Recovery and redispersion of gold nanoparticles using the self-assembly of a pH sensitive zwitterionic amphiphile

Morita-Imura, Clara; Imura, Yoshiro; Kawai, Takeshi; Shindo, Hitoshi

doi:10.1039/c4cc04935g

Cited by 24 publications

(38 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the zwitterionic state of C16CA at pH 4 (Figure 1b), the amine groups are protonated and tend to neutralize the anionic charge of the carboxylate groups by ion complexation. 28 Thus, the hydrophilicity of C16CA decreased around the isoelectric point of pH ∼ 3.5. It was also noted that the strong molecular packing of the long alkyl chains (C 16 H 33 ) of C16CA induced lamellar structure formation in water.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

See 1 more Smart Citation

Stimuli-Responsive Extraction and Ambidextrous Redispersion of Zwitterionic Amphiphile-Capped Silver Nanoparticles

et al. 2016

Self Cite

View full text Add to dashboard Cite

Citrate-stabilized silver nanoparticles (AgNPs) were functionalized with a pH-responsive amphiphile, 3-[(2-carboxy-ethyl)-hexadecyl-amino]-propionic acid (C16CA). At pH ∼ 4, the zwitterionic C16CA assembled into lamellar structures due to the protonation of the amine groups of the amphiphile that neutralized the anionic charge of the carboxylate groups. The lamellar supramolecules incorporated the AgNPs into their 3D network and extracted them from water. C16CA supramolecules dissolved into water (at pH > 6) and organic solvents; consequently, the recovered C16CA-AgNPs were redispersed not only to water but also to chloroform and tetrahydrofuran without any additional functionalization. C16CA acted as a pH-responsive stabilizer of AgNPs and formed a solvent-switchable molecular layer such as a bilayered structure in water and densely packed monolayer in chloroform and tetrahydrofuran. Redispersion of the AgNPs was achieved in different solvents by changing the solvent affinity of the adsorbed C16CA molecular layer based on the protonation of the amine groups of the pH-responsive amphiphile. The morphology of redispersed AgNPs did not change during the recovery and redispersion procedure, due to the high steric effect of the network structure of C16CA supramolecules. These observations can lead to a novel solvent-exchange method for nanocrystals without aggregation and loss of nanocrystals, and they enable effective preparations of stimuli-responsive plasmonic nanomaterials.

show abstract

Section: ■ Results and Discussionmentioning

confidence: 98%

“…28,29 The lamellar supramolecules of C16CA have been found to incorporate gold nanocrystals with a spherical or rod-like morphology due to the adsorption of the amphiphile on the metal surface. Carboxyl and amine groups also adsorb onto silver surfaces 32,33 such as amino acid or DNA.…”

Section: ■ Introductionmentioning

confidence: 99%

Stimuli-Responsive Extraction and Ambidextrous Redispersion of Zwitterionic Amphiphile-Capped Silver Nanoparticles

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…Over the past few decades, the continuous development of new routes for the synthesis of NCs has resulted in the availability of NCs with desired sizes, size distributions, shapes and compositions . Recently, the preparation and application of NCs that respond to external stimuli, such as light, temperature and pH, have become attractive . It is known that external‐stimuli‐responsive NCs are applied in sensors, photochromic paper, and novel NC recovery systems .…”

Section: Introductionmentioning

confidence: 99%

“…Recently, the preparation and application of NCs that respond to external stimuli, such as light, temperature and pH, have become attractive . It is known that external‐stimuli‐responsive NCs are applied in sensors, photochromic paper, and novel NC recovery systems . External‐stimuli‐responsive NCs have often been prepared using capping agents that respond to external stimuli .…”

