Stealth® liposomes: from theory to product

Cˇeh, Boris; Winterhalter, Mathias; Frederik, Peter M.; Vallner, J.J.; Lasiç, Danilo D.

doi:10.1016/s0169-409x(96)00456-5

Cited by 174 publications

(95 citation statements)

References 48 publications

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Section: -9)mentioning

confidence: 99%

“…5,6,10) For active targeting, specific ligands for bioactive molecules such as nucleic acids, peptides, proteins, and antibodies are attached to the surface of nanoparticles via a PEG spacer. 11) Many attempts have been made to develop various types of specific ligands for use in active targeting, which is critical for targeting non-fenestrated tissues such as the brain, lung and related tissues.…”

Section: -9)mentioning

confidence: 99%

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Topology of Surface Ligands on Liposomes: Characterization Based on the Terms, Incorporation Ratio, Surface Anchor Density, and Reaction Yield

Lee

Sato

Hyodo

et al. 2016

Biological & Pharmaceutical Bulletin

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The surface topology of ligands on liposomes is an important factor in active targeting in drug delivery systems. Accurately evaluating the density of anchors and bioactive functional ligands on a liposomal surface is critical for ensuring the efficient delivery of liposomes. For evaluating surface ligand density, it is necessary to clarify that on the ligand-modified liposomal surfaces, some anchors are attached to ligands but some are not. To distinguish between these situations, a key parameter, surface anchor density, was introduced to specify amount of total anchors on the liposomal surface. Second, the parameter reaction yield was introduced to identify the amount of ligand-attached anchors among total anchors, since the conjugation efficiency is not always the same nor 100%. Combining these independent parameters, we derived: incorporation ratio surface anchor density reaction yield. The term incorporation ratio defines the surface ligand density. Since the surface anchor density represents the density of polyethylene glycol (PEG) on the surfaces in most cases, it also determines liposomal function. It is possible to accurately characterize various PEG and ligand densities and to define the surface topologies. In conclusion, this quantitative methodology can standardize the liposome preparation process and qualify the modified liposomal surfaces.Key words active targeting; surface ligand density; incorporation ratio; surface anchor density; reaction yield; surface topology Nanotechnology has the capability to deliver drugs to specific cell types, but it is important to maximize therapeutic effects and minimize unexpected adverse effects, for this technology to be effectively used.1-4) In using nanoparticles for specific drug delivery, they need to have both a stealth function to prevent non-specific recognition by the reticuloendothelial system (RES), 5,6) and an active targeting function to allow them to bind to the specific cell type of interest. 7-9)Polyethylene glycol (PEG) modification is frequently used to confer a stealth function to nanoparticles. 5,6,10) For active targeting, specific ligands for bioactive molecules such as nucleic acids, peptides, proteins, and antibodies are attached to the surface of nanoparticles via a PEG spacer.11) Many attempts have been made to develop various types of specific ligands for use in active targeting, which is critical for targeting non-fenestrated tissues such as the brain, lung and related tissues. [12][13][14] The procedures used to prepare ligands that are used in modifying nanoparticles are relatively complicated because this increases the number of steps in the preparation process that can lead to conditions where ligand molecules can be unstable.15) Therefore, optimal reaction (modification) conditions and methods for quantifying the density of the attached ligand that is attached to the nanoparticles need to be evaluated precisely.Problems are usually encountered in evaluating both the density of the liposomal ligands and the PEG, since a variety of m...

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Section: -9)mentioning

confidence: 99%

Section: -9)mentioning

confidence: 99%

Topology of Surface Ligands on Liposomes: Characterization Based on the Terms, Incorporation Ratio, Surface Anchor Density, and Reaction Yield

Lee

Sato

Hyodo

et al. 2016

Biological & Pharmaceutical Bulletin

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“…Stealth or long-circulating liposomes are sterically stable [2] and do not appear to the defence mechanism of the body mainly the Kupffer cells of liver and macrophages of the spleen [3]. The disadvantage of liposomes is the rapid clearance from the circulation, which can be avoided by using stealth liposomes [4].…”

Section: Long-circulating Liposomesmentioning

confidence: 99%

“…It only takes minutes for intravenously administered drug to be engulfed by phagocytes and due to this, the drug does not reach the site of action. To increase circulation cohesive bilayers like disteroyl lecithin or sphingomyelin can be used [2]. The major reason for clearance is the adsorption of the blood macromolecules and their opsonization into the liposomal surface leading to phagocytosis [4].…”

Section: Long-circulating Liposomesmentioning

confidence: 99%

“…Longer circulation is achieved by the liposome due to the dissociation of PEG-lipid from the layer which uses stronger hydrophobic anchors or polymerised bilayers. The electrostatic and hydrophobic interactions are prevented due to the high local concentration of hydrated groups at the surface of PEG-liposomes [2]. Stealth liposome named Doxil is present in the market as doxorubicin hydrochloride for treating AIDS-related Kaposi's sarcoma [4].…”

Section: Long-circulating Liposomesmentioning

confidence: 99%

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Advances in Liposomal Drug Delivery System: Fascinating Types and Potential Applications

Bonde

Nair

2017

Int J App Pharm

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Liposomes are an efficient novel drug delivery system. They are used because of their structure which is stable and due to their ability to accommodate both lipophilic and hydrophilic drug. Various fascinating types of liposomes have been developed in recent past to further enhance their utility. Long-circulating liposomes or stealth liposomes are able to hide from the defence system of the body and circulate for a longer time in the blood. Targeted liposomes namely immuno-liposomes consists of antibodies conjugated on their surface to improve the specificity of the cell. Liposomes have been modified as per the conditions of pH and temperature, specifically designed to improve drug delivery to targeted tumor cells. Liposomes are being used in the treatment of various diseases and there are various liposomal drug formulations available today. Liposomes can be used as carriers for genetic materials such as antisense, DNA, RNA which are useful in the treatment of diseases. Liposomes are also efficient carriers of cytokines which further activate macrophages. This review provides the detailed insight of types and applications of liposomes and the potential challenges in the development of liposomal drug delivery systems.

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