Cholesterol mediates spontaneous insertion of Lycium barbarum polysaccharides in biomembrane model

• Published in: Adsorption : journal of the International Adsorption Society Vol. 26; no. 6; pp. 855 - 862
• Main Authors: Zhang, Ziyi, Hao, Changchun, Liu, Hengyu, Zhang, Xianggang, Sun, Runguang
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.08.2020; Springer Nature B.V
• Subjects: Adsorption; Adsorptivity; Atomic force microscopy; Buffer solutions; Chemistry; Chemistry and Materials Science; Cholesterol; Engineering Thermodynamics; Gibbs free energy; Heat and Mass Transfer; Hydrogen bonds; Industrial Chemistry/Chemical Engineering; Insertion; Isotherms; Lipids; Monolayers; Morphology; Network formation; Polysaccharides; Pressure; Surface chemistry; Surfaces and Interfaces; T.I.: Adsorption in Drug Delivery; Thin Films; polysaccharides; glycero-3-phosphocholine; Atomic force microscopy; 1,2-Dipalmitoyl; Cholesterol; 1-Palmitoyl-2-oleoyl
• ISSN: 0929-5607; 1572-8757
• DOI: 10.1007/s10450-019-00180-9

In this work, the adsorptive behavior of Lycium barabrum polysaccharides (LBP) on 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphocholine(POPC)/1,2-dipalmitoyl- sn -glycero-3-phosphocholine (DPPC) and POPC/DPPC/Cholesterol (Chol) monolayer films were investigated using the Langmuir films technique and atomic force microscopy (AFM). For the POPC/DPPC system, the π-A isotherms shifted to larger areas and the surface pressure variations (Δπ) in the adsorption curves (10 mN/m and 35 mN/m) increased with the increase in the LBP concentration. For the POPC/DPPC/Chol system, π-A isotherms moved to larger areas with the addition of LBP, and the Δπ values were also lower than those of the POPC/DPPC system. These were ascribed to hydrogen bond network formation between LBP and the lipids. The excess per molecular area (ΔA exc ) and the excess Gibbs free energy of mixing ( Δ G mix Exc ) revealed that the repulsion force was the interaction between POPC and DPPC molecules. Meanwhile, the repulsion force increased with the addition of LBP. The addition of cholesterol decreased the force. The interactions among molecules were also evaluated by the values of K (the speed of adsorption of LBP), A p (the number of each lipid molecule combining with the polysaccharide molecules in the mixed monolayer), Γ (the surface excess concentration) and A (the area per molecule). As shown in AFM images, the morphology of the monolayer films also indicated that LBP was easily adsorbed onto the POPC/DPPC monolayer film via hydrogen bond and the weak Van der Waals interaction. In summary, cholesterol could affect spontaneous insertion of LBP into the POPC/DPPC monolayer films from phosphate buffer solution.