Fluorescence quenching of Acridine Orange in microemulsions induced by the non-steroidal anti-inflammatory drug Piroxicam

Abstract

The singlet excited-state quenching of Acridine Orange (AO) by methyl viologen (MV2+) and the non-steroidal anti-inflammatory drug Piroxicam (Prx), incorporated in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane/water and Triton X-100 (Trx-100)/cyclohexane-hexanol/water (w/o) microemulsions, was followed by steady- and transient-state fluorescence. The water content was varied by using different values of omega 0 (omega 0 = [H2O]/[S]) at fixed AOT (0.1 M) and Trx-100 (0.2 M) concentrations. In AOT, MV2+ resides at the interface, while Prx partitions between the interface and bulk water, but considerably biased towards the latter compared to AO. The quenching process efficiency increases with increasing omega 0, but reaches a diffusional value similar to that of free water only for the case of Prx, underlining the electrostatic effect of the AOT interface. The quenching process in Trx-100 microemulsions is more efficient for Prx than for MV2+, pointing to a similar polyoxyethylene intra-chain location for the former and AO. In both cases, data obtained allowed the microviscosity of the aqueous interior at different omega 0 to be extrapolated and indicate an increase in eta w values with water content, reflecting changes in the shape of Trx-100 microemulsions, which occur at omega 0 = 8.

Interactions of a Sulfonated Aluminum Phthalocyanine and Cytochrome c in Micellar Systems: Binding and Electron-Transfer Kinetics

“…Afterward, it decreases to a plateau, similar to the value obtained in Brij 35 micelles. This result indicates a sharp change of behavior as w 0 increases in Triton X-100 microemulsions as it was observed previously. ,,, This happens whenever K b is measured from the fluorescence quantum yields or from the pre-exponential factors of the decays calculated through eq 6 (see Table ). A possible explanation for such effect is that, below w 0 = 10, the complex may sense a more hydrophobic environment as water is introduced in the system, probably because of a relocation of the protein in which the binding site is directed toward the apolar side of the micellar interface.…”

“…However, the decay of the complex dominates the data obtained, and, thus, parameters such as aggregation numbers are not possible to calculate. This is mostly important in the Triton X-100 microemulsions, where information about its nanostructure is still scarce. ,− ,, There is a strong change at w 0 ≈ 10; this effect is observed both in this work and in the previous work performed by Andrade et al The strong increase of k q (by 1 order of magnitude) obtained from w 0 = 4 to w 0 = 20 may be an indication of more “homogeneous” media, in which both solutes are not separated from each other in individual aggregates . Such behavior is typical of a system above the percolation threshold, which is reached either by droplets infinitely connected in clusters of reversed micelles or in bicontinuous microemulsions.…”

“…In microheterogeneous systems (Figure ), the sort of behavior shown in water/sucrose mixtures is enhanced because the polarity decreases very much in this media. ,,, At low w 0 , the complex displays a G ( τ ) profile that is obviously similar to those observed in water/sucrose mixtures, whereas at high w 0 and in Triton X-100 micelles, the profile is similar to that observed in aqueous solutions. Major differences are observed in Brij 35 micelles and at intermediate w 0 values, where the system changes its behavior.…”

Topical non steroidal antiinflammatorydrug (NSAIDs microemulsions: Rationale, review and future prospective

“…[38] Formulation, development and evaluation of topical microemulsion gels for nimsulide Aceclofenac [39] Development and characterization of microemulsion formulation for transdermal delivery of Aceclofenac: A research Ibuprofen [40] Fabrication and evaluation of hydrogel thickened microemulsion of ibuprofen for topical delivery Ketoprofen [41] Formulation and in vitro evaluation of ketoprofen in palm oil esters nanoemulsion for topical delivery Ketoprofen [42] The novel formulation design of o/w microemulsion of ketoprofen for improving transdermal absorption Diclofenac [43] Topical delivery of diclofenac using microemulsion systems Indomethacin [44] Microemulsions as vehicles for transdermal permeation of drugs Piroxicam [45] Fluorescence quenching of acridine orange in microemulsions induced by the non-steroidal anti-inflammatory drug piroxicam Ketoprofen [46] Lecithin microemulsions for the topical administration of ketoprofen: Percutaneous adsorption through human skin and in vivo human skin tolerability Ketoprofen [47] Transdermal delivery of ketoprofen using microemulsions Piroxicam [48] Inclusion complex of piroxicam with beta-cyclodextrin and incorporation in cationic microemulsion. in vitro drug release and in vivo topical anti-inflammatory effect Indomethacin [49] Influence of phase transformation on indomethacin release from microemulsions…”

Investigating the Binding of Acridine, Acridine Orange, and Acridine Yellow G to Humic Acid through Fluorescence Quenching

“…27 Further, when coupled with rhodamine 6G, acridine orange quenching has been used to determine vitamin B 12 concentrations. 28 Acridine orange has been investigated in other systems of biological importance, 29–30 and when combined with calf thymus DNA it has been quenched using resveratrol, a compound that could be considered a model for humic acid. 31 In a related study, nitrated PAHs have been used to quench the fluorescence of other fluorophores.…”