Polymerization of unsaturated phospholipids as large unilamellar liposomes at low temperature

Tsuchida, Eishun; Hatashita, Masanori; Makino, Chisato; Hasegawa, Etsuo; Kimura, Noboru

doi:10.1021/ma00027a035

Cited by 48 publications

(73 citation statements)

References 12 publications

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“…Tsuchida et al 33 studied polymerization of mono-DenPC vesicles using redox and visible sensitization methods, and found that both methods generated a larger X n when the lipids were in the L α phase. Lipid diffusion was not measured in any of these studies.…”

Section: Resultsmentioning

confidence: 99%

Photopolymerization of Dienoyl Lipids Creates Planar Supported Poly(lipid) Membranes with Retained Fluidity

et al. 2016

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Polymerization of substrate-supported bilayers composed of dienoyl phosphatidylcholine (PC) lipids is known to greatly enhance their chemical and mechanical stability, however the effects of polymerization on membrane fluidity have not been investigated. Here planar supported lipid bilayers (PSLBs) composed of dienoyl PCs on glass substrates were examined to assess the degree to which UV-initiated polymerization affects lateral lipid mobility. Fluorescence recovery after photobleaching (FRAP) was used to measure the diffusion coefficients (D) and mobile fractions of rhodamine-DOPE in unpolymerized and polymerized PSLBs composed of bis-sorbyl phosphatidylcholine (bis-SorbPC), mono-sorbyl phosphatidylcholine (mono-SorbPC), bis-dienoyl phosphatidylcholine (bis-DenPC) and mono-dienoyl phosphatidylcholine (mono-DenPC). Polymerization was performed in both the Lα and Lβ phase for each lipid. In all cases, polymerization reduced membrane fluidity, however measurable lateral diffusion was retained which is attributed to a low degree of polymerization. The D values for sorbyl lipids were less than those of the denoyl lipids; this may be a consequence of the distal location of polymerizable group in the sorbyl lipids which may facilitate inter-leaflet bonding. The D values measured after polymerization were 0.1 to 0.8 of those measured before polymerization, a range that corresponds to fluidity intermediate between that of a Lα phase and a Lβ phase. This D range is comparable to ratios of D values reported for liquid-disordered (Ld) and liquid-ordered (Lo) lipid phases, and indicates that the effect of UV polymerization on lateral diffusion in a dienoyl PSLB is similar to the transition from a Ld phase to a Lo phase. The partial retention of fluidity in UV polymerized PSLBs, their enhanced stability, and the activity of incorporated transmembrane proteins and peptides is discussed.

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Section: Resultsmentioning

confidence: 99%

Photopolymerization of Dienoyl Lipids Creates Planar Supported Poly(lipid) Membranes with Retained Fluidity

et al. 2016

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“…Other research groups have reported that for radical polymerization of lipids using K 2 S 2 O 4 /NaHSO 3 initiation, increasing the temperature above the main phase transition temperature (T m ) of the lipid increases the degree of polymerization ( X n ) 65, 66. The increase in X n was attributed to enhanced lateral diffusion of lipid molecules and improved permeability of free radicals into the bilayer.…”

Section: Resultsmentioning

confidence: 99%

Preparation and characterization of asymmetric planar supported bilayers composed of poly(bis-sorbylphosphatidylcholine) on n-octadecyltrichlorosilane SAMs

