The presence of monocrotophos induced a change of the fluorescence intensity that
was related to the pesticide concentration. Optical properties of AuNPs have been
exploited for the development of localized SPR (LSPR) sensor (Fu et al. 2009). The
resonance frequency of the LSPR is highly dependent upon the local environment of
the nanoparticle and more specifically upon the binding events that occur to the
functionalized NPs. The LSPR was used to develop a biosensor for the detection of
paraoxon by immobilizing AChE onto AuNPs layer using a self-assembling technique (Lin et al. 2006). In the presence of pesticides, the enzymatic activity was
inhibited causing a change of the light attenuation. The detection limit with optimal
conditions was 0.2 ppb. The biosensor retained 94% of its original activity after
6 cycles of inhibition with 500 ppb paraoxon followed by reactivation of AChE with
0.5 mM 2-pyridine aldoxime methiodide. In addition, the sensor retained its activity
after 2 months storage in the dry state at 4
C.
Carbon nanotubes (CNTs) consist of cylindrical graphene sheets with diameter in
nanometer diameters. They present unique mechanical, physical, and chemical
properties. CNTs include both single-walled and multi-walled structures. Since
their discovery, CNTs have been used in nanoelectronics, biomedical engineering,
biosensing, and bioanalysis. Recently, CNTs have been used for the development of
biosensors based on the inhibition of AChE activity (Du et al. 2007; Oliveira and
Mascaro 2011; Firdoz et al. 2010). An amperometric biosensor based on layer-bylayer assembly of single-walled CNT-poly(diallyldimethylammonium chloride) and
AChE was developed for the analysis of carbaryl (Firdoz et al. 2010). The biosensor
showed good sensitivity and stability toward the monitoring of pesticides in water.
The detection limit was 4.9 Â 10–15 M. In some cases, the authors developed
efficient biosensors for the detection of pesticides by associating the properties of
CNTs with those of nanoparticles (Du et al. 2010).
A simple and selective aptamer-based colorimetric assay for the detection of
omethoate has been developed by Wang et al. (2016). The principle of the assay is
that single-stranded DNA (ssDNA)-wrapped gold nanoparticles (AuNPs) are resistant to salt-induced aggregation. By employing an “artificial antibody” organophosphorus pesticide-binding aptamer (OBA) as the recognition element, aptamerwrapped AuNPs (Au-apta) show high selectivity toward omethoate, resulting in
the disconnection of aptamers from AuNPs and the aggregation of AuNPs. As there
is a significant color change from the interparticle plasmon coupling during the
aggregation of AuNPs, the established assay showed good linearity between 0.1 and
10 μmol/L, with a low detection limit of 0.1 μmol/L.
A novel nanohybrid composite with good electrochemical responses was developed by Xu et al. (2017), and it was prepared by the esterification reaction of
hydroxyl-terminated polybutadiene (HTPB) with MWCNT-COOH, followed by
atom transfer radical polymerization of 4-acryloyloxybutyl(ethyl) ferrocene carboxylates with different spacers. The nanohybrid composites were characterized by
FTIR, TGA, Raman, XRD, XPS, SEM, and TEM techniques. Cyclic voltammetry
(CV) determination showed that a longer spacer between the side ferrocene groups
and main chains endowed the electrochemically modified electrodes with active
electron response, obvious redox current, and reversible electrochemical properties
3 Application of Nanobiosensors for Food Safety Monitoring
113
was related to the pesticide concentration. Optical properties of AuNPs have been
exploited for the development of localized SPR (LSPR) sensor (Fu et al. 2009). The
resonance frequency of the LSPR is highly dependent upon the local environment of
the nanoparticle and more specifically upon the binding events that occur to the
functionalized NPs. The LSPR was used to develop a biosensor for the detection of
paraoxon by immobilizing AChE onto AuNPs layer using a self-assembling technique (Lin et al. 2006). In the presence of pesticides, the enzymatic activity was
inhibited causing a change of the light attenuation. The detection limit with optimal
conditions was 0.2 ppb. The biosensor retained 94% of its original activity after
6 cycles of inhibition with 500 ppb paraoxon followed by reactivation of AChE with
0.5 mM 2-pyridine aldoxime methiodide. In addition, the sensor retained its activity
after 2 months storage in the dry state at 4
C.
Carbon nanotubes (CNTs) consist of cylindrical graphene sheets with diameter in
nanometer diameters. They present unique mechanical, physical, and chemical
properties. CNTs include both single-walled and multi-walled structures. Since
their discovery, CNTs have been used in nanoelectronics, biomedical engineering,
biosensing, and bioanalysis. Recently, CNTs have been used for the development of
biosensors based on the inhibition of AChE activity (Du et al. 2007; Oliveira and
Mascaro 2011; Firdoz et al. 2010). An amperometric biosensor based on layer-bylayer assembly of single-walled CNT-poly(diallyldimethylammonium chloride) and
AChE was developed for the analysis of carbaryl (Firdoz et al. 2010). The biosensor
showed good sensitivity and stability toward the monitoring of pesticides in water.
The detection limit was 4.9 Â 10–15 M. In some cases, the authors developed
efficient biosensors for the detection of pesticides by associating the properties of
CNTs with those of nanoparticles (Du et al. 2010).
A simple and selective aptamer-based colorimetric assay for the detection of
omethoate has been developed by Wang et al. (2016). The principle of the assay is
that single-stranded DNA (ssDNA)-wrapped gold nanoparticles (AuNPs) are resistant to salt-induced aggregation. By employing an “artificial antibody” organophosphorus pesticide-binding aptamer (OBA) as the recognition element, aptamerwrapped AuNPs (Au-apta) show high selectivity toward omethoate, resulting in
the disconnection of aptamers from AuNPs and the aggregation of AuNPs. As there
is a significant color change from the interparticle plasmon coupling during the
aggregation of AuNPs, the established assay showed good linearity between 0.1 and
10 μmol/L, with a low detection limit of 0.1 μmol/L.
A novel nanohybrid composite with good electrochemical responses was developed by Xu et al. (2017), and it was prepared by the esterification reaction of
hydroxyl-terminated polybutadiene (HTPB) with MWCNT-COOH, followed by
atom transfer radical polymerization of 4-acryloyloxybutyl(ethyl) ferrocene carboxylates with different spacers. The nanohybrid composites were characterized by
FTIR, TGA, Raman, XRD, XPS, SEM, and TEM techniques. Cyclic voltammetry
(CV) determination showed that a longer spacer between the side ferrocene groups
and main chains endowed the electrochemically modified electrodes with active
electron response, obvious redox current, and reversible electrochemical properties
3 Application of Nanobiosensors for Food Safety Monitoring
113