Construction of a Fluorescence-Based Logic Gate Seeing the Effect of Perchlorate Ions on Hemicyanine Dye-β-Cyclodextrin Complexes to Certify Safe Drinking Water.

Perchlorate ions (ClO ) are prevalent contaminants in the surface, and drinking water that disrupt thyroid function by competitively inhibiting the sodium-iodide symporter (NIS), posing significant health risks. Here, fluorescence-based logic gates have been constructed by leveraging the binding interactions between a hemicyanine dye, 4-[4-(dimethylamino)-styryl]-1-docosylpyridinium bromide (DASPC22) and β-cyclodextrin (β-CD) that could be useful to know whether ClO ions in water are within the toxicity range or not. In aqueous media, DASPC22 forms nonfluorescent H-aggregates, but fluorescence is enhanced upon forming host-guest inclusion complexes with β-CD.

ct-DNA compaction by nanoparticles formed by silica and gemini surfactants having hydroxyl group substituted spacers: In vitro, in vivo, and ex vivo gene uptake to cancer cells.

Hybrid nanoparticles formed by Silica (SiO) coated with cationic gemini surfactants with variable hydroxyl group substituted spacers, 12-4(OH)-12,2Br and 12-4(OH)-12,2Br have shown a great extent of compaction of calf thymus DNA (ct-DNA) compared to conventional counterpart cationic surfactant, dodecyl trimethylammonium bromide (DTAB). Study shows not only the hydrophobicity of the spacer but also the hydrogen bonding interactions between the hydroxyl group substituted spacer and DNA have a great role in DNA compaction. 12-4(OH)-12,2Br is more efficient in compacting ct-DNA compared to 12-4(OH)-12,2Br due to the stronger binding of the former with ct-DNA than the latter.

Compaction of Calf Thymus DNA by a Potential One-Head-Two-Tail Surfactant: Properties of Nanomaterials and Biological Testing for Gene Delivery.

A one-head-two-tail cationic surfactant, Dilauryldimethylammonium bromide (DDAB) has shown a great extent of calf thymus DNA (ct-DNA) compaction being adsorbed on the surfaces of negatively charged SiO nanoparticles (NPs). DDAB molecules show high adsorption efficiency and induce many positive surface charges per-unit surface area of the SiO NPs compared to cationic Gemini (12-6-12) and conventional (DTAB) surfactants in an aqueous medium at pH 7.4, as evident from zeta potential and EDAX data.

Role of Gemini Surfactants with Variable Spacers and SiO Nanoparticles in ct-DNA Compaction and Applications toward / Gene Delivery.

Compaction of calf thymus DNA (ct-DNA) by two cationic gemini surfactants, 12-4-12 and 12-8-12, in the absence and presence of negatively charged SiO nanoparticles (NPs) (∼100 nm) has been explored using various techniques. 12-8-12 having a longer hydrophobic spacer induces a greater extent of ct-DNA compaction than 12-4-12, which becomes more efficient with SiO NPs. While 50% ct-DNA compaction in the presence of SiO NPs occurs at ∼77 nM of 12-8-12 and ∼130 nM of 12-4-12, but a conventional counterpart surfactant, DTAB, does it at its concentration as high as ∼7 μM.

Refolding of denatured gold nanoparticles-conjugated bovine serum albumin through formation of catanions between gemini surfactant and sodium dodecyl sulphate.

The present work elucidates binding interactions of sodium dodecyl sulphate (SDS) with the conjugated gold nanoparticles (AuNPs)-bovine serum albumin (BSA), unfolded by each of two gemini surfactants, 1,4-bis(dodecyl-,-dimethylammonium bromide)-butane (12-4-12,2Br) or 1,8-bis(dodecyl-,-dimethylammonium bromide)-octane (12-8-12,2Br). Initially, at a low concentration of SDS there is a relaxation of bioconjugates from their compressed form due to the formation of catanions between SDS and gemini surfactants. On moving towards higher concentrations of SDS, these relaxed unfolded bioconjugates renature by removal of residual bound gemini surfactants.

Binding interactions of cationic gemini surfactants with gold nanoparticles-conjugated bovine serum albumin: A FRET/NSET, spectroscopic, and docking study.

