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Enhancing electrochemical detection on graphene oxide-CNT nanostructured electrodes using magneto-nanobioprobes.

Sharma P, Bhalla V, Dravid V, Shekhawat G - Sci Rep (2012)

Bottom Line: Sensitive detection was achieved by precisely designing the nanohybrid and correlating the available metal ions with analyte concentration.We confirmed the ultrahigh sensitivity of this method for a new generation herbicide diuron and its analogues up to sub-picomolar concentration in standard water samples.The novel immune-detection platform showed the excellent potential applicability in rapid and sensitive screening of environmental pollutants or toxins in samples.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microbial Technology (CSIR), Sector 39-A, Chandigarh 160036, India.

ABSTRACT
Graphene and related materials have come to the forefront of research in electrochemical sensors during recent years due to the promising properties of these nanomaterials. Further applications of these nanomaterials have been hampered by insufficient sensitivity offered by these nanohybrids for the type of molecules requiring lower detection ranges. Here, we report a signal amplification strategy based on magneto-electrochemical immunoassay which combines the advantages of carbon nanotube and reduced graphene oxide together with electrochemical bursting of magnetic nanoparticles into a large number of metal ions. Sensitive detection was achieved by precisely designing the nanohybrid and correlating the available metal ions with analyte concentration. We confirmed the ultrahigh sensitivity of this method for a new generation herbicide diuron and its analogues up to sub-picomolar concentration in standard water samples. The novel immune-detection platform showed the excellent potential applicability in rapid and sensitive screening of environmental pollutants or toxins in samples.

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(a) TEM micrograph of Au/Fe nanoparticles.(b) The line map curve showing the ratio of Au:Fe in a single selected nanoparticle (c) EDX spectra of the whole scan area (d) The whole area mapping analysis of nanoparticles in dark field showing the distribution of Fe and Au in the synthesized nanoparticles. In (e) and (f), pink and red dots represent Fe and Au respectively.
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f2: (a) TEM micrograph of Au/Fe nanoparticles.(b) The line map curve showing the ratio of Au:Fe in a single selected nanoparticle (c) EDX spectra of the whole scan area (d) The whole area mapping analysis of nanoparticles in dark field showing the distribution of Fe and Au in the synthesized nanoparticles. In (e) and (f), pink and red dots represent Fe and Au respectively.

Mentions: High resolution transmission electron microscopy (HR-TEM) was done to characterize the surface morphology and elemental mapping of synthesized nanobioprobes (Figure 2). Figure 2a shows the morphology of the synthesized Au/Fe nanoparticles with an average dia of ~30 nm. In the micrographs, the nanoparticles after coating with gold appear much darker than the Fe3O4 nanoparticles because gold is more electron dense than iron oxide. The line mapping of the selected nanoparticles indicates the inclusion of Fe core and Au shell as single Au/Fe nanostructure. The relative ratios of Au:Fe in the selected nanoparticle was found to be nearly 11:1 as depicted in figure 2b, and has also been concluded by atomic absorption spectrometry (see supplementary information S1). Further, the elemental compositions of the selected area scan as determined by the energy dispersive X-ray spectroscopy (EDX) (Fig. 2c) demonstrates Au LR, Au Lâ, Fe KR, and Fe Kâ lines at 9.8 keV, 11.6 keV, 6.4 keV, and 7.0 keV respectively. Similarly, whole area mapping analysis shows Fe NPs with pink dots (Fig. 2e) and Au NPs in red dots (Fig. 2f) and their merging (2d) exemplifies the formation of mosaic type Au/Fe nanoparticles.


Enhancing electrochemical detection on graphene oxide-CNT nanostructured electrodes using magneto-nanobioprobes.

Sharma P, Bhalla V, Dravid V, Shekhawat G - Sci Rep (2012)

(a) TEM micrograph of Au/Fe nanoparticles.(b) The line map curve showing the ratio of Au:Fe in a single selected nanoparticle (c) EDX spectra of the whole scan area (d) The whole area mapping analysis of nanoparticles in dark field showing the distribution of Fe and Au in the synthesized nanoparticles. In (e) and (f), pink and red dots represent Fe and Au respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3500845&req=5

f2: (a) TEM micrograph of Au/Fe nanoparticles.(b) The line map curve showing the ratio of Au:Fe in a single selected nanoparticle (c) EDX spectra of the whole scan area (d) The whole area mapping analysis of nanoparticles in dark field showing the distribution of Fe and Au in the synthesized nanoparticles. In (e) and (f), pink and red dots represent Fe and Au respectively.
Mentions: High resolution transmission electron microscopy (HR-TEM) was done to characterize the surface morphology and elemental mapping of synthesized nanobioprobes (Figure 2). Figure 2a shows the morphology of the synthesized Au/Fe nanoparticles with an average dia of ~30 nm. In the micrographs, the nanoparticles after coating with gold appear much darker than the Fe3O4 nanoparticles because gold is more electron dense than iron oxide. The line mapping of the selected nanoparticles indicates the inclusion of Fe core and Au shell as single Au/Fe nanostructure. The relative ratios of Au:Fe in the selected nanoparticle was found to be nearly 11:1 as depicted in figure 2b, and has also been concluded by atomic absorption spectrometry (see supplementary information S1). Further, the elemental compositions of the selected area scan as determined by the energy dispersive X-ray spectroscopy (EDX) (Fig. 2c) demonstrates Au LR, Au Lâ, Fe KR, and Fe Kâ lines at 9.8 keV, 11.6 keV, 6.4 keV, and 7.0 keV respectively. Similarly, whole area mapping analysis shows Fe NPs with pink dots (Fig. 2e) and Au NPs in red dots (Fig. 2f) and their merging (2d) exemplifies the formation of mosaic type Au/Fe nanoparticles.

Bottom Line: Sensitive detection was achieved by precisely designing the nanohybrid and correlating the available metal ions with analyte concentration.We confirmed the ultrahigh sensitivity of this method for a new generation herbicide diuron and its analogues up to sub-picomolar concentration in standard water samples.The novel immune-detection platform showed the excellent potential applicability in rapid and sensitive screening of environmental pollutants or toxins in samples.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microbial Technology (CSIR), Sector 39-A, Chandigarh 160036, India.

ABSTRACT
Graphene and related materials have come to the forefront of research in electrochemical sensors during recent years due to the promising properties of these nanomaterials. Further applications of these nanomaterials have been hampered by insufficient sensitivity offered by these nanohybrids for the type of molecules requiring lower detection ranges. Here, we report a signal amplification strategy based on magneto-electrochemical immunoassay which combines the advantages of carbon nanotube and reduced graphene oxide together with electrochemical bursting of magnetic nanoparticles into a large number of metal ions. Sensitive detection was achieved by precisely designing the nanohybrid and correlating the available metal ions with analyte concentration. We confirmed the ultrahigh sensitivity of this method for a new generation herbicide diuron and its analogues up to sub-picomolar concentration in standard water samples. The novel immune-detection platform showed the excellent potential applicability in rapid and sensitive screening of environmental pollutants or toxins in samples.

Show MeSH