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Filipczak N, Pan J, Yalamarty SSK, Torchilin VP. Recent advancements in liposome technology. Adv Drug Deliv Rev 2020; 156:4-22. [PMID: 32593642 DOI: 10.1016/j.addr.2020.06.022] [Citation(s) in RCA: 249] [Impact Index Per Article: 62.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 06/16/2020] [Accepted: 06/21/2020] [Indexed: 12/22/2022]
Abstract
The liposomes have continued to be well-recognized as an important nano-sized drug delivery system with attractive properties, such a characteristic bilayer structure assembling the cellular membrane, easy-to-prepare and high bio-compatibility. Extensive effort has been devoted to the development of liposome-based drug delivery systems during the past few decades. Many drug candidates have been encapsulated in liposomes and investigated for reduced toxicity and extended duration of therapeutic effect. The liposomal encapsulation of hydrophilic and hydrophobic small molecule therapeutics as well as other large molecule biologics have been established among different academic and industrial research groups. To date, there has been an increasing number of FDA-approved liposomal-based therapeutics together with more and more undergoing clinical trials, which involve a wide range of applications in anticancer, antibacterial, and antiviral therapies. In order to meet the continuing demand for new drugs in clinics, more recent advancements have been investigated for optimizing liposomal-based drug delivery system with more reproducible preparation technique and a broadened application to novel modalities, including nucleic acid therapies, CRISPR/Cas9 therapies and immunotherapies. This review focuses on the recent liposome' preparation techniques, the excipients of liposomal formulations used in various novel studies and the routes of administration used to deliver liposomes to targeted areas of disease. It aims to update the research in liposomal delivery and highlights future nanotechnological approaches.
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Math RK, Reddy S, Dae Yun H, Kambiranda D, Ghebreiyessus Y. Modeling the clay minerals-enzyme binding by fusion fluorescent proteins and under atomic force microscope. Microsc Res Tech 2019; 82:884-891. [PMID: 30775836 DOI: 10.1002/jemt.23233] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 12/28/2018] [Accepted: 01/21/2019] [Indexed: 11/06/2022]
Abstract
In the present study, binding of cellulase protein to different clay minerals were tested using fluorescent-protein complex and microscopic techniques. Cellulase gene (Cel5H) was cloned into three fluorescent vectors and expressed as fusion enzymes. Binding of Cel5H-mineral particles was confirmed by confocal microscopy, and enzyme assay. Among the Cel5H-fusion enzymes, green-fusion enzyme showed higher intensity compared with other red and yellow fusion-proteins. Intensity of fusion-proteins was dependent on the pH of the medium. Confocal microscopy revealed binding of the all three fusion proteins with different clay minerals. However, montmorillonite displayed higher binding capacity than kaolinite clay. Likewise, atomic force microscopy (AFM) image profile analysis showed proteins appeared globular molecules in free-state on mica surface with an average cross sectional diameter of 110 ± 2 nm and rough surface of montmorillonite made protein appear flattened due to structural alteration. Even surface of kaolinite also exerted some strain on protein molecular conformation after binding to surface. Our results provide further evidence for 3D visualization of enzyme-soil complex and encourage furthering study of the force involved interactions. Therefore, our results indicate that binding of proteins to clay minerals was external and provides a molecular method to observe the interaction of clay minerals-enzyme complex.
