Alexa fluor-labeled fluorescent cellulose nanocrystals for bioimaging solid cellulose in spatially structured...

Area of Science:

• Materials Science
• Biotechnology
• Nanotechnology

Background:

• Cellulose nanocrystals (CNCs) are versatile nanomaterials with potential in various applications.
• Developing methods to track CNCs in complex environments is crucial for understanding their behavior.
• Covalent conjugation of fluorescent dyes to CNCs can provide a reliable tracking mechanism.

Purpose of the Study:

• To develop methods for covalently conjugating Alexa Fluor dyes to cellulose nanocrystals.
• To ensure the conjugation methods retain the structural integrity of the cellulose nanocrystals.
• To demonstrate the utility of fluorescent CNCs in bioimaging and degradation studies.

Main Methods:

• Two distinct chemical approaches were employed for Alexa Fluor dye conjugation: reductive amination and reaction with a triazine-modified dye.
• Sodium periodate oxidation was used to introduce aldehyde groups for reductive amination.
• The modified dyes were reacted with CNCs in acetonitrile at elevated temperatures.

Main Results:

• Successful covalent conjugation of Alexa Fluor dyes to CNCs was achieved, with minimal labeling (approx. 1% of glucopyranose rings).
• The resulting fluorescent CNCs retained their characteristic spectral properties.
• Proof-of-principle bioimaging experiments demonstrated the localization and time-dependent degradation of CNCs in microfluidic structures.

Conclusions:

• Covalent labeling of CNCs with Alexa Fluor dyes is feasible using the developed methods.
• Fluorescent CNCs serve as effective probes for monitoring cellulose material behavior in microfluidic and biological systems.
• Single molecule fluorescence microscopy offers a sensitive approach to track CNC degradation over time.