Binding of a double-chain surfactant-cobalt(III) complex to CT DNA: Effect of β-cyclodextrin in the medium

Metallosurfactant aggregates: Structures, properties, and potentials for multifarious applications

Metallosurfactants offer important scientific and technological advances due to their novel interfacial properties. As a special class of structures formed by the integration of metal ions into amphiphilic surfactant molecules, these metal-based amphiphilic molecules possess both organometallic and surface chemistries. This review critically examines the structural transitions of metallosurfactants from micelle to vesicle upon metal coordination. The properties of a metallosurfactant can be changed by tuning the coordination between the metal ions and surfactants. The self-assembled behavior of surfactants can be controlled by selecting transition-metal ions that enhance their catalytic efficiency in environmental applications by applying a hydrogen evolution reaction or oxygen evolution reaction. We present the different scattering techniques available to examine the properties of metallosurfactants (e.g., size, shape, structure, and aggregation behavior). The utility of metallosurfactants in catalysis, the synthesis of nanoparticles, and biomedical applications (involving diagnostics and therapeutics) is also explored.

Multi-spectroscopic and free energy landscape analysis on the binding of antiviral drug remdesivir with calf thymus DNA

Remdesivir (REM) is an antiviral drug, which exercises its effect by targeting specifically RNA-dependent RNA polymerase. The interaction of REM with calf thymus DNA (CT-DNA) was investigated by multi-spectroscopic techniques (UV-Vis, fluorescence, circular dichroism and ³¹P NMR) in combination with different biophysical experiments and metadynamics simulation studies. UV-Vis and fluorescence spectroscopic analysis indicated formation of a complex between REM and CT-DNA, whose binding constant is in the order of 10⁴ M^-1. Competitive displacement assays with ethidium bromide (EB) and Hoechst 33258 shown that REM binds to CT-DNA via intercalation mode. Significant alteration in the band due to base stacking pairs at 274 nm in the circular dichroism spectrum, appreciable increase in relative viscosity of the biomolecule upon binding with REM and the results of potassium iodide quenching studies confirmed that REM intercalates into the base pairs of CT-DNA. Thermodynamic parameters revealed that the binding of REM to CT-DNA is a spontaneous process (ΔG⁰ < 0) and the main force which holds them together in the REM/CT-DNA complex is electrostatic interaction (ΔH⁰ < 0 and ΔS⁰ > 0). The up-field shift in the ³¹P NMR signal of REM on interaction with CT-DNA suggested that phenyl ring adjacent to the phosphate moiety of REM may involve in the intercalation process. This is well supported by the analysis of free energy surface landscape derived from metadynamics simulation studies.

Biophysical insights into the intercalative interaction of surfactant cobalt(III) complexes of certain diimine ligands bound to yeast tRNA: Effects of hydrophobicity

The interaction of two surfactant cobalt(III) complexes, cis-[Co(ip)₂(DA)₂](ClO₄)₃ 1 and cis-[Co(dpq)₂(DA)₂](ClO₄)₃ 2 where ip=imidazo[4,5-f][1,10]phenanthroline and dpq=dipyrido[3,2-d:2'-3'-f]quinoxaline with yeast tRNA have been explored by using electronic absorption, competitive binding, electrochemical studies and viscosity measurements. The results suggest that these complexes can bind to tRNA by intercalation. The presence of hydrophobic diimine ligand and the long aliphatic double chains of these complexes facilitate its intercalative interaction with the hydrophobic interior of the tRNA. The extent of tRNA binding of complex 2 has greater affinity than that of complex containing imidazo[4,5-f][1,10]phenanthroline ligands.

Influence of self-assembly on intercalative DNA binding interaction of double-chain surfactant Co(III) complexes containing imidazo[4,5-f][1,10]phenanthroline and dipyrido[3,2-d:2'-3'-f]quinoxaline ligands: experimental and theoretical study

A new class of surfactant Co(III) complexes, cis-[Co(ip)2(C12H25NH2)2](ClO4)3 (1) and cis-[Co(dpq)2(C12H25NH2)2](ClO4)3 (2) (ip = imidazo[4,5-f][1,10]phenanthroline, dpq = dipyrido[3,2-d:2'-3'-f]quinoxaline), have been synthesized and characterized by various spectroscopic and physico-chemical techniques. The critical micelle concentration (CMC) values of these complexes in aqueous solution were obtained from conductance measurements. The specific conductivity data (at 303, 308, 313, 318 and 323 K) served for the evaluation of the temperature-dependent CMC and the thermodynamics of micellization (ΔG(0)(m), ΔH(0)(m) and ΔS(0)(m)). The trend in DNA-binding affinities and the spectral properties of a series of complexes, cis-[Co(ip)2(C12H25NH2)2](ClO4)3 (1) and cis-[Co(dpq)2(C12H25NH2)2](ClO4)3 (2), have been experimentally and theoretically investigated. The experimental results indicate that the size and shape of the intercalated ligand and hydrophobicity of the complexes have a marked effect on the binding affinity of the complexes to CT DNA in intercalation mode, and the order of their intrinsic DNA-binding constants Kb is Kb(1) < Kb(2). In addition, the influence of the extended aromatic ring and optical properties of the complexes can be reasonably explained by applying the DFT calculations. The energy gap between HOMO and LUMO indicates that these complexes are prone to interact with CT DNA. Further, molecular docking calculations have also been performed to understand the nature of binding of the complexes and the result confirms that the complexes interact with CT DNA through the alkyl chain. The cytotoxic activity of these complexes on human liver carcinoma cancer cells were determined adopting MTT assay and specific staining techniques, which revealed that the viability of the cells thus treated was significantly decreased and the cells succumbed to apoptosis as seen in the changes in the nuclear morphology and cytoplasmic features.

Nucleic acid binding study of surfactant copper(ii) complex containing dipyrido[3,2-a:2′-3′-c]phenazine ligand as an intercalator: in vitro antitumor activity of complex in human liver carcinoma (HepG2) cancer cells

A new surfactant copper(ii) complex, [Cu(dppz)₂DA](ClO₄)₂, where dppz = dipyrido[3,2-a:2′-3′-c]phenazine and DA-dodecylamine, has been synthesized and characterized by physico-chemical and spectroscopic methods.