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Ultra-pure, water-dispersed Au nanoparticles produced by femtosecond laser ablation and fragmentation.

Kubiliūtė R, Maximova KA, Lajevardipour A, Yong J, Hartley JS, Mohsin AS, Blandin P, Chon JW, Sentis M, Stoddart PR, Kabashin A, Rotomskis R, Clayton AH, Juodkazis S - Int J Nanomedicine (2013)

Bottom Line: Fluorescence quenching behavior and its intricacies were revealed by fluorescence lifetime imaging microscopy in rhodamine 6G water solution.We show that surface-enhanced Raman scattering of rhodamine 6G on gold nanoparticles can be detected with high fidelity down to micromolar concentrations using the nanoparticles.Application potential of pure gold nanoparticles with polydispersed and nearly monodispersed size distributions are discussed.

View Article: PubMed Central - PubMed

Affiliation: Centre for Micro-Photonics and Industrial Research Institute Swinburne, Faculty of Engineering and Industrial Sciences Swinburne University of Technology, Hawthorn, VIC, Australia.

ABSTRACT
Aqueous solutions of ultra-pure gold nanoparticles have been prepared by methods of femtosecond laser ablation from a solid target and fragmentation from already formed colloids. Despite the absence of protecting ligands, the solutions could be (1) fairly stable and poly size-dispersed; or (2) very stable and monodispersed, for the two fabrication modalities, respectively. Fluorescence quenching behavior and its intricacies were revealed by fluorescence lifetime imaging microscopy in rhodamine 6G water solution. We show that surface-enhanced Raman scattering of rhodamine 6G on gold nanoparticles can be detected with high fidelity down to micromolar concentrations using the nanoparticles. Application potential of pure gold nanoparticles with polydispersed and nearly monodispersed size distributions are discussed.

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Transmission electron microscopy (TEM) images of nanoparticles from the most stable gold (Au) colloidal solution (protocol 2; sample Number 2) fragmented by femtosecond-laser irradiation in pure pH = 7 water (at different magnifications). Inset shows the size (diameter) distribution 24 ± 5 nm using TEM image analysis.
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f2-ijn-8-2601: Transmission electron microscopy (TEM) images of nanoparticles from the most stable gold (Au) colloidal solution (protocol 2; sample Number 2) fragmented by femtosecond-laser irradiation in pure pH = 7 water (at different magnifications). Inset shows the size (diameter) distribution 24 ± 5 nm using TEM image analysis.

Mentions: As the second protocol, we employed methods of two step femtosecond laser fragmentation procedure introduced in a previous study34 The 10 mL of nanoparticle solution prepared by the first protocol was transferred into a glass cuvette and irradiated in the very center of the cuvette, by a focused laser beam of the Yb:KGW femtosecond laser (using the same focusing lens), while the solution was stirred by a magnet to homogenize the ablation process. We used relatively low laser fluences (1 J•cm2) to avoid the phenomenon of laser-assisted plasma breakdown of the liquid but the radiation intensity was high enough to ablate the suspended nanoparticles. As shown in previous studies,32–4 when the pumping laser wavelength is relatively far from the absorption band of Au nanoparticles (depending on nanoparticle size), the nanoparticles are predominantly ablated by radiation from a white light supercontinuum (presenting a wide spectrum from ultraviolet [UV] to infrared of femtosecond pulse length), generated in the water environment due to nonlinear self-focusing effects that normally accompany femtosecond laser–liquid interaction.37 In our experiments, this white light supercontinuum was clearly visible in the liquid volume. The femtosecond-laser fragmentation process led to a change of solution color into deep (dark) red without any sign of yellow tints. Afiter 40 minutes of fragmentation, the nanoparticle solutions were extremely stable and did not show any sign of precipitation, even afiter months of storage at room temperature. As shown in Figure 2, the mean size of nanoparticles was about 24 nm, while the size dispersion was very weak (less than 10 nm FWHM). To study solution stability effects, we carried out fragmentation for 20 minutes, which led to a smaller mean size (15–17 nm) and broader size dispersion (14 nm FWHM). Samples prepared by femtosecond-laser ablation from the Au target (protocol 1; Figure 1) are referred to as sample Number 1. Samples prepared by complete and partial femtosecond-laser fragmentation (protocol 2) are referred to as Number 2 ( Figure 2) and Number 2a, respectively.


