Silver nanoparticles self assembly as SERS substrates with near single molecule detection limit

被引:218
作者
Fan, Meikun [1 ]
Brolo, Alexandre G. [1 ]
机构
[1] Univ Victoria, Dept Chem, Victoria, BC V8W 3V6, Canada
基金
加拿大创新基金会; 加拿大自然科学与工程研究理事会;
关键词
ENHANCED RAMAN-SCATTERING; GOLD NANOPARTICLES; SURFACE-PLASMON; TRACE ANALYSIS; HOLE ARRAYS; METAL-FILMS; SPECTROSCOPY; NANOSCALE; NANOSTRUCTURES; MONOLAYERS;
D O I
10.1039/b904744a
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Highly sensitive SERS substrates with a limit of detection in the zeptomole (for Nile blue A and oxazine 720) range were fabricated through a bottom-up strategy. Ag nanoparticles (Ag NPs) were self-assembled onto glass slides by using 3-mercaptopropyltrimethoxysilane (MPTMS) sol-gel as linker. The substrates were characterized by UV-Vis and AFM after each deposition of Ag NPs. It was found that the glass slide presented just a few Ag NPs aggregates scattered throughout the surface after just one deposition. The glass surface was gradually covered by a homogeneous distribution of Ag NPs aggregates as the deposition number increased. Surface-enhanced Raman scattering (SERS) of the substrates was examined at different numbers of Ag NPs deposition using nile blue A and oxazine 720 as probe molecules and two laser excitations (632.8 nm and 785 nm). Optimum SERS was observed after six depositions of Ag NPs. SERS mapping indicated that at lower deposition numbers (less than 3 Ag NPs depositions) the substrates presented a few SERS "hot-spots'' randomly distributed at the surface. After 7 Ag NPs depositions, spatial distribution of the SERS signal followed a Gaussian statistics, with a percent relative standard deviation (RSD%) of similar to 19%. In addition, the sample-to-sample reproducibility of the SERS intensities under both laser excitations was lower than 20%. It was also found that these substrates can provide giant Raman signal enhancement. At optimum conditions and with a 632.8 nm laser, the signal from an estimated of only similar to 44 probe molecules (100x objective) can still be detected.
引用
收藏
页码:7381 / 7389
页数:9
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