Fluorescence and fluorescence resonance energy transfer of N-(aminobutyl)-N-(ethylisoluminol) functionalized gold nanoparticles

The synthesis of N-(aminobutyl)-N-(ethylisoluminol) (ABEI) functionalized gold nanoparticles (ABEI-AuNPs) and their chemiluminescence properties were described in our previous work. Since the ABEI molecules coated on the surface of ABEI-AuNPs have the fluorescence (FL) activity, the FL property of these ABEI-AuNPs was studied in the present work. It was observed that the FL intensity of a single gold nanoparticle was 634 times brighter than that of one free ABEI molecule, even though 86% of the FL emission of ABEI molecules on the surface of ABEI-AuNPs was inhibited by gold cores through intra- and inter-particle quenching effects. Moreover, the photostability of ABEI-AuNPs was studied and 96% FL intensity of as-prepared ABEI-AuNPs solution remained after 5 min continuous excitation, almost 70% FL intensity remained after 45 min. ABEI-AuNPs exhibited much better resistance to photobleaching property than luminol-AuNPs. Furthermore, ABEI-AuNPs and acriflavine were designed as energy donor and energy acceptor, respectively, to construct a novel fluorescence resonance energy transfer (FRET) system. The efficient energy transfer from ABEI-AuNPs to acriflavine was observed. Taking advantage of excellent labeling property of gold nanomaterials, the FRET behavior between ABEI-AuNPs and acriflavine may find future applications in bioassays based on the FL detection.