Raman Tweezers for Small Microplastics and Nanoplastics Identification in Seawater.

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Current methods for detecting micro- and nanoplastics in marine environments face significant challenges in particle detection, quantification, and chemical identification.
• Existing techniques like light scattering, vibrational spectroscopies, and microscopy have limitations in analyzing small particles in liquid media.

Purpose of the Study:

• To introduce Raman Tweezers (RTs) as a novel analytical tool for studying micro- and nanoplastics in seawater.
• To demonstrate the capability of RTs for optical trapping and chemical identification of plastic particles down to the nanometer range.

Main Methods:

• Raman Tweezers (RTs) combine optical tweezers with Raman spectroscopy for single-particle analysis.
• The technique allows for optical trapping and chemical identification of sub-20 μm plastic particles, including those as small as 50 nm.
• RTs provide single-particle analysis, enabling discrimination from organic matter and mineral sediments, unlike standard Raman spectroscopy in liquid.

Main Results:

• Successfully demonstrated optical trapping and chemical identification of micro- and nanoplastics (down to 50 nm) in seawater.
• RTs enabled unambiguous discrimination of plastic particles from environmental matrices at the single-particle level.
• The technique accurately assessed the size and shape of various plastic types (polyethylene, polypropylene, nylon, polystyrene) including aged environmental samples and particles with eco-coronas.

Conclusions:

• Raman Tweezers offer a powerful new capability for the analysis of micro- and nanoplastics in marine environments.
• This technique overcomes limitations of conventional methods, enabling detailed study of plastic pollution.
• RTs have the potential to significantly advance research on micro- and nanoplastics, including fragmentation processes.