Nanopore formation by self-assembly of the model genetically engineered elastin-like polymer [(VPGVG)2(VPGEG)(VPGVG)2]15.
The self-assembly characteristics of the model genetically engineered elastin-like polymer [(VPGVG)2(VPGEG)(VPGVG)2]15 have been studied in this work. An AFM study of the topology of polymer films deposited from acid and basic solutions on a hydrophobic silicon substrate has been carried out. Under acidic conditions, polymer deposition results in a flat surface with no particular topological features. However, from basic solutions, polymer deposition clearly shows an aperiodic pattern of nanopores ( approximately 70 nm width and separated about 150 nm). This dramatic dependence of film topology on pH is explained in terms of the different polarity of the free gamma-carboxyl group of the glutamic acid. In the carboxylate form, this moiety shows a markedly higher polarity than the rest of the polymer domains and the substrate itself. Under these conditions, the charged carboxylates impede hydrophobic contact with their surroundings, which is the predominant assembly pathway for this type of polymer. The charged domains, along with their hydration sphere, are then segregated from the hydrophobic surroundings giving rise to nanopores.
Dpto. Física de la Materia Condensada, E.T.S.I.I., Universidad de Valladolid, Paseo del Cauce s/n, 47011 Valladolid, Spain.
Javier
J
Reguera
Amir
A
Fahmi
Philip
P
Moriarty
Alessandra
A
Girotti
José Carlos
JC
Rodríguez-Cabello
D040761:Biomimetic Materials / Q000737:chemistry; D004549:Elastin / Q000737:chemistry*; D005818:Genetic Engineering; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*
D010455:Peptides; C058088:valyl-prolyl-glycyl-valyl-glycine polypeptide; D004549:Elastin