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Affiliation(s)
- Renukaradhya K Math
- Division of Applied Life Sciences, Gyeongsang National University, Chinju 660701, Republic of Korea
| | - Srinivasa Reddy
- Division of Applied Life Sciences, Gyeongsang National University, Chinju 660701, Republic of Korea
| | - Han Dae Yun
- Division of Applied Life Sciences, Gyeongsang National University, Chinju 660701, Republic of Korea
| | - Devaiah Kambiranda
- Department of Agricultural Sciences, Southern University Agriculture Research and Extension Center, Baton Rouge, Louisiana
| | - Yemane Ghebreiyessus
- Department of Agricultural Sciences, Southern University Agriculture Research and Extension Center, Baton Rouge, Louisiana
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3
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Chabanon M, Stachowiak JC, Rangamani P. Systems biology of cellular membranes: a convergence with biophysics. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2017; 9:10.1002/wsbm.1386. [PMID: 28475297 PMCID: PMC5561455 DOI: 10.1002/wsbm.1386] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 02/02/2017] [Accepted: 02/21/2017] [Indexed: 12/12/2022]
Abstract
Systems biology and systems medicine have played an important role in the last two decades in shaping our understanding of biological processes. While systems biology is synonymous with network maps and '-omics' approaches, it is not often associated with mechanical processes. Here, we make the case for considering the mechanical and geometrical aspects of biological membranes as a key step in pushing the frontiers of systems biology of cellular membranes forward. We begin by introducing the basic components of cellular membranes, and highlight their dynamical aspects. We then survey the functions of the plasma membrane and the endomembrane system in signaling, and discuss the role and origin of membrane curvature in these diverse cellular processes. We further give an overview of the experimental and modeling approaches to study membrane phenomena. We close with a perspective on the converging futures of systems biology and membrane biophysics, invoking the need to include physical variables such as location and geometry in the study of cellular membranes. WIREs Syst Biol Med 2017, 9:e1386. doi: 10.1002/wsbm.1386 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Morgan Chabanon
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA
| | - Jeanne C. Stachowiak
- Department of Biomedical Engineering, Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA
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Bryła A, Juzwa W, Weiss M, Lewandowicz G. Lipid nanoparticles assessment by flow cytometry. Int J Pharm 2017; 520:149-157. [PMID: 28161665 DOI: 10.1016/j.ijpharm.2017.01.047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 01/23/2017] [Indexed: 11/28/2022]
Abstract
BACKGROUND Liposomes are promising carriers for drugs and bioactive compounds. Size and structure are their crucial parameters. Thus, it is essential to assess individual vesicles as prepared. Currently available techniques fail to measure liposome's size and structure simultaneously, with a high throughput. To solve this problem, we have developed a novel, flow cytometric method quantifying liposomes. METHODS Firstly, the following fluorescent staining combinations were tested: DiD/TO, Rh123/DiD, Syto9/DiD. Further, chosen fluorochromes were used to compare three populations of vesicles: raw (R), obtained by thin film hydration and extruded ones (populations E10 and E21). Dynamic light scattering (DLS) was used for determination of average diameter and size distribution of nanocarriers. Structural differences between the raw and the extruded liposomes, as well as additional information concerning vesicles size were acquired employing atomic force microscopy (AFM). RESULTS DLS analysis indicated that, three distinct populations of vesicles were obtained. Liposomes were characterized by mean diameter of 323nm, 220nm and 170nm for population R, E10 and E21 respectively. All the populations were stable and revealed zeta potential of -29mV. AFM confirmed that raw and extruded liposomes were differed in structure. CONCLUSIONS AND GENERAL SIGNIFICANCE DiD/TO was the optimal fluorochrome combination that enabled to resolve distinctly the sub-populations of liposomes. Results obtained by flow cytometry were in a good agreement with those from DLS and AFM. It was proved that, flow cytometry, when proper fluorescent dyes are used, is an adequate method for liposomes assessment. The proposed method enables fast and reliable analysis of liposomes in their native environment.
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Affiliation(s)
- Anna Bryła
- Institute of Chemical Technology and Engineering, Poznan University of Technology, 4 Berdychowo Street, 60-965 Poznan, Poland.
| | - Wojciech Juzwa
- Department of Biotechnology and Food Microbiology, Poznan University of Life Sciences, 48 Wojska Polskiego Street, 60-627 Poznan, Poland.
| | - Marek Weiss
- Institute of Physics, Poznan University of Technology, 3 Piotrowo Street, 60-965 Poznan, Poland.
| | - Grażyna Lewandowicz
- Department of Biotechnology and Food Microbiology, Poznan University of Life Sciences, 48 Wojska Polskiego Street, 60-627 Poznan, Poland.
