The formation and properties of supported lipid bilayers (SLB) containing hydrophobic nanoparticles (NP) was studied in relation to underlying cushion obtained from selected polyelectrolyte multilayers. Lipid vesicles were formed from zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) in phosphate buffer (PBS). As hydrophobic nanoparticles - quantum dots (QD) with size of 3.8nm (emission wavelength of 420nm) were used. Polyelectrolyte multilayers (PEM) were constructed by the sequential, i.e., layer-by-layer (LbL) adsorption of alternately charged polyelectrolytes from their solutions. Liposomes and Liposome-QDs complexes were studied with Transmission Cryo-Electron Microscopy (Cryo-TEM) to verify the quality of vesicles and the position of QD within lipid bilayer. Deposition of liposomes and liposomes with quantum dots on polyelectrolyte films was studied in situ using quartz crystal microbalance with dissipation (QCM-D) technique. The fluorescence emission spectra were analyzed for both: suspension of liposomes with nanoparticles and for supported lipid bilayers containing QD on PEM. It was demonstrated that quantum dots are located in the hydrophobic part of lipid bilayer. Moreover, we proved that such QD-modified liposomes formed supported lipid bilayers and their final structure depended on the type of underlying cushion.

• Klíčová slova
• Cryo-TEM, Quantum dots, Quantum dots-liposome complex, Supported lipid bilayer, Theranostic nanocontainers,
• MeSH
• elektronová kryomikroskopie MeSH
• fosfatidylcholiny chemie   MeSH
• fosfatidylethanolaminy chemie   MeSH
• fosforylcholin chemie   MeSH
• hydrofobní a hydrofilní interakce MeSH
• kvantové tečky * MeSH
• lipidové dvojvrstvy chemie   MeSH
• polyelektrolyty chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine MeSH Prohlížeč
• 1-palmitoyl-2-oleoylphosphatidylcholine MeSH Prohlížeč
• fosfatidylcholiny MeSH
• fosfatidylethanolaminy MeSH
• fosforylcholin MeSH
• lipidové dvojvrstvy MeSH
• polyelektrolyty MeSH

The lateral diffusion coefficients of a BODIPY tail-labeled lipid in two model systems, namely, free-standing giant unilamellar vesicles (GUVs) and supported phospholipid bilayers (SPBs), were determined by fluorescence correlation spectroscopy (FCS) using the Z-scan approach. For the first time, the performed measurements on 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers maintain exactly the same experimental conditions for both systems, which allows for a quantitative comparison of lipid diffusion in these two commonly used model membranes. The results obtained revealed that the lipid mobility in free-standing bilayers (D=7.8+/-0.8 microm2 s-1) is significantly higher than in the bilayer created on the solid support (mica) (D=3.1+/-0.3 microm2 s-1).

• MeSH
• časové faktory MeSH
• difuze MeSH
• fosfatidylcholiny chemie   MeSH
• lipidové dvojvrstvy chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 1,2-oleoylphosphatidylcholine MeSH Prohlížeč
• fosfatidylcholiny MeSH
• lipidové dvojvrstvy MeSH

The temporal evolution of effects of antimicrobial peptide melittin on supported phospholipid bilayers (SPBs) containing negatively charged phospholipids was monitored by ellipsometry and laser scanning microscopy together with measurements of lipid mobility by Z-scan fluorescence correlation spectroscopy. Under all conditions used in our study, we observed reproducibly two effects. The first one is formation of pores in the SPB, which occupy approximately 40% of the bilayer. The formation of pores was accompanied by a decrease in lateral diffusion coefficient of the lipids to approximately 60% of its initial value. The second, simultaneous, effect is the formation of tubules of approximately 30nm radius and length of the order of 10mum. Flushing of the sample with excess of buffer removes most of the tubules, but it does not affect the pores. Further experiments performed under various conditions demonstrated reproducibility of both phenomena.

• MeSH
• antiinfekční látky chemie   farmakologie   MeSH
• fluidita membrány účinky léků   MeSH
• fluorescenční spektrometrie MeSH
• lipidové dvojvrstvy chemie   MeSH
• melitten chemie   farmakologie   MeSH
• mikroskopie atomárních sil MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antiinfekční látky MeSH
• lipidové dvojvrstvy MeSH
• melitten MeSH

Membranes prepared by the adsorption of phospholipid vesicles on solid supports are much-used model systems in biomedical research. However, there is accumulating evidence that such membranes may not always be equivalent to the free-standing cellular membranes that they are modeling. In the present study, sonicated DOPC/DOPS (80/20 mol %) vesicles were adsorbed on hydrophilic silica surfaces, a system that has been demonstrated to produce confluent bilayers. In addition, pure DOPC and DLPC membranes were studied. It is demonstrated that ethanol-induced membrane interdigitation, as demonstrated for free-standing bilayers, does not occur in these supported membranes.

