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Detection of formaldehyde in water: a shape-effect on the plasmonic sensing properties of the gold nanoparticles.

Nengsih S, Umar AA, Salleh MM, Oyama M - Sensors (Basel) (2012)

Bottom Line: In typical results, it was found that the plasmonic properties of gold nanostructures were very sensitive to the presence of formaldehyde in their surrounding medium by showing the change in both the plasmonic peaks position and the intensity.However, in the present study, effective plasmonic peak shift was not observed due to the intense plasmonic coupling of closely packed nanorod structures on the surface.Nevertheless, the present results at least provide a potential strategy for response enhancement via shape-effects.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microengineering and Nanoelectronic (IMEN), Universiti Kebangsaan Malaysia, UKM Bangi 43600, Selangor, Malaysia. sri_nengsih85@yahoo.com

ABSTRACT
The effect of morphology on the plasmonic sensing of the presence of formaldehyde in water by gold nanostructures has been investigated. The gold nanostructures with two different morphologies, namely spherical and rod, were prepared using a seed-mediated method. In typical results, it was found that the plasmonic properties of gold nanostructures were very sensitive to the presence of formaldehyde in their surrounding medium by showing the change in both the plasmonic peaks position and the intensity. Spherical nanoparticles (GNS), for example, indicated an increase in the sensitivity when the size was increased from 25 to 35 nm and dramatically decreased when the size was further increased. An m value, the ratio between plasmonic peak shift and refractive index change, as high as 36.5 nm/RIU (refractive index unit) was obtained so far. An expanded sensing mode to FD was obtained when gold nanostructures with nanorods morphology (GNR) were used because of the presence of two plasmonic modes for response probing. However, in the present study, effective plasmonic peak shift was not observed due to the intense plasmonic coupling of closely packed nanorod structures on the surface. Nevertheless, the present results at least provide a potential strategy for response enhancement via shape-effects. High performance plasmonic sensors could be obtained if controlled arrays of nanorods can be prepared on the surface.

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Dynamic response of GNR under variation of FD concentrations measured at the plasmonic peak, namely 552 nm.
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f9-sensors-12-10309: Dynamic response of GNR under variation of FD concentrations measured at the plasmonic peak, namely 552 nm.

Mentions: Figure 9 shows the responses of the GNR under various concentration of FD that were measured at both plasmonic peaks. As can be seen from the figure, generally the GNR shows good response characteristics as measured at the two plasmonic peaks, in particular at the LSPR mode, by showing a linear decrease in the absorbance with the increasing FD concentration. The response can be very well-returned to the original position when the FD were removed from the sensor chamber. However, when measured at the TSPR mode, judging from the absorbance change, the GNR shows a lower sensitivity if compared to the measurement performed at the LSPR mode as the presence of small changes in the absorption when the FD concentration was increased in the chamber. It was also found that, in this TSPR mode, the GNR response exhibits an intense fluctuation when high FD concentrations are used. Actually, this phenomenon is quite abnormal since the gold nanostructure is very sensitive to the change in the refractive index of the medium as demonstrated in Figure 6 for the case of GNS. This could be probably due to the effect of strong plasmonic coupling between the GNR as the result of closely packed-structure on the surface. This probably decreases the sensitivity as well as the stability of the responses to the variation of FD concentration in the surrounding medium. Thus, the response fluctuates. Despite the fact the present results for GNR indicate a relatively low stability and performance if related to the unique morphology of the gold nanostructures, we hypothesize that if the GNR can be prepared on the surface with ordered-arrangement, the plasmonic detection should be enhanced. Therefore, the effort to prepare the GNR with ordered-arrangement on the surface is being pursued.


Detection of formaldehyde in water: a shape-effect on the plasmonic sensing properties of the gold nanoparticles.

Nengsih S, Umar AA, Salleh MM, Oyama M - Sensors (Basel) (2012)

Dynamic response of GNR under variation of FD concentrations measured at the plasmonic peak, namely 552 nm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472829&req=5

f9-sensors-12-10309: Dynamic response of GNR under variation of FD concentrations measured at the plasmonic peak, namely 552 nm.
Mentions: Figure 9 shows the responses of the GNR under various concentration of FD that were measured at both plasmonic peaks. As can be seen from the figure, generally the GNR shows good response characteristics as measured at the two plasmonic peaks, in particular at the LSPR mode, by showing a linear decrease in the absorbance with the increasing FD concentration. The response can be very well-returned to the original position when the FD were removed from the sensor chamber. However, when measured at the TSPR mode, judging from the absorbance change, the GNR shows a lower sensitivity if compared to the measurement performed at the LSPR mode as the presence of small changes in the absorption when the FD concentration was increased in the chamber. It was also found that, in this TSPR mode, the GNR response exhibits an intense fluctuation when high FD concentrations are used. Actually, this phenomenon is quite abnormal since the gold nanostructure is very sensitive to the change in the refractive index of the medium as demonstrated in Figure 6 for the case of GNS. This could be probably due to the effect of strong plasmonic coupling between the GNR as the result of closely packed-structure on the surface. This probably decreases the sensitivity as well as the stability of the responses to the variation of FD concentration in the surrounding medium. Thus, the response fluctuates. Despite the fact the present results for GNR indicate a relatively low stability and performance if related to the unique morphology of the gold nanostructures, we hypothesize that if the GNR can be prepared on the surface with ordered-arrangement, the plasmonic detection should be enhanced. Therefore, the effort to prepare the GNR with ordered-arrangement on the surface is being pursued.

Bottom Line: In typical results, it was found that the plasmonic properties of gold nanostructures were very sensitive to the presence of formaldehyde in their surrounding medium by showing the change in both the plasmonic peaks position and the intensity.However, in the present study, effective plasmonic peak shift was not observed due to the intense plasmonic coupling of closely packed nanorod structures on the surface.Nevertheless, the present results at least provide a potential strategy for response enhancement via shape-effects.

View Article: PubMed Central - PubMed

Affiliation: Institute of Microengineering and Nanoelectronic (IMEN), Universiti Kebangsaan Malaysia, UKM Bangi 43600, Selangor, Malaysia. sri_nengsih85@yahoo.com

ABSTRACT
The effect of morphology on the plasmonic sensing of the presence of formaldehyde in water by gold nanostructures has been investigated. The gold nanostructures with two different morphologies, namely spherical and rod, were prepared using a seed-mediated method. In typical results, it was found that the plasmonic properties of gold nanostructures were very sensitive to the presence of formaldehyde in their surrounding medium by showing the change in both the plasmonic peaks position and the intensity. Spherical nanoparticles (GNS), for example, indicated an increase in the sensitivity when the size was increased from 25 to 35 nm and dramatically decreased when the size was further increased. An m value, the ratio between plasmonic peak shift and refractive index change, as high as 36.5 nm/RIU (refractive index unit) was obtained so far. An expanded sensing mode to FD was obtained when gold nanostructures with nanorods morphology (GNR) were used because of the presence of two plasmonic modes for response probing. However, in the present study, effective plasmonic peak shift was not observed due to the intense plasmonic coupling of closely packed nanorod structures on the surface. Nevertheless, the present results at least provide a potential strategy for response enhancement via shape-effects. High performance plasmonic sensors could be obtained if controlled arrays of nanorods can be prepared on the surface.

Show MeSH