Table 1
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![Figure 1. (A) Fluorescence emission of AO ([AO] = 10 À 6 M) in the...](profile/Avik_Samanta/publication/51637240/figure/fig1/AS:305707661447178@1449897794962/A-Fluorescence-emission-of-AO-AO-10-A-6-M-in-the-presence-of-SDS-micelle-SDS_Q320.jpg)
![Figure 2. (A) Fluorescence emission of AO ([AO] = 10 À6 M) in the...](profile/Avik_Samanta/publication/51637240/figure/fig3/AS:738506376740866@1553085049354/A-Fluorescence-emission-of-AO-AO-10-A6-M-in-the-presence-of-CTAB-micelle-CTAB_Q320.jpg)
![Figure 3. (A) Fluorescence emission of AO ([AO] = 10 À6 M) in the...](profile/Avik_Samanta/publication/51637240/figure/fig4/AS:738506376757249@1553085049444/A-Fluorescence-emission-of-AO-AO-10-A6-M-in-the-presence-of-TX-micelle-TX_Q320.jpg)
Photophysical properties of cationic Acridine Orange (AO) have been studied in different micellar environments [anionic SDS (sodium dodecyl sulfate), nonionic TX (TritonX-100), and cationic CTAB (cetyl trimethyl ammonium bromide)] at different pH, in the presence of a metal ion (Cu(2+)). At pH ∼ 8, addition of Cu(2+) results in AO fluorescence quen...
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Context 1
... is obtained from the ratio of absorbance of the AO monomer (at 491 nm) to absorbance of the AO dimer (at 465 nm), in the presence of different charged micelles (Supporting Information), by assum- ing the amount of monomer or dimer present in the micellar solution will be proportional to the absorbance value of the respective species. 41 Results obtained based on Poisson distribu- tion are summarized in Table 1. It is evident that the availability of the AO monomer (fluorophore) is less because of a partition of AO as monomer and dimer and a further partition of the AO monomer in the micellar and water phase. ...
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... The broad application of this dye includes photodynamic therapy, staining of cellular particles, and as an intracellular pH indicator [35][36][37] . In addition, this dye exhibits microenvironment sensitive modulations in its photophysical properties and, thus, has been extensively used to explore various supramolecular and suprabiomolecular systems such as ionic liquids, nanoparticles, macrocyclic host-guest complexations, micelles, reverse micelles, biomolecules, etc [38][39][40][41][42][43][44][45][46][47] . ...
Current study explores the contrasting supramolecular recognition behavior of protonated (AOH⁺, pH ∼ 7) and neutral (AO, pH ∼ 12) forms of the acridine orange dye with γ-cyclodextrin (γCD) host, investigated using various photophysical techniques. Intriguingly, AOH⁺ undergoes sequential multi-mode binding interactions with the γCD host showing the predominant formation of dimeric AOH⁺-γCD inclusion complexes at lower γCD concentration region, and subsequently, these initially formed γCD bound AOH⁺ dimers undergo disintegration to form a monomeric AOH⁺-γCD inclusion complexes at higher γCD concentration region. On the contrary, surprisingly, upon interaction with γCD, the neutral AO dye preferentially undergoes only dimeric AO-γCD complex formation throughout the entire host concentration used. The distinctly different supramolecular recognition of the AOH⁺ and AO with γCD suggests that the difference in the protonation state of the dye and involvement of mainly hydrophobic driving forces in the complexation process plays the directing role in determining the overall distinctly different complexation behavior of the present AOH⁺-γCD and AO-γCD systems. Notably, the present study is the first report to reveal the pH dependent contrasting interaction mechanism of the different protonation states of the dye with the macrocyclic host. The observed results may provide a suitable approach to design pH-controlled supramolecular assemblies, potentially applying to drug delivery, molecular sensor, molecular devices, logic gates, and stimuli-responsive functional material.
... 279 Additionally, some acridine derivatives showed a cation specific fluorescence. [280][281][282] This is possible because acridine has a nitrogen donor atom. When it coordinates to an atom, it influences the electronic structure of the fluorophore thus creating different ligand based fluorescent colours. ...
