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Photoluminescent Peptide‐Based Nanostructures as FRET Donor for Fluorophore Dye
Author(s) -
Diaferia Carlo,
Sibillano Teresa,
Giannini Cinzia,
Roviello Valentina,
Vitagliano Luigi,
Morelli Giancarlo,
Accardo Antonella
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201701381
Subject(s) - fluorophore , förster resonance energy transfer , fluorescence , photoluminescence , chemistry , photochemistry , circular dichroism , polyethylene glycol , materials science , crystallography , organic chemistry , optics , optoelectronics , physics
A great interest has been recently generated by the discovery that peptide‐based nanostructures (NSs) endowed with cross‐β structure may show interesting photoluminescent (PL) properties. It was shown that NSs formed by PEGylated hexaphenylalanine (PEG 8 ‐F6, PEG=polyethylene glycol) are able to emit at 460 nm when excited at 370 or 410 nm. Here, the possibility to transfer the fluorescence of these PEG 8 ‐F6‐based NSs by foster resonance electron transfer (FRET) phenomenon to a fluorescent dye was explored. To achieve this aim, the 4‐chloro‐7‐nitrobenzofurazan (NBD) dye was encapsulated in these NSs. Structural data in solution and in solid state, obtained by a variety of techniques (circular dichroism, Fourier‐transform infrared spectroscopy, wide‐angle X‐ray scattering, and small‐angle X‐ray scattering), indicated that the organization of the peptide spine of PEG 8 ‐F6 NS, which consists of anti‐parallel β‐sheets separated by a dry interface made of interacting phenylalanine side chains, was maintained upon NBD encapsulation. The spectroscopic characterization of these NSs clearly showed a red‐shift of the emission fluorescence peak both in solution and in solid state. This shift from 460 to 530 nm indicated that a FRET phenomenon from the peptide‐based to the fluorophore‐encapsulated NS occurred. FRET could also be detected in the PEG 8 ‐F6 conjugate, in which the NBD was covalently bound to the amine of the compound. On the basis of these results, it is suggested that the red‐shift of the intrinsic PL of NSs may be exploited in the bio‐imaging field.