Ratnayaka

Wysocki

Saavedra

2008

Journal of Colloid and Interface Science

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Planar supported lipid bilayers (PSLBs) have been widely studied as biomembrane models and biosensor scaffolds. For technological applications, a major limitation of PSLBs composed of fluid lipids is that the bilayer structure is readily disrupted when exposed to chemical, mechanical, and thermal stresses. A number of asymmetric supported bilayer structures, such as the hybrid bilayer membrane (HBM) and the tethered bilayer lipid membrane (tBLM), have been created as an alternative to symmetric PSLBs. In both HBMs and tBLMs, the inner monolayer is covalently attached to the substrate while the outer monolayer is typically composed of a fluid lipid. Here we address if cross-linking polymerization of the lipids in the outer monolayer of an asymmetric supported bilayer can achieve the high degree of stability observed previously for symmetric PSLBs in which both monolayers are cross-linked [Ross, E. E., et al., Langmuir 2003, 19, 1752-1765. To explore this issue, HBMs composed of an outer monolayer of a cross-linkable lipid, bisSorbylphosphatidylcholine (bis-SorbPC), and an inner SAM were prepared and characterized. Several experimental conditions were varied: vesicle fusion time, polymerization method, and polymerization time and temperature. Under most conditions, bis-SorbPC cross-linking stabilized the HBM such that its bilayer structure was largely preserved after drying; however these films invariably contained sub-micron scale defects that exposed the hydrophobic core of the HBM. The defects appear to be caused by desorption of low molecular weight oligomers when the film is removed from water, rinsed, and dried. In contrast, poly(bis-SorbPC) PSLBs prepared under similar conditions by Ross et al. were nearly defect free. This comparison shows that formation of a crosslinked network in the outer leaflet of an asymmetric supported bilayer is insufficient to prevent lipid desorption; inter-leaflet covalent linking appears to be necessary to create supported poly(lipid) assemblies that are impervious to repeated drying and rehydration. The difference in stability is attributed to inter-leaflet cross-linking between monolayers which can form in symmetric bis-SorbPC PSLBs.

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“…Photoirradiation of dienoyl and sorbyl groups in lipid bilayers has previously been reported to yield oligomers (X n of 3-10). 14,20 The direct UV polymerization of heterobifunctional double diene PC gave oligomers with X n about 10. 12 The UV polymerization of lipids 8 were performed under argon, in air, and in oxygen and they all showed the same polymerization rate ( Figure 6).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Polymerization of Heterobifunctional Amphiphiles to Cross-Link Supramolecular Assemblies

2000

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The cross-linking of supramolecular assemblies of hydrated amphiphiles is an effective method to stabilize the assembly. A well-known strategy for cross-linking of lipids in lyotropic phases is the inclusion of identical reactive groups in each hydrophobic tail of the lipids. An alternative approach is to incorporate two similar but distinct groups into different locations within a single hydrophobic tail of the amphiphile. In principle, these heterobifunctional amphiphiles could react to form ladderlike polymers or cross-linked polymers. This report describes the synthesis, characterization, and polymerization in lipid vesicles of two series of heterobifunctional phosphatidylcholine (PC) lipids with different separation distances between the two reactive groups. One of the groups, i.e., dienoyl (Den), is attached to the secondary oxygen of the glycerol backbone of the lipid, and the other is either an acryloyl (Acryl) or sorbyl (Sorb) functional group located at the sn-2 chain terminus. Polymerization of both reactive groups in the Acryl/DenPC or the Sorb/DenPC was achieved by either redox polymerization or direct photoirradiation. The degree of polymerization depends on the initiation chemistry. Photoirradiation yields oligomers that are insufficient to cross-link the vesicles, whereas redox-initiated radical polymerization affords cross-linked polymeric vesicles. Under radical polymerization conditions a spacer length of seven or more atoms between the two reactive groups was long enough to ensure that each reactive group can follow an independent reaction path.

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Polymerization of unsaturated phospholipids as large unilamellar liposomes at low temperature

Cited by 48 publications

References 12 publications

Photopolymerization of Dienoyl Lipids Creates Planar Supported Poly(lipid) Membranes with Retained Fluidity

Photopolymerization of Dienoyl Lipids Creates Planar Supported Poly(lipid) Membranes with Retained Fluidity

Preparation and characterization of asymmetric planar supported bilayers composed of poly(bis-sorbylphosphatidylcholine) on n-octadecyltrichlorosilane SAMs

Synthesis and Polymerization of Heterobifunctional Amphiphiles to Cross-Link Supramolecular Assemblies

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