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... For instance, it exists in cationic and deprotonated forms under and above pH 10, respectively [Eq. (1)] [38]. The weak oxidation peak around a potential of 0.711 V (Fig. 1B) could be ascribed to the neutral AO oxidation to the AO +• (radical cation form) [Eq. ...
Developing highly specific, rapid, and cost-effective electrochemiluminescence (ECL) methods capable of detecting multiple analytes remains a compelling research goal but it is still a substantial challenge due to narrow choice of ECL systems. In this study, efficient ECL detections were achieved by using anodic Ru(bpy)3²⁺-acridine orange (AO) ECL system. In present system, dimethylamino substituent on acridine ring acts as active sites for strong ECL generation, while heterocyclic nitrogen atom (–N–) contributes to specific complex formation with metal ion. Accordingly, this anodic ECL method was exploited for highly sensitive detection of both mercury (II) (Hg²⁺) and dopamine (DA), with detection limits as low as 0.36 nM (linear range 0.01–50 μM) and 1.0 nM (linear range 0.01–10 μM), respectively. The detection mechanism of Hg²⁺ detection was supported by density functional theory (DFT) calculations. Notably, the ECL method exhibit superior selectivity over numerous competing interfering agents. Moreover, the method achieved the detection of both targets in practical media with excellent recoveries (96.0-103.8%). Importantly, the method demonstrates potential advantages in terms of selectivity, sensitivity, rapidity, simplicity, and low cost. This work realizes a successful attempt to further expand the analytical applications of ECL systems and may initiate new thoughts in utilizing acridines in diverse ECL-based sensing and imaging applications.
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This study is aimed at developing sensing schemes without obtaining selective receptors. A series of simple carbocyanine dyes was synthesized, whose emission was quenched in water with formation of nanoparticles in the range of 20–100 nm. Fluorescence in near-IR region is “turned on” in the presence of a drug cation of middle molecular weight (400–700 Da) and sodium dodecyl sulfate (SDS), as well as anionic drugs and a cationic surfactant (cetyltrimethylammonium bromide, CTAB). Aggregates (clusters) up to 100–200 nm in size were detected using dynamic light scattering (DLS) and Rayleigh light scattering (RLS) techniques in the systems: cationic analyte–SDS, carbocyanine dye–CTAB, and in all brightly fluorescent ternary systems dye–surfactant–analyte. Small ions (<200 Da) incapable of multi-point binding do not form the aggregates or cause the emission enhancement. The “turn-on” signal is only observed at the surfactant submicellar concentrations insufficient to solubilize the dye nanoparticles. Based on these findings, we suggest a rapid and simple method for the detection of ≥4·10⁻⁵ mol/L of neomycin in urine. The proposed strategy paves the way for developing more selective methods.
... [26][27][28] This dye is also used as an intracellular pH indicator and in photodynamic therapy. [29][30][31] Fluorescence properties of AOH + is highly sensitive to its microenvironment, which makes it a very popular probe for investigating various important microheterogeneous systems, such as cyclodextrins, 32,33 cucurbiturils, 14,32,[34][35][36] octaacid, 34 pillarenes, [37][38][39] microemulsions, 40 micelles, 41 reverse micelles, 42 ionic liquids, 36 biomolecules, 35,42 etc. Recently, good number of studies have been reported involving AOH + based host-guest systems demonstrating the indicator displacement strategy to detect various important analytes like paraquat, 37 trinitrophenol, 38 acetaminophen, 39 amino acids, 43 choline, 44 acetylcholine 44 and others. ...
