A novel quaternary ammonium-based cationic gemini surfactant (S6) having 1,6 di-bromo hexane as a spacer, have been used and its interaction with insulin in aqueous solution (pH, 7.40) was investigated by several methods including fluorescence spectroscopy, UV-Vis spectroscopy, circular dichroism, dynamic light scattering, ζ-potential measurements, conductivity and transmission electron microsc...