Ligand accessibility as means to control cell response to bioactive bilayer membranes

Abstract

We report a new method to create a biofunctional surface in which the accessibility of a ligand is used as a means to influence the cell behavior. Supported bioactive bilayer membranes were created by Langmuir-Blodgett (LB) deposition of either a pure poly(ethylene glycol) (PEG) lipid, having PEG head groups of various lengths, or 50 mol % binary mixtures of a PEG lipid and a novel collagen-like peptide amphiphile on a hydrophobic surface. The peptide amphiphile contains a peptide synthetically lipidated by covalent linkage to hydrophobic dialkyl tails. The amphiphile head group lengths were determined using neutron reflectivity. Cell adhesion and spreading assays showed that the cell response to the membranes depends on the length difference between head groups of the membrane components. Cells adhere and spread on mixtures of the peptide amphiphile with the PEG lipids having PEG chains of 120 and 750 molecular weight (MW). In contrast, cells adhered but did not spread on the mixture containing the 2000 MW PEG. Cells did not adhere to any of the pure PEG lipid membranes or to the mixture containing the 5000 MW PEG. Selective masking of a ligand on a surface is one method of controlling the surface bioactivity.

Patterning Solid-Supported Lipid Bilayer Membranes by Lithographic Polymerization of a Diacetylene Lipid

“…Previous unsuccessful attempts to identify the bi-2H-azirin-2-yls 4. activities, [16] separation of membrane proteins by 2D electrophoresis, [17] creation of addressable arrays of modified lipid bilayer membranes for combinatorial chemistry, [18] and controlled cell culture on designed membrane surfaces. [19] Experimental Section Materials: Diacetylene lipid 1 and egg PC were purchased from Avanti Polar Lipids, Alabaster, AL, USA. NBD-PE (N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine) was purchased from Molecular Probes, Eugene, OR, USA.…”

Induction of Endothelial Cell Activation by a Triple Helical α2β1 Integrin Ligand, Derived from Type I Collagen α1(I)496–507

“…The transfer of peptide-amphiphiles to hydrophobic surfaces and the subsequent effect of the surface on peptide conformation and orientation have been studied extensively. Atomic force microscopy shows the appropriate height "differential" for peptide-amphiphiles and lipids if peptide-amphiphiles are oriented upright (34,36). Neutron reflectivity data for triple helical peptideamphiphiles demonstrated that peptide head groups are oriented perpendicular to the air-water interface and retain the same conformation as in solution (36,45).…”

“…Atomic force microscopy shows the appropriate height "differential" for peptide-amphiphiles and lipids if peptide-amphiphiles are oriented upright (34,36). Neutron reflectivity data for triple helical peptideamphiphiles demonstrated that peptide head groups are oriented perpendicular to the air-water interface and retain the same conformation as in solution (36,45). In addition, peptideamphiphile orientation is nearly unaffected by changes in surface density (45).…”

Peptide-presenting two-dimensional protein matrix on supported lipid bilayers: An efficient platform for cell adhesion

“…In addition, the formation of SLBs is simple 14 and they are highly resistant to nonspecific adsorption by proteins or cells. 12,[15][16][17][18] SLBs consist of a continuous lipid bilayer, 5 nm thick, separated from the substrate by a ϳ1 nm thin water cushion. Previous studies of cell adhesion with SLBs have relied on the use of lipids functionalized with peptides.…”

“…Previous studies of cell adhesion with SLBs have relied on the use of lipids functionalized with peptides. [18][19][20][21][22][23][24][25][26] The influence of the orientation, 20,22,23 accessibility, 18,26 a͒ Author to whom correspondence should be addressed. Electronic mail: a.brisson@iecb.u-bordeaux.fr conformation, 20,22 or mobility 27 of lipo-peptides on cell attachment and spreading have been characterized, thanks to the availability of a wealth of surface-sensitive techniques adapted to the SLB format.…”