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4 nm) and SiO2 (100 nm) deposited by electron-beam evaporation in sequence on the thermal silicon oxide substrate. The diameters of SWNTs on the samples with upper SiO2 layer of different deposition rates were characterized by atomic force microscopy (AFM) and micro-Raman spectroscopy. It was observed that the average diameter and density of SWNTs increased as the deposition rate of upper SiO2 layer increased. The differences of the SWNTs diameter distribution were attributed to the differences in the curvature of the SiO2 porous structure deposited with different deposition rates. The high-resolution transmission electron micrographs and the corresponding diffractogram showed that SWNTs with diameter as low as 0.51 nm could be found and the AFM measurements revealed that a high percentage (
doi:10.1016/j.bios.2006.04.004 
Copyright © 2006 Elsevier B.V. All rights reserved.
Short communication
Enhanced surface plasmon resonance with the modified catalytic growth of Au nanoparticles
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Xiaohai Yanga, c, Qing Wanga, c, Kemin Wanga, c, 
, 
, Weihong Tana, c and Huimin Lib, c
Received 30 December 2005;
Abstract
The catalytic growth of Au nanoparticles (AuNPs) has been employed in several analytical methods for improving the detection sensitivity, or integrated with the enzyme reactions for the quantitative detection of the respective substrates. However, the catalytic growth of Au nanoparticles do not work in some situations, such as surface plasmon resonance (SPR), electrochemistry, where metal matrices were used, because metal matrices used in these techniques, e.g. Au, are susceptible to metal deposition, which increased the background seriously. In this work, a SiO2 layer was vapor-deposited on the gold film. The inhibition of metal deposition by this SiO2 layer was investigated by SPR sensor. The results showed that the SiO2 layer could avoid the deposition of metal on Au film. With the low background achieved by SiO2-coated Au films, sensitive detection of DNA hybridization using the catalytic growth of Au nanoparticles enhanced SPR was demonstrated. The work described here maybe helpful for the development of sensitive bioanalytical methods.
Keywords: SiO2; Catalytic growth; Au nanoparticles; Surface plasmon resonance
Article Outline
- 1. Introduction
- 2. Materials and methods
- 2.1. Materials
- 2.2. SPR instrument
- 2.3. Surface modification of SiO2-coated Au films
- 2.4. Preparation and characterization of DNA-linked AuNPs
- 2.5. Hybridization and denaturation of DNA
- 2.6. Catalytic growth of AuNPs
- 2.7. X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM) and atomic force microscopy (AFM) measurements
- 3. Results and discussion
- 3.1. The inhibition of Au deposition by SiO2 layer on the Au film
- 3.2. DNA detection using the catalytic growth of AuNPs enhanced SPR
- 4. Conclusions
- Acknowledgements
- References