• MeSH
• adsorpce MeSH
• časové faktory MeSH
• ethanol chemie   MeSH
• fosfolipidy chemie   MeSH
• lipidové dvojvrstvy chemie   MeSH
• membrány umělé * MeSH
• oxid křemičitý chemie   MeSH
• povrchové vlastnosti MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ethanol MeSH
• fosfolipidy MeSH
• lipidové dvojvrstvy MeSH
• membrány umělé * MeSH
• oxid křemičitý MeSH

Biomembranes, important building blocks of living organisms, are often exposed to large local fluctuations of pH and ionic strength. To capture changes in the membrane organization under such harsh conditions, we investigated the mobility and hydration of zwitterionic and anionic lipid bilayers upon elevated H3O+ and Ca2+ content by the time-dependent fluorescence shift (TDFS) technique. While the zwitterionic bilayers remain inert to lower pH and increased calcium concentrations, anionic membranes are responsive. Specifically, both bilayers enriched in phosphatidylserine (PS) and phosphatidylglycerol (PG) become dehydrated and rigidified at pH 4.0 compared to at pH 7.0. However, their reaction to the gradual Ca2+ increase in the acidic environment differs. While the PG bilayers exhibit strong rehydration and mild loosening of the carbonyl region, restoring membrane properties to those observed at pH 7.0, the PS bilayers remain dehydrated with minor bilayer stiffening. Molecular dynamics (MD) simulations support the strong binding of H3O+ to both PS and PG. Compared to PS, PG exhibits a weaker binding of Ca2+ also at a low pH.

• Klíčová slova
• Laurdan, anionic lipids, calcium, headgroup mobility, headgroup organization, lipid hydration, molecular dynamics, phospholipid bilayer, proton, time dependent fluorescence shift,
• MeSH
• fosfatidylseriny MeSH
• ionty MeSH
• lipidové dvojvrstvy * chemie   MeSH
• protony * MeSH
• simulace molekulární dynamiky MeSH
• vápník chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fosfatidylseriny MeSH
• ionty MeSH
• lipidové dvojvrstvy * MeSH
• protony * MeSH
• vápník MeSH

Z-scan fluorescence correlation spectroscopy (FCS) is employed to characterize the interaction between arenicin-1 and supported lipid bilayers (SLBs) of different compositions. Lipid analogue C8-BODIPY 500/510C5-HPC and ATTO 465 labelled arenicin-1 are used to detect changes in lipid and peptide diffusion upon addition of unlabelled arenicin-1 to SLBs. Arenicin-1 decreases lipid mobility in negatively charged SLBs. According to diffusion law analysis, microdomains of significantly lower lipid mobility are formed. The analysis of peptide FCS data confirms the presence of microdomains for anionic SLBs. No indications of microdomain formation are detected in SLBs composed purely of zwitterionic lipids. Additionally, our FCS results imply that arenicin-1 exists in the form of oligomers and/or aggregates when interacting with membranes of both compositions.

• MeSH
• biologické modely MeSH
• difuze MeSH
• fluorescenční spektrometrie metody   MeSH
• kationické antimikrobiální peptidy chemie   metabolismus   MeSH
• lipidové dvojvrstvy chemie   metabolismus   MeSH
• lipidy chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kationické antimikrobiální peptidy MeSH
• lipidové dvojvrstvy MeSH
• lipidy MeSH

In the present work we introduce a straightforward fluorescent assay that can be applied in studies of the transbilayer movement (flip-flop) of fluorescent lipid analogues across supported phospholipid bilayers (SPBs). The assay is based on the distance dependent fluorescence quenching by light absorbing surfaces. Applied to SPBs this effect leads to strong differences in fluorescence lifetimes when the dye moves from the outer lipid leaflet to the leaflet in contact with the support. Herein, we present the basic principles of this novel approach, and comment on its advantages over the commonly used methods for investigating flip-flop dynamics across lipid bilayers. We test the assay on the fluorescent lipid analog Atto633-DOPE and the 3-hydroxyflavone F2N12S probe in SPBs composed of DOPC/ DOPS lipids. Moreover, we compare and discuss the flip-flop rates of the probes with respect to their lateral diffusion coefficients.

