Single Walled Carbon Nanotubes Exhibit Dual-Phase Regulation to Exposed Arabidopsis Mesophyll Cells.

Hengguang Yuan,Kan Wang,Shanglian Hu,Rong He,Peng Huang,Hua Song,Daxiang Cui,Jing Ruan

doi:10.1007/s11671-010-9799-3

Abstract

Herein we are the first to report that single-walled carbon nanotubes (SWCNTs) exhibit dual-phase regulation to Arabidopsis mesophyll cells exposed to different concentration of SWCNTs. The mesophyll protoplasts were prepared by enzyme digestion, and incubated with 15, 25, 50, 100 μg/ml SWCNTs for 48 h, and then were observed by optical microscopy and transmission electron microscopy, the reactive oxygen species (ROS) generation was measured. Partial protoplasts were stained with propidium iodide and 4'-6- diamidino-2-phenylindole, partial protoplasts were incubated with fluorescein isothiocyanate-labeled SWCNTs, and observed by fluorescence microscopy. Results showed that SWCNTs could traverse both the plant cell wall and cell membrane, with less than or equal to 50 μg/ml in the culture medium, SWCNTs stimulated plant cells to grow out trichome clusters on their surface, with more than 50 μg/ml SWCNTs in the culture medium, SWCNTs exhibited obvious toxic effects to the protoplasts such as increasing generation of ROS, inducing changes of protoplast morphology, changing green leaves into yellow, and inducing protoplast cells' necrosis and apoptosis. In conclusion, single walled carbon nanotubes can get through Arabidopsis mesophyll cell wall and membrane, and exhibit dose-dependent dual-phase regulation to Arabidopsis mesophyll protoplasts such as low dose stimulating cell growth, and high dose inducing cells' ROS generation, necrosis or apoptosis.

Highlights

Carbon nanotubes, as a class of stiff, stable and hollow nanomaterials with unique physical and chemical properties, have been being actively explored potential in applications such as biomedical engineering, bioelectronics, etc. [1,2,3,4,5]
We put the Arabidopsis mesophyll cells into different temperature solution such as 4, 25 and 40°C, and observed the fluorescent signal intensity, we did not observe the obvious changes of fluorescent intensity, which highly suggest that single walled carbon nanotubes (SWCNTs) likely get through plant cell wall and membrane by non-energy dependent endocytosis manner
Protoplasts often were live in washing and incubation (WI) solution for 4 days, our results showed that 50 μg/ml SWCNTs in a WI solution could speed up the death of protoplasts in WI solution, inducing green leaves into yellow leaves similar phenomena was observed for those protoplasts treated with 100 μg/ml SWCNTs in a WI solution

Summary

Introduction

As a class of stiff, stable and hollow nanomaterials with unique physical and chemical properties, have been being actively explored potential in applications such as biomedical engineering, bioelectronics, etc. [1,2,3,4,5]. As a class of stiff, stable and hollow nanomaterials with unique physical and chemical properties, have been being actively explored potential in applications such as biomedical engineering, bioelectronics, etc. Carbon nanotubes’ biosafety cause more and more attention from government and people. Arabidopsis, as an important model in plant biology and genetics, has been broadly investigated [18,19,20]. Many findings with direct relation to human health and diseases have been elaborated by using Arabidopsis thaliana, and several processes important to human biology are more studied in this versatile model plant [21]. Investigating the influence of SWCNTs on Arabidopsis thaliana owns broad representative

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Results

Discussion

Conclusion