Binding Interaction and Rotational-Relaxation Dynamics of a Cancer Cell Photosensitizer with Various Micellar Assemblies

Paul, Bijan Kumar; Ray, Debarati; Guchhait, Nikhil

doi:10.1021/jp304280m

Cited by 35 publications

(83 citation statements)

References 70 publications

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“…This increment in non-radiative decay channels in CTAB micelles can be rationalized in terms of the heavy atom perturbation effect. The obtained hydrodynamic diameter values for different micelles (Table 3) are in good agreement with literature values, [51][52][53] which further validate the encapsulation of the drug in micellar environments. 47 Thus, the excited state lifetime of the alkanolamine form decreases in the presence of a CTAB micellar environment due to the enhancement in non-radiative decay pathways.…”

Section: Time Resolved Studysupporting

confidence: 86%

Fluorescence switching of sanguinarine in micellar environments

Satpathi

Gavvala

Hazra

2015

Phys. Chem. Chem. Phys.

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Sanguinarine (SANG), a key member of the benzylisoquinoline alkaloid family, is well-known for its various therapeutic applications such as antimicrobial, antitumor, anticancer, antifungal and anti-inflammatory etc. Depending on the medium pH, SANG exists in the iminium or alkanolamine form, which emits at 580 nm and 420 nm, respectively. Nucleophilic attack on the C6 carbon atom converts the iminium form to the alkanolamine form of SANG, and these two forms are equally important for the medicinal activities of SANG. To improve its potency as a drug, it is essential to get a physical insight into this conversion process. In this study, we have deployed steady sate and time-resolved spectroscopic techniques to probe this conversion process inside different micellar environments. We have observed that the conversion from the iminium to alkanolamine form takes place in neutral OBG (octyl-β-d-glucopyranoside) and positively charged CTAB micelles, whereas the iminium form exclusively exists in negatively charged SDS micelles. This conversion from the iminium to alkanolamine form in the case of OBG and CTAB micelles may be attributed to the reduced pKa of this conversion process owing to the enhanced hydrophobicity experienced by the iminium form in between the surfactant head groups. On the other hand, the electrostatic attraction between positively charged iminium and negatively charged surfactant head groups stabilizes the iminium form in the stern layer of the SDS micelle. We believe that our observations are useful for selective transportation of any particular form of the drug into the active site. Moreover, loading of any particular form of drug can be easily monitored with the help of fluorescence color switch from orange (iminium) to violet (alkanolamine) without pursuing any sophisticated or complex technique.

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Section: Time Resolved Studysupporting

confidence: 86%

Fluorescence switching of sanguinarine in micellar environments

Satpathi

Gavvala

Hazra

2015

Phys. Chem. Chem. Phys.

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“…There are reports on the decrease in binding constant for the conventional surfactants with decreasing aggregation numbers. 53, 75 The standard Gibbs free energy of binding (ΔG°) of C-153 with gemini surfactants has been calculated using the relation ΔG°= −RT ln K, and the values obtained are also complied in Table 3. The values of ΔG°are negative for all of the studied systems.…”

Section: Resultsmentioning

confidence: 99%

“…The decrease in the rotational relaxation time of the probe molecule with the decreasing aggregation number of micelles has been reported in the literature. 53, 75 The fluorescence anisotropy decays of C-153 in all micellar media are biexponential in nature. A biexponential anisotropy decay is due to various kinds of rotational motions but is not due to different locations of the probe.…”

Section: The Journal Of Physical Chemistry Bmentioning

confidence: 99%

Effect of Polymethylene Spacer of Cationic Gemini Surfactants on Solvation Dynamics and Rotational Relaxation of Coumarin 153 in Aqueous Micelles

