Elastic compliance as a tool to understand Hofmeister ion specific effect in DMPC liposomes

• Published in: Biophysical chemistry Vol. 249; p. 106148
• Main Authors: Madhumitha, D., A., Bruntha, Vaidyanathan, V.G., Reddy, Bhargavi Gari Narayana, Sreeram, K.J., Dhathathreyan, A.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.06.2019
• Subjects: Dimyristoylphosphatidylcholine - chemistry; Elasticity; Electrolytes - chemistry; Lipid Bilayers - chemistry; Liposomes - chemistry; Quartz Crystal Microbalance Techniques; Scattering, Small Angle; X-Ray Diffraction
• ISSN: 0301-4622; 1873-4200
• DOI: 10.1016/j.bpc.2019.106148

Elastic compliance of DMPC liposomes with Hofmeister electrolytes: NaCl, Na2SO4, Na2CO3, NaNO3, KCl and MgCl2 studied using Quartz crystal microbalance with dissipation has been correlated with changes in their lamellar spacing from SAXS. The study suggests that hydration water of the different ions has an effect on the overall packing of the lipid bilayer that results as either a dehydrated liposome or where water smears the surface of the liposomes. Ratio of hydrogen bonded carbonyl and phosphate of polar region of the liposomes from ATR-FTIR spectroscopy, suggests that the polar groups are less hydrated due to the displacement of water by the electrolytes compared to pure DMPC and ordered in the sequence for cations as: K+ < Na+,Mg2+ and for anions as SO42− < CO32– < Cl− < NO3−. These findings show the usefulness of Elastic compliance for structural studies of composite phospholipid bilayers, lipid–protein complexes and lipid systems of reduced dimensionalities. [Display omitted] •Elastic compliance as an indicator to study dehydration of liposomes.•Hofmeister ions influence physical properties of membranes.•Increased penetration of cations in the polar region compared to anions.•Ions co-localize to the polar oxygen atoms of the phosphate and ester groups in the polar region of the lipid.