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Deng NN, Yelleswarapu M, Huck WTS. Monodisperse Uni- and Multicompartment Liposomes. J Am Chem Soc 2016; 138:7584-91. [DOI: 10.1021/jacs.6b02107] [Citation(s) in RCA: 162] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Nan-Nan Deng
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Maaruthy Yelleswarapu
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Wilhelm T. S. Huck
- Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
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Langowska K, Kowal J, Palivan CG, Meier W. A general strategy for creating self-defending surfaces for controlled drug production for long periods of time. J Mater Chem B 2014; 2:4684-4693. [PMID: 32262280 DOI: 10.1039/c4tb00277f] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Infections associated with bacterial adhesion and subsequent biofilm formation constitute a grave medical issue for which conventional antibiotic therapies remain ineffective. Here, we introduce a new strategy employing nanotechnology to create smart surfaces with self-defending properties that result in controlled drug production and controlled release for long periods of time. Self-defending surfaces on solid supports are prepared by immobilizing polymer nanoreactors containing an encapsulated biocatalyst that can convert non-antibiotic substrates to an abiotic drug. For medical applications and biosensing, the immobilization method must fulfill specific criteria, and these were achieved by an immobilization strategy based on Schiff base formation between aldehyde groups on the outer surface of nanoreactors and amino groups on the solid support surface, followed by reductive amination. The resulting self-defending surfaces allow control of drug production at a specific rate for a specific period of time by adding predetermined amounts of substrate to the outer medium, minimization of dosages and therefore systemic toxicity, and limitation of the immune response. Such self-defending surfaces producing drugs offer a versatile strategy for the development of smart surfaces with improved stability and efficacy (by changing the biocatalyst) to serve as biosensors, antifouling surfaces, or smart packages.
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Affiliation(s)
- Karolina Langowska
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, 4056 Basel, Switzerland.
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Wu KCW, Yang CY, Cheng CM. Using cell structures to develop functional nanomaterials and nanostructures – case studies of actin filaments and microtubules. Chem Commun (Camb) 2014; 50:4148-57. [DOI: 10.1039/c4cc00005f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Actin filaments and microtubules are utilized as building blocks to create functional nanomaterials and nanostructures for nature-inspired small-scale devices and systems.
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Affiliation(s)
- Kevin Chia-Wen Wu
- Department of Chemical Engineering
- National Taiwan University
- Taipei 10617, Taiwan
| | - Chung-Yao Yang
- Institute of Nanoengineering and Microsystems
- National Tsing Hua University
- Hsinchu 30013, Taiwan
| | - Chao-Min Cheng
- Institute of Nanoengineering and Microsystems
- National Tsing Hua University
- Hsinchu 30013, Taiwan
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Abstract
Liposome structures have a wide range of applications in biology, biochemistry, and biophysics. As a result, several methods for forming liposomes have been developed. This review provides a critical comparison of existing microfluidic technologies for forming liposomes and, when applicable, a comparison with their analogous macroscale counterparts. The properties of the generated liposomes, including size, size distribution, lamellarity, membrane composition, and encapsulation efficiency, form the basis for comparison. We hope that this critique will allow the reader to make an informed decision as to which method should be used for a given biological application.