Ultra-pure, water-dispersed Au nanoparticles produced by femtosecond laser ablation and fragmentation.

Kubiliūtė R, Maximova KA, Lajevardipour A, Yong J, Hartley JS, Mohsin AS, Blandin P, Chon JW, Sentis M, Stoddart PR, Kabashin A, Rotomskis R, Clayton AH, Juodkazis S - Int J Nanomedicine (2013)

Transmission electron microscopy (TEM) images of nanoparticles from the most stable gold (Au) colloidal solution (protocol 2; sample Number 2) fragmented by femtosecond-laser irradiation in pure pH = 7 water (at different magnifications). Inset shows the size (diameter) distribution 24 ± 5 nm using TEM image analysis.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3722033&req=5

f2-ijn-8-2601: Transmission electron microscopy (TEM) images of nanoparticles from the most stable gold (Au) colloidal solution (protocol 2; sample Number 2) fragmented by femtosecond-laser irradiation in pure pH = 7 water (at different magnifications). Inset shows the size (diameter) distribution 24 ± 5 nm using TEM image analysis.
Mentions: As the second protocol, we employed methods of two step femtosecond laser fragmentation procedure introduced in a previous study34 The 10 mL of nanoparticle solution prepared by the first protocol was transferred into a glass cuvette and irradiated in the very center of the cuvette, by a focused laser beam of the Yb:KGW femtosecond laser (using the same focusing lens), while the solution was stirred by a magnet to homogenize the ablation process. We used relatively low laser fluences (1 J•cm2) to avoid the phenomenon of laser-assisted plasma breakdown of the liquid but the radiation intensity was high enough to ablate the suspended nanoparticles. As shown in previous studies,32–4 when the pumping laser wavelength is relatively far from the absorption band of Au nanoparticles (depending on nanoparticle size), the nanoparticles are predominantly ablated by radiation from a white light supercontinuum (presenting a wide spectrum from ultraviolet [UV] to infrared of femtosecond pulse length), generated in the water environment due to nonlinear self-focusing effects that normally accompany femtosecond laser–liquid interaction.37 In our experiments, this white light supercontinuum was clearly visible in the liquid volume. The femtosecond-laser fragmentation process led to a change of solution color into deep (dark) red without any sign of yellow tints. Afiter 40 minutes of fragmentation, the nanoparticle solutions were extremely stable and did not show any sign of precipitation, even afiter months of storage at room temperature. As shown in Figure 2, the mean size of nanoparticles was about 24 nm, while the size dispersion was very weak (less than 10 nm FWHM). To study solution stability effects, we carried out fragmentation for 20 minutes, which led to a smaller mean size (15–17 nm) and broader size dispersion (14 nm FWHM). Samples prepared by femtosecond-laser ablation from the Au target (protocol 1; Figure 1) are referred to as sample Number 1. Samples prepared by complete and partial femtosecond-laser fragmentation (protocol 2) are referred to as Number 2 ( Figure 2) and Number 2a, respectively.

Bottom Line: Fluorescence quenching behavior and its intricacies were revealed by fluorescence lifetime imaging microscopy in rhodamine 6G water solution.We show that surface-enhanced Raman scattering of rhodamine 6G on gold nanoparticles can be detected with high fidelity down to micromolar concentrations using the nanoparticles.Application potential of pure gold nanoparticles with polydispersed and nearly monodispersed size distributions are discussed.

View Article: PubMed Central - PubMed

Affiliation: Centre for Micro-Photonics and Industrial Research Institute Swinburne, Faculty of Engineering and Industrial Sciences Swinburne University of Technology, Hawthorn, VIC, Australia.

ABSTRACT
Aqueous solutions of ultra-pure gold nanoparticles have been prepared by methods of femtosecond laser ablation from a solid target and fragmentation from already formed colloids. Despite the absence of protecting ligands, the solutions could be (1) fairly stable and poly size-dispersed; or (2) very stable and monodispersed, for the two fabrication modalities, respectively. Fluorescence quenching behavior and its intricacies were revealed by fluorescence lifetime imaging microscopy in rhodamine 6G water solution. We show that surface-enhanced Raman scattering of rhodamine 6G on gold nanoparticles can be detected with high fidelity down to micromolar concentrations using the nanoparticles. Application potential of pure gold nanoparticles with polydispersed and nearly monodispersed size distributions are discussed.

Show MeSH
Related in: MedlinePlus