Special Issue "Liposome Technologies"

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A special issue of Pharmaceutics (ISSN 1999-4923).

Deadline for manuscript submissions: closed (30 June 2013)

Special Issue Editor

Guest Editor
Dr. Timothy D. Heath (Website)

School of Pharmacy University of Wisconsin 777 Highland Ave. Madison, WI 53705, USA
Phone: 608 238 1280
Interests: liposome technology; drug delivery and gene delivery systems; drug carrier

Special Issue Information

Dear Colleagues,

This special issue “Liposome Technologies” will deal with all aspects of liposome-mediated delivery of therapeutic agents. Therapeutic agents may include drugs, or any biological agents including DNA, RNA, proteins, or antigens for vaccination. The mode of delivery may be passive or ligand-mediated targeting, controlled release, or systemic localization. The topic of papers can be the preparation of novel formulations, study of their properties, the in vivo or in vitro testing of such agents for their efficacy or stability, or study of their localization within cells in vitro or in vivo. In addition to papers that focus directly on therapeutic applications, studies dealing with the fundamental aspects of liposomes of concern for their use in drug delivery will also be considered.

Dr. Timothy D. Heath
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Pharmaceutics is an international peer-reviewed Open Access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 500 CHF (Swiss Francs). English correction and/or formatting fees of 250 CHF (Swiss Francs) will be charged in certain cases for those articles accepted for publication that require extensive additional formatting and/or English corrections.

Keywords

  • liposome
  • drug delivery
  • cationic lipids
  • gene delivery
  • controlled release
  • liposome targeting
  • liposome-mediated therapeutics
  • membrane permeability
  • liposome-based vaccines

Published Papers (12 papers)