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Affiliation(s)
- Dirk van Swaay
- Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
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Vogel SK, Schwille P. Minimal systems to study membrane-cytoskeleton interactions. Curr Opin Biotechnol 2012; 23:758-65. [PMID: 22503237 DOI: 10.1016/j.copbio.2012.03.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 03/21/2012] [Accepted: 03/22/2012] [Indexed: 11/16/2022]
Abstract
In the context of minimal systems design, there are two areas in which the reductionist approach has been particularly successful: studies of molecular motors on cytoskeletal filaments, and of protein-lipid interactions in model membranes. However, a minimal cortex, that is, the interface between membrane and cytoskeleton, has just begun to be functionally reconstituted. A key property of living cells is their ability to change their shape in response to extracellular and intracellular stimuli. Although studied in live cells since decades, the mutual dependence between cytoskeleton and membrane dynamics in these large-scale transformations is still poorly understood. Here we report on inspiring recent in vitro work in this direction, and the promises it holds for a better understanding of key cellular processes.
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Affiliation(s)
- Sven K Vogel
- Max Planck Institute of Biochemistry, Department of Cellular and Molecular Biophysics, Am Klopferspitz 18, D-82152 Martinsried, Germany
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Vermette P. Liposome characterization by quartz crystal microbalance measurements and atomic force microscopy. Methods Enzymol 2010; 465:43-73. [PMID: 19913161 DOI: 10.1016/s0076-6879(09)65003-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Abstract
This chapter reviews liposome characterization by quartz crystal microbalance (QCM) measurements and atomic force microscopy (AFM). In many studies, AFM imaging is simply used to image liposomes with resolution often that does not allow morphological analysis. Although liposome size can be obtained by processing AFM images, it is found that liposomes flatten upon surface adsorption or immobilization. Liposome stability and stiffness have been characterized by using AFM imaging or AFM force measurements, although the latter method, using a microsphere attached on the AFM cantilever, seems more appropriate to limit liposome damage and to obtain more quantitative analysis, such as the Young's modulus. Investigation of liposome layers by QCM revealed that liposomes can be detected from a combined analysis of frequency and bandwidth shifts. However, QCM by itself provides only limited information on liposomes. QCM can be used to assess the presence of a layer and also to discriminate between rigid and viscoelastic ones. Liposome properties have been derived from QCM curves, but often this requires making hypotheses that are difficult to assess. AFM and QCM analyses need to be combined with other techniques to provide complementary information.
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Affiliation(s)
- Patrick Vermette
- Laboratoire de Bioingénierie et de Biophysique de l'Université de Sherbrooke, Department of Chemical and Biotechnological Engineering, Université de Sherbrooke, Sherbrooke, Québec, Canada
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Brgles M, Jurašin D, Sikirić MD, Frkanec R, Tomašić J. Entrapment of Ovalbumin into Liposomes—Factors Affecting Entrapment Efficiency, Liposome Size, and Zeta Potential. J Liposome Res 2008; 18:235-48. [DOI: 10.1080/08982100802312762] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Rakhmatullina E, Meier W. Solid-supported block copolymer membranes through interfacial adsorption of charged block copolymer vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:6254-6261. [PMID: 18481881 DOI: 10.1021/la8003068] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The properties of amphiphilic block copolymer membranes can be tailored within a wide range of physical parameters. This makes them promising candidates for the development of new (bio)sensors based on solid-supported biomimetic membranes. Here we investigated the interfacial adsorption of polyelectrolyte vesicles on three different model substrates to find the optimum conditions for formation of planar membranes. The polymer vesicles were made from amphiphilic ABA triblock copolymers with short, positively charged poly(2,2-dimethylaminoethyl methacrylate) (PDMAEMA) end blocks and a hydrophobic poly( n-butyl methacrylate) (PBMA) middle block. We observed reorganization of the amphiphilic copolymer chains from vesicular structures into a 1.5+/-0.04 nm thick layer on the hydrophobic HOPG surface. However, this film starts disrupting and dewetting upon drying. In contrast, adsorption of the vesicles on the negatively charged SiO2 and mica substrates induced vesicle fusion and formation of planar, supported block copolymer films. This process seems to be controlled by the surface charge density of the substrate and concentration of the block copolymers in solution. The thickness of the copolymer membrane on mica was comparable to the thickness of phospholipid bilayers.
