Paramagnetic chlorine functionalized nitrogenated multiwall carbon nanotubes (N-MWCNTs: Cl) in biomedical application

Chlorine-functionalized nitrogenated multiwall carbon nanotubes (N-MWCNTs: Cl) were synthesized, and their structural, electronic, and paramagnetic behavior was investigated to explore their potential future paramagnetic biomedical applications. The structural and electronic characteristics were analysed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray absorption near-edge spectroscopy, and a superconducting quantum interference device magnetometer was employed to study the paramagnetic behavior of N-MWCNTs: Cl. Chlorine functionalization modifies the local structural defects and electronic structure of N-MWCNTs via charge transfer from chloride ions (Cl⁻) to the nanotube framework, thereby increasing charge-carrier density. The formation of various bonds, viz. C-Cl, N-Cl, and C-N, along with the induced sp³ hybridized carbon atoms, lead to an elongation of the neighboring C-C bond lengths, which contributes to the enhancement of the paramagnetic nature of N-MWCNTs: Cl. The synthesized N-MWCNTs: Cl display paramagnetic behavior that could be useful in various future biomedical applications.