Development of Labeled Polyethylene Nanoparticles as Reference Materials for the Analysis of Nanoplastics

The intern will join the CP2M laboratory (UMR 5128, UCBL–CNRS), a research team recognized for its expertise in
catalysis and polymerization. The intern will benefit from close supervision by three faculty members and research engineers, as well as access to shared analytical facilities at UCBL: NMR spectroscopy (UAR2045), electron microscopy (CTµ), and Py-GC-MS (DEEP UR 7429).

Scientific background

Plastic pollution represents a major environmental and public health threat, with polyethylene (PE) being the predominant polymer found in plastic waste. Under the effects of photochemical degradation, these wastes progressively fragment into micro- and nanoplastics (MNPs), which can enter the food chain and exert toxic effects by crossing biological barriers.
Recent studies have reported the detection of MNPs in human organs (liver, kidney, brain), mainly through pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS). However, the reliability of this technique is currently being questioned: interferences between PE carbon chains and biological lipids may lead to a significant overestimation of the measured concentrations. Furthermore, toxicological studies almost exclusively rely on commercial polystyrene nanoparticles (NPs), as PE NPs are extremely difficult to obtain commercially.
At the CP2M laboratory, an original surfactant-free aqueous emulsion polymerization process for ethylene has been developed, enabling the direct production of colloidal PE NP dispersions with controlled characteristics (size, surface charge, carbonyl index). This internship builds upon this expertise to produce labelled PE NPs, providing the missing reference materials needed in this field.

Internship Objectives
The intern will contribute to the production and characterization of two types of labelled PE nanoparticles:

• Isotopically labelled nanoparticles (deuterium, ²H) will be used as analytical standards to validate PE detection by Py-GC-MS in the presence of biological lipids, and to investigate the photodegradation of NPs using 2D NMR spectroscopy.
• Fluorescent nanoparticles (FLUO-NPs), obtained by incorporating suitable fluorophores (rhodamine B and others) during synthesis or through post-functionalization, will enable cellular and tissue tracking of NPs using flow cytometry and fluorescence microscopy.

Main Responsibilities

• Synthesis of PE nanoparticles by ethylene polymerization in aqueous emulsion (under pressure reactor)
• Incorporation of fluorophores during polymerization (through electrostatic strategies and/or covalent approaches via copolymerization with vinyl ester-type monomers)
• Synthesis of isotopically labelled PE nanoparticles (²H-ethylene)
• Comprehensive physicochemical characterization: DLS, zeta potential measurements, TEM, IR spectroscopy, NMR, UV–Vis spectroscopy, and fluorescence analysis
• Preparation of model lipid formulations and analysis by Py-GC-MS in collaboration with the DEEP laboratory (UR 7429 – INSA Lyon) and/or the IPREM laboratory (UMR 5254 – UPPA/CNRS)
• Verification of the absence of fluorophore leaching under harsh environmental conditions
• Writing of an internship report and contribution to the scientific dissemination of the project: oral or poster presentation at the next GDR Plastiques, Environnement, Santé conference

Education: Master’s Year 2 degree in Polymer Chemistry, Macromolecular Chemistry, Materials Chemistry, or a
related field.

Desired skills: A strong background in polymer chemistry and/or organic chemistry is expected, along with experience in characterization techniques such as dynamic light scattering (DLS), spectroscopy, and microscopy. An interest in aqueous-phase chemistry and emulsion processes, as well as awareness of environmental issues and analytical sciences, will be highly valued. The candidate should demonstrate autonomy, scientific rigor, and the ability to work effectively within an interdisciplinary team. Proficiency in French (minimum C1 level) is required, and experience with scientific English is an asset.