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Research

Jump to: Review

Open AccessArticle Pectosomes and Chitosomes as Delivery Systems for Metronidazole: The One-Pot Preparation Method
Pharmaceutics 2013, 5(3), 445-456; doi:10.3390/pharmaceutics5030445
Received: 16 August 2013 / Revised: 29 August 2013 / Accepted: 4 September 2013 / Published: 6 September 2013
Cited by 5 | PDF Full-text (696 KB) | HTML Full-text | XML Full-text
Abstract
Mucoadhesive liposomes offer a potential for improved residence time of liposomal systems targeting contact with mucosal tissues, such as in buccal, oral, colon, and vaginal drug delivery. Most of the currently available methods rely on the coating of preformed liposomes by various [...] Read more.
Mucoadhesive liposomes offer a potential for improved residence time of liposomal systems targeting contact with mucosal tissues, such as in buccal, oral, colon, and vaginal drug delivery. Most of the currently available methods rely on the coating of preformed liposomes by various mucoadhesive polymers. The aim of this study was to develop novel mucoadhesive system by the one-pot preparation method. The pectin- and chitosan-containing liposomes, namely pectosomes and chitosomes, were prepared by the modified solvent injection method. In order to optimize this novel delivery system, we used pectins and chitosans of both high and low degree of esterification/deacetylation (DE/DD), respectively. Sonication was applied to reduce the original vesicle size. All vesicles were characterized for their size, zeta potential, metronidazole entrapment, and stability. Both pectosomes and chitosomes were found to entrap more metronidazole than conventional plain liposomes. Preliminary data indicate that the polymer is present on the liposomal surface, embedded within inner liposomal bilayers, and entrapped inside the aqueous compartment. The next step in the evaluation of this system is the testing of its mucoadhesiveness. Full article
(This article belongs to the Special Issue Liposome Technologies)
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Open AccessArticle Physical and Oxidative Stability of Uncoated and Chitosan-Coated Liposomes Containing Grape Seed Extract
Pharmaceutics 2013, 5(3), 421-433; doi:10.3390/pharmaceutics5030421
Received: 27 June 2013 / Revised: 8 August 2013 / Accepted: 12 August 2013 / Published: 20 August 2013
Cited by 11 | PDF Full-text (475 KB) | HTML Full-text | XML Full-text
Abstract
Polyphenol-rich grape seed extract (0.1 w/w%) was incorporated in liposomes (1 w/w% soy lecithin) by high pressure homogenization (22,500 psi) and coated with chitosan (0.1 w/w%). Primary liposomes and chitosan-coated secondary liposomes containing [...] Read more.
Polyphenol-rich grape seed extract (0.1 w/w%) was incorporated in liposomes (1 w/w% soy lecithin) by high pressure homogenization (22,500 psi) and coated with chitosan (0.1 w/w%). Primary liposomes and chitosan-coated secondary liposomes containing grape seed extract showed good physical stability during 98 days of storage. Most of the polyphenols were incorporated in the shell of the liposomes (85.4%), whereas only 7.6% of the polyphenols of grape seed extract were located in the interior of the liposomes. Coating with chitosan did not change the polyphenol content in the liposomes (86.6%). The uncoated liposomes without grape seed extract were highly prone to lipid oxidation. The cationic chitosan coating, however, improved the oxidative stability to some extent, due to its ability to repel pro-oxidant metals. Encapsulated grape seed extract showed high antioxidant activity in both primary and secondary liposomes, which may be attributed to its polyphenol content. In conclusion, the best chemical stability of liposomes can be achieved using a combination of grape seed extract and chitosan. Full article
(This article belongs to the Special Issue Liposome Technologies)
Open AccessArticle Adjuvant Effect of Cationic Liposomes for Subunit Influenza Vaccine: Influence of Antigen Loading Method, Cholesterol and Immune Modulators
Pharmaceutics 2013, 5(3), 392-410; doi:10.3390/pharmaceutics5030392
Received: 10 May 2013 / Revised: 17 July 2013 / Accepted: 17 July 2013 / Published: 25 July 2013
Cited by 8 | PDF Full-text (657 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Cationic liposomes are potential adjuvants for influenza vaccines. In a previous study we reported that among a panel of cationic liposomes loaded with influenza hemagglutinin (HA), DC-Chol:DPPC (1:1 molar ratio) liposomes induced the strongest immune response. However, it is not clear whether [...] Read more.
Cationic liposomes are potential adjuvants for influenza vaccines. In a previous study we reported that among a panel of cationic liposomes loaded with influenza hemagglutinin (HA), DC-Chol:DPPC (1:1 molar ratio) liposomes induced the strongest immune response. However, it is not clear whether the cholesterol (Chol) backbone or the tertiary amine head group of DC-Chol was responsible for this. Therefore, in the present work we studied the influence of Chol in the lipid bilayer of cationic liposomes. Moreover, we investigated the effect of the HA loading method (adsorption versus encapsulation) and the encapsulation of immune modulators in DC-Chol liposomes on the immunogenicity of HA. Liposomes consisting of a neutral lipid (DPPC or Chol) and a cationic compound (DC-Chol, DDA, or eDPPC) were produced by film hydration-extrusion with/without an encapsulated immune modulator (CpG or imiquimod). The liposomes generally showed comparable size distribution, zeta potential and HA loading. In vitro studies with monocyte-derived human dendritic cells and immunization studies in C57Bl/6 mice showed that: (1) liposome-adsorbed HA is more immunogenic than encapsulated HA; (2) the incorporation of Chol in the bilayer of cationic liposomes enhances their adjuvant effect; and (3) CpG loaded liposomes are more efficient at enhancing HA-specific humoral responses than plain liposomes or Alhydrogel. Full article
(This article belongs to the Special Issue Liposome Technologies)

