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.
Highlights
Gold nanoparticles have become a promising material for chemical sensing purposes in recent years due to their unique broad range of bio-compatibility, expanded catalytic behavior which is inherently related to the nanocrystals facet effect, and excellent chemical stability, as the basic parameters for interacting with analytes [1,2,3]
The plasmonic responses of two different gold nanostructures morphologies embedded on a quartz substrate, namely gold nanoparticles (GNS) and gold nanorods (GNR), to the presence of formaldehyde in water has been investigated
For the case of GNS, it was found that their plasmonic responses exhibited high-sensitivity to a small change in the refractive index of the medium due to the presence of formaldehyde (FD)
Summary
Gold nanoparticles have become a promising material for chemical sensing purposes in recent years due to their unique broad range of bio-compatibility, expanded catalytic behavior which is inherently related to the nanocrystals facet effect, and excellent chemical stability, as the basic parameters for interacting with analytes [1,2,3] This material exhibits peculiar optical properties [4,5,6,7,8,9] with the presence of surface plasmon resonance bands that are very sensitive to the changes in the dielectricity of the surrounding medium and their surface chemistry [1], making them a promising agent for the detection of analytes. The mechanism for the responses of gold nanostructures related to their morphology is discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
