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BMC Proceedings

Open Access

Size-dependent antioxidative activity of platinum nanoparticles

  • Hidekazu Nakanishi1,
  • Takeki Hamasaki2,
  • Tomoya Kinjo1,
  • Kiichiro Teruya1, 2,
  • Shigeru Kabayama3 and
  • Sanetaka Shirahata1, 2
BMC Proceedings20137(Suppl 6):P41

https://doi.org/10.1186/1753-6561-7-S6-P41

Published: 4 December 2013

Background

So far, most of studies on nanometer-sized metal particles have focused on biological safety and potential hazards. However, anti-oxidative activity of noble metal nanoparticles (NPs) attracts much attention, recently. Platinum nanoparticles (Pt NPs) are one of the most important noble metals in nanotechnology because Pt NPs have negative surface potential from negative charges and are stably suspended from an electric repulsion between the same charged particles [1]. We previously reported that Pt NPs of 2-3 nm sizes scavenged reactive oxygen species (ROS) such as superoxide anion radical, hydrogen peroxide and hydroxyl radical in vitro [2]. Here, we report the cytotoxicity and size-dependent antioxidative activity of Pt NPs on rat skeletal muscle cell line, L6.

Materials and methods

Pt NPs were synthesized by a modified citrate reduction method of Hydrogen hexachloroplatinate (IV). Particle size and concentrations of Pt NPs were determined by a transmittance electron microscope (TEM) and ICP-MS, respectively. To find the toxic effect of Pt NPs rat myoblast L6 cells were pre-cultured for 24 hours in culture medium with a 10-3 to 10 mg/l of Pt NPs and cell viability was determined by WST-1 assay. To investigate the anti-oxidative effect of Pt NPs on L6 cells, the relative amount of intracellular H2O2 was measured with a Bes-H2O2-AC florescent probe, which is designed to detect intracellular H2O2 specifically [3]. The intracellular ROS levels when treated with 1 mg/l of Pt NPs for 2 hours were measured using IN Cell Analyzer 1000.

Results and conclusions

The particle sizes we synthesized were determined to 1-2 nm, 2-3 nm and 4 nm respectively (data not shown). Cytotoxicity of Pt NPs of these sizes was not observed at a concentration below 10 mg/l (data not shown). Intracellular ROS levels are thought to result from a primary response to internalized NPs leading to decreased cell viability [4]. Thus, the suppression of excess ROS is of prime importance for cell survival. The intracellular ROS levels were decreased significantly by the whole sizes of Pt NPs treatment and 2-3 nm of Pt NPs scavenged the ROS most efficiently (Figure 1). The relative fluorescence level treated with 2-3 nm of Pt NPs decreased significantly to about 60% (*** P < 0.001) compared with that of non-treated cells. Smaller NPs should be more taken up by the cells efficiently and might more scavenge ROS effectively [5]. However, the Pt NPs of 1-2 nm less scavenged the intracellular ROS than that of 2-3 nm. The one reason might be that 1-2 nm of Pt NPs is rather too small to activate intracellular anti-oxidant defense pathways than 2-3 nm of Pt NPs because of their less cytotoxicity. However, we have no data to show. Therefore, we have to make more effort to investigate the relationship between the sizes of Pt NPs and ROS scavenging activity.
Figure 1

The scavenging effect of several sized Pt NPs on intracellular hydrogen peroxide in L6 cells. Asterisks donate significant difference from the untreated control cells. (***P < 0.001).

Our results suggest Pt NPs of 2-3 nm sizes have no cytotoxity below 10 mg/l and are useful materials to scavenge ROS. In this regard Pt NPs are expected as redox regulation factors for suppression of various ROS-related diseases.

Authors’ Affiliations

(1)
Division of Life Engineering, Graduate School of Systems Life Sciences, Kyushu University
(2)
Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University
(3)
Nihon Trim Co. Ltd

References

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Copyright

© Nakanishi et al.; licensee BioMed Central Ltd. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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