Review

Jump to: Research

Open AccessReview Inhalable PEGylated Phospholipid Nanocarriers and PEGylated Therapeutics for Respiratory Delivery as Aerosolized Colloidal Dispersions and Dry Powder Inhalers
Pharmaceutics 2014, 6(2), 333-353; doi:10.3390/pharmaceutics6020333
Received: 4 March 2014 / Revised: 25 April 2014 / Accepted: 4 June 2014 / Published: 20 June 2014
Cited by 6 | PDF Full-text (1292 KB) | HTML Full-text | XML Full-text
Abstract
Nanomedicine is making groundbreaking achievements in drug delivery. The versatility of nanoparticles has given rise to its use in respiratory delivery that includes inhalation aerosol delivery by the nasal route and the pulmonary route. Due to the unique features of the respiratory [...] Read more.
Nanomedicine is making groundbreaking achievements in drug delivery. The versatility of nanoparticles has given rise to its use in respiratory delivery that includes inhalation aerosol delivery by the nasal route and the pulmonary route. Due to the unique features of the respiratory route, research in exploring the respiratory route for delivery of poorly absorbed and systemically unstable drugs has been increasing. The respiratory route has been successfully used for the delivery of macromolecules like proteins, peptides, and vaccines, and continues to be examined for use with small molecules, DNA, siRNA, and gene therapy. Phospholipid nanocarriers are an attractive drug delivery system for inhalation aerosol delivery in particular. Protecting these phospholipid nanocarriers from pulmonary immune system attack by surface modification by polyethylene glycol (PEG)ylation, enhancing mucopenetration by PEGylation, and sustaining drug release for controlled drug delivery are some of the advantages of PEGylated liposomal and proliposomal inhalation aerosol delivery. This review discusses the advantages of using PEGylated phospholipid nanocarriers and PEGylated therapeutics for respiratory delivery through the nasal and pulmonary routes as inhalation aerosols. Full article
(This article belongs to the Special Issue Liposome Technologies)
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Open AccessReview Application of Pharmacokinetic and Pharmacodynamic Analysis to the Development of Liposomal Formulations for Oncology
Pharmaceutics 2014, 6(1), 137-174; doi:10.3390/pharmaceutics6010137
Received: 14 January 2014 / Revised: 22 February 2014 / Accepted: 26 February 2014 / Published: 18 March 2014
Cited by 9 | PDF Full-text (1169 KB) | HTML Full-text | XML Full-text
Abstract
Liposomal formulations of anticancer agents have been developed to prolong drug circulating lifetime, enhance anti-tumor efficacy by increasing tumor drug deposition, and reduce drug toxicity by avoiding critical normal tissues. Despite the clinical approval of numerous liposome-based chemotherapeutics, challenges remain in the [...] Read more.
Liposomal formulations of anticancer agents have been developed to prolong drug circulating lifetime, enhance anti-tumor efficacy by increasing tumor drug deposition, and reduce drug toxicity by avoiding critical normal tissues. Despite the clinical approval of numerous liposome-based chemotherapeutics, challenges remain in the development and clinical deployment of micro- and nano-particulate formulations, as well as combining these novel agents with conventional drugs and standard-of-care therapies. Factors requiring optimization include control of drug biodistribution, release rates of the encapsulated drug, and uptake by target cells. Quantitative mathematical modeling of formulation performance can provide an important tool for understanding drug transport, uptake, and disposition processes, as well as their role in therapeutic outcomes. This review identifies several relevant pharmacokinetic/pharmacodynamic models that incorporate key physical, biochemical, and physiological processes involved in delivery of oncology drugs by liposomal formulations. They capture observed data, lend insight into factors determining overall antitumor response, and in some cases, predict conditions for optimizing chemotherapy combinations that include nanoparticulate drug carriers. Full article
(This article belongs to the Special Issue Liposome Technologies)
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Open AccessReview Phototriggerable Liposomes: Current Research and Future Perspectives
Pharmaceutics 2014, 6(1), 1-25; doi:10.3390/pharmaceutics6010001
