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Experimental aspects of colloidal interactions in mixed systems of liposome and inorganic nanoparticle and their applications.

Michel R, Gradzielski M - Int J Mol Sci (2012)

Bottom Line: Research on these systems has led to the observation of novel hybrid structures whose morphology strongly depends on the charge, composition and size of the interacting colloidal species as well as on the nature (pH, ionic strength) of their dispersing medium.A central role is played by the phase behaviour of phospholipid bilayers which have a tremendous influence on the liposome properties.Another central aspect is the incorporation of nanoparticles into vesicles, which is intimately linked to the conditions required for transporting a nanoparticle through a membrane.

View Article: PubMed Central - PubMed

Affiliation: Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Berlin D-10623, Germany; E-Mails: raphael.michel@mailbox.tu-berlin.de (R.M.); michael.gradzielski@tu-berlin.de (M.G.); Tel.: +49-30-314-22822 (R.M.); +49-30-314-24934 (M.G.); M.G.).

ABSTRACT
In the past few years, growing attention has been devoted to the study of the interactions taking place in mixed systems of phospholipid membranes (for instance in the form of vesicles) and hard nanoparticles (NPs). In this context liposomes (vesicles) may serve as versatile carriers or as a model system for biological membranes. Research on these systems has led to the observation of novel hybrid structures whose morphology strongly depends on the charge, composition and size of the interacting colloidal species as well as on the nature (pH, ionic strength) of their dispersing medium. A central role is played by the phase behaviour of phospholipid bilayers which have a tremendous influence on the liposome properties. Another central aspect is the incorporation of nanoparticles into vesicles, which is intimately linked to the conditions required for transporting a nanoparticle through a membrane. Herein, we review recent progress made on the investigations of the interactions in liposome/nanoparticle systems focusing on the particularly interesting structures that are formed in these hybrid systems as well as their potential applications.

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Related in: MedlinePlus

Membrane Internalization. (A)-CryoTEM image of a Vesicle-NP hybrid surrounded by normal small unilamellar vesicles (SUVs); (B)-CryoTEM image of janus vesicles; (C)-Schematic illustration of membrane-internalized hydrophobic NP clustering inside the membrane. Figure reprinted and adapted with permission from [71].
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f8-ijms-13-11610: Membrane Internalization. (A)-CryoTEM image of a Vesicle-NP hybrid surrounded by normal small unilamellar vesicles (SUVs); (B)-CryoTEM image of janus vesicles; (C)-Schematic illustration of membrane-internalized hydrophobic NP clustering inside the membrane. Figure reprinted and adapted with permission from [71].

Mentions: However, in the case of the internalization of small NPs in the hydrophobic interior of the phospholipid bilayer, the phospholipid membrane must “unzip”, i.e., dissociate the acyl-chains of both layers (Figure 8C). The unzipping creates void spaces in the vicinity of the incorporated NP, an energetically unfavourable situation. In order to minimize this void space as well as the free energy of deformation, incorporated NPs have been found to cluster within the bilayer (Figure 8C) [71,129] resulting in the appearance of either a few fully loaded liposomes (vesicle in the center with dark rim) within a “normal” SUV dispersion (Figure 8A) of vesicles without NPs contained in the membrane. In other specific cases, Janus-type vesicle structures are formed where internalized NPs are concentrated on one side of the vesicle (Figure 8B) [71]. Very recent work on this phenomenon has underlined the importance of the bilayer phase behaviour in this process of particle aggregation. Nanoparticle clustering is observed upon lipid melting, and believed to be driven by greater hydrophobic mismatch between embedded particles in the fluid phase coupled with lipid mediated forces driven by lateral capillarity [129]. Nonetheless, although the argument justifying the clustering of particles is quite convincing, the preferential embedding of particles in a few vesicles within a liposome dispersion or in one side of a vesicle (case of Janus-vesicles) has not been reported in other similar works [130,133,135] and therefore is still a topic open for discussion.


