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Published on: December 22, 2015
Label-Free Two-Photon Spectral Microscopy to Track Black Carbon Fate in Live Copepod.
Maria L F Vicente1,2, Jeanne Blanchet2, Mariana M Veras3
1São Carlos Institute of Physics, University of São Paulo, São Carlos 13566-590, Brazil.
Environmental Science & Technology
|May 25, 2026
Summary
Researchers used two-photon spectral microscopy to track black carbon (BC) uptake in zooplankton. They observed BC transformation within the gut, revealing new insights into marine pollutant interactions and carbon cycling.
Area of Science:
- Marine biology
- Environmental science
- Biophysics
Background:
- Black carbon (BC) is a significant climate forcer and marine pollutant from incomplete combustion.
- Biological interactions and transformations of BC in marine organisms are poorly understood.
- Current methods lack the resolution to study BC at a molecular level within live organisms.
Purpose of the Study:
- To apply two-photon (2P) spectral microscopy for tracking BC uptake and transformation in live zooplankton.
- To establish a label-free method for discriminating BC from biological autofluorescence and food pigments.
- To investigate the in vivo changes in BC aggregation state within the marine zooplankton gut.
Main Methods:
- Utilized two-photon (2P) spectral microscopy for label-free, high-resolution 3D visualization of copepods (Acartia spp.).
- Developed spectral mapping techniques to differentiate particulate BC (PBC) and dissolved/colloidal BC (DBC) based on intrinsic photophysical properties.
- Established a pigment-free intestinal baseline by coupling intestinal clearing protocols with spectral mapping.
- Quantified intestinal swelling using a dimensionless ratio (d/D) as an indicator of gut distension.
Main Results:
- Demonstrated 2P spectral microscopy's capability to track BC uptake and localization in the digestive tract of live copepods.
- Observed partial reorganization of particulate BC (PBC) into colloidal fractions (DBC-like emission) within the posterior gut.
- Documented intestinal swelling correlated with BC ingestion, quantified by the d/D ratio.
- Provided the first pigment-free intestinal baseline for marine zooplankton, eliminating interference from autofluorescence and food pigments.
Conclusions:
- Two-photon spectral microscopy offers a powerful, label-free approach to study pollutant-organism interactions at a molecular level.
- Black carbon undergoes biological transformation within the zooplankton gut, generating colloidal fractions.
- These findings advance our understanding of marine pollutant dynamics and their implications for marine carbon cycling.
