Lysozyme Dispersed Single-Walled Carbon Nanotubes: Interaction and Activity

Abstract

The noncovalent interaction between lysozyme (LSZ) and single-walled carbon nanotubes (SWNT) was probed using a combination of methods including scanning electron microscopy, UV–vis spectroscopy, Raman spectroscopy, circular dichroism (CD), and fluorescence anisotropy. In addition to supporting the previously hypothesized importance of π–π stacking, the results of this research suggest that the key interaction is between the hydrophobic tryptophan residue within LSZ and the sidewall of SWNT. The hydrophobic interaction is so critical to dispersion stabilization that increasing SWNT hydrophilicity through oxidation actually reduces dispersibility in aqueous LSZ. The combination of the strong LSZ–SWNT interaction with the inherent stability of LSZ and preservation of secondary structure enable retention of antibacterial activity both in solution and solid assemblies. This work provides a foundation for advancing understanding and design of materials that combine carbon nanotube properties with natural enzymatic activity.