Received: 11 November 2013 / Revised: 28 November 2013 / Accepted: 5 December 2013 / Published: 19 December 2013
Cited by 13 | PDF Full-text (1181 KB) | HTML Full-text | XML Full-text
Abstract
The field of cancer nanomedicine is considered a promising area for improved delivery of bioactive molecules including drugs, pharmaceutical agents and nucleic acids. Among these, drug delivery technology has made discernible progress in recent years and the areas that warrant further focus [...] Read more.
The field of cancer nanomedicine is considered a promising area for improved delivery of bioactive molecules including drugs, pharmaceutical agents and nucleic acids. Among these, drug delivery technology has made discernible progress in recent years and the areas that warrant further focus and consideration towards technological developments have also been recognized. Development of viable methods for on-demand spatial and temporal release of entrapped drugs from the nanocarriers is an arena that is likely to enhance the clinical suitability of drug-loaded nanocarriers. One such approach, which utilizes light as the external stimulus to disrupt and/or destabilize drug-loaded nanoparticles, will be the discussion platform of this article. Although several phototriggerable nanocarriers are currently under development, I will limit this review to the phototriggerable liposomes that have demonstrated promise in the cell culture systems at least (but not the last). The topics covered in this review include (i) a brief summary of various phototriggerable nanocarriers; (ii) an overview of the application of liposomes to deliver payload of photosensitizers and associated technologies; (iii) the design considerations of photoactivable lipid molecules and the chemical considerations and mechanisms of phototriggering of liposomal lipids; (iv) limitations and future directions for in vivo, clinically viable triggered drug delivery approaches and potential novel photoactivation strategies will be discussed. Full article
(This article belongs to the Special Issue Liposome Technologies)
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Open AccessReview Surface Engineering of Liposomes for Stealth Behavior
Pharmaceutics 2013, 5(4), 542-569; doi:10.3390/pharmaceutics5040542
Received: 2 September 2013 / Revised: 10 October 2013 / Accepted: 14 October 2013 / Published: 25 October 2013
Cited by 34 | PDF Full-text (692 KB) | HTML Full-text | XML Full-text
Abstract
Liposomes are used as a delivery vehicle for drug molecules and imaging agents. The major impetus in their biomedical applications comes from the ability to prolong their circulation half-life after administration. Conventional liposomes are easily recognized by the mononuclear phagocyte system and [...] Read more.
Liposomes are used as a delivery vehicle for drug molecules and imaging agents. The major impetus in their biomedical applications comes from the ability to prolong their circulation half-life after administration. Conventional liposomes are easily recognized by the mononuclear phagocyte system and are rapidly cleared from the blood stream. Modification of the liposomal surface with hydrophilic polymers delays the elimination process by endowing them with stealth properties. In recent times, the development of various materials for surface engineering of liposomes and other nanomaterials has made remarkable progress. Poly(ethylene glycol)-linked phospholipids (PEG-PLs) are the best representatives of such materials. Although PEG-PLs have served the formulation scientists amazingly well, closer scrutiny has uncovered a few shortcomings, especially pertaining to immunogenicity and pharmaceutical characteristics (drug loading, targeting, etc.) of PEG. On the other hand, researchers have also begun questioning the biological behavior of the phospholipid portion in PEG-PLs. Consequently, stealth lipopolymers consisting of non-phospholipids and PEG-alternatives are being developed. These novel lipopolymers offer the potential advantages of structural versatility, reduced complement activation, greater stability, flexible handling and storage procedures and low cost. In this article, we review the materials available as alternatives to PEG and PEG-lipopolymers for effective surface modification of liposomes. Full article
(This article belongs to the Special Issue Liposome Technologies)
Open AccessReview Liposome Formulation of Fullerene-Based Molecular Diagnostic and Therapeutic Agents
