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Nonviral gene delivery vectors are acquiring greater attention in the field of gene therapy by replacing the biological viral vectors. DNA-cationic polymer complexes are one of the most promising systems to find application in gene therapy. Hence, a complete insight of their biophysical characterization and binding energy profile is important in understanding the mechanism involved in nonviral gene therapy. In this investigation, the interaction between calf thymus DNA (ctDNA) and imidazolium-based poly(ionic liquids) (PILs) also known as polyelectrolytes with three different alkyl side chains (ethyl, butyl, and hexyl) in physiological conditions using various spectroscopic experiments with constant DNA concentration and varying polyelectrolyte concentrations is reported. UV-visible absorption, fluorescence quenching studies, gel electrophoresis, circular dichroism (CD), and Fourier transform infrared spectroscopy (FTIR) have confirmed the binding of polyelectrolytes with DNA. UV-vis absorption measurements and fluorescence quenching revealed that the binding between DNA and the polyelectrolyte is dominated by electrostatic interactions. Additionally, CD and FTIR results indicated that the DNA retained its B-form with minor perturbation in the phosphate backbone without significant change in the conformation of its base pairs. Preference for alkyl side chains (K(PIL-Ethyl Br) < K(PIL-Butyl Br) < K(PIL-Hexyl Br)) toward efficient binding between the polyelectrolyte and DNA was inferred from the binding and quenching constants calculated from the absorption and emission spectra, respectively. Further, in silico molecular docking studies not only validated the observed binding trend but also provided insight into the binding mode of the polyelectrolyte-DNA complex.

Self assembly of amphiphilic homo-PILs.

A series of six different ionic liquids (ILs) of the kind 1-alkyl-3-methylimidazolium bromide/hydroxide (IL-Br and IL-OH) tailored with different N-alkyl side chains (ethyl, butyl, octyl) were synthesized and evaluated for their vermicidal activity against Indian earthworm, Pheretima posthuma. The percentage of paralysis and mortality of earthworms against ILs were recorded in dose dependent (at different concentrations 2, 4, 8 and 16 mM) and time dependent manner. ILs with hydroxide as counter anion (IL-OH) showed higher vermicidal activity compared to their bromide counter parts (IL-Br). Moreover, ILs with the longest alkyl chain (octyl) are observed with significant vermicidal activity compared to the rest (ethyl and butyl) as well as the standard drug, Albendazole. Furthermore, theoretical modeling was carried out to visualize the preferential docking positions of these ILs into the active site of β-Tubulin.Fascinatingly, it was found that ILs with longest alkyl side chain showed remarkable vermicidal activity compared to the rest and the molecular docking studies not only validated the 2 experimental results but also showed per residue interaction analysis between ILs and different components of β-Tubulin.