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Peptide-Liposome Model Systems for Triggered Release
Linköping University, Department of Physics, Chemistry and Biology, Molecular Physics. Linköping University, Faculty of Science & Engineering.ORCID iD: 0000-0002-9481-8828
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Liposomes are widely used in drug delivery to improve drug efficacy and to reduce side effects. For liposome-encapsulated drugs to become bioavailable and provide a therapeutic effect they must be released, which typically is a slow process that primarily relies on passive diffusion, liposome rupture or endocytotic uptake. Achieving drug concentrations within the therapeutic window can thus be challenging, resulting in poor efficacy and higher risks drug resistance. Finding means to modulate lipid membrane integrity and to trigger rapid and efficient release of liposomal cargo is thus critical to improve current and future liposomal drug delivery systems. The possibilities to tailor lipid composition and surface functionalization is vital for drug delivery applications but also make liposomes attractive model systems for studies of membrane active biomolecules.

The overall aim of this thesis work has been to develop new strategies for triggering and controlling changes in lipid membrane integrity and to study the interactions of membrane active peptides with model lipid membranes using both de novo designed and biologically derived synthetic amphipathic cationic peptides. Two different sets of designed peptides have been explored that can fold and heterodimerize into a coiled coil and helix-loop-helix fourhelix bundle, respectively. Conjugation of the cationic lysine rich peptides to liposomes triggered a rapid and concentration dependent release. The additions of their corresponding glutamic acid-rich complementary peptides inhibited the release of liposomal cargo. Possibilities to reduce the inhibitory effect by both proteolytic digestion of the inhibitory peptide and by means of heterodimer exchange have been investigated. Moreover, the effects of peptide size and composition and ability to fold have been studied in order to elucidate the factors that influence the membrane permeabilizing effects of the peptides.

In addition, the membrane activity of a the two-peptide bacteriocin PLNC8α and PLNC8β has been explored using liposomes as a model system. PLNC8αβ are expressed by Lactobacillus plantarum and were shown to display pronounced membrane-partition folding coupling, leading to rapid release of liposome encapsulated carboxyfluorescein. PLNC8αβ also kill and suppressed growth of the gram-negative bacteria Porphyromonas gingivalis by efficiently damaging the bacterial membrane.

Although membrane active peptides are highly efficient in perturbing lipid membrane integrity, possibilities to trigger release using external stimuli are also of large interest for therapeutic applications. Light-induced heating of liposome encapsulated gold nanoparticles (AuNPs) has been shown by others as a potential strategy to trigger drug release. To facilitate fabrication of thermoplasmonic liposome systems we developed a simple method for synthesis of small AuNPs inside liposomes, using the liposomes as nanoscale reaction vessels.

The work presented in this thesis provides new knowledge and techniques for future development of liposome-based drug delivery systems, peptide-based therapeutics and increase our understanding of peptide-lipid interactions.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2018. , p. 78
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1922
National Category
Biophysics Biomaterials Science Biochemistry and Molecular Biology Physical Chemistry
Identifiers
URN: urn:nbn:se:liu:diva-150419DOI: 10.3384/diss.diva-150419ISBN: 978-91-7685-337-5 (print)OAI: oai:DiVA.org:liu-150419DiVA, id: diva2:1240765
Public defence
2018-09-21, Planck, Fysikhuset, Campus Valla, Linköping, 09:15 (English)
Opponent
Supervisors
Available from: 2018-08-22 Created: 2018-08-22 Last updated: 2018-09-12Bibliographically approved
List of papers
1. Tuning Liposome Membrane Permeability by Competitive Peptide Dimerization and Partitioning-Folding Interactions Regulated by Proteolytic Activity
Open this publication in new window or tab >>Tuning Liposome Membrane Permeability by Competitive Peptide Dimerization and Partitioning-Folding Interactions Regulated by Proteolytic Activity
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2016 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, no 21123, p. 1-9Article in journal (Refereed) Published
Abstract [en]

Membrane active peptides are of large interest for development of drug delivery vehicles and therapeutics for treatment of multiple drug resistant infections. Lack of specificity can be detrimental and finding routes to tune specificity and activity of membrane active peptides is vital for improving their therapeutic efficacy and minimize harmful side effects. We describe a de novo designed membrane active peptide that partition into lipid membranes only when specifically and covalently anchored to the membrane, resulting in pore-formation. Dimerization with a complementary peptide efficiently inhibits formation of pores. The effect can be regulated by proteolytic digestion of the inhibitory peptide by the matrix metalloproteinase MMP-7, an enzyme upregulated in many malignant tumors. This system thus provides a precise and specific route for tuning the permeability of lipid membranes and a novel strategy for development of recognition based membrane active peptides and indirect enzymatically controlled release of liposomal cargo.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2016
National Category
Physical Sciences Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:liu:diva-126131 (URN)10.1038/srep21123 (DOI)000370532500002 ()26892926 (PubMedID)
Note

Funding Agencies|Linkoping University; Swedish Research Council (VR); Swedish Foundation for Strategic Research (SSF); Knut and Alice Wallenberg Foundation (KAW); Centre in Nanoscience and Technology (CeNano); Provost Office, NTU

Available from: 2016-03-15 Created: 2016-03-15 Last updated: 2019-01-22
2. Antibacterial effects of Lactobacillus and bacteriocin PLNC8 alpha beta on the periodontal pathogen Porphyromonas gingivalis
Open this publication in new window or tab >>Antibacterial effects of Lactobacillus and bacteriocin PLNC8 alpha beta on the periodontal pathogen Porphyromonas gingivalis
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2016 (English)In: BMC Microbiology, ISSN 1471-2180, E-ISSN 1471-2180, Vol. 16, no 188Article in journal (Refereed) Published
Abstract [en]

