Measurement of Microplastics in Mouse Lung Tissue by 3D Measuring Laser Microscope and Infrared and Raman Microscope

Importance of the topic

Microplastics measuring less than 5 mm have emerged as a pervasive environmental contaminant. Their unintended ingestion and inhalation can lead to physical obstruction and potential chemical toxicity in organs including lungs and gastrointestinal tract. Reliable detection and identification of microplastics in biological tissues are therefore essential for assessing health risks and understanding the fate of pollutants in living systems.

Objectives and overview of the study

This application study presents a combined workflow for screening and identifying microplastics in mouse lung tissue. Simulated 3 µm polystyrene particles were administered by inhalation to an experimental mouse. The approach uses the OLS5100 3D measuring laser microscope for rapid scanning and morphological characterization, followed by qualitative identification via Raman spectroscopy using the AIRsight infrared and Raman microscope.

Methodology and instrumentation

Biological sample preparation

• Lung tissue slices containing simulated microplastics were frozen, stored, then thawed and dried on glass slides.

Microscopic screening with OLS5100

• Laser scanning microscope (405 nm) captured high-resolution 2D and 3D images across wide fields (up to 5120 µm × 5120 µm).
• Particle analysis algorithms extracted characteristic parameters (diameter, height) to locate candidate spherical particles (~3 µm).

Raman identification with AIRsight

• Wide-view camera (up to 10 mm × 13 mm) guided positioning to match OLS5100 coordinates.
• 785 nm excitation, 100× objective, 5 s exposure, 5 accumulations collected Raman spectra from each candidate.

Main results and discussion

Screening with the OLS5100 revealed spherical objects around 3 µm diameter in two lung tissue samples (A and B). High-magnification color and height images showed distinct reflectivity and topography for these particles. Raman spectra collected by AIRsight confirmed the identity of the spherical particle in sample B as polystyrene by matching library peaks. No characteristic peaks were observed for the particle in sample A, indicating it was not the administered microplastic. The difference in color tone and height contrast in LSM images proved valuable for distinguishing true microplastics from other tissue features.

Benefits and practical applications

This two-step technique offers several advantages:

• High-throughput screening across wide fields significantly reduces the time spent in spectroscopic measurement.
• Combined morphological and chemical data enable confident particle identification.
• Micron-scale resolution allows detection of extremely small microplastics within complex biological matrices.

Instrumentation used

OLS5100 3D measuring laser microscope (405 nm laser) 
AIRsight infrared and Raman microscope with CCD detector, 785 nm excitation, 100× objective

Future trends and possibilities

Advances could include automated image recognition and particle tracking, expansion to smaller nanoplastic analysis, integration with complementary spectroscopies (e.g. FT-IR imaging), and application in clinical or environmental monitoring. Machine learning algorithms may further streamline the workflow for high-throughput analysis in diverse tissue types.

Conclusion

The combined use of OLS5100 for rapid morphological screening and AIRsight for Raman-based chemical identification provides an effective workflow for detecting and identifying microplastics in lung tissue. This approach enhances throughput and confidence in microplastic analysis in biomedical research and environmental toxicology.

Reference

1) Lina Fu, Jing Li, Guoyu Wang, “Adsorption behavior of organic pollutants on microplastics,” Ecotoxicology and Environmental Safety, Volume 217, 112207, July 2021.