Detecting trace melamine in solution by SERS using Ag nanoparticle coated poly(styrene-co-acrylic acid) nanospheres as novel active substrates.
A systematic study for the preparation of Ag nanoparticle (Ag-NP) coated poly(styrene-co-acrylic acid) (PSA) composite nanospheres by in situ chemical reduction is reported. The experimental results showed that the reaction temperature and the surface coverage of the -COOH determined the surface coverage and grain size of Ag nanoparticles on the PSA nanospheres. The surface enhanced Raman spectroscopy (SERS) sensitivity was investigated using 4-hydroxythiophenol (4-HBT) as the model probe in the solution of composite nanospheres stabilized by polyvinylpyrrolidone (PSA/Ag-NPs/PVP), with the detection limit of about 1 × 10(-6) M. Potential application of the new SERS substrate was demonstrated with the detection of melamine, and the detection limit was about 1 × 10(-3) M. Chemical noises from PVP and other impurities were observed and attributed mainly to the competitive adsorption of PVP on the surfaces of Ag-NPs. After tetrahydrofuran washing of the PSA/Ag-NPs/PVP substrates that removed the PVP and other residuals, the signal/noise levels of SERS were greatly improved and the detection limit of melamine was determined to be 1 × 10(-7) M. This result indicated that the new PSA/Ag-NPs system is highly effective and can be used as the SERS-active substrate for trace analysis of a variety of drugs and food additives.
Key Laboratory of Molecular Engineering of Polymers, Ministry of Education, and Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China.
Ju-Mei
JM
Li
Wan-Fu
WF
Ma
Chuan
C
Wei
Li-Jun
LJ
You
Jia
J
Guo
Jun
J
Hu
Chang-Chun
CC
Wang
D000179:Acrylates / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D012996:Solutions; D013059:Spectrum Analysis, Raman; D013499:Surface Properties; D014227:Triazines / Q000032:analysis*
D000179:Acrylates; D011137:Polystyrenes; D012996:Solutions; D014227:Triazines; C509855:poly(styrene-b-acrylic acid); D012834:Silver; C011907:melamine