Background: The complications in healthcare systems associated with antibiotic-resistant microorganisms have resulted in an intense search for new effective antimicrobials. Attractive substances from which novel antibiotics may be developed are the bacteriocins. These naturally occurring peptides are generally considered to be safe and efficient at eliminating pathogenic bacteria. Among specific keystone pathogens in periodontitis, Porphyromonas gingivalis is considered to be the most important pathogen in the development and progression of chronic inflammatory disease. The aim of the present study was to investigate the antimicrobial effects of different Lactobacillus species and the two-peptide bacteriocin PLNC8 alpha beta on P. gingivalis. Results: Growth inhibition of P. gingivalis was obtained by viable Lactobacillus and culture media from L. plantarum NC8 and 44048, but not L. brevis 30670. The two-peptide bacteriocin from L. plantarum NC8 (PLNC8 alpha beta) was found to be efficient against P. gingivalis through binding followed by permeabilization of the membranes, using Surface plasmon resonance analysis and DNA staining with Sytox Green. Liposomal systems were acquired to verify membrane permeabilization by PLNC8 alpha beta. The antimicrobial activity of PLNC8 alpha beta was found to be rapid (1 min) and visualized by TEM to cause cellular distortion through detachment of the outer membrane and bacterial lysis. Conclusion: Soluble or immobilized PLNC8 alpha beta bacteriocins may be used to prevent P. gingivalis colonization and subsequent pathogenicity, and thus supplement the host immune system against invading pathogens associated with periodontitis.

Place, publisher, year, edition, pages
BIOMED CENTRAL LTD, 2016
Keywords
Periodontitis; P. gingivalis; Lactobacillus; Bacteriocin; PLNC8
National Category
Microbiology
Identifiers
urn:nbn:se:liu:diva-131904 (URN)10.1186/s12866-016-0810-8 (DOI)000383422500001 ()27538539 (PubMedID)
Note

Funding Agencies|Swedish Heart-Lung Foundation; Foundation of Magnus Bergvall; Foundation of Olle Engkvist; Knowledge Foundation, Sweden

Available from: 2016-10-13 Created: 2016-10-11 Last updated: 2018-08-22
3. Liposomes as nanoreactors for the photochemical synthesis of gold nanoparticles
Open this publication in new window or tab >>Liposomes as nanoreactors for the photochemical synthesis of gold nanoparticles
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2015 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 456, p. 206-209Article in journal (Refereed) Published
Abstract [en]

A simple and novel method for the photochemical synthesis of AuNPs in liposomes is described. Gold salt is co-encapsulated with the photoinitiator Irgacure-2959 in POPC liposomes prepared via traditional thin-film hydration technique. UVA irradiation for 15 min results in encapsulated AuNPs of 2.8 +/- 1.6 nm in diameter that are primarily dispersed in the aqueous interior of the liposomes. (C) 2015 Elsevier Inc. All rights reserved.

Place, publisher, year, edition, pages
Elsevier, 2015
Keywords
Liposomes; AuNPs; Nanoreactors
National Category
Clinical Medicine Physical Sciences
Identifiers
urn:nbn:se:liu:diva-120718 (URN)10.1016/j.jcis.2015.06.033 (DOI)000358458500027 ()26125517 (PubMedID)
Note

Funding Agencies|Swedish Foundation for Strategic Research (SSF); Center for Integrative Regenerative Medicine (IGEN) at Linkoping University

Available from: 2015-08-24 Created: 2015-08-24 Last updated: 2018-08-22
4. Tuning Liposome Membrane Permeability by Competitive Coiled Coil Heterodimerization and Heterodimer Exchange
Open this publication in new window or tab >>Tuning Liposome Membrane Permeability by Competitive Coiled Coil Heterodimerization and Heterodimer Exchange
2018 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 34, no 22, p. 6529-6537Article in journal (Refereed) Published
Abstract [en]

Membrane-active peptides that enable the triggered release of liposomal cargo are of great interest for the development of liposome-based drug delivery systems but require peptide-lipid membrane interactions that are highly defined and tunable. To this end, we have explored the possibility to use the competing interactions between membrane partitioning and heterodimenzation and the folding of a set of four different de novo designed coiled coil peptides Covalent conjugation of the cationic peptides triggered rapid destabilization of membrane mtegrity and the release of encapsulated species. The release was inhibited when introducing complementary peptides as a result of heterodimenzation and folding into coiled mils The degree of inhibition was shown to be dictated by the coiled coil peptide heterodimer dissociation constants, and liposomal release could be reactivated by a heterodimer exchange to render the membrane bound peptide free and thus membrane-active. The possibility to tune the permeability of lipid membranes using highly specific peptide-folding-dependent interactions delineates a new possible approach for the further development of responsive liposome-based drug delivery systems.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Biophysics
Identifiers
urn:nbn:se:liu:diva-149349 (URN)10.1021/acs.langmuir.8b00592 (DOI)000434893600023 ()29758162 (PubMedID)
Note

Funding Agencies|Swedish Research Council (VR) [2017-04475]; Swedish Cancer Foundation [CAN 2017/430]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]

Available from: 2018-07-02 Created: 2018-07-02 Last updated: 2019-01-22

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