• MeSH
• časové faktory MeSH
• chemické techniky analytické metody   MeSH
• difuze MeSH
• fluorescence * MeSH
• fluorescenční barviva chemie   MeSH
• fosfatidylcholiny chemie   MeSH
• fosfatidylethanolaminy chemie   MeSH
• fosfatidylseriny chemie   MeSH
• fosfolipidy chemie   MeSH
• kinetika MeSH
• lipidové dvojvrstvy chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 1,2-dielaidoylphosphatidylethanolamine MeSH Prohlížeč
• 1,2-dioleoylphosphatidylserine MeSH Prohlížeč
• 1,2-oleoylphosphatidylcholine MeSH Prohlížeč
• fluorescenční barviva MeSH
• fosfatidylcholiny MeSH
• fosfatidylethanolaminy MeSH
• fosfatidylseriny MeSH
• fosfolipidy MeSH
• lipidové dvojvrstvy MeSH

The present study has two main objectives. The first is to characterize antimicrobial peptide (AMP) cryptdin-4 (Crp-4) interactions with biological membranes and to compare those interactions with those of magainin 2. The second is to combine the complementary experimental approaches of laser scanning microscopy (LSM), ellipsometry, and Z-scan fluorescence correlation spectroscopy (FCS) to acquire comprehensive information on mechanisms of AMP interactions with supported phospholipid bilayers (SPBs)-a popular model of biological membranes. LSM shows appearance of inhomogeneities in spatial distribution of lipids in the bilayer after treatment with Crp-4. Ellipsometric measurements show that binding of Crp-4 does not significantly change the lipid structure of the bilayer (increase in adsorbed mass without a change in thickness of adsorbed layer). Furthermore, Crp-4 slows the lateral diffusion of lipids within the membrane as shown by Z-scan FCS. All changes of the bilayer induced by Crp-4 can be partially reversed by flushing the sample with excess of buffer. Bilayer interactions of magainin 2 are significantly different, causing large loss of lipids and extensive damage to the bilayer. It seems likely that differences in peptide mode of action, readily distinguished using these combined experimental methods, are related to the distinctive beta-sheet and alpha-helical structures of the respective peptides.

• MeSH
• fluorescenční spektrometrie metody   MeSH
• fosfolipidy chemie   metabolismus   MeSH
• konfokální mikroskopie metody   MeSH
• lipidové dvojvrstvy chemie   metabolismus   MeSH
• proteinové prekurzory chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• cryptdin MeSH Prohlížeč
• fosfolipidy MeSH
• lipidové dvojvrstvy MeSH
• proteinové prekurzory MeSH

We demonstrate for the first time that ellipsometry and confocal fluorescence correlation spectroscopy (FCS) are complementary methods for the characterisation of supported planar phospholipid bilayers (SPBs) formed on mica, a mineral used in atomic force microscopy investigations of SPBs. Addition of small unilamellar vesicles containing 20% dioleoyl-phosphatidylserine (DOPS) and 80% dioleoyl-phosphatidylcholine (DOPC) to an oxidised borosilicate surface, on the other hand, results in a planar lipid system characterised by lateral diffusion coefficients which are three time smaller than those obtained for SPBs. Moreover, seven labelled phospholipids were tested for their suitability in the FCS characterisation of vesicles as well as of SPBs.

• MeSH
• fluorescenční mikroskopie MeSH
• fosfatidylcholiny chemie   MeSH
• fosfatidylseriny chemie   MeSH
• fosfolipidy chemie   MeSH
• fúze membrán MeSH
• konfokální mikroskopie MeSH
• lipidové dvojvrstvy chemie   MeSH
• povrchové vlastnosti MeSH
• silikáty hliníku chemie   MeSH
• silikáty chemie   MeSH
• sloučeniny boru chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 1,2-dioleoylphosphatidylserine MeSH Prohlížeč
• 1,2-oleoylphosphatidylcholine MeSH Prohlížeč
• fosfatidylcholiny MeSH
• fosfatidylseriny MeSH
• fosfolipidy MeSH
• lipidové dvojvrstvy MeSH
• mica MeSH Prohlížeč
• silikáty hliníku MeSH
• silikáty MeSH
• sloučeniny boru MeSH

Pristine graphene, a range of graphene oxides, and silica substrates were used to investigate the effect of surface hydrophilicity on supported lipid bilayers by means of all-atom molecular dynamics simulations. Supported 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid bilayers were found in close-contact conformations with hydrophilic substrates with as low as 5% oxidation level, while self-assembled monolayers occur on pure hydrophobic graphene only. Lipids and water at the surface undergo large redistribution to maintain the stability of the supported bilayers. Deposition of bicelles on increasingly hydrophilic substrates shows the continuous process of reshaping of the supported system and makes intermediate stages between self-assembled monolayers and supported bilayers. The bilayer thickness changes with hydrophilicity in a complex manner, while the number of water molecules per lipid in the hydration layer increases together with hydrophilicity.

• MeSH
• fosfatidylcholiny MeSH
• grafit * MeSH
• hydrofobní a hydrofilní interakce MeSH
• lipidové dvojvrstvy MeSH
• molekulární konformace MeSH
• oxid křemičitý MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fosfatidylcholiny MeSH
• grafit * MeSH
• lipidové dvojvrstvy MeSH
• oxid křemičitý MeSH