Retention of biological activity and near-infrared absorbance upon adsorption of horseradish peroxidase on single-walled carbon nanotubes

The objective of this study is to demonstrate the adsorption of horseradish peroxidase ( HRP) on single-walled carbon nanotubes ( SWNTs) using the sodium cholate suspension-dialysis method and to determine the effect of HRP adsorption on the biological activity of HRP and the UV-vis-NIR spectra of the SNWTs. The results indicate that this method results in a stable SWNT-protein suspension with complete retention of enzymatic activity of adsorbed HRP and also retention of a substantial fraction of the NIR absorption at 980 nm. The loading of protein on the SWNTs is high, and the overall yield of preparing the SWNT-protein suspension is also high. This process is promising for preparing SWNT-protein suspensions for biological applications where maintaining protein activity and SWNT absorption are important.