Heterodimeric particle assemblies: Preparation of anisotropically connected spherical silica particles via surface-bound gold nanoparticles

Ohnuma, Akira; Abe, Ryu; Shibayama, Tamaki; Ohtani, Bunsho

doi:10.1039/b705697d

Cited by 21 publications

(9 citation statements)

References 18 publications

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“…50 15 To check which hypothesis is correct, we examined indirect modification of titania with gold through connection with thiol groups, as we previously used for heterodimeric particle assemblies of a silica-gold-silica structure. 51 If hypothesis (b) is correct, direct deposition of gold on the titania surface (electronic contact) would not be necessary, as LSPR is observed up to tens of nanometers from the gold nanoparticle. 41 However, preliminary 20 results suggest that direct electron transfer from gold to titania as the reaction rate was dramatically decreased by deposition of gold on the modified titania surface.…”

Section: (2)mentioning

confidence: 99%

Visible-light-induced photocatalysis through surface plasmon excitation of gold on titania surfaces

Kowalska

Mahaney

Abe

et al. 2010

Phys. Chem. Chem. Phys.

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514

419

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Fifteen commercial titania (titanium(IV) oxide; TiO 2 ) powders were modified with gold by photodeposition to prepare photocatalysts that work under irradiation with light in the visible range (vis). The gold-modified titania (Au/TiO 2 ) powders were characterized by diffuse reflectance spectroscopy (DRS), field-emission scanning electron microscopy (FE-SEM), scanning transmission microscopy (STEM) and X-ray powder diffraction analysis (XRD). It was shown that all tested powders could absorb visible light with an absorption maximum at localized surface plasmon resonance (LSPR) wavelengths (530-600 nm) and that the size and shape of gold nanoparticles determined absorption ranges.The photocatalytic activity of Au/TiO 2 powders was examined both under ultraviolet and vis irradiation (mainly >450 nm) for acetic acid and 2-propanol photooxidation. It was found that the activity depended strongly on gold and titania properties, such as particle size and shape, surface area and crystalline form. Under vis irradiation, large rutile particles loaded with gold particles of a wide range of sizes showed the highest level of photocatalytic activity, possibly due to greater light absorption ability in a wide wavelength range resulting from transverse and longitudinal LSPR of rod-like gold particles. Action spectrum analyses showed that visible light-induced oxidation of organic compounds by aerated gold-titania suspensions was initiated by excitation of LSPR absorption of gold. Although photocatalytic activity of nanosized gold particles under vis irradiation with a wavelength of ca. 430 nm and catalytic activity of goldmodified titania during dark reaction were also found, it was shown that the activities of 2 Au/TiO 2 particles originated from activation of LSPR of gold by light of wavelength of 530-650 nm. Participation of molecular oxygen as an electron acceptor and titania as a conductor of electrons was suggested by comparison with results obtained under deaerated conditions and results obtained using a system containing gold-deposited silica instead of gold-titania, respectively. On the basis of these results, the mechanism of visible light-induced oxidation of organic compounds on gold-titania is proposed. IntroductionTitanium(IV) oxide (TiO 2 ; titania) is an inexpensive particulate material that is readily available and has substantial photocatalytic activity, stability toward inorganic and organic compounds and non-toxicity. 1 However, one drawback of titania is that it can only be excited by ultraviolet light, i.e., with wavelengths shorter than ca. 400 nm.Therefore, only a very small portion of solar radiation (3-5%) can be utilized to drive chemical reactions. 2 Thus, extension of its absorption wavelength range to the visible region (vis) is an important issue. Another important issue is improvement of quantum efficiency, i.e., an efficiency of utilization of the photoexcited state of photocatalysts, since an electronic excited state of titania is deactivated by recombination of electrons and holes to lower qu...

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Section: (2)mentioning

confidence: 99%

Visible-light-induced photocatalysis through surface plasmon excitation of gold on titania surfaces

Kowalska

Mahaney

Abe

et al. 2010

Phys. Chem. Chem. Phys.