Section: Introductionmentioning

confidence: 99%

“…It is known that external‐stimuli‐responsive NCs are applied in sensors, photochromic paper, and novel NC recovery systems . External‐stimuli‐responsive NCs have often been prepared using capping agents that respond to external stimuli . However, the external‐stimuli‐responsive capping agent can only be used to prepare specific external‐stimuli‐responsive metal NCs due to the low stability of metal NCs.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

pH‐Responsive Supported and Unsupported Gold Nanocrystals

Imura

Morita-Imura

et al. 2017

ChemistrySelect

Self Cite

View full text Add to dashboard Cite

The pH-responsive zwitterionic amphiphile (C18Tyr) was used for the functionalization of unsupported Au nanocrystals, a SiO 2 support, and SiO 2 -supported Au nanocrystals in a biphasic water/chloroform system, for useful supported nanomaterials. The solubility of C18Tyr was controlled by adjusting the pH of the water/chloroform system; at pH 8.0 and 3.5, almost all of the C18Tyr dissolved in the water and chloroform phases, respectively. This pH-dependent solubility control is due to protonation/deprotonation of the amino and carboxyl groups of C18Tyr. The unsupported Au nanocrystals in C18Tyr/water/ chloroform were reversibly transferred between the water and chloroform phases by pH control, but the phase transfer yield was low due to the aggregation and deposition of Au nanocrystals. Therefore, we prepared pH-responsive supported nanocrystals, as they are known to have high stabilities compared to unsupported nanocrystals. The SiO 2 support, without Au nanocrystals, was reversibly dispersed and precipitated in the C18Tyr/water/chloroform system by pH control, and not reversibly transferred between the water and chloroform phases. SiO 2 -supported Au nanocrystals were also reversibly dispersed and precipitated as was observed for the SiO 2 support. Therefore, the dispersion-precipitation response of the SiO 2 -supported Au nanocrystals is due to the SiO 2 support, not the Au nanocrystals. Furthermore, no loss of Au nanocrystals was observed due to the improved stability of the Au nanocrystals supported by this method. These results are very useful for preparation and application of externally responsive supported nanocrystals with high stabilities.

show abstract

Ultrafine Au and Ag Nanoparticles Synthesized from Self‐Assembled Peptide Fibers and Their Excellent Catalytic Activity

Hong

et al. 2016

ChemPhysChem

View full text Add to dashboard Cite

The self-assembly of an amphiphilic peptide molecule to form nanofibers facilitated by Ag(+) ions was investigated. Ultrafine AgNPs (NPs=nanoparticles) with an average size of 1.67 nm were synthesized in situ along the fibers due to the weak reducibility of the -SH group on the peptide molecule. By adding NaBH4 to the peptide solution, ultrafine AgNPs and AuNPs were synthesized with an average size of 1.35 and 1.18 nm, respectively. The AuNPs, AgNPs, and AgNPs/nanofibers all exhibited excellent catalytic activity toward the reduction of 4-nitrophenol, with turnover frequency (TOF) values of 720, 188, and 96 h(-1) , respectively. Three dyes were selected for catalytic degradation by the prepared nanoparticles and the nanoparticles showed selective catalysis activity toward the different dyes. It was a surprising discovery that the ultrafine AuNPs in this work had an extremely high catalytic activity toward methylene blue, with a reaction rate constant of 0.21 s(-1) and a TOF value of 1899 h(-1) .

show abstract

Recovery and redispersion of gold nanoparticles using the self-assembly of a pH sensitive zwitterionic amphiphile

Cited by 24 publications

References 34 publications

Stimuli-Responsive Extraction and Ambidextrous Redispersion of Zwitterionic Amphiphile-Capped Silver Nanoparticles

Stimuli-Responsive Extraction and Ambidextrous Redispersion of Zwitterionic Amphiphile-Capped Silver Nanoparticles

pH‐Responsive Supported and Unsupported Gold Nanocrystals

Ultrafine Au and Ag Nanoparticles Synthesized from Self‐Assembled Peptide Fibers and Their Excellent Catalytic Activity

Contact Info

Product

Resources

About