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Santamaria A, Batchu KC, Fragneto G, Laux V, Haertlein M, Darwish TA, Russell RA, Zaccai NR, Guzmán E, Maestro A. Investigation on the relationship between lipid composition and structure in model membranes composed of extracted natural phospholipids. J Colloid Interface Sci 2023; 637:55-66. [PMID: 36682118 DOI: 10.1016/j.jcis.2023.01.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 12/09/2022] [Accepted: 01/09/2023] [Indexed: 01/13/2023]
Abstract
HYPOTHESIS Unravelling the structural diversity of cellular membranes is a paramount challenge in life sciences. In particular, lipid composition affects the membrane collective behaviour, and its interactions with other biological molecules. EXPERIMENTS Here, the relationship between membrane composition and resultant structural features was investigated by surface pressure-area isotherms, Brewster angle microscopy and neutron reflectometry on in vitro membrane models of the mammalian plasma and endoplasmic-reticulum-Golgi intermediate compartment membranes in the form of Langmuir monolayers. Natural extracted yeast lipids were used because, unlike synthetic lipids, the acyl chain saturation pattern of yeast and mammalian lipids are similar. FINDINGS The structure of the model membranes, orthogonal to the plane of the membrane, as well as their lateral packing, were found to depend strongly on their specific composition, with cholesterol having a major influence on the in-plane morphology, yielding a coexistence of liquid-order and liquid-disorder phases.
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Affiliation(s)
- Andreas Santamaria
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France; Departamento de Química Física, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
| | - Krishna C Batchu
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France
| | - Giovanna Fragneto
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France; École doctorale de Physique, Université Grenoble Alpes, 38400 Saint-Martin-d'Héres, France
| | - Valérie Laux
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France
| | - Michael Haertlein
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France
| | - Tamim A Darwish
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Lucas Heights 2232, NSW, Australia
| | - Robert A Russell
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Lucas Heights 2232, NSW, Australia
| | - Nathan R Zaccai
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB22 7QQ, United Kingdom
| | - Eduardo Guzmán
- Departamento de Química Física, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain; Instituto Pluridisciplinar, Universidad Complutense de Madrid, Paseo Juan XXIII 1, 28040 Madrid, Spain
| | - Armando Maestro
- Centro de Fı́sica de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain; IKERBASQUE-Basque Foundation for Science, Plaza Euskadi 5, Bilbao 48009, Spain.
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Zaborowska M, Dobrowolski MA, Matyszewska D. Revealing the structure and mechanisms of action of a synthetic opioid with model biological membranes at the air-water interface. Colloids Surf B Biointerfaces 2023; 226:113289. [PMID: 37028230 DOI: 10.1016/j.colsurfb.2023.113289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 03/04/2023] [Accepted: 03/28/2023] [Indexed: 04/03/2023]
Abstract
Synthetic opioids such as piperazine derivative called MT-45 interact with opioid receptors in a manner similar to morphine leading to euphoria, a sense of relaxation and pain relief and are commonly used as substituents of natural opioids. In this study we show the changes in the surface properties of nasal mucosa and intestinal epithelial model cell membranes formed at the air - water interface using Langmuir technique upon the exposure to MT-45. Both membranes constitute the first barrier to absorb this substance into the human body. The presence of the piperazine derivative affects the organization of both DPPC and ternary DMPC:DMPE:DMPS monolayers treated as simple models of nasal mucosa and intestinal cell membranes, respectively. This novel psychoactive substance (NPS) leads to the fluidization of the model layers, which may indicate their increased permeability. MT-45 has a greater influence on the ternary monolayers characteristic of the intestinal epithelial cells than nasal mucosa. It might be attributed to the increased attractive interactions between the components of the ternary layer, which in turn increase the interactions with a synthetic opioid. Additionally, the crystal structures of MT-45 determined by single-crystal and powder X-ray diffraction methods allowed us to both provide useful data for facilitating the identification of synthetic opioids as well as to attribute the effect of MT-45 to the ionic interactions between protonated nitrogen atoms and negatively charged parts of the polar heads of the lipids.
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Santamaria A, Carrascosa-Tejedor J, Guzmán E, Zaccai NR, Maestro A. Unravelling the orientation of the inositol-biphosphate ring and its dependence on phosphatidylinositol 4,5-bisphosphate cluster formation in model membranes. J Colloid Interface Sci 2023; 629:785-795. [PMID: 36195018 DOI: 10.1016/j.jcis.2022.09.095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 09/03/2022] [Accepted: 09/18/2022] [Indexed: 10/14/2022]
Abstract
HYPOTHESIS Inositol phospholipids are well known to form clusters in the cytoplasmic leaflet of the plasma membrane that are responsible for the interaction and recruitment of proteins involved in key biological processes like endocytosis, ion channel activation and secondary messenger production. Although their phosphorylated inositol ring headgroup plays an important role in protein binding, its orientation with respect to the plane of the membrane and its lateral packing density has not been previously described experimentally. EXPERIMENTS Here, we study phosphatidylinositol 4,5-bisphosphate (PIP2) planar model membranes in the form of Langmuir monolayers by surface pressure-area isotherms, Brewster angle microscopy and neutron reflectometry to elucidate the relation between lateral (in-plane) and perpendicular (out-of-plane) molecular organization of PIP2. FINDINGS Different surface areas were explored through monolayer compression, allowing us to correlate the formation of transient PIP2 clusters with the change in orientation of the inositol-biphosphate headgroup, which was experimentally determined by neutron reflectometry.
