Hyperspectral TERS Imaging Reveals Strain Heterogeneity in Individual Nanoplastic Particles

Area of Science:

• Environmental Science
• Materials Science
• Analytical Chemistry

Background:

• Nanoplastics present significant environmental and health concerns.
• Label-free, nondestructive detection of single nanoplastic particles is difficult.

Purpose of the Study:

• To develop a method for label-free, nondestructive chemical characterization of individual nanoplastic particles.
• To investigate intraparticle heterogeneity in nanoplastics at the single-particle level.

Main Methods:

• Atomic force microscopy-based tip-enhanced Raman spectroscopy (AFM-TERS) was employed for hyperspectral imaging.
• Characterization was performed on individual polystyrene (PS) nanoplastic particles under ambient conditions.
• Correlative AFM phase imaging was used to assess local stiffness variations.

Main Results:

• AFM-TERS achieved single-particle sensitivity for nanoplastics as small as 32 nm.
• Hyperspectral TERS maps showed significant intraparticle heterogeneity in chemical composition.
• Spectral shifts correlated with nanoscale variations in local stiffness, indicating strain heterogeneity.

Conclusions:

• AFM-TERS enables sensitive, label-free chemical mapping of individual nanoplastics.
• The study demonstrates the capability to detect and analyze intraparticle heterogeneity in nanoplastics.
• This technique offers new avenues for identifying nanoplastics and monitoring their chemical transformations in complex matrices.