TY - JOUR
T1 - Focused-ion-beam-fabricated Au nanorods coupled with Ag nanoparticles used as surface-enhanced Raman scattering-active substrate for analyzing trace melamine constituents in solution
AU - Sivashanmugan, Kundan
AU - Liao, Jiunn Der
AU - Liu, Bernard Haochih
AU - Yao, Chih Kai
N1 - Funding Information:
This work was financially supported by the National Science Council of Taiwan under grant NSC-100-2221-E-006-025-MY3 and the Medical Device Innovation Center of National Cheng Kung University under grant D102-21007.
PY - 2013/10/24
Y1 - 2013/10/24
N2 - A well-ordered Au-nanorod array with a controlled tip ring diameter (Au_NRsd) was fabricated using the focused ion beam method. Au_NRsd was then coupled with Ag nanoparticles (Ag NPs) to bridge the gaps among Au nanorods. The effect of surface-enhanced Raman scattering (SERS) on Au_NRsd and Ag NPs/Au_NRsd was particularly verified using crystal violet (CV) as the molecular probe. Raman intensity obtained from a characteristic peak of CV on Au_NRsd was estimated by an enhancement factor of ≈107 in magnitude, which increased ≈1012 in magnitude for that on Ag NPs/Au_NRsd. A highly SERS-active Ag NPs/Au_NRsd was furthermore applied for the detection of melamine (MEL) at very low concentrations. Raman-active peaks of MEL (10-3 to 10-12M) in water or milk solution upon Au_NRsd or Ag NPs/Au_NRsd were well distinguished. The peaks at 680 and 702cm-1 for MEL molecules were found suitable to be used as the index for sensing low-concentration MEL in a varied solution, while that at 1051cm-1 was practical to interpret MEL molecules in water or milk solution bonded with Au (i.e., Au_NRsd) or Ag (i.e., Ag NPs/Au_NRsd) surface. At the interface of Ag NPs/Au_NRsd and MEL molecules in milk solution, a laser-induced electromagnetic field or hotspot effect was produced and competent to sense low-concentration MEL molecules interacting with Ag and Au surfaces. Accordingly, Ag NPs/Au_NRsd is very promising to be used as a fast and sensitive tool for screening MEL in complex matrices such as adulteration in e.g., food and pharmaceutical products.
AB - A well-ordered Au-nanorod array with a controlled tip ring diameter (Au_NRsd) was fabricated using the focused ion beam method. Au_NRsd was then coupled with Ag nanoparticles (Ag NPs) to bridge the gaps among Au nanorods. The effect of surface-enhanced Raman scattering (SERS) on Au_NRsd and Ag NPs/Au_NRsd was particularly verified using crystal violet (CV) as the molecular probe. Raman intensity obtained from a characteristic peak of CV on Au_NRsd was estimated by an enhancement factor of ≈107 in magnitude, which increased ≈1012 in magnitude for that on Ag NPs/Au_NRsd. A highly SERS-active Ag NPs/Au_NRsd was furthermore applied for the detection of melamine (MEL) at very low concentrations. Raman-active peaks of MEL (10-3 to 10-12M) in water or milk solution upon Au_NRsd or Ag NPs/Au_NRsd were well distinguished. The peaks at 680 and 702cm-1 for MEL molecules were found suitable to be used as the index for sensing low-concentration MEL in a varied solution, while that at 1051cm-1 was practical to interpret MEL molecules in water or milk solution bonded with Au (i.e., Au_NRsd) or Ag (i.e., Ag NPs/Au_NRsd) surface. At the interface of Ag NPs/Au_NRsd and MEL molecules in milk solution, a laser-induced electromagnetic field or hotspot effect was produced and competent to sense low-concentration MEL molecules interacting with Ag and Au surfaces. Accordingly, Ag NPs/Au_NRsd is very promising to be used as a fast and sensitive tool for screening MEL in complex matrices such as adulteration in e.g., food and pharmaceutical products.
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U2 - 10.1016/j.aca.2013.09.011
DO - 10.1016/j.aca.2013.09.011
M3 - Article
C2 - 24120168
AN - SCOPUS:84885193903
SN - 0003-2670
VL - 800
SP - 56
EP - 64
JO - Analytica Chimica Acta
JF - Analytica Chimica Acta
ER -