Immobilization of Trypsin from the Subphase to the Langmuir Monolayer of Fluorocarbon-Modified Single-Walled Carbon Nanotube and Its Activity Maintenance

Single-walled carbon nanotubes (SWCNTs) synthesized by the improved arc discharge method were modified with a fluorocarbon chain, and the maintenance of trypsin activity upon adsorption from the subphase to the interfacial monolayer of SWCNTs was evaluated. The adsorption of trypsin on the fluorocarbon-modified SWCNT monolayer was confirmed by morphological and spectroscopic evaluations. Fiber morphology studies revealed that the fluorocarbon-modified SWCNT monolayer was covered by trypsin, and a trypsin-derived amide band was detected in the infrared spectra of the multilayers. After adsorption onto the fluorocarbon-modified SWCNT film, the ability of trypsin to cleave the fluorescent casein chain was maintained even at 160 degrees C. Furthermore, circular dichroism (CD) spectra showed that the secondorder structure of the activity of trypsin adsorbed on the fluorocarbon-modified SWCNT was maintained up to nearly 200 degrees C. At 200 degrees C, the enhancement of emission intensity by casein chain cleavage was negligible, and the CD signal resulting from the negative Cotton effect was completely altered at 250 degrees C.

Automated summary

Single-walled carbon nanotubes modified with a fluorocarbon chain can adsorb trypsin and maintain its activity, including the ability to cleave a fluorescent casein chain at 160 degrees C. The secondary structure activity of trypsin adsorbed on the fluorocarbon-modified SWCNT can also be maintained up to nearly 200 degrees C.