Abstract
We studied real-time interaction between poly(ethylene glycol)-conjugated phospholipids (PEG-lipids) and a supported lipid membrane by surface plasmon resonance (SPR) spectroscopy to understand dynamic behaviors of PEG-lipids on living cell membranes. Supported lipid membranes formed on a hydrophobic surface were employed as a model of living cell membrane. We prepared three kinds of PEG-lipids that carried alkyl chains of different lengths for SPR measurements and also performed fluorescence recovery after photobleaching (FRAP) to study the influence of acyl chain length on dynamics on the supported membrane. PEG-lipids were uniformly anchored to lipid membranes with high fluidity without clustering. Incorporation and dissociation rates of PEG-lipids into supported membranes strongly depended on the length of acyl chains; longer acyl chains reduced the incorporation rate and the dissociation rate of PEG-lipid. Furthermore, protein adsorption experiment with bovine serum albumin indicated that PEG modification prevented the adsorption of bovine serum albumin on such supported membrane.
Highlights
We studied the adsorption of bovine serum albumin (BSA) onto a supported lipid membrane modified with MeO-PEG-DPPE to evaluate whether PEG modification effectively suppresses protein adsorption onto lipid membrane
Since amphiphilic polymers tend to disappear from the cell surface with time after surface modification,[16,18] it is necessary to understand the dynamic behaviors of amphiphilic polymers
Supported lipid membrane with a neutral charge was used as a model membrane of cell surfaces, and the physicochemical interaction of PEG-lipids with lipid membrane was analyzed by surface plasmon resonance (SPR) measurement
Summary
Various synthetic and natural polymers have been widely used to modify the surface of materials to modulate the immunogenicity after implantation or infusion into the human body.[1,2,3] Recently, the surfaces of cells have been engineered in order to improve graft survival in cell transplantation.[4,5] Approaches for modifying cell surfaces include: covalent conjugation to membrane proteins,[6,7,8,9,10,11] electrostatic interaction with a negatively charged cell surface,[12,13,14] and hydrophobic interaction with a lipid bilayer of a cell.[15,16] Cell surface modification with polymers should be both highly efficient and minimally cytotoxic. Poly(ethylene glycol)conjugated phospholipid (PEG-lipids); supported lipid membrane; surface modification; membrane fluidity; hydrophobic interaction. We have studied amphiphilic polymers including poly(ethylene glycol)-phospholipid conjugate (PEGlipid) derivatives and partially alkylated poly(vinyl alcohol)s (PVA-alkyls) for cell surface modifications.[16,18]. Interaction with serum albumin was examined to study protein adsorption on PEG-lipid modified membranes
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