title: Lysozyme binds onto functionalized carbon nanotubes.
abstract: Single walled carbon nanotubes have singular physicochemical properties making them attractive in a wide range of applications. Studies on carbon nanotubes and biological macromolecules exist in literature. However, ad hoc investigations are helpful to better understand the interaction mechanisms. We report on a system consisting of single walled carbon nanotubes and lysozyme. The phenomenology of nanotube-protein interactions and its effects on protein conformation were determined. We investigated the formation of oxidized nanotube-lysozyme conjugates, by studying the effect of both protein concentration and pH. Electrophoretic mobility, dielectric spectroscopy and dynamic light scattering were used to determine the interaction pathways, monitoring the surface charge density and the size of the complexes. The results allowed identifying the conditions of surface saturation at different pH values. The secondary structure of nanotube-adsorbed protein was controlled by circular dichroism; it was observed that it substantially retains its native conformation. Interestingly, we found that the interactions among oxidized nanotubes and lysozyme molecules are mainly of electrostatic nature and easily tunable by varying the pH of the solutions.
authors.affiliation: Department of Physics, La Sapienza University, P.le A. Moro 5, I-00185 Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Bomboi
authors.forename: Franco
authors.initials: F
authors.lastname: Tardani
authors.forename: Delia
authors.initials: D
authors.lastname: Gazzoli
authors.forename: Adalberto
authors.initials: A
authors.lastname: Bonincontro
authors.forename: Camillo
authors.initials: C
authors.lastname: La Mesa
mesh_terms: D000818:Animals; D002645:Chickens; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D008027:Light; D009113:Muramidase / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012542:Scattering, Radiation; D012996:Solutions; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D037742:Nanotubes, Carbon; D012996:Solutions; D009113:Muramidase