Molecular Insights Into Human Serum Albumin Interaction and Binding With Gemini and Pluronic F‐127 Binary Surfactants—A Multitechnique Approach

This study examined the systematic binding of human serum albumin (HSA) to the non-ionic surfactant Pluronic F-127, gemini surfactant 2-butanol-1, 4-bis (dimethyldodecylammonium bromide) (12-4(OH)-12) and their binary mixtures at 300 K. While fluorescence, FTIR and circular dichroism (CD) spectroscopy offered molecular-level insights into protein-surfactant micelle interactions, surface tension measurements were utilized to ascertain the micellization and interfacial behavior of binary surfactant mixture (F-127 + 12-4(OH)-12). The interest in examining current employed system arises from a diverse array of bioactivities associated with macromolecules. Pluronic surfactants have demonstrated their ability to transport various biologically active compounds. Strong attractive effects and advantageous micellization thermodynamics were indicated by the mixed gemini-pluronic system's CMC values, which were lower than those expected by ideal mixing. Non-optimal mixing at the air-solution interface was confirmed by interaction parameters (β). Mixed micellization of F-127 + 12-4(OH)-12 are found to be spontaneous as indicated by the negative free energies of micellization ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mi>Δ</mml:mi> <mml:msubsup><mml:mi>G</mml:mi> <mml:mi>mic</mml:mi> <mml:mo>∘</mml:mo></mml:msubsup> </mml:mrow> <mml:annotation>$$ \Delta {G}_{\mathrm{mic}}^{\circ } $$</mml:annotation></mml:semantics> </mml:math> ) values. Fluorescence data were used to determine the binding type of F-127 + 12-4(OH)-12 with HSA. Partial unfolding of HSA is confirmed by CD analysis, which reveals significant α-helix loss at higher fractions but little structural change at low gemini levels. The secondary structure of HSA is disrupted, as evidenced by FTIR band shifts, especially in the amide I region. This confirms partial unfolding upon binding with the 12-4(OH)-12 + F-127 mixture. Gemini-rich mixtures increased HSA binding affinity and caused notable conformational changes, according to spectroscopic analyses, which may indicate that the protein's natural structure was disrupted.