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514

419

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“…Finally, resulting SAMs patterns were immersed into the aqueous colloidal solution of citrate-stabilized Au nanoparticles in order to attach the nanoparticles onto them. In the sample preparation for Au nanoparticles, an aqueous colloidal solution of citrate-stabilized gold nanoparticles was prepared following the method of Frens [21][22][23]. The structure obtained was imaged with a FE-SEM and the position control of Au nanoparticles was characterized.…”

Section: Methodsmentioning

confidence: 99%

Controlled Array of Gold Nanoparticles by Combination of Nano Imprint and Self-assembly

Yamamoto

Ohnuma

Ohtani

et al. 2016

J. Photopol. Sci. Technol.

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The fundamental limitations associated with top-down lithographic techniques gradually have approached. One of methods to overcome these limitations is the combination technique of top-down nanofabrication such as nano imprint and bottom-up nanofabrication such as self-assembly. Nanoparticles has been expected to use as the building blocks. In order to realize this method, it is desirable to place nanometer sized components such as nanoparticles in exact positions for nano-fabrication with high precision and reproducibility. In particular, gold (Au) nanoparticles, which covalently linked to biomolecules such as DNA, peptides, nucleic acids, proteins, and cell have attracted much attention for biosensing, bioimaging, and plasmonics application, and so on. In this study, we present a simple method of controlled array of Au nanoparticles on a nanopattern by the combination of self-assembly techniques bottom-up nano-fabrication such as self-assembled monolayers and top-down nano-fabrication such as nano imprint. We believe this method will contribute to studies on the observation of single biomolecules such as DNA, peptides, nucleic acids, proteins, plasmonics and so on.

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“…Finally, resulting SAMs patterns were immersed into the aqueous colloidal solution of citrate-stabilized Au nanoparticles in order to attach the nanoparticles onto them. In the sample preparation for Au nanoparticles, an aqueous colloidal solution of citrate-stabilized gold nanoparticles was prepared following the method of Frens [27][28][29]. The structure obtained was imaged with a FE-SEM and the position control of Au nanoparticles was characterized.…”

Section: Methodsmentioning

confidence: 99%

Position Control of Metal Nanoparticles by Self-Assembly

Yamamoto

Ohnuma

Ohtani

et al. 2014

J. Photopol. Sci. Technol.

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Bottom-up self-assembly has the capacity to overcome the limitation of top down nanofabrication. Recently, nanoparticles or molecules are expected to use as the building blocks. By using them it is desirable to place nanometer sized components such as nanopartilces in exact positions for nano-fabrication with high precision and reproducibility. In particular, gold (Au) nanoparticles, which covalently linked to biomolecules such as DNA, peptides, nucleic acids, proteins, and cell have attracted much attention for biosensing application, bioimaging application and so on. In this study, we present a novel and simple method of position control of Au nanoparticles on a nanopattern by self-assembly techniques such as block copolymer phase separation and self-assembled monolayers. Spherical Au nanoparticles were immobilized above the Au nanopatterns with a gap of a few nanometers. We believe this method will contribute to studies on the observation of single biomolecules such as DNA, peptides, nucleic acids, proteins, and so on.

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Heterodimeric particle assemblies: Preparation of anisotropically connected spherical silica particles via surface-bound gold nanoparticles

Abstract: Assemblies of heterodimeric particles were prepared through selective coupling of two kinds of spherical silica particles of different sizes by connection with gold nanoparticles attached anisotropically to the particles

Cited by 21 publications

References 18 publications

Visible-light-induced photocatalysis through surface plasmon excitation of gold on titania surfaces

Visible-light-induced photocatalysis through surface plasmon excitation of gold on titania surfaces

Controlled Array of Gold Nanoparticles by Combination of Nano Imprint and Self-assembly

Position Control of Metal Nanoparticles by Self-Assembly

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