This work demonstrates binding interactions of two cationic gemini surfactants, 12-4-12,2Br and 12-8-12,2Br with gold nanoparticles (AuNPs)-conjugated bovine serum albumin (BSA) presenting binding isotherms from specific binding to saturation binding regions of surfactants. The binding isotherm has been successfully constructed using Förster's resonance energy transfer (FRET) and nanometal surface energy transfer (NSET) parameters calculated based on fluorescence quenching of donor, tryptophan (Trp) residue by acceptor, AuNP. Energy transfer efficiency (E) changes due to alteration in the donor-acceptor distance when surfactants interact with bioconjugates.

Binding interactions and FRET between bovine serum albumin and various phenothiazine-/anthracene-based dyes: a structure-property relationship.

The present study demonstrates binding interactions and Förster resonance energy transfer (FRET) between bovine serum albumin (BSA) and a series of structurally and electronically diverse phenothiazine (PTZ) and anthracene (ANT) dyes. Upon selective excitation of tryptophan (Trp) residues of BSA, radiationless energy transfer to a dye takes place, resulting in fluorescence quenching of the former. Fluorescence quenching mechanisms, FRET parameters, possible locations, and binding constants of dyes with the BSA have been examined to deduce a structure-property relationship.

Role of Different States of Solubilized Water on Solvation Dynamics and Rotational Relaxation of Coumarin 490 in Reverse Micelles of Gemini Surfactants, Water/12--12.2Br ( = 5, 6, 8)/-Propanol/Cyclohexane.

The present study demonstrates how the different states of solubilized water viz. quaternary ammonium headgroup-bound, bulklike, counterion-bound, and free water in reverse micelles of a series of cationic gemini surfactants, water/12--12 ( = 5, 6, 8).2Br/-propanol/cyclohexane, control the solvation dynamics and rotational relaxation of Coumarin 490 (C-490) and microenvironment of the reverse micelles.

Fluorescence Resonance Energy Transfer, Small-Angle Neutron Scattering, and Dynamic Light Scattering Study on Interactions of Gemini Surfactants Having Different Spacer Groups with Protein at Various Regions of Binding Isotherms.

The binding interactions of three gemini surfactants having different spacer groups (12-4-12, 12-8-12, and 12-4(OH)-12) with a high concentration (150 μM) of bovine serum albumin (BSA) at various regions of binding isotherms have been studied by means of steady-state fluorescence and fluorescence anisotropy, time-correlated single-photon counting fluorescence of -2-[4-(dimethylamino)styryl]benzothiazole, small-angle neutron scattering (SANS), and dynamic light scattering (DLS) measurements. The fluorescence resonance energy transfer phenomenon between the twisted intramolecular charge transfer fluorescent molecule, -2-[4-(dimethylamino)styryl]benzothiazole as an acceptor, and tryptophan 213 (Trp-213) of BSA as a donor has been successfully used to probe the binding interactions of gemini surfactants with protein at all regions of binding isotherms. The increasing order of energy transfer efficiency at a higher concentration range of surfactants is 12-8-12 > 12-4-12 > 12-4(OH)-12.

Effect of Urea on Solvation Dynamics and Rotational Relaxation of Coumarin 480 in Aqueous Micelles of Cationic Gemini Surfactants with Different Spacer Groups.

The present work highlights the effect of urea on solvation dynamics and the rotational relaxation of Coumarin 480 (C-480) in the Stern layer of aqueous micelles of cationic gemini surfactants, 12-4(OH) -12 ( = 0, 1, 2). UV-visible absorption, steady-state fluorescence and fluorescence anisotropy, time-resolved fluorescence and fluorescence anisotropy, and dynamic light scattering measurements have been carried out for this study. The formation of micelles becomes disfavored in the presence of urea at high concentration.

Effect of Hydrophobicity of Tails and Hydrophilicity of Spacer Group of Cationic Gemini Surfactants on Solvation Dynamics and Rotational Relaxation of Coumarin 480 in Aqueous Micelles.

