Thermodynamic characteristics of DSPC/DSPE-PEG2000 mixed monolayers on the water subphase at different temperatures

Chou, Tzung-Han; Chu, I‐Ming

doi:10.1016/s0927-7765(02)00096-6

Cited by 32 publications

(59 citation statements)

References 19 publications

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“…Few studies have deeply investigated the thermodynamic characteristics (endothermic, exothermic, and phase transition) of mixed rifampicin mPEG-DSPE at different temperatures and intermolecular interaction between rifampicin and mPEG-DSPE, which may be important in understanding the intrinsic properties of these PEG-linked lipids (26). There were no endoand exothermic peaks observed in the thermograms of rifampicin (Figs.…”

Section: Dscmentioning

confidence: 99%

Rehydrated Lyophilized Rifampicin-Loaded mPEG–DSPE Formulations for Nebulization

2010

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Abstract. Rifampicin-loaded nanoparticles were prepared using two different molecular weights of poly-(ethylene oxide)-block-distearoyl phosphatidyl-ethanolamine (mPEG2000-DSPE and mPEG5000-DSPE) polymers. Particle sizes of all formulations studied were in the range of 162-395 nm. The entrapment efficiency (EE) was not affected by the copolymer's molecular weight, and the highest EE (100%) was obtained with drug to copolymer ratio of 1:5. The differential scanning calorimetry (DSC) thermograms showed Tg of rifampicin-loaded PEG-DSPE nanoparticles that shifted to a lower value, indicating entrapment of rifampicin in polymer matrix. The Fourier transformed infrared spectra revealed no chemical interactions between the drug and both copolymers. The in vitro drug release from the formulations occurred over 3 days and followed first-order release kinetic and Higuchi diffusion model. The nebulization of rehydrated lyophilized rifampicin mPEG-DSPE formulations had mass median aerodynamic diameter of 2.6 µm and fine particle fraction of 42%. The aerodynamic characteristic of the preparations was not influenced by the molecular weight of the copolymers. Therefore, it is suggested that both mPEG-DSPE are promising candidates as rifampicin carrier for pulmonary delivery.

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Section: Dscmentioning

confidence: 99%

Rehydrated Lyophilized Rifampicin-Loaded mPEG–DSPE Formulations for Nebulization

2010

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“…We encapsulated D-luciferin within a liposomal system incorporating concentrations of polyethelene glycol (PEG) up to 10 mole % [9, 10]. Liposomes can protect their contents from metabolism and inactivation in the plasma, reduce drug toxicity and prolong the blood circulation of encapsulated materials [11–14].…”

Section: Introductionmentioning

confidence: 99%

Enhanced in vivo bioluminescence imaging using liposomal luciferin delivery system

Kheirolomoom

Kruse

Qin

et al. 2010

Journal of Controlled Release

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To provide a continuous and prolonged delivery of the substrate D-luciferin for bioluminescence imaging in vivo, luciferin was encapsulated into liposomes using either the pH-gradient or acetategradient method. Under optimum loading conditions, 0.17 mg luciferin was loaded per mg of lipid with 90-95% encapsulation efficiency, where active loading was 6 to 18-fold higher than obtained with passive loading. Liposomal luciferin in a long-circulating formulation had good shelf stability, with 10% release over 3-month storage at 4°C. Pharmacokinetic profiles of free and liposomal luciferin were then evaluated in transgenic mice expressing luciferase. In contrast to rapid in vivo clearance of free luciferin (t 1/2 =3.54 min), luciferin encapsulated into long-circulating liposomes showed a prolonged release over 24 hours. The first order release rate constant of luciferin from longcirculating liposomes, as estimated from the best fit of the analytical model to the experimental data, was 0.01 h −1 . Insonation of luciferin-loaded temperature sensitive liposomes directly injected into one tumor of Met1-luc tumor-bearing mice resulted in immediate emission of light. Systemic injection of luciferin-loaded long-circulating liposomes into Met1-luc tumor-bearing mice, followed by unilateral ultrasound-induced hyperthermia, produced a gradual increase in radiance over time, reaching a peak 4-7 h post-ultrasound.

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“…Referring to the lipid-PEG-2000 molecule, due to its molecular size it is harder to compress, so that in the traditional Langmuir trough is difficult to obtain a complete compression isotherm of the monolayer. Apparently this is because the molecule is regrouping forming islands which create spaces, due to the presence of repulsive forces between the hydrophilic groups in the polyethylene glycol chain [7]. …”

Section: Compression Isothermmentioning

confidence: 99%

Lipid Bilayer Preparation on Hydrophilically Modified Gold Electrode

Velázquez-Manzanares¹,

Kycia²,

Lipkoswki³

2011

ECS Trans.

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The Au(111) electrode surface was modified by deposition of a self-assembled hydrophilic monolayer of thioglucose. A combination of Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) techniques was then used to deposit a lipid bilayer containing cholesterol (Chol) 30 mol%, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy(polyethyleneglycol)-2000 (Lipid-PEG-2000) (6 mol%) and dimyristoylphophatidylcholine (DMPC) 64 mol% the thioglucose modified gold surface. Compression isotherms were recorded at the air-solution interface to determine the best conditions for the transfer of the (DMPC/Lipid-PEG-2000/Chol) and (DMPC/Chol) monolayers onto the metal electrode surface. The LB transfer of DMPC/Lipid-PEG-2000/Chol was carried out at surface pressure π = 20 mN m -1 (30 o C) corresponding to liquid condensed phase of lipids. The bilayer was completed with the outer leaflet of DMPC/Chol transferred by the Langmuir Schaefer method at π = 40 mN m -1 . The capacitance of the gold electrode covered by the bilayer was measured. At a single frequency the value of ~ 3.5 μF cm 2 was obtained. This value indicates that the bilayer was deposited onto the electrode and that this architecture can be used for further biomimetic studies.

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Thermodynamic characteristics of DSPC/DSPE-PEG2000 mixed monolayers on the water subphase at different temperatures

Cited by 32 publications

References 19 publications

Rehydrated Lyophilized Rifampicin-Loaded mPEG–DSPE Formulations for Nebulization

Rehydrated Lyophilized Rifampicin-Loaded mPEG–DSPE Formulations for Nebulization

Enhanced in vivo bioluminescence imaging using liposomal luciferin delivery system

Lipid Bilayer Preparation on Hydrophilically Modified Gold Electrode

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