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Affiliation(s)
- Ekaterina Rakhmatullina
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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14
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Li S, Byrne B, Welsh J, Palmer AF. Self-assembled poly(butadiene)-b-poly(ethylene oxide) polymersomes as paclitaxel carriers. Biotechnol Prog 2008; 23:278-85. [PMID: 17269699 PMCID: PMC2525785 DOI: 10.1021/bp060208+] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, self-assembled poly(butadiene)-b-poly(ethylene oxide) (PB-PEO) polymersomes (polymer vesicles) and worm micelles were evaluated as paclitaxel carriers. Paclitaxel was successfully incorporated into PB-PEO polymersomes and worm micelles. The loading capacity of paclitaxel inside PB-PEO colloids ranged from 6.7% to 13.7% w/w, depending on the morphology of copolymer colloids and the molecular weight of diblock copolymer. Paclitaxel loaded OB4 (PB219-PEO121) polymersome formulations were colloidally stable for 4 months at 4 degrees C and exhibited slow steady release of paclitaxel over a 5 week period at 37 degrees C. Evaluation of the in vitro cytotoxicity of paclitaxel-polymersome formulations showed that the ability of paclitaxel-loaded polymersomes to inhibit proliferation of MCF-7 human breast cancer cells was less compared to paclitaxel alone. By increasing the concentration of paclitaxel in polymersomes from 0.02 to 0.2 mug/mL, paclitaxel-polymersome formulations showed comparable activity in inhibiting the growth of MCF-7 cells. Taken together, these results demonstrate that paclitaxel-polymersomes have desirable restrained release profile and exhibit long-term stability.
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Affiliation(s)
- Shuliang Li
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Belinda Byrne
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - JoEllen Welsh
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Andre F. Palmer
- Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH 43210, USA
- To whom correspondence should be addressed. Telephone: 1-574-631-4776.
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Li S, Byrne B, Welsh J, Palmer AF. Self-assembled poly(butadiene)-b-poly(ethylene oxide) polymersomes as paclitaxel carriers. Biotechnol Prog 2008. [PMID: 17269699 DOI: 10.1021/bp060208] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In this work, self-assembled poly(butadiene)-b-poly(ethylene oxide) (PB-PEO) polymersomes (polymer vesicles) and worm micelles were evaluated as paclitaxel carriers. Paclitaxel was successfully incorporated into PB-PEO polymersomes and worm micelles. The loading capacity of paclitaxel inside PB-PEO colloids ranged from 6.7% to 13.7% w/w, depending on the morphology of copolymer colloids and the molecular weight of diblock copolymer. Paclitaxel loaded OB4 (PB219-PEO121) polymersome formulations were colloidally stable for 4 months at 4 degrees C and exhibited slow steady release of paclitaxel over a 5 week period at 37 degrees C. Evaluation of the in vitro cytotoxicity of paclitaxel-polymersome formulations showed that the ability of paclitaxel-loaded polymersomes to inhibit proliferation of MCF-7 human breast cancer cells was less compared to paclitaxel alone. By increasing the concentration of paclitaxel in polymersomes from 0.02 to 0.2 mug/mL, paclitaxel-polymersome formulations showed comparable activity in inhibiting the growth of MCF-7 cells. Taken together, these results demonstrate that paclitaxel-polymersomes have desirable restrained release profile and exhibit long-term stability.
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Affiliation(s)
- Shuliang Li
- Department of Chemical and Biomolecular Engineering and Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA
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16
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Tribet C, Vial F. Flexible macromolecules attached to lipid bilayers: impact on fluidity, curvature, permeability and stability of the membranes. SOFT MATTER 2007; 4:68-81. [PMID: 32907085 DOI: 10.1039/b708431p] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This review summarizes recent investigations on the association of macromolecules on lipid bilayers. Hydrophilic and flexible polymers can form soft coronae tenuously adsorbed or anchored on the lipid membrane. Other synthetic macromolecules are embedded in the apolar region of the membrane. Recent experimental and theoretical works focus on the perturbation of lipid properties achieved depending on the nature and strength of binding. Of importance to biomimicry, to tethered model membranes, and drug carriers, the effects achievable include modulation of the lateral diffusivity of lipids, shape distortions, lateral segregations, formation of well-defined nanopores and ultimately the stimuli responsive disruption of the membrane.