Experimental aspects of colloidal interactions in mixed systems of liposome and inorganic nanoparticle and their applications.

Michel R, Gradzielski M - Int J Mol Sci (2012)

Membrane Internalization. (A)-CryoTEM image of a Vesicle-NP hybrid surrounded by normal small unilamellar vesicles (SUVs); (B)-CryoTEM image of janus vesicles; (C)-Schematic illustration of membrane-internalized hydrophobic NP clustering inside the membrane. Figure reprinted and adapted with permission from [71].
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3472766&req=5

f8-ijms-13-11610: Membrane Internalization. (A)-CryoTEM image of a Vesicle-NP hybrid surrounded by normal small unilamellar vesicles (SUVs); (B)-CryoTEM image of janus vesicles; (C)-Schematic illustration of membrane-internalized hydrophobic NP clustering inside the membrane. Figure reprinted and adapted with permission from [71].
Mentions: However, in the case of the internalization of small NPs in the hydrophobic interior of the phospholipid bilayer, the phospholipid membrane must “unzip”, i.e., dissociate the acyl-chains of both layers (Figure 8C). The unzipping creates void spaces in the vicinity of the incorporated NP, an energetically unfavourable situation. In order to minimize this void space as well as the free energy of deformation, incorporated NPs have been found to cluster within the bilayer (Figure 8C) [71,129] resulting in the appearance of either a few fully loaded liposomes (vesicle in the center with dark rim) within a “normal” SUV dispersion (Figure 8A) of vesicles without NPs contained in the membrane. In other specific cases, Janus-type vesicle structures are formed where internalized NPs are concentrated on one side of the vesicle (Figure 8B) [71]. Very recent work on this phenomenon has underlined the importance of the bilayer phase behaviour in this process of particle aggregation. Nanoparticle clustering is observed upon lipid melting, and believed to be driven by greater hydrophobic mismatch between embedded particles in the fluid phase coupled with lipid mediated forces driven by lateral capillarity [129]. Nonetheless, although the argument justifying the clustering of particles is quite convincing, the preferential embedding of particles in a few vesicles within a liposome dispersion or in one side of a vesicle (case of Janus-vesicles) has not been reported in other similar works [130,133,135] and therefore is still a topic open for discussion.

Bottom Line: Research on these systems has led to the observation of novel hybrid structures whose morphology strongly depends on the charge, composition and size of the interacting colloidal species as well as on the nature (pH, ionic strength) of their dispersing medium.A central role is played by the phase behaviour of phospholipid bilayers which have a tremendous influence on the liposome properties.Another central aspect is the incorporation of nanoparticles into vesicles, which is intimately linked to the conditions required for transporting a nanoparticle through a membrane.

View Article: PubMed Central - PubMed

Affiliation: Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Berlin D-10623, Germany; E-Mails: raphael.michel@mailbox.tu-berlin.de (R.M.); michael.gradzielski@tu-berlin.de (M.G.); Tel.: +49-30-314-22822 (R.M.); +49-30-314-24934 (M.G.); M.G.).

ABSTRACT
In the past few years, growing attention has been devoted to the study of the interactions taking place in mixed systems of phospholipid membranes (for instance in the form of vesicles) and hard nanoparticles (NPs). In this context liposomes (vesicles) may serve as versatile carriers or as a model system for biological membranes. Research on these systems has led to the observation of novel hybrid structures whose morphology strongly depends on the charge, composition and size of the interacting colloidal species as well as on the nature (pH, ionic strength) of their dispersing medium. A central role is played by the phase behaviour of phospholipid bilayers which have a tremendous influence on the liposome properties. Another central aspect is the incorporation of nanoparticles into vesicles, which is intimately linked to the conditions required for transporting a nanoparticle through a membrane. Herein, we review recent progress made on the investigations of the interactions in liposome/nanoparticle systems focusing on the particularly interesting structures that are formed in these hybrid systems as well as their potential applications.

Show MeSH
Related in: MedlinePlus