Nile Red staining for detecting microplastics in biota: Preliminary evidence

Area of Science:

• Environmental Science
• Marine Biology
• Analytical Chemistry

Background:

• Nile Red is a lipophilic dye used for microplastic identification in biological samples.
• Its use in biota is limited due to potential overestimation from co-staining with organic residues.

Purpose of the Study:

• Investigate the limitations of using Nile Red for microplastic detection in marine biota.
• Assess the accuracy of Nile Red in identifying low-density polyethylene (LDPE) microplastics in marine mussels.

Main Methods:

• Marine mussels were experimentally contaminated with LDPE microplastics.
• Samples underwent digestion, and stained particles were visualized using high-magnification, stitched images.
• Particle recognition was evaluated based on size and fluorescence characteristics.

Main Results:

• LDPE microplastics appeared yellowish and fluorescent, posing identification challenges due to similarity with organic residues.
• Recognition difficulty increased with smaller particle size, especially for particles <180 μm.
• Particle fluorescence consistently aided in LDPE identification across all sizes.

Conclusions:

• Nile Red can be used to identify LDPE microplastics in marine mussels, but careful differentiation from organic matter is crucial.
• Particle size significantly impacts accurate identification, with smaller fragments (<180 μm) being particularly difficult to distinguish.
• The fluorescence property of Nile Red remains a valuable tool for operator-assisted identification of LDPE microplastics in biota.