Gold nanoparticles (AuNPs) featuring quaternary amine head groups by this way it inhibit the activity of enzyme. When AuNPs binds with bacteria, the attached β-galactosidase is released restoring its activity and this binding activity and colour formation because of the enzymatic reaction was measured by colorimetric means. Using this method, bacteria can be detected at the concen-

bacteria/mL in solution [48]. In an effort to ensure food safety,

*DOI: http://dx.doi.org/10.5772/intechopen.95345*

increase the limit of detection [39].

on the safety status of food [26, 41].

**4.1 Nanobiosensors for food pathogen detection**

**4. Nanobiosensor application in food**

at a nanoscale level [36, 37]. Recent technological advancement in nanotechnology enable to synthesize nanomaterials with extraordinary optical and electronic properties for electronics and sensing applications [38]. The efficiency of biosensor can be improved by increase the detection limit and the overall performance through using nanomaterials. Nanomaterials provide friendly platform for the assembly of bio-recognition element, the high surface area, high electronic conductivity that increase the limit of detection [39].