2015

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The present work demonstrates the solvation dynamics and rotational relaxation of Coumarin 153 (C-153) in the micelles of a series of cationic gemini surfactants, 12-s-12, 2Br(-) containing a hydrophobic polymethylene spacer with s = 3, 4, 6, 8, 12. Steady-state and time-correlated single-photon counting (TCSPC) fluorescence spectroscopic techniques have been used to carry out this study. Steady-state and TCSPC fluorescence data suggest that C-153 molecules are located at the Stern layer of micelles. While probe molecules feel more or less the same micropolarity in the micellar phase, the microviscosity of micelles decreases with spacer chain length. Solvation dynamics at the Stern layer is bimodal in nature with fast solvation as a major component. Counter ions and water molecules bonded with the polar headgroups of surfactant molecules are responsible for the slow component. Average solvation time increases with spacer chain length because of the increased degree of counter ion dissociation. Some water molecules are involved in the solvation of counter ions themselves, resulting in the decrease in "free" water molecules to be available for the solvation of C-153. The hydrophobic spacer chain also has an effect on increasing the solvation time with increasing chain length. The average rotational relaxation time for C-153 decreases with spacer chain length with a rapid decrease at s > 4. The anisotropy decay of C-153 in micelles is biexponential in nature. The slow rotational relaxation is due to the lateral diffusion of C-153 in micelles. Lateral diffusion is much faster than the rotational motion of a micelle as a whole. The rotational motion of the micelle as a whole becomes faster with the decreasing size of micelles.

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“…Herein, the energy of the O d ―H 1 ···O a hydrogen bond (numbering of atoms according to Scheme c) has been assessed based on a comparative analysis of the energy difference between the hydrogen bonded closed conformation and the nonhydrogen bonded open conformation obtained by rotating the O d ―H 1 functional moiety away from the plane of the IMHB interaction. The variation of energy as a function of the angle of rotation is depicted in Figure corresponding to an energy difference of 8.96 kcal mol −1 between the closed (with IMHB) and open (without IMHB) conformations (it is pertinent to state in this context that the open form of 7H1I was obtained by rotating the O d ―H 1 functional group on the optimized geometry of 7H1I (that is, the closed form of 7H1I having the IMHB), and thus it corresponds to a partially relaxed calculation). However, this method of evaluation of IMHB energy does not yield an accurate result because of the inherent assumption of ignoring any sort of stabilizing/destabilizing influence on the concerned equilibrium geometry other than the IMHB.…”

Section: Resultsmentioning

confidence: 99%

“…Obviously, the phenomenon of resonance assistance involving π‐electron delocalization from the aromatic nucleus (Scheme b) within the quasi‐ring formed due to the intramolecular hydrogen bond (IMHB) will accompany depletion of aromatic stabilization of the concerned moiety whereby providing a measure of the extent of resonance assistance in the system …”

Section: Introductionmentioning

confidence: 99%

Lack of resonance assistance in a classical intramolecular hydrogen bond: An exploration from quantum theory of atoms‐in‐molecules perspective

Paul¹

2019

J of Physical Organic Chem

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A computational investigation has been performed to characterize the intramolecular hydrogen bond (IMHB) interaction in 7‐hydroxy‐2,3‐dihydro‐1H‐inden‐1‐one (7H1I). The results of natural bond orbital (NBO) analysis describe the formation of the IMHB in 7H1I in terms of hyperconjugative charge transfer from the lone electron pair of the acceptor oxygen atom (Oa) to the σ* antibonding orbital of the Od―H1 proton donating bond. However, the key motivation of the present work rests on characterization of the IMHB interaction by calculation of electron density (ρc), its Laplacian (∇2ρc), and electron energy density parameters at the bond critical point (BCP) based on the quantum theory of atoms‐in‐molecules (QTAIM). The topological parameters reveal the intriguing result of the lack of resonance assistance in the IMHB of 7H1I despite the presence of an apparently suitable route for the same, contrary to its aromatic (salicylic acid) and nonaromatic ((Z)‐3‐hydroxyacrylaldehyde) analogues. This inference is further supported by an analysis of the aromaticity of the conjoined benzene nucleus. The predominance of hyperconjugation as compared with rehybridization underlying the formation of IMHB in 7H1I is also argued in this context.

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Binding Interaction and Rotational-Relaxation Dynamics of a Cancer Cell Photosensitizer with Various Micellar Assemblies

Cited by 35 publications

References 70 publications

Fluorescence switching of sanguinarine in micellar environments

Fluorescence switching of sanguinarine in micellar environments

Effect of Polymethylene Spacer of Cationic Gemini Surfactants on Solvation Dynamics and Rotational Relaxation of Coumarin 153 in Aqueous Micelles

Lack of resonance assistance in a classical intramolecular hydrogen bond: An exploration from quantum theory of atoms‐in‐molecules perspective

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