Interaction of acridine orange (AOH⁺) dye with water soluble anionic p-sulfonatocalix[n]arene (SCXn) hosts, SCX4 and SCX6, having different cavity dimensions, has been investigated using multispectroscopic techniques. Intriguing modulation in the photophysical properties of AOH⁺ upon interaction with SCXn hosts indicate the formation of different host-guest complexes at different regions of the host concentrations. At lower host concentrations, AOH⁺ undergoes SCXn assisted aggregation, causing a drastic reduction in fluorescence intensity. At higher host concentrations, aggregated-AOH⁺-SCXn complexes disintegrate and monomeric-AOH⁺-SCXn exo and inclusion complexes are eventually formed, leading to a huge fluorescence enhancement finally. Observed effects are more pronounced with SCX6 as compared to SCX4 host. Time-resolved fluorescence studies indicate that at very high host concentrations, there is also a diffusion-controlled dynamic quenching for both monomeric-AOH⁺-SCXn exo and inclusion complexes, caused by the free SCXn present in the solution, a phenomenon not reported before for such host-guest systems. The aggregated-AOH⁺-SCXn complexes at lower host concentration were employed to investigate displacement study using an antiviral drug, 1-Adamantanamine (AD) and a neurotransmitter, acetylcholine (AcCh), as the competitive binders cum external stimuli, which resulted in a drastic recovery of the fluorescence reduced initially due to aggregation process. Though both the AOH⁺-SCXn systems act as efficient supramolecular assemblies in sensing AD and AcCh as the analytes through fluorescence “OFF-ON” mechanism, the effect is more pronounced for AOH⁺-SCX4 system as compared to AOH⁺-SCX6. SCXn induced interesting modulation in the photophysical properties of AOH⁺ and the stimulus responsive dye displacement observed for aggregated-AOH⁺-SCXn systems can expectedly find applications in fluorescence OFF-ON sensing, supramolecular functional materials and similar others
... 27 It is known that acridine and its derivatives show a typical electrochemical response depending on the pH value (e.g. in cationic form at pH o 10, while in deprotonated form at pH 4 10) [eqn (1)]. 28 As shown in Fig. 1B, a weak irreversible anodic peak at 0.708 V could correspond to the oxidation of AO (neutral) to the radical cation form (AO + ) [eqn (2)]. Previous studies documented that AO + has very low structural stability and will immediately transform into AOH + . ...
A new and efficient anodic Ru(bpy)32+ ECL system by using acridine orange (3,6-Bis(dimethylamino)acridine, AO) as a coreactant was reported in neutral medium. The developed Ru(bpy)32+–AO system displayed higher ECL intensity...
... Also, fluorescent dyes and quantum dots entrapped into hydrophilic lipid-based particles were developed as attractive targets for selective delivery of imaging agents to tumor cells [2,3]. The photophysical properties of encapsulated fluorophores are often regulated by the micellar structure improving the sensory capability of the dye [2,4]. Although liposomes promise the improvement of diverse abilities of the entrapped molecules [5], several drawbacks inherent to their structural assembling need being considered. ...
... The enhancement in AO fluorescence quenching with Cu 2+ in anionic SDS micellar environments is already reported in the literature and was attributed to electrostatic and steric effects on Cu 2+ quenching introduced by the micelle surface [4]. In fact, Cu 2+ ions quenching may take place on the surface of the CaP-coated liposomes as Cu 2+ is well known to efficiently absorb on calcium phosphate [37]. ...
... Acridine Orange can be in mono-cationic, di-cationic, and tri-cationic form depending on pH of medium (pKa * 10.4). The cationic forms are dominant below pH 10 while the completely deprotonated form exists at higher pHs [22][23][24]. Cu 2? ions act as a quencher to cationic AO at low pHs, whereas it forms a complex with AO at pH 8.0 and shifts dimer-monomer equilibrium toward monomer [25]. We have been suggesting a similar mechanism for Sn 2? and Pb 2? ions. ...
A cloud point extraction (CPE) method has been developed for the pre-concentration and simultaneous determination of lead [Pb(II)] and tin [Sn(II)] using Acridine Orange as complexing reagent and mediated by nonionic surfactant (Triton X-114) by flame atomic absorption spectrometry (FAAS). The main factors affecting analytical performance of CPE have been investigated in detail. The extracted surfactant-rich phase was diluted with (1.0 mol L−1) nitric acid in methanol, prior to subjecting FAAS. The calibration graphs obtained from Pb(II) and Sn(II) were linear in the concentration ranges of 5–1,000 and 10–5,000 μg L−1 with detection limits of 1.40 and 2.86 μg L−1, respectively. The relative standard deviations for 10 replicates containing 25 μg L−1 of Pb(II) and Sn(II) were 2.15 and 2.50 %, respectively. The analytical procedure was verified by the analysis of the standard reference materials NWTMDA-61.2 (water-trace elements) and NIST SRM 1548a (typical diet). The developed method has been applied to the simultaneous determination of total Pb and Sn in canned food samples including juices, tomato paste, corn, and green pea.
