Viscosity sensitive near-infrared fluorescent probes based on functionalized single-walled carbon nanotubes

A viscosity-sensitive fluorescent probe is demonstrated by grafting a rotatable 4- N , N ′-dimethylaniline group on (6,5) single-walled carbon nanotubes. The rotation of the grafted group is constricted by solution viscosity, causing changes in the photoluminescence behaviors of the nanotubes. This enables a highly sensitive fluorescent probe for determining solution ratiometric viscosity in the biologically transparent second near-infrared region. A new family of viscosity sensitive near-infrared fluorescent probes is created by grafting rotors on single walled carbon nanotubes. The new photoluminescence emission peaks are highly sensitive to the viscosity of solutions.