Interaction of collagen triple-helix with carbon nanotubes: Geometric property of rod-like molecules

Abstract

The interactions between carbon nanotubes and important biomolecules, above all collagen molecules, have not been studied in detail. This situation is partly due to the fact that CNT are solid entities, while most of the biomolecules can be prepared in solution. We used turbidity as a means of evaluating the interaction between CNT and collagen molecules. To a stable suspension of CNT (10 ppm in 0.1% Triton), collagen solution was added to obtain a final concentration of 25 ppm. The degree of aggregation was evaluated by measuring the turbidity of the suspension at 660 nm. It was found that native collagen induced distinct aggregation with CNT, while denaturation of this protein at 60°C for 1 hr deprived the molecules of their ability to aggregate with CNT. Also other globular molecules, albumin and lysozyme, did not induce aggregation of CNT. These results indicate that the rigid rod-like structure of the native collagen triple helix is essential for interaction with CNT to cause aggregation. The mechanisms are considered to be dependent upon geometric properties of rod-like collagen molecules. The findings in this paper will open a new avenue to clarify the detailed mechanism of the interaction between collagen molecules and CNT.