Interaction Between Phospholipid Assemblies and Hemoglobin (Hb)

Takeoka, Shinji; Terase, Kouichiro; Yokohama, Hiroaki; Sakai, Hiromi; Nishide, Hiroyuki; Tsuchida, Eishun

doi:10.1080/10601329409349720

Cited by 5 publications

(7 citation statements)

References 16 publications

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“…The pKa of phosphatidylglycerol is reported to be 1.1 (Toccane et al, 1990), so nearly 100% DPPG dissociates in the bilayer membrane. The ion concentration of an Hb solution for preparation must be controlled as low as possible because the electrostatic interaction is shielded by ionic strength (Takeoka et al, 1994). The HbCO solution is dialyzed in advance against pure water to remove the small solutes, and necessary ions such as PLP, Hcy, and sodium carbonate for pH adjustment are added to the solution.…”

Section: Resultsmentioning

confidence: 99%

“…We have for the first time succeeded in preparing the HbV with the following high performances superior to previous reports for this type of red cell substitute: (1) The particle is small enough to pass through sterilizable filters, and (2) the HbV contains a high Hb concentration with a lower level of lipids. The high encapsulation efficiency was obtained with controlling the electrostatic interaction among the lipid bilayers and Hb molecules and the microviscosity of the membrane (Sakai et al, 1992; Takeoka et al, 1994). (3) The oxygen affinity is controlled with the coencapsulation of the allosteric effectors that are used to increase the oxygen transporting efficiency (Wang et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

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Physical Properties of Hemoglobin Vesicles as Red Cell Substitutes

et al. 1996

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Hemoglobin vesicles (HbV) as red cell substitutes were prepared from a purified carbonylhemoglobin (HbCO) solution and a lipid mixture composed of phospholipids, cholesterol, and alpha-tocopherol. The diameter was controlled to 251 +/- 87 nm using an extrusion method; the vesicles penetrated through the membrane filters with regulated pore sizes. After the ligand exchanging reaction (HbCO-->HbO2), the oxygen affinity (P50) of HbV was 32 Torr, which was controlled with the coencapsulation of pyridoxal 5'-phosphate. The rate of metHb formation in HbV was nonenzymatically reduced with the coencapsulation of DL-homocysteine. The Hb concentration of the HbV suspension, which was dispersed in a phosphate buffered saline solution (pH 7.4), was controlled at 10 g/dL. At this concentration, the total lipid concentration was 6.2 g/dL and the viscosity, 2.6 cP (230 s-1), was lower than that of the blood (4.4 cP). The HbV suspension showed a typical non-Newtonian flow for a particle dispersion and agreed well with the Casson model. The viscosity at shear rates lower than 23 s-1 showed a maximum with increasing the mixing ratio of human blood, plasma, or albumin, while no maximum was observed for the mixture with washed red blood cells. The aggregates of HbV are formed by interaction with plasma proteins, including albumin, while the aggregates reversibly dissociate at higher shear rate.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Physical Properties of Hemoglobin Vesicles as Red Cell Substitutes

et al. 1996

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“…As suggested in the previous literature, if we wish to obtain giant liposomes that effectively entrap soluble proteins, we may wish to use conditions in which proteins and lipid membranes are oppositely charged and lipid films are hydrated simultaneously at a slower rate. For several decades, smaller liposomes (∼100 nm in diameter) have been conventionally used for pharmaceutical applications such as drug delivery systems, and artificial blood cells (hemoglobin-vesicles (HbV)) based on conventional liposomes have also been devised. − Importantly, when they prepared HbV, Tsuchida and collaborators identified optimal conditions for achieving the highly efficient entrapment of hemoglobin, in which the pH of an Hb solution is adjusted to the isoelectric point (pI) of Hb. − Under these conditions, electrostatic repulsion between Hb proteins and negatively charged phospholipid membranes is reduced, resulting in an optimal encapsulation efficiency. In the case of Hb, a pH below the pI is unsuitable because of the functional deterioration induced by inversion of the charge of Hb.…”

Section: Introductionmentioning

confidence: 99%

pH Switching That Crosses over the Isoelectric Point (pI) Can Improve the Entrapment of Proteins within Giant Liposomes by Enhancing Protein–Membrane Interaction

et al. 2014

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The ability to encapsulate various molecules including proteins within giant liposomes is needed for studies on model cell membranes and artificial cells. In this report, we demonstrate how to improve the efficiency of protein entrapment with the gentle hydration (natural swelling) method, which is a well-known protocol for the preparation of giant liposomes. We found that when the initial pH of a solution was kept below the pI of a target protein during hydration and then changed to above the pI, the protein could be entrapped more efficiently compared to the sample that was kept at above the pI during the hydration. An examination of the ratio of the mass of entrapped protein to the moles of phospholipid in liposomes (dioleoylphosphatidylcholine (DOPC)/dioleoylphosphatidylglycerol (DOPG)) indicated that entrapment of target proteins like bovine serum albumin, myoglobin, and lysozyme could be improved using this procedure, and this trend was consistent with microscopic observations at the level of a single giant liposome. The conditions that resulted in good efficiencies were affected by the NaCl concentration and the temperature of the hydration solution, implying that protein entrapment in giant liposomes may be enhanced by associative interaction between lipid lamellar membranes and target proteins.

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“…Preformed polymersomes obtained from polymer 2b were first subjected to lyophilization, and then added to purified COHb solution. Since COHb was stable against heating up to 70 C, 44 the mixture was allowed to stir at 60 C to soften the shell layer and incorporate the COHb. TEM analysis showed that the spherical morphology was well preserved after encapsulation, and no obvious contrast was detected between the shell and core compared with the void vesicles because of the incorporation of Hb (Fig.…”

Section: Characterization Of Pehmentioning

confidence: 99%