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Affiliation(s)
- Christophe Tribet
- Physico-chimie des Polymères et Milieux Dispersés, CNRS UMR 7615 and Université Paris 6, ESPCI, 10 rue Vauquelin, F-75005 Paris, France
| | - Florent Vial
- Physico-chimie des Polymères et Milieux Dispersés, CNRS UMR 7615 and Université Paris 6, ESPCI, 10 rue Vauquelin, F-75005 Paris, France
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17
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HARRIS DAVIDR, PALMER ANDREF. Novel strategies for transporting cellular hemoglobin-based oxygen carriers in the systemic circulation. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1778-428x.2007.00082.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Lee CK, Wang YM, Huang LS, Lin S. Atomic force microscopy: Determination of unbinding force, off rate and energy barrier for protein–ligand interaction. Micron 2007; 38:446-61. [PMID: 17015017 DOI: 10.1016/j.micron.2006.06.014] [Citation(s) in RCA: 182] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2005] [Revised: 06/17/2006] [Accepted: 06/19/2006] [Indexed: 11/19/2022]
Abstract
Recently, atomic force microscopy (AFM) based force measurements have been applied biophysically and clinically to the field of molecular recognition as well as to the evaluation of dynamic parameters for various interactions between proteins and ligands in their native environment. The aim of this review is to describe the use of the AFM to measure the forces that control biological interaction, focusing especially on protein-ligand and protein-protein interaction modes. We first considered the measurements of specific and non-specific unbinding forces which together control protein-ligand interactions. As such, we will look at the theoretical background of AFM force measurement curves for evaluating the unbinding forces of protein-ligand complexes. Three AFM model dynamic parameters developed recently for use in protein-ligand interactions are reviewed: (i) unbinding forces, (ii) off rates, and (iii) binding energies. By reviewing the several techniques developed for measuring forces between biological structures and intermolecular forces in the literature, we show that use of an AFM for these applications provides an excellent tool in terms of spatial resolution and lateral resolution, especially for protein-protein and protein-ligand interactions.
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Affiliation(s)
- Chih-Kung Lee
- Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan
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Uzun O, Xu H, Jeoung E, Thibault RJ, Rotello VM. Recognition-Induced Polymersomes: Structure and Mechanism of Formation. Chemistry 2005; 11:6916-20. [PMID: 16187370 DOI: 10.1002/chem.200500809] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Random polystyrene copolymers grafted with complementary recognition elements were combined in chloroform producing vesicular aggregates, that is, recognition-induced polymersomes (RIPs). Reflection interference contrast microscopy (RICM) in solution, coupled with optical microscopy (OM) and atomic force microscopy (AFM) on solid substrates, were used to determine the wall thickness of the RIPs. Rather than a conventional mono- or bilayer structure (approximately 10 or approximately 20 nm, respectively) the RIP membrane was 43+/-7 nm thick. Structural arrangement of the polymer chains on the RIP wall were characterized by using angle-resolved X-ray photoelectron spectroscopy (AR-XPS). The interior portion of the vesicle membrane was found to be more polar, containing more recognition units, than the exterior part. This gradient suggests that a rapid self-sorting of polymers takes place during the formation of RIPs, providing the likely mechanism for vesicle self-assembly.
