In this study, we have covalently coupled the human protein annexin V to carboxymethylcellulose adsorbed on single-walled carbon nanotubes (SWNTs) by using a zero-length crosslinking agent that couples carboxyl groups to primary amines (1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride, or EDC). The binding of annexin V (biotinylated) to phosphatidylserine allowed for the determination of the dissociation constant (Kd). The dissociation constant indicates a relatively high affinity of the receptor (phosphatidylserine) for the ligand (annexin V). The UV-vis-NIR absorption spectra of the SWNT-CMC-biotinylated annexin V complex was determined.
The SWNT-CMC-annexin V complex bound to human endothelial cells in vitro was subjected to laser irradiation at 980 nm on a 24-well plate in order to determine the effect of the energy adsorption by the SWNTs on cell viability. The cell viability was evaluated by performing the Alamar Blue assay, cell counting and cell observation with a microscope.