Kinetic analysis of superoxide anion radical-scavenging and hydroxyl radical-scavenging activities of platinum nanoparticles

Takeki Hamasaki, Taichi Kashiwagi, Toshifumi Imada, Noboru Nakamichi, Shinsuke Aramaki, Kazuko Toh, Shinkatsu Morisawa, Hisashi Shimakoshi, Yoshio Hisaeda, Sanetaka Shirahata

Research output: Contribution to journalArticlepeer-review

131 Citations (Scopus)

Abstract

There are few reports on the physiological effects of metal nanoparticles (nps), especially with respect to their functions as scavengers for superoxide anion radical (O2.-) and hydroxy 1 radical (·OH). We tried to detect the scavenging activity of Pt nps using a hypoxanthine-xanthine oxidase system for O2.- and using a Fenton and a UV/H2O2 system for ·OH. Electron spin resonance analysis revealed that 2 nm particle size Pt nps have the ability to scavenge O2.- and ·OH. The calculated rate constant for the O2.-scavenging reaction was 5.03 ± 0.03 × 107 M-1 s-1. However, the analysis of the Fenton and UV/H2O2 system in the presence of Pt nps suggested that the ·OH-scavenging reaction cannot be determined in both systems. Among particle sizes tested from 1 to 5 nm, 1 nm Pt nps showed the highest O2.-scavenging ability. Almost no cytotoxicity was observed even after adherent cells (TIG-1, HeLa, HepG2, WI-38, and MRC-5) were exposed to Pt nps at concentrations as high as 50 mg/L. Pt nps scavenged intrinsically generated reactive oxygen species (ROS) in HeLa cells. Additionally, Pt nps significantly reduced the levels of intracellular O 2.- generated by UVA irradiation and subsequently protected HeLa cells from ROS damage-induced cell death. These findings suggest that Pt nps may be a new type of antioxidant capable of circumventing the paradoxical effects of conventional antioxidants.

Original languageEnglish
Pages (from-to)7354-7364
Number of pages11
JournalLangmuir
Volume24
Issue number14
DOIs
Publication statusPublished - Jul 15 2008

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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