Inhibiting Au nanoparticle aggregation in freeze-thawing by presence of various additives

Miki Kadowaki, Hidetaka Yokota, Hiroyuki Imanaka, Naoyuki Ishida, Koreyoshi Imamura

Research output: Contribution to journalArticlepeer-review

Abstract

After freezing aqueous suspensions of gold nanoparticles (AuNPs) in the presence of various substances, the resulting aggregation of the nanoparticles was evaluated and the anti-aggregation effects of the different additives were compared. Many of the additives exhibited an anti-aggregation effects during freeze-thawing, the extent of which was greater at higher additive concentrations and the effects were 5 ~ 35% less than during the actual freeze-drying. Dextran and polyvinylpyrrolidone highly inhibited the aggregation even at markedly low additive concentrations (2 µg/mL). The use of a combination of a disaccharide (2 mg/mL of sucrose) and a sugar ester (20 µg/mL of sucrose palmitate) successfully preserved the redispersibility of the product after freeze-thawing while using each separately did not. Regarding the influence freezing and thawing conditions, a higher thawing temperature (from 4˚C to 60˚C) resulted in 10 ~ 20% better redispersibility of the AuNPs whereas the freezing temperature had no significant affect. The effect of freezing/thawing cycles of suspensions of AuNPs was also examined. The concentration of additive molecules on the surfaces of the frozen particles was monitored by In-situ Fourier transform IR spectroscopy. The collective findings of this study indicate that the additives essentially exert an anti-aggregation effect by slowing down the movement of the AuNPs.

Original languageEnglish
JournalAdvanced Powder Technology
DOIs
Publication statusAccepted/In press - 2021

Keywords

  • Additives
  • Aggregation
  • Freezing
  • Gold nano particles
  • Redispersibility
  • Suspension
  • Thawing

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Mechanics of Materials

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