Excimer Emission of Acridine Orange Adsorbed on Gadolinium-Yttrium Orthovanadate Nanoparticles

Abstract

Studying the complexes of inorganic nanoparticles - organic dye molecules is of great importance for their theranostics application. In this paper, we report gadolinium-yttrium orthovanadate nanoparticles (VNPs) - Acridine Orange (AO) complex formation in water solutions. To study the interactions between VNPs and AO, the methods of steady-state and time-resolved spectroscopy were used. It was shown that in aqueous solutions containing VNPs, AO aggregation takes place with a sandwich-like stacking of AO molecules in the near-surface layer of VNPs. The VNPs-AO complex formation causes significant changes in the AO fluorescence spectrum, namely, the appearance of a new broad, structureless band in the long-wavelength spectral edge, which was not observed in AO spectrum in a pure water solution. By analyzing of the absorption, fluorescence excitation spectra and fluorescence decay, the static excimer origin of the long-wavelength fluorescence band has been established.

Spectral phasor plot for hyperspectral imaging of acridine orange photophysics within the cell

“…These results seem to show the well-studied interaction of AO with organelles like lysosomes [6], [9], [10], [27], [28], [30]. AO in these cellular environments can form multimers, such as dimers and excimers that fluoresce with a peak at 640 nm [5], [11], [31]. To study the nature of C3-positive granules, and evidence if they correspond to acidic subcellular compartments, we co-labeled living with LysoTracker Deep Red and AO.…”

“…As the concentration of AO rises, it leads to the formation of aggregates in the form of dimers and excimers, which subsequently generates a red metachromatic shift. [2], [5], [10], [11].…”

Nanoscale Supramolecular Probes for the Naked-Eye Detection of Illicit Drugs

“…Indeed, when free in solution at pH = 5.5 and 10 μM concentration, its absorption spectrum featured, in the visible region, a main band at 599 nm accompanied by a shoulder at 558 nm (Figure ). The addition of CB[8] caused a blue shift of the main band and shoulder to 557 and 521 nm, respectively (Figure ), likely a result of the formation of a plane-to-plane dimer (H-dimer) inside the cavity . The appearance of the shorter-wavelength band at the expense of the longer-wavelength one can be detected by the naked eye as a change of color from blue to violet (Figure ).…”

“…The addition of CB [8] caused a blue shift of the main band and shoulder to 557 and 521 nm, respectively (Figure 4), likely a result of the formation of a plane-to-plane dimer (H-dimer) inside the cavity. 30 The appearance of the shorter-wavelength band at the expense of the longerwavelength one can be detected by the naked eye as a change of color from blue to violet (Figure 4). The absorption intensity at 599 nm linearly decreased by increasing the concentration of CB [8] to sharply level off after the addition of 0.5 equiv of cucurbituril, suggesting the formation of a TH 2 • CB [8] species with high affinity (Figure S4).…”