Graphene oxide sheets as a template for dye assembly: graphene oxide sheets induce H-aggregates of pyronin (Y) dye

Abstract

The highly stable colloidal structure of graphene oxide (GO) in aqueous dispersion behaves as a platform for the molecular aggregation of dyes via a simple adsorption process. The interaction between dye and GO sheets is a critical factor for dye aggregation. Positively charged dyes interact with the negatively charged GO sheets in an aqueous dispersion via both electrostatic and p-p stacking interactions. The cationic nature of Pyronin Y (PyY) ensures that the dye molecules are quickly adsorbed on the GO sheets in the aqueous dispersion. GO-PyY composites with different ratios, which are stable for months, are prepared by simply mixing diluted aqueous dispersions of both components. Transition dipole-dipole interactions between the adsorbed dye molecules on the surface of the GO sheet causes the formation of H-aggregates of the dye at dilute concentrations. H-aggregates of PyY are characterized by spectroscopic techniques (UV-Vis, steady-state and time-resolved fluorescence spectroscopy). The morphology and thickness of the GO sheets and the dye adsorbed GO sheets were determined using atomic force microscopy (AFM) in tapping mode. AFM studies revealed that a great deal of PyY molecules interact on the edges of the GO sheets.3 Electronic supplementary information (ESI) available: Synthesis of graphene oxide (GO), SEM image of natural graphite flakes, EDX spectra of natural graphite flakes and GO, Raman spectra of natural graphite flakes and GO, TGA spectra of natural graphite flakes and GO, cross-sectional analysis of AFM images of GO and PyY adsorbed GO on a mica surface, and absorption spectra of PyY in deionized water and the GO aqueous dispersion. See

Dual Roles of Graphene Oxide in Chondrogenic Differentiation of Adult Stem Cells: Cell‐Adhesion Substrate and Growth Factor‐Delivery Carrier

“…At dye concentrations lower than 1.5 µM, dye fl uorescence quenching was observed. [ 17 ] Since the fl uorescent dye concentration (6.25 mM) in this study was much higher than the reported threshold dye concentration (1.5 µM) and the GO sheet concentration (1 µg mL -1 ) used was much lower, quenching could have been negligible and thus fl uorescence was observed (Figure 3 B and Figure S1, Supporting Information). TEM images revealed GO sheet interaction with hASCs in the hybrid pellets (Figure 3 C).…”

Molecular aggregates of Merocyanine 540 in aqueous suspensions containing natural and CTAB-modified bentonite

“…In general, H-aggregate structures are nonfluorescent and characterized with a red-shifted absorption band compared to that of monomeric species. In contrast, J-aggregates show a red-shifting and narrow absorption band compared to that of the monomer, and they are strong fluorescent species [2,4,8]. Chemically modified clays and clay minerals are an effective and popular class of adsorptive materials [9].…”

“…The figure showed that the absorbance of H-dimer in the bentonite suspension increased when the monomer absorbance decreased in the range of 0.1 to 10.0% CEC. This stemmed from the changing absorption characteristics of the dye due to the transition dipole-dipole interaction of dye monomers [2,4,8]. The fluorescence spectra of the dye in the natural bentonite aqueous suspension were shown in Fig.…”

“…The dye aggregations occurring in various media are a common phenomenon producing dye aggregates. Although the dye aggregation occurs at higher dye concentrations in deionized (DI) water [5], it is observed at diluted dye concentration in the presence of polyelectrolytes [6], colloidal nanoparticles [7], and graphene oxide [8]. In this respect, two main aggregate types, which are called H and J-aggregates, are exited depending on their photophysical properties.…”

The interaction of fluorescent Pyronin Y molecules with monodisperse silver nanoparticles in chloroform

“…It is reported that PyY can be exposed to molecular aggregation processes [13][14][15]. More recently, it is demonstrated that the photophysical properties of PyY can be affected by their interaction with other materials [16]. For example, graphene oxide, clays, polyelectrolytes and metallic NPs are commonly used changing the photophysical properties of dye molecules in M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 liquid media [13][14][15][16].…”