Flow cytometric investigation of the toxic effects of nanoparticles on bacteria is highly challenging due to the interference of aggregated nanoparticles: aggregated nanoparticles and bacteria are similar in size.

Prof. WU Lijun and prof. XU An in Institute of Technical Biology & Agriculture Engineering, Hefei Institutes of Physical Science (CAHIPS), has made great progress in establishing a dual fluorescence analysis to assess the toxicity of silver nanoparticles (AgNPs) in Escherichia. coli. Their study entitled Investigating the environmental factors affecting the toxicity of silver nanoparticles in Escherichia. coli with dual fluorescence analysiswas published in Chemosphere.

In their study, researchers employed PI-Lac::GFP (propidium iodide stained Escherichia. coli (Lac::GFP)) to develop a high-performance analytical method for accurate and sensitive evaluation of AgNPs toxicity. Besides, the GFP fluorescence was used to distinguish living E.coli cells from aggregated nanoparticles and dead cells, and PI was employed to differentiate dead or compromised cells from living cells and aggregated nanoparticles.

Compared with single fluorescence analysis, this dual fluorescence analysis enabled more accurate evaluation of the toxic effects of AgNPs. Using this dual fluorescence analysis, they investigated how AgNPs toxicity affected by two typical environmental factors, divalent metal ions and surfactants. The data revealed that Cu²⁺ and SDS significantly enhanced toxicity of AgNPs. Their results suggested that this dual fluorescence analysis can be used to accurate and sensitive evaluation of the AgNPs toxicity.

This study was sponsored by grants from Major National Scientific Research Projects and Strategic Leading Science & Technology Program (B).

 Schematic drawing of detecting the toxicity of silver nanoparticles in Escherichia. coli with dual fluorescence analysis. (Image by HONG Wei)

Contact:

CHEN Shaopeng, Ph.D

Institute of Technical Biology & Agriculture, Hefei Institutes of Physical Science

Hefei, Anhui 230000, P. R. China

Tel.: +86-551-65593096.

Fax: +86-551-65595670.

E-mail addresses: spchen035@ipp.ac.cn.