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Affiliation(s)
- Oktay Uzun
- Department of Chemistry, University of Massachusetts, Amherst, MA 01003, USA
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20
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Arifin DR, Palmer AF. Physical properties and stability mechanisms of poly(ethylene glycol) conjugated liposome encapsulated hemoglobin dispersions. ACTA ACUST UNITED AC 2005; 33:137-62. [PMID: 15960077 DOI: 10.1081/bio-200055880] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Liposomes encapsulating hemoglobin (LEHs) surface-conjugated with 2000 and 550 Da poly(ethylene glycol) (PEG) were produced via extrusion through 400, 200 and 100 nm pore diameter membranes in two types of phosphate buffer with different ionic strengths. The lipid bilayers were composed of dimyristoyl-phosphatidylcholine (DMPC), cholesterol, dimyristoyl-phosphoethanolamine-PEG (DMPE-PEG), dimyristoyl-phosphatidylglycerol (DMPG), and alpha-tocopherol (in a 43:40:10:5:2 mole ratio). N-acetyl-L-cysteine was coencapsulated in order to suppress hemoglobin (Hb) oxidation. Various physical properties of PEG-LEH dispersions were determined: size distribution, encapsulation efficiency, P50 (partial pressure of O2 where half of the oxygen binding sites are saturated with O2), cooperativity coefficient, and encapsulated methemoglobin (MetHb) level. In order to study the stabilization mechanism of these dispersions, the effective bending constant (KB) and the spontaneous radius of curvature (R0) of PEG-LEHs were extracted by fitting a mathematical model describing the size distribution of a liposome dispersion to the experimentally measured size distributions. We observed that liposome dispersions extruded in phosphate buffer (PB) were more monodisperse than liposomes extruded in phosphate buffered saline (PBS), and higher molecular weight PEG promoted the formation of narrower size distributions. Moreover, extrusion in PB and lipid conjugation with higher molecular weight PEG imparted higher bilayer rigidity (high KB), and stabilized the liposome dispersions by the spontaneous curvature mechanism, whereas the other liposome dispersions were stabilized by thermal undulations (low KB). The P50 and cooperativity coefficient of PEG-LEHs extruded in PBS and PB was comparable to that of human blood, and the encapsulated MetHb levels were less than 5%. The highest encapsulation efficiencies obtained were 27%-36% (82-109 mg Hb/mL) for LEH dispersions extruded in PBS and grafted with 2000 Da PEG. These dispersions yielded KBs' ranging from 7kT to 27kT, which indicated that these dispersions were stabilized by spontaneous curvature. Whereas the same lipid combination extruded in PBS, however, instead conjugated with 550 Da PEG resulted in KBs' ranging from 2 kT to 2.7 kT, which indicated that these dispersions were stabilized by thermal undulations. Thermal undulations permitted Hb leakage through the lipid bilayers, which in turn lowered the encapsulation efficiency to 1%-10.7% (3-32 mg Hb/mL). Taken together, the experimentally measured size distributions and encapsulation efficiencies of PEG-LEH dispersions can be readily explained through analysis of the magnitude of KB, which dictates the stability mechanism of the liposome dispersion.
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Affiliation(s)
- Dian R Arifin
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
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21
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Abstract
The demand for artificial blood substitutes in cases of elective surgeries, trauma, and civilian mass catastrophes increases every day. However, few studies have been done to characterize the mechanical stability of blood substitutes, especially liposome encapsulated hemoglobin (LEHb) dispersions. In this work, the stability of LEHb dispersions was investigated by fitting Jung et al.'s liposome size distribution model to experimentally measured LEHb size distributions [6] (produced via extrusion) using asymmetric flow field-flow fractionation coupled with multi-angle static light scattering. The effective bending constant (KB) and radius of curvature (R0) of each liposome dispersion were regressed from the size distribution fits. The model was found to be in agreement with the size distributions of LEHbs extruded through 400, 200 and 100 nm pore diameter membranes, but not in agreement with LEHbs extruded through 80 and 50 nm pore diameter membranes. Although the magnitude of KB fluctuated, we deduced a general trend for KB to decrease with decreasing pore diameter, and increasing initial Hb concentration. LEHbs extruded through 400nm pore diameter membranes were stabilized by the spontaneous curvature effect, while those extruded through 80 and 50 nm pore diameter membranes were mostly stabilized by thermal undulations, regardless of the initial Hb concentration. For LEHb dispersions extruded through 200 and 100 nm pore diameter membranes, there was a transition of stabilization mechanism from spontaneous curvature to thermal undulations with increasing initial Hb concentration. Taken together, these results suggest that moderate Hb encapsulation might actually impart better mechanical stability to LEHb dispersions extruded through 200 and 100 nm pore diameter membranes.
