title: Arraying of intact liposomes into chemically functionalized microwells.
abstract: Here, we describe a protocol to bind individual, intact phospholipid bilayer liposomes, which are on the order of 1 microm in diameter, in microwells etched in a regular array on a silicon oxide substrate. The diameter of the wells is on the order of the liposome diameter, so only one liposome is located in each well. The background of the silicon oxide surface is functionalized with a PEG oligomer using the contact printing of a PEG silane to present a surface that resists the adsorption of proteins, lipid material, and liposomes. The interiors of the wells are functionalized with an aminosilane to facilitate the conjugation of biotin, which is then bound to Neutravidin. The avidin-coated well interiors bind the liposomes whose surfaces contain biotinylated lipids. The specific binding of the liposomes to the surface using the biotin-avidin linkage, together with the resistant nature of the background and the physical confinement of the wells, allows the liposomes to remain intact and to not unravel, rupture, and fuse onto the surface. We demonstrate this intact arraying using confocal laser scanning microscopy of fluorophores specifically tagging the microwells, the lipid bilayer, and the aqueous interior of the liposome.
authors.affiliation: Department of Chemical Engineering, City University of New York, New York, USA.
authors.forename: Nikhil D
authors.initials: ND
authors.lastname: Kalyankar
authors.forename: Manoj K
authors.initials: MK
authors.lastname: Sharma
authors.forename: Shyam V
authors.initials: SV
authors.lastname: Vaidya
authors.forename: David
authors.initials: D
authors.lastname: Calhoun
authors.forename: Charles
authors.initials: C
authors.lastname: Maldarelli
authors.forename: Alexander
authors.initials: A
authors.lastname: Couzis
authors.forename: Lane
authors.initials: L
authors.lastname: Gilchrist
mesh_terms: D001360:Avidin / Q000737:chemistry; D001710:Biotin / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D046210:Microfluidic Analytical Techniques; D018613:Microscopy, Confocal; D011092:Polyethylene Glycols / Q000737:chemistry; D012822:Silicon Dioxide
chemical_list: D008051:Lipid Bilayers; D008081:Liposomes; C093483:neutravidin; D001360:Avidin; D011092:Polyethylene Glycols; D001710:Biotin; D012822:Silicon Dioxide