Pharmaceutics 2013, 5(4), 525-541; doi:10.3390/pharmaceutics5040525
Received: 19 August 2013 / Revised: 26 September 2013 / Accepted: 27 September 2013 / Published: 18 October 2013
Cited by 5 | PDF Full-text (689 KB) | HTML Full-text | XML Full-text
Abstract
Fullerene medicine is a new but rapidly growing research subject. Fullerene has a number of desired structural, physical and chemical properties to be adapted for biological use including antioxidants, anti-aging, anti-inflammation, photodynamic therapy, drug delivery, and magnetic resonance imaging contrast agents. Chemical [...] Read more.
Fullerene medicine is a new but rapidly growing research subject. Fullerene has a number of desired structural, physical and chemical properties to be adapted for biological use including antioxidants, anti-aging, anti-inflammation, photodynamic therapy, drug delivery, and magnetic resonance imaging contrast agents. Chemical functionalization of fullerenes has led to several interesting compounds with very promising preclinical efficacy, pharmacokinetic and safety data. However, there is no clinical evaluation or human use except in fullerene-based cosmetic products for human skincare. This article summarizes recent advances in liposome formulation of fullerenes for the use in therapeutics and molecular imaging. Full article
(This article belongs to the Special Issue Liposome Technologies)
Open AccessReview Proteoliposomes as Tool for Assaying Membrane Transporter Functions and Interactions with Xenobiotics
Pharmaceutics 2013, 5(3), 472-497; doi:10.3390/pharmaceutics5030472
Received: 23 July 2013 / Revised: 15 August 2013 / Accepted: 4 September 2013 / Published: 18 September 2013
Cited by 10 | PDF Full-text (826 KB) | HTML Full-text | XML Full-text
Abstract
Proteoliposomes represent a suitable and up to date tool for studying membrane transporters which physiologically mediate absorption, excretion, trafficking and reabsorption of nutrients and metabolites. Using recently developed reconstitution strategies, transporters can be inserted in artificial bilayers with the same orientation as [...] Read more.
Proteoliposomes represent a suitable and up to date tool for studying membrane transporters which physiologically mediate absorption, excretion, trafficking and reabsorption of nutrients and metabolites. Using recently developed reconstitution strategies, transporters can be inserted in artificial bilayers with the same orientation as in the cell membranes and in the absence of other interfering molecular systems. These methodologies are very suitable for studying kinetic parameters and molecular mechanisms. After the first applications on mitochondrial transporters, in the last decade, proteoliposomes obtained with optimized methodologies have been used for studying plasma membrane transporters and defining their functional and kinetic properties and structure/function relationships. A lot of information has been obtained which has clarified and completed the knowledge on several transporters among which the OCTN sub-family members, transporters for neutral amino acid, B0AT1 and ASCT2, and others. Transporters can mediate absorption of substrate-like derivatives or drugs, improving their bioavailability or can interact with these compounds or other xenobiotics, leading to side/toxic effects. Therefore, proteoliposomes have recently been used for studying the interaction of some plasma membrane and mitochondrial transporters with toxic compounds, such as mercurials, H2O2 and some drugs. Several mechanisms have been defined and in some cases the amino acid residues responsible for the interaction have been identified. The data obtained indicate proteoliposomes as a novel and potentially important tool in drug discovery. Full article
(This article belongs to the Special Issue Liposome Technologies)
Open AccessReview Advances in Lipid Nanoparticles for siRNA Delivery
Pharmaceutics 2013, 5(3), 498-507; doi:10.3390/pharmaceutics5030498
Received: 1 July 2013 / Revised: 4 September 2013 / Accepted: 12 September 2013 / Published: 18 September 2013
Cited by 25 | PDF Full-text (466 KB) | HTML Full-text | XML Full-text
Abstract
Technological advances in both siRNA (small interfering RNA) and whole genome sequencing have demonstrated great potential in translating genetic information into siRNA-based drugs to halt the synthesis of most disease-causing proteins. Despite its powerful promises as a drug, siRNA requires a sophisticated [...] Read more.
