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New techniques to understand nanoplastics

Dangerous micro- and nano-plastics, found throughout our environment, have been linked to serious health consequences. A new approach to analysing these types of samples using Raman microscopy is being trialled at Flinders Microscopy and Microanalysis and is overcoming imaging limitations to help us understand nanoplastics, so we can better manage this emerging environmental and health challenge.

Microplastics, generated from things like washing synthetic clothes to the abrasion of tyres, are becoming ubiquitous in our environment. They have been detected everywhere from the air and ocean to fresh water and food. Microplastics can accumulate in the bodies of the animals and humans that ingest them, and could contribute to cancer, birth defects and unwanted immune responses.

Of increasing concern are nanoplastics. While microplastics range in size from 5mm to 1μm, one percent of the width of a human hair, nanoplastics include anything below this. A full understanding of the kinds of nanoplastics in our environment is currently hampered by the limited resolution of the microscopy techniques currently used for imaging these plastics.

Micrographs of nanoplastics. Optical micrograph (a), Scanning Electron Microscopy image (b), Raman mapping image (c) and typical spectra from the Raman mapping (d). Reproduced, with permission, from Identification and visualisation of microplastics/nanoplastics by Raman imaging (i): Down to 100 nm,
Water Research, Volume 174, 2020, 115658, ISSN 0043-1354

To overcome this challenge, the Microscopy Australia team at Flinders Microscopy and Microanalysis are trialling Raman mapping for imaging nanoplastics. The research lead by scientists from the University of Newcastle, involves optimising existing Raman mapping techniques to allow imaging and composition of nanoplastics down to 100nm, less than the wavelength of visible light. Raman is far more sensitive and specific than the current methods and allows the type of plastic to be identified. By using Raman to identify the type of plastic in each particle, researchers have a chance to identify their likely source, and if they are a hazard to human health.

“We urgently need to know more about the health impact of microplastics because they are everywhere –  including in our drinking-water,” says Dr Maria Neira, Director of the Department of Public Health, Environment and Social Determinants of Health at WHO, in a recent report on microplastic in our water.

Read the paper in Water Research.

Story published 28 May 2021