Bundled Up Nanorods Detect Pesticides In Water

These silver nanorod bundles make it possible to sensitively and reliably detect pesticides in environmental samples.

AsianScientist (Nov. 15, 2016) – Researchers in China have developed a simple and inexpensive method of producing pesticide-detecting nanorods. Their findings have been published in Advanced Materials.

Excessive exposure to pesticides can cause severe side effects. In particular, chronic exposure to pesticides is a growing concern; environmental contamination is now so widespread that pesticides have even been detected in human breast milk.

Currently, pesticides are measured with large-scale analytical instruments such as high-performance liquid chromatographs. Portable but sensitive sensors are urgently needed for monitoring pesticide levels in the field. Surface-enhanced Raman scattering (SERS) devices have emerged as a promising solution, but developing SERS substrates that are suitably reliable and sensitive has remained a challenge.

Working with researchers at West Virginia University and the Institute of Technical Biology and Agricultural Engineering, a team led by Professor Meng Guowen at the Hefei Institutes of Physical Science, Chinese Academy of Sciences, has developed a simple and cost-effective method to fabricate ordered arrays of silver nanorod bundles that can reliably detect pesticides in water.

Each nanorod bundle consisted of 30-45 nanorods. The small gaps formed between adjacent nanorods created a large number of high-density “hot spots” which enhanced the scattering of photons by up to 108 times. Simulations showed that this high sensitivity was due to strong electromagnetic field coupling between the neighboring nanorods.

Importantly, the SERS signals generated by the nanorod bundle array were reliable and reproducible, with characteristic peak intensities that had a relative standard deviation of less than ten percent. The nanorod bundle array was successfully used to detect trace phenolic pollutants such as methyl parathion (an organophosphorous pesticide), 2,4-dichlorophenoxyacetic acid (2,4-D, an organochlorine pesticide), and a mixture of the two pesticides.

This work sheds new light on nanoscale fabrication of a large-area, highly ordered nanorod bundle array with good uniformity and reproducibility, facilitating the application of SERS detection in chemical analysis, environmental monitoring, food safety and healthcare.

The article can be found at: Zhu et al. (2016) A Hierarchically Ordered Array of Silver-Nanorod Bundles for Surface-Enhanced Raman Scattering Detection of Phenolic Pollutants.


Source: Chinese Academy of Sciences; Photo: Pixabay.
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