Urazole-Functionalized Carbon Nanotubes as Artificial DNA Strands and Their In Vivo Toxicity

Area of Science:

• Nanotechnology
• Biomaterials Science
• Molecular Biology

Background:

• Single-walled carbon nanotubes (SWCNTs) are versatile nanomaterials with potential in biological applications.
• Functionalization of SWCNTs with specific ligands can impart unique binding properties.
• Developing nanomaterials with selective DNA interactions and biocompatibility is crucial for advanced applications.

Purpose of the Study:

• To synthesize and characterize functionalized SWCNTs (f-SWCNTs) with DNA-binding moieties.
• To investigate the binding preferences of f-SWCNTs with single-stranded (ssDNA) and double-stranded DNA (dsDNA).
• To evaluate the biocompatibility and ecotoxicity of the developed f-SWCNTs.

Main Methods:

• Grafting SWCNTs with phenoxy-triazole-(ethylene glycol) ligands functionalized with DNA-binding moieties (imidazolidin-2-one, hydantoin, urazole).
• Formation of pseudoduplex and pseudotriplex DNA structures through entwinement with ss- and dsDNAs.
• Hybridization assays using ss-oligomers (dA25, dT25, dC25) and duplex oligomers (dA25•dT25, dG25•dC25) at different pH levels.
• Ecotoxicity assessment using touch response and thrashing assays on *C. elegans*.

Main Results:

• f-SWCNTs functionalized with urazoles (1c) showed strong binding to ss-dA25 and exclusive binding to ss-dT25.
• ss-dC25 selectively bound to f-SWCNTs with imidazolidin-2-one (1a) and hydantoin (1b).
• d(A•T) pairs bound strongly to 1c, while d(G•C) pairs bound strongly to 1a.
• f-SWCNT 1c exhibited the strongest binding under acidic conditions (pH 5.4).
• Shortened f-SWCNT 1c showed no significant toxicity to *C. elegans* up to 250 μg/mL, being ~2500-fold less toxic than SWCNT-COOH.

Conclusions:

• Functionalized SWCNTs exhibit potent binding capabilities and nucleobase selectivity, particularly f-SWCNT 1c with urazoles.
• The developed f-SWCNTs can form stable pseudoduplex and pseudotriplex DNA structures.
• These f-SWCNTs are highly biocompatible and significantly less toxic than unmodified SWCNTs, indicating potential for broad biological applications.