Technological advances in both siRNA (small interfering RNA) and whole genome sequencing have demonstrated great potential in translating genetic information into siRNA-based drugs to halt the synthesis of most disease-causing proteins. Despite its powerful promises as a drug, siRNA requires a sophisticated delivery vehicle because of its rapid degradation in the circulation, inefficient accumulation in target tissues and inability to cross cell membranes to access the cytoplasm where it functions. Lipid nanoparticle (LNP) containing ionizable amino lipids is the leading delivery technology for siRNA, with five products in clinical trials and more in the pipeline. Here, we focus on the technological advances behind these potent systems for siRNA-mediated gene silencing. Full article
(This article belongs to the Special Issue Liposome Technologies)
Open AccessReview Bioavailability of Polyphenol Liposomes: A Challenge Ahead
Pharmaceutics 2013, 5(3), 457-471; doi:10.3390/pharmaceutics5030457
Received: 1 August 2013 / Revised: 29 August 2013 / Accepted: 4 September 2013 / Published: 17 September 2013
Cited by 15 | PDF Full-text (332 KB) | HTML Full-text | XML Full-text
Abstract
Dietary polyphenols, including flavonoids, have long been recognized as a source of important molecules involved in the prevention of several diseases, including cancer. However, because of their poor bioavailability, polyphenols remain difficult to be employed clinically. Over the past few years, a [...] Read more.
Dietary polyphenols, including flavonoids, have long been recognized as a source of important molecules involved in the prevention of several diseases, including cancer. However, because of their poor bioavailability, polyphenols remain difficult to be employed clinically. Over the past few years, a renewed interest has been devoted to the use of liposomes as carriers aimed at increasing the bioavailability and, hence, the therapeutic benefits of polyphenols. In this paper, we review the causes of the poor bioavailability of polyphenols and concentrate on their liposomal formulations, which offer a means of improving their pharmacokinetics and pharmacodynamics. The problems linked to their development and their potential therapeutic advantages are reviewed. Future directions for liposomal polyphenol development are suggested. Full article
(This article belongs to the Special Issue Liposome Technologies)
Open AccessReview New Transfection Agents Based on Liposomes Containing Biosurfactant MEL-A
Pharmaceutics 2013, 5(3), 411-420; doi:10.3390/pharmaceutics5030411
Received: 27 June 2013 / Revised: 29 July 2013 / Accepted: 8 August 2013 / Published: 16 August 2013
PDF Full-text (493 KB) | HTML Full-text | XML Full-text
Abstract
Nano vectors are useful tools to deliver foreign DNAs, oligonucleotides, and small interfering double-stranded RNAs (siRNAs) into mammalian cells with gene transfection and gene regulation. In such experiments we have found the liposomes with a biosurfacant mannosylerythriol lipid (MEL-A) are useful because [...] Read more.
Nano vectors are useful tools to deliver foreign DNAs, oligonucleotides, and small interfering double-stranded RNAs (siRNAs) into mammalian cells with gene transfection and gene regulation. In such experiments we have found the liposomes with a biosurfacant mannosylerythriol lipid (MEL-A) are useful because of their high transfer efficiency, and their unique mechanism to transfer genes to target cells with the lowest toxicity. In the present review we will describe our current work, which may contribute to the great advance of gene transfer to target cells and gene regulations. For more than two decades, the liposome technologies have changed dramatically and various methods have been proposed in the fields of biochemistry, cell biology, biotechnology, and so on. In addition, they were towards to pharmaceutics and clinical applications. The liposome technologies were expected to use gene therapy, however, they have not reached a requested goal as of yet. In the present paper we would like to present an approach using a biosurfactant, MEL-A, which is a surface-active compound produced by microorganisms growing on water-insoluble substrates and increases efficiency in gene transfection. The present work shows new transfection agents based on liposomes containing biosurfactant MEL-A. Full article
(This article belongs to the Special Issue Liposome Technologies)

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