Advancements in the Surface Functionalization of Carbon Nanotubes for Optoelectronic Modulation and Sensing Applications

Single-walled carbon nanotubes (SWCNTs) demonstrate tunable optoelectronic properties that enable diverse applications in biosensing. These properties are often tailored by altering the functionalization of the SWCNT surface. This work provides an overview of established and emerging approaches for modifying the chemistry of SWCNTs for applications in optical sensors. We review covalent and non-covalent approaches based on chemical modification, small molecule functionalization, surfactant and lipid solubilization, polymer wrapping, and biomolecule conjugation to modulate optical properties, especially the intrinsic, near-infrared photoluminescence (fluorescence) of SWCNTs. Finally, we discuss emerging approaches based on machine learning for designing functionalization strategies. These advancements in surface functionalization provide an avenue not only for tailoring SWCNTs with precision for specific applications, but also for elucidating the underlying mechanisms that govern their optoelectronic properties.