d-Glucose derived novel gemini surfactants: synthesis and study of their surface properties, interaction with DNA, and cytotoxicity

• A simple synthetic strategy for m-s-m type cationic gemini surfactants is reported.
• They were prepared by utilizing C-3 functionality of diisopropylidene d-glucose.
• The CMCs of all surfactants were found to be considerably low.
• They show chain length dependent binding capability with plasmid DNA.
• The best candidate of this series binds to DNA at an N/P ratio 3.

Four new d-glucose derived m-s-m type gemini surfactants with variable spacer and tail length have been synthesized by a simple and efficient synthetic methodology utilizing the free C-3 hydroxy group of diisopropylidene glucose. The synthetic route to these gemini surfactants with a quaternary ammonium group as polar head group involves a sequence of simple reactions including alkylation, imine formation, quaternization of amine etc. The surface properties of the new geminis were evaluated by surface tension and conductivity measurements. These gemini surfactants showed low cytotoxicity by MTT assay on HeLa cell line. The DNA binding capabilities of these surfactants were determined by agarose gel electrophoresis, fluorescence titration, and DLS experiments. The preliminary studies by agarose gel electrophoresis indicated chain length dependent DNA binding abilities, further supported by ethidium bromide exclusion experiments. Two of the d-glucose derived gemini surfactants showed effective binding with pET-28a plasmid DNA (pDNA) at relatively low N/P ratio (i.e., cationic nitrogen/DNA phosphate molar ratio).

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