abstract
The green fluorescent protein (GFP) is extensively used as a biomarker for fluorescence biological imaging. The chromophore in GFP is only fluorescent when confined into the beta-barrel of the protein. Similarly, synthetic analogues of the fluorophore of GFP are usually non-emissive in solution, due to free rotation around the aryl-alkene bond and (Z/E)-isomerization of the double bond. Here, the synthesis and characterization of three analogues of the fluorophore of GFP are reported. The introduction of more electron donating substituents induces a red-shift in the absorption and emission. The fluomphores are more emissive in the solid state than in solution, and a study of their crystal structure reveals that the (Z/E)-isomerization is efficiently blocked in the crystals.
keywords
GFP-CHROMOPHORE; EMISSION ENHANCEMENT; NITRO
subject category
Chemistry; Engineering; Materials Science
authors
Esteves, CIC; Fonseca, ID; Rocha, J; Silva, AMS; Guieu, S
our authors
João Rocha
Full Professor
Samuel Jacques André Guieu
Junior Researcheracknowledgements
Thanks are due to University of Aveiro, FCT/MEC for the financial support to the QOPNA research Unit (FCT UID/QUI/00062/2019) and also to the Portuguese NMR Network. This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, FCT Ref. UID/CTM/50011/2019, financed by national funds through the FCT/MCTES. S. Guieu acknowledges the fundings from national funds (OE), through FCT -Fundacao para a Ciencia e a Tecnologia, I.P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19, and from the Integrated Programme of SR&TD pAGE -Protein aggregation Across the Lifespan (reference CENTRO01-0145-FEDER-000003). C.I.C. Esteves acknowledges the 016385PAC NETDIAMOND project (POCI-01-0145-FEDER-016385) for her Post-Doctoral grant (BPD/UI50/7664/2017). Professor Rute AS Ferreira (phantom-g, CICECO, Department of Physics, University of Aveiro) is acknowledged for the solid state quantum yield measurements.