Heterogeneous rotational diffusion of a fluorescent probe in lipid monolayers

Dadashvand, Neda; Williams, LaNell A.; Othon, Christina M.

doi:10.1063/1.4894379

Cited by 7 publications

(12 citation statements)

References 43 publications

(27 reference statements)

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“…We explore heterogeneous relaxation in in a single constituent lipid monolayer of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) by measuring the rotational diffusion of a fluorescent probe, 1-palmitoyl-2-[1]-sn-glycero-3phosphocholine (NBD-PC), using wide-field time-resolved fluorescence anisotropy (TRFA). The observed relaxation exhibits a narrow, liquid-like distribution at high temperatures (τ ~ 2.4 ns), consistent with previous experimental measures [1,2]. However, as the temperature is quenched, the distribution broadens, and we observe the appearance of a long relaxation population (τ ~ 16.5 ns).…”

supporting

confidence: 90%

“…This bimodal distribution remains unaltered throughout the phase coexistence regime (Figure 4), which is consistent with the behavior observed previously for the phase coexistence regime of DPPC [1]. As the surface tension pushes the monolayer through the phase coexistence regime, the probe remains partitioned solely to the liquid phase of the lipids.…”

supporting

confidence: 90%

“…The time-resolved fluorescence anisotropy and lifetime of the probe were measured on our wide-field time-resolved fluorescence anisotropy microscope as described elsewhere [1]. The As the temperature is lowered the rotational correlation time extends and broadens, see Figure 3.…”

mentioning

confidence: 99%

“…The time-resolved fluorescence anisotropy and lifetime of the probe were measured on our wide-field time-resolved fluorescence anisotropy microscope as described elsewhere [1]. The excitation is tuned to 463 nm by frequency doubling (LBO Type I, 5×5×2mm) the output of a tunable ultrafast oscillator (Coherent Chameleon Ultra II, 140 fs).…”

mentioning

confidence: 99%

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Temperature dependent heterogeneous rotational correlation in lipids

Dadashvand¹,

Othon²

2016

Phys. Biol.

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Lipid structures exhibit complex and highly dynamic lateral structure; and changes in lipid density and fluidity are believed to play an essential role in membrane targeting and function. The dynamic structure of liquids on the molecular scale can exhibit complex transient density fluctuations. Here the lateral heterogeneity of lipid dynamics is explored in free standing lipid monolayers. As the temperature is lowered the probes exhibit increasingly broad and heterogeneous rotational correlation. This increase in heterogeneity appears to exhibit a critical onset, similar to those observed for glass forming fluids. We explore heterogeneous relaxation in in a single constituent lipid monolayer of 1, 2-dimyristoyl-sn-glycero-3-phosphocholine by measuring the rotational diffusion of a fluorescent probe (1-palmitoyl-2-[1]-sn-glycero-3-phosphocholine), which is embedded in the lipid monolayer at low labeling density. Dynamic distributions are measured using wide-field time-resolved fluorescence anisotropy. The observed relaxation exhibits a narrow, liquid-like distribution at high temperatures (τ ∼ 2.4 ns), consistent with previous experimental measures (Dadashvand et al 2014 Struct. Dyn. 1 054701, Loura and Ramalho 2007 Biochim. Biophys. Acta 1768 467-478). However, as the temperature is quenched, the distribution broadens, and we observe the appearance of a long relaxation population (τ ∼ 16.5 ns). This supports the heterogeneity observed for lipids at high packing densities, and demonstrates that the nanoscale diffusion and reorganization in lipid structures can be significantly complex, even in the simplest amorphous architectures. Dynamical heterogeneity of this form can have a significant impact on the organization, permeability and energetics of lipid membrane structures.

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supporting

confidence: 90%

supporting

confidence: 90%

mentioning

confidence: 99%

“…The time-resolved fluorescence anisotropy and lifetime of the probe were measured on our wide-field time-resolved fluorescence anisotropy microscope as described elsewhere [1]. The excitation is tuned to 463 nm by frequency doubling (LBO Type I, 5×5×2mm) the output of a tunable ultrafast oscillator (Coherent Chameleon Ultra II, 140 fs).…”

mentioning

confidence: 99%

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Temperature dependent heterogeneous rotational correlation in lipids

Dadashvand¹,

Othon²

2016

Phys. Biol.

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“…25 Nonentrapped Rhodamine B was separated from the NBD-PC-labeled ethosomes by centrifugation (Thermo Scientific Sorvall Legend Mach; Thermo Fisher Scientific, Waltham, MA, USA). In brief, the ethosomes were added to an ultrafiltration tube (EMD Millipore, Billerica, MA, USA), with a cut-off molecular weight of 3,000 Da, and centrifuged at 11,185 rpm and 4°C for 60 min.…”

Section: Separation Of Nonentrapped Rhodamine B From Ethosomesmentioning

confidence: 99%

Mechanism of transdermal permeation promotion of lipophilic drugs by ethosomes

Yang

et al. 2017

IJN

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Ethosomes can promote the penetration of lipophilic drugs into the skin, but the underlying mechanism is still unknown. The purpose of this study was to investigate the mechanism of transdermal permeation promotion of lipophilic drugs by ethosomes. The formulation of ethosomes was optimized using the Box–Behnken experimental design, in which Rhodamine B and 1-palmitoyl-2-{12-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]dodecanoyl}- sn -glycero-3-phosphocholine were used to simulate a model lipophilic drug and act as a fluorescent tracer of ethosomal phospholipids, respectively. Liposomes with the same phospholipid concentration and a hydroethanolic solution with the same ethanol concentration were also prepared as controls. The percutaneous progression of the above fluorescent preparations was observed by confocal laser scanning microscopy, and the fluorescence intensity of the images was analyzed. The optimized ethosome formulation consisted of 2.45% yolk phospholipids, 30% ethanol, and 67.55% distilled water. The percutaneous permeation of Rhodamine B in the optimized ethosomes was superior to that in hydroethanolic solution ( P <0.05) and liposomes ( P <0.05). The ethosomes could penetrate the skin via the percutaneous pathway of the hair follicle and stratum corneum, while during the process of penetration, the vesicles were broken and the phospholipids were retained in the upper epidermis, with the test compounds penetrating gradually. The superior percutaneous penetration of ethosomes was linked to the synergistic effects of their ingredients. The percutaneous pathways of ethosomes included open hair follicles and stratum corneum pathways. In addition, the vesicles might break up during percutaneous penetration in the superficial layer of the skin, allowing the test compounds to keep permeating into the deeper layer alone, while the phospholipid was retained in the upper epidermis.

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