Fluorescently labeled cellulose nanofibrils for detection and loss analysis

Area of Science:

• Materials Science
• Food Safety
• Nanotechnology

Background:

• Cellulose nanofibrils (CNFs) are increasingly used in various applications, including food packaging.
• Assessing the safety of CNFs, particularly their potential leaching from materials, is crucial for food contact applications.
• Standardized methods are needed to quantify CNF migration and ensure consumer safety.

Purpose of the Study:

• To develop and validate a method for detecting and quantifying cellulose nanofibril (CNF) leaching from paper-based food contact materials.
• To evaluate the suitability of fluorescently labeled CNFs as a mimic for native CNFs in safety assays.
• To determine the extent of CNF loss from paper under different conditions (e.g., water temperature).

Main Methods:

• Cellulose pulp was labeled with 5-([4,6-Dichlorotriazin-2-yl]amino)fluorescein hydrochloride (DTAF) to create fluorescent CNFs.
• Fluorescent CNFs were incorporated into laboratory paper formulations (100% CNF and CNF-fiber blends).
• Standard cold and hot-water extraction assays were performed to measure CNF leaching, with detection limits around 20 ppb.

Main Results:

• DTAF labeling allowed for quantitative detection of CNFs at parts-per-billion (ppb) levels without significantly altering material properties.
• Leaching of CNFs from paper samples was found to be below 3 wt% under both cold and hot water conditions.
• Finer CNF quality exhibited lower leaching, and hot water extraction resulted in greater CNF loss compared to cold water extraction.

Conclusions:

• DTAF-labeled CNFs serve as a reliable mimic for native CNFs in safety evaluations.
• The developed fluorescence-based method is effective for detecting low concentrations of CNFs and assessing their leaching behavior.
• CNF leaching from paper food contact materials is minimal, providing valuable data for safety assessments and material development.