Solvation dynamics and rotational relaxation of coumarin 480 in aqueous micelles of cationic gemini surfactants with diethyl ether (EE) spacer group (-EE-) and tails with varying tail lengths ( = 12, 14, and 16) have been studied. Studies have been carried out by measuring UV-visible absorption, steady-state fluorescence and fluorescence anisotropy, time-resolved fluorescence and fluorescence anisotropy, H NMR spectroscopy, and dynamic light scattering. Effects of hydrocarbon tail length and hydrophilicity of spacer group on solvation dynamics and rotational relaxation processes at inner side of the Stern layer of micelles have been studied.

Solvation dynamics and rotational relaxation of coumarin 153 in mixed micelles of Triton X-100 and cationic gemini surfactants: effect of composition and spacer chain length of gemini surfactants.

Solvation dynamics and rotational relaxation of coumarin 153 (C-153) in mixed micelles of non-ionic surfactant, Triton X-100 and a series of cationic gemini surfactants, 12-s-12, 2Br with varying polymethylene spacer chain length (s = 3, 6, 8, 12) at different bulk mole fractions of a surfactant were studied. Studies were carried out by means of UV-Vis absorption, steady-state fluorescence and fluorescence anisotropy, time-resolved fluorescence and fluorescence anisotropy, and dynamic light scattering measurements. While micropolarity of the environment around C-153 in mixed micelles increased, the microviscosity decreased with increasing amount of a gemini surfactant.

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

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.

Study on metal nanoparticles synthesis and orientation of gemini surfactant molecules used as stabilizer.

In the present study, we report the synthesis of gold (Au), silver (Ag), and gold-silver alloy (Au-Ag) nanoparticles (NPs) by seed-mediated method using gemini surfactant, containing diethyl ether spacer group as a stabilizer. As-synthesized NPs are found very much stable and have been characterized using UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and zeta potential techniques. The orientation of gemini surfactant molecules surrounding the metal NPs has been investigated exploiting twisted intramolecular charge transfer (TICT) fluorescence properties of a probe 4-(N,N-dimethylamino) cinnamaldehyde (DMACA).

Effect of hydroxyl group substituted spacer group of cationic gemini surfactants on solvation dynamics and rotational relaxation of Coumarin-480 in aqueous micelles.

The solvation dynamics and rotational relaxation of Coumarin 480 (C-480) have been investigated in the micelles of a series of gemini surfactants, 12-4(OH)n-12 (n = 0, 1, and 2), with increasing hydroxyl group substitution within the spacer group. Steady-state and time-correlated single photon counting (TCSPC) fluorescence spectroscopic techniques have been used to carry out such study. Steady-state and TCSPC fluorescence data support the location of probe molecule at the Stern layer.

Fluorescent probe studies of micropolarity, premicellar and micellar aggregation of non-ionic Brij surfactants.

The dipolar nature of trans-2-[4-(dimethylamino)styryl]benzothiazole (DMASBT) in its twisted intramolecular charge transfer (TICT) excited state makes it useful as a surface probe for phenomena such as premicellar and micellar aggregation of non-ionic Brij surfactants. The process of micellization of Brij 35, Brij 58, Brij 78, and Brij 98 through the formation of smaller premicellar aggregates results in a progressive change in the nature of the DMASBT molecule and its location in the aggregates, reflecting the changes in its photophysical properties, which have been studied using steady-state fluorescence, fluorescence anisotropy, and time-correlated single-photon counting measurements. The microenvironment polarity around the DMASBT probe in the micellar phase is greater than that in corresponding premicellar phases.

Fragmentation of molecule-induced gamma-cyclodextrin nanotubular suprastructures due to drug dosage.

The guest-host concentration has already been proved to be a very important factor in the drug delivery process. In the present work we demonstrate the formation of compound induced gamma-cyclodextrin nanotubular suprastructure. The nanotubes formed are found to be highly sensitive to the concentration of the guest molecule.

Defining the different phases of premicellar aggregation using the photophysical changes of a surface-probing compound.

Photophysical changes of a cylindrical compound undergoing twisted intramolecular charge transfer may be used as a surface probe to study the different phases of premicellar aggregate formation. The probe molecule, trans-2-[4-(dimethylamino)styryl] benzothiazole (DMASBT), attaches itself to the premicellar and the micellar aggregates of cationic, anionic, and neutral surfactants in different orientations because of its dipolar nature in the excited state. The micelle formation is preceded by a few typical rearrangements of the surfactant molecules.