Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Sep 5;12(17):3080.
doi: 10.3390/nano12173080.

Detailed Investigation of Factors Affecting the Synthesis of SiO2@Au for the Enhancement of Raman Spectroscopy

Nguyen Thi Phuong Thao  1 , Loc Ton-That  2   3 , Cong-Thuan Dang  2   3 , Jan Nedoma  1
Affiliations

Detailed Investigation of Factors Affecting the Synthesis of SiO2@Au for the Enhancement of Raman Spectroscopy

Nguyen Thi Phuong Thao et al. Nanomaterials (Basel). .

Abstract

The reaction time, temperature, ratio of precursors, and concentration of sodium citrate are known as the main factors that affect the direct synthesis process of SiO2@Au based on the chemical reaction of HAuCl4 and sodium citrate. Hence, we investigated, in detail, and observed that these factors played a crucial role in determining the shape and size of synthesized nanoparticles. The significant enhancement of the SERS signal corresponding to the fabrication conditions is an existing challenge. Our study results show that the optimal reaction conditions for the fabrication of SiO2@Au are a 1:21 ratio of HAuCl4 to sodium citrate, with an initial concentration of sodium citrate of 4.2 mM, and a reaction time lasting longer than 6 h at a temperature of 80 °C. Under optimal conditions, our synthesis process result is SiO2@Au nanoparticles with a diameter of approximately 350 nm. In particular, the considerable enhancement of Raman intensities of SiO2@Au compared to SiO2 particles was examined.

Keywords: Raman spectroscopy; SERS; SiO2@Au; core shell.

PubMed Disclaimer

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
Process of preparing SiO2@Au material.
Figure 1
Figure 1
Pictures of samples at different temperatures (a). UV-Vis spectra of samples at different temperatures (b) and their UV-Vis baseline spectra (c).
Figure 1
Figure 1
Pictures of samples at different temperatures (a). UV-Vis spectra of samples at different temperatures (b) and their UV-Vis baseline spectra (c).
Figure 2
Figure 2
Pictures of samples at different reaction times (a). UV-Vis spectra of samples at different reaction times (b) and their UV-Vis baseline spectra (c).
Figure 2
Figure 2
Pictures of samples at different reaction times (a). UV-Vis spectra of samples at different reaction times (b) and their UV-Vis baseline spectra (c).
Figure 3
Figure 3
Pictures of samples at different ratios of HAuCl4 to sodium citrate (a). UV-Vis spectra of samples at different ratios of HAuCl4 to sodium citrate (b) and their UV-Vis baseline spectra (c).
Figure 3
Figure 3
Pictures of samples at different ratios of HAuCl4 to sodium citrate (a). UV-Vis spectra of samples at different ratios of HAuCl4 to sodium citrate (b) and their UV-Vis baseline spectra (c).
Figure 4
Figure 4
Pictures of samples at different concentrations of sodium citrate (a). UV-Vis spectra of samples at different concentrations of sodium citrate (b) and their UV-Vis baseline spectra (c). N1: 0.21 mM; N2: 0.42 mM; N3: 0.84 mM; N4: 1.5 mM; N5: 4.2 mM.
Figure 5
Figure 5
Pictures of SiO2, SiO2@PEI, AuNPs, and SiO2@Au synthesized under optimal conditions (a). UV-Vis spectra of SiO2, SiO2@PEI, AuNPs, and SiO2@Au synthesized under optimal conditions (b) and their UV-Vis baseline spectra (c).
Figure 6
Figure 6
SEM images of SiO2 (a), SiO2@PEI (b), and SiO2@Au (c).
Figure 6
Figure 6
SEM images of SiO2 (a), SiO2@PEI (b), and SiO2@Au (c).
Figure 7
Figure 7
Dynamic Light Scattering results of SiO2 (a) and SiO2@Au (b).
Figure 8
Figure 8
Raman spectra of methylene blue solution deposited on SiO2 and SiO2@Au.
See this image and copyright information in PMC

References

    1. Guerrini L., Lopez-Tobar E., Garcia-Ramos J.V., Domingo C., Sanchez-Cortes S. New insights on the Aucore/Ptshellnanoparticle structure in the sub-monolayer range: SERS as a surface analyzing tool. Chem. Commun. 2011;47:3174–3176. doi: 10.1039/c0cc05013j. - DOI - PubMed
    1. Das G.M., Managò S., Mangini M., De Luca A.C. Biosensing Using SERS Active Gold Nanostructures. Nanomaterials. 2021;11:2679. doi: 10.3390/nano11102679. - DOI - PMC - PubMed
    1. Burgmeier J., Feizpour A., Schade W., Reinhard B.M. Plasmonic nanoshell functionalized etched fiber Bragg gratings for highly sensitive refractive index measurements. Opt. Lett. 2015;40:546–549. doi: 10.1364/OL.40.000546. - DOI - PubMed
    1. Peeters H., Keulemans M., Nuyts G., Vanmeert F., Li C., Minjauw M., Detavernier C., Bals S., Lenaerts S., Verbruggen S.W. Plasmonic gold-embedded TiO2 thin films as photocatalytic self-cleaning coatings. Appl. Catal. B Environ. 2020;267:118654. doi: 10.1016/j.apcatb.2020.118654. - DOI
    1. Kang H., Buchman J.T., Rodriguez R.S., Ring H.L., He J., Bantz K.C., Haynes C.L. Stabilization of Silver and Gold Nanoparticles: Preservation and Improvement of Plasmonic Functionalities. Chem. Rev. 2019;119:664–699. doi: 10.1021/acs.chemrev.8b00341. - DOI - PubMed

LinkOut - more resources