title: Influence of Divalent Cations on Deformation and Rupture of Adsorbed Lipid Vesicles.
abstract: The fate of adsorbed lipid vesicles on solid supports depends on numerous experimental parameters and typically results in the formation of a supported lipid bilayer (SLB) or an adsorbed vesicle layer. One of the poorly understood questions relates to how divalent cations appear to promote SLB formation in some cases. The complexity arises from the multiple ways in which divalent cations affect vesicle-substrate and vesicle-vesicle interactions as well as vesicle properties. These interactions are reflected, e.g., in the degree of deformation of adsorbed vesicles (if they do not rupture). It is, however, experimentally challenging to measure the extent of vesicle deformation in real-time. Herein, we investigated the effect of divalent cations (Mg(2+), Ca(2+), Sr(2+)) on the adsorption of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipid vesicles onto silicon oxide- and titanium oxide-coated substrates. The vesicle adsorption process was tracked using the quartz crystal microbalance-dissipation (QCM-D) and localized surface plasmon resonance (LSPR) measurement techniques. On silicon oxide, vesicle adsorption led to SLB formation in all cases, while vesicles adsorbed but did not rupture on titanium oxide. It was identified that divalent cations promote increased deformation of adsorbed vesicles on both substrates and enhanced rupture on silicon oxide in the order Ca(2+) > Mg(2+) > Sr(2+). The influence of divalent cations on different factors in these systems is discussed, clarifying experimental observations on both substrates. Taken together, the findings in this work offer insight into how divalent cations modulate the interfacial science of supported membrane systems.
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore.|Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore.
authors.forename: Marija
authors.initials: M
authors.lastname: Dacic
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore.|Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore.
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Jackman
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore.|Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore.
authors.forename: Saziye
authors.initials: S
authors.lastname: Yorulmaz
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore.|Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore.|Boreskov Institute of Catalysis, Russian Academy of Sciences , Novosibirsk 630090, Russia.
authors.forename: Vladimir P
authors.initials: VP
authors.lastname: Zhdanov
authors.affiliation: Department of Physics, Chalmers University of Technology , 41296 Göteborg, Sweden.
authors.forename: Bengt
authors.initials: B
authors.lastname: Kasemo
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University , 50 Nanyang Avenue 639798, Singapore.|Centre for Biomimetic Sensor Science, Nanyang Technological University , 50 Nanyang Drive 637553, Singapore.|School of Chemical and Biomedical Engineering, Nanyang Technological University , 62 Nanyang Drive 637459, Singapore.
authors.forename: Nam-Joon
authors.initials: NJ
authors.lastname: Cho