Biocatalytic self-assembly of supramolecular charge-transfer nanostructures based on n-type semiconductor-appended peptides

Abstract

The reversible in situ formation of a self-assembly building block (naphthalenediimide (NDI)-dipeptide conjugate) by enzymatic condensation of NDI-functionalized tyrosine (NDI-Y) and phenylalanine-amide (F-NH2) to form NDI-YF-NH2 is described. This coupled biocatalytic condensation/assembly approach is thermodynamically driven and gives rise to nanostructures with optimized supramolecular interactions as evidenced by substantial aggregation induced emission upon assembly. Furthermore, in the presence of di-hydroxy/alkoxy naphthalene donors, efficient charge-transfer complexes are produced. The dynamic formation of NDI-YF-NH2 and electronic and H-bonding interactions are analyzed and characterized by different methods. Microscopy (TEM and AFM) and rheology are used to characterize the formed nanostructures. Dynamic nanostructures, whose formation and function are driven by free-energy minimization, are inherently self-healing and provide opportunities for the development of aqueous adaptive nanotechnology. Built through biocatalysis: 1D chiral charge-transfer nanofibers were fabricated through the biocatalytic self-assembly of naphthalenediimide amino acid/dipeptide conjugate acceptors and dialkoxy/hydroxy naphthalene donors. In the obtained aqueous hydrogels, the charge-transfer-induced gel-sol-gel transformation led to major morphological changes. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.