Aqueous cationic, anionic and non-ionic multi-walled carbon nanotubes, functionalised with minimal framework damage,...

Area of Science:

• Materials Science and Nanotechnology
• Biomedical Engineering
• Toxicology

Background:

• Multi-walled carbon nanotubes (MWNTs) possess unique properties but require surface functionalization for many applications.
• Conventional acid oxidation damages MWNT structure, limiting their utility.
• Developing methods to functionalize MWNTs while preserving their inherent structure is crucial for biomedical and toxicological studies.

Purpose of the Study:

• To develop a thermochemical grafting approach for functionalizing MWNTs without altering their structure.
• To prepare water-compatible MWNTs with controlled surface charges (anionic, cationic, non-ionic).
• To evaluate the structural integrity, solubility, stability, bioreactivity, and cellular uptake of functionalized MWNTs.

Main Methods:

• Thermochemical grafting of MWNTs with varying reagents to control surface charge.
• Thermal analysis (TGA) to determine the degree of grafting.
• High-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy to assess structural integrity.
• Zeta-potential analysis for surface charge quantification.
• In vitro assays (MTS, LDH) to evaluate cytotoxicity and inflammatory mediator release (IL-6, IL-8) on TT1 cells.
• Transmission electron microscopy (TEM) for cell uptake studies.

Main Results:

• Thermochemical grafting successfully functionalized MWNTs without structural damage, unlike acid oxidation.
• Grafted MWNTs exhibited enhanced water solubility and stability, with controllable surface charges.
• MWNTs showed low bioreactivity and suppressed inflammatory responses (IL-6, IL-8) in TT1 cells.
• Efficient cellular uptake of MWNTs was observed, with cationic MWNTs demonstrating greater interaction with cell membranes.

Conclusions:

• Thermochemical grafting is a versatile and effective method for preparing structurally intact, water-compatible MWNTs.
• Controlled surface functionalization influences MWNT solubility, stability, and cellular interactions.
• These functionalized MWNTs show promise for biomedical applications due to their low bioreactivity and potential for targeted cellular uptake.