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Affiliation(s)
- Dian R Arifin
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46656, USA
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Li S, Nickels J, Palmer AF. Liposome-encapsulated actin–hemoglobin (LEAcHb) artificial blood substitutes. Biomaterials 2005; 26:3759-69. [PMID: 15621266 DOI: 10.1016/j.biomaterials.2004.09.015] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2004] [Accepted: 09/08/2004] [Indexed: 10/26/2022]
Abstract
A new approach to enhance the circulation persistence of liposomes has been applied to develop liposome-encapsulated actin-hemoglobin (LEAcHb) dispersions as potential blood substitutes by introducing an actin matrix into the liposome aqueous core. Asymmetric flow field-flow fractionation coupled with multi-angle static light scattering was used to study the shape, size distribution, and encapsulation efficiency of liposome-encapsulated hemoglobin (LEHb) and LEAcHb dispersions. By polymerizing monomeric actin into filamentous actin inside the liposome aqueous core, LEAcHb particles transformed into a disk-like shape. We studied the effect of an encapsulated actin matrix on the size distribution, hemoglobin (Hb) encapsulation efficiency, oxygen affinity, and methemoglobin (MetHb) level of LEAcHb dispersions, and compared them with plain LEHb dispersions (without actin). LEHb, and LEAcHb dispersions extruded through 400 nm membranes were injected into rats and it was observed that LEAcHb dispersions with 1mg/mL of actin enhanced the circulatory half-life versus LEHb dispersions. The circulatory characteristics of empty PEGylated and non-PEGylated actin-containing liposomes (without Hb) were studied as controls for the LEHb and LEAcHb dispersions in this paper, which displayed maximum circulatory half-lives greater than 72 h. Taken together the results of this study supports our hypothesis that a lipid membrane supported by an underlying actin matrix will extend the circulatory half-life of LEHb dispersions.
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Affiliation(s)
- Shuliang Li
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, 171 Fitzpatrick Hall, Notre Dame, IN 46556, USA
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23
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Owen RL, Strasters JK, Breyer ED. Lipid vesicles in capillary electrophoretic techniques: characterization of structural properties and associated membrane-molecule interactions. Electrophoresis 2005; 26:735-751. [PMID: 15714573 DOI: 10.1002/elps.200410288] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This paper reviews the use of lipid vesicles as model membranes in capillary electrophoresis (CE). The history and utility of CE in the characterization of microparticles is summarized, focusing on the application of colloidal electromigration theories to lipid vesicles. For instance, CE experiments have been used to characterize the size, surface properties, enclosed volumes, and electrophoretic mobilities of lipid vesicles and of lipoprotein particles. Several techniques involving small molecules or macromolecules separated in the presence of lipid vesicles are discussed. Interactions between the analytes and the lipid vesicles - acting as a pseudostationary phase or coated stationary phase in electrokinetic chromatography (EKC) - can be used to obtain additional information on the characteristics of the vesicles and analytes, and to study the biophysical properties of membrane-molecule interactions in lipid vesicles and lipoproteins. Different methods of determining binding constants by EKC are reviewed, along with the relevant binding constant calculations and a discussion of the application and limitations of these techniques as they apply to lipid vesicle systems.
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Affiliation(s)
- Rebecca L Owen
- Georgia State University, Department of Chemistry, Atlanta, GA 30302-4098, USA
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