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Affiliation(s)
- Andreas Santamaria
- Large Scale Structures Group, Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France; Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain
| | - Javier Carrascosa-Tejedor
- Large Scale Structures Group, Institut Laue-Langevin, 71 Avenue des Martyrs, 38042 Grenoble, Cedex 9, France; Division of Pharmacy and Optometry, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Eduardo Guzmán
- Departamento de Química-Física, Facultad de Ciencias Químicas, Universidad Complutense, Ciudad Universitaria s/n, 28040 Madrid, Spain; Instituto Pluridisciplinar, Universidad Complutense de Madrid, Paseo Juan XXIII 1, 28040 Madrid, Spain.
| | - Nathan R Zaccai
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB22 7QQ, United Kingdom.
| | - Armando Maestro
- Centro de Fı́sica de Materiales (CSIC, UPV/EHU) - Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, E-20018 San Sebastián, Spain; IKERBASQUE-Basque Foundation for Science, Plaza Euskadi 5, Bilbao 48009, Spain.
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Beraldo-Araújo VL, Flávia Siqueira Vicente A, van Vliet Lima M, Umerska A, Souto EB, Tajber L, Oliveira-Nascimento L. Levofloxacin in nanostructured lipid carriers: Preformulation and critical process parameters for a highly incorporated formulation. Int J Pharm 2022; 626:122193. [PMID: 36108993 DOI: 10.1016/j.ijpharm.2022.122193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 08/05/2022] [Accepted: 09/07/2022] [Indexed: 10/14/2022]
Abstract
The first step of a successful nanoformulation development is preformulation studies, in which the best excipients, drug-excipient compatibility and interactions can be identified. During the formulation, the critical process parameters and their impact must be studied to establish the stable system with a high drug entrapment efficiency (EE). This work followed these steps to develop nanostructured lipid carriers (NLCs) to deliver the antibiotic levofloxacin (LV). The preformulation studies covered drug solubility in excipients and thorough characterization using thermal analysis, X-ray diffraction and spectroscopy. A design of experiment based on the process parameters identified nanoparticles with < 200 nm in size, polydispersity <= 0.3, zeta potential -21 to -24 mV, high EE formulations (>71 %) and an acceptable level of LV degradation products (0.37-1.13 %). To the best of our knowledge, this is the first time that a drug degradation is reported and studied in work on nanostructured lipids. LV impurities following the NLC production were detected, mainly levofloxacin N-oxide, a degradation product that has no antimicrobial activity and could interfere with LV quantification in spectrophotometric experiments. Also, the achievement of the highest EE in lipid nanoparticles than those described in the literature to date and the apparent protective action of NLC of entrapped-LV against degradation are important findings.
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Affiliation(s)
- Viviane Lucia Beraldo-Araújo
- Faculty of Pharmaceutical Sciences, State University of Campinas, Campinas, Brazil; School of Pharmacy and Pharmaceutical Sciences, Trinity College Dublin, College Green, Dublin 2, Ireland; Centre of Biological Engineering (CEB), University of Minho, Campus de Gualtar, 4700 Braga, Portugal
| | | | - Marcelo van Vliet Lima
- Faculty of Pharmaceutical Sciences, State University of Campinas, Campinas, Brazil; Sanofi Medley Farmacêutica Ltda, Campinas, Brazil
| | - Anita Umerska
- School of Pharmacy and Pharmaceutical Sciences, Trinity College Dublin, College Green, Dublin 2, Ireland
| | - Eliana B Souto
- Department of Pharmaceutical Technology, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal; REQUIMTE/UCIBIO, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal
| | - Lidia Tajber
- School of Pharmacy and Pharmaceutical Sciences, Trinity College Dublin, College Green, Dublin 2, Ireland.
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Liu X, Wang D, Chen Z, Wei W, Mannina G, Ni BJ. Advances in pretreatment strategies to enhance the biodegradability of waste activated sludge for the conversion of refractory substances. BIORESOURCE TECHNOLOGY 2022; 362:127804. [PMID: 36007767 DOI: 10.1016/j.biortech.2022.127804] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 08/14/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
Anaerobic digestion (AD) is a low-cost technology widely used to divert waste activated sludge (WAS) to renewable energy production, but is generally restricted by its poor biodegradability which mainly caused by the endogenous and exogenous refractory substances present in WAS. Several conventional methods such as thermal-, chemical-, and mechanical-based pretreatment have been demonstrated to be effective on organics release, but their functions on refractory substances conversion are overlooked. This paper firstly reviewed the presence and role of endogenous and exogenous refractory substances in anaerobic biodegradability of WAS, especially on their inhibition mechanisms. Then, the pretreatment strategies developed for enhancing WAS biodegradability by facilitating refractory substances conversion were comprehensively reviewed, with the conversion pathways and underlying mechanisms being emphasized. Finally, the future research needs were directed, which are supposed to improve the circular bioeconomy of WAS management from the point of removing the hindering barrier of refractory substances on WAS biodegradability.
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Affiliation(s)
- Xuran Liu
- State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, PR China
| | - Dongbo Wang
- College of Environmental Science and Engineering and Key Laboratory of Environmental Biology and Pollution Control (Ministry of Education), Hunan University, Changsha 410082, PR China
| | - Zhijie Chen
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Wei Wei
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Giorgio Mannina
- Engineering Department - Palermo University, Ed. 8 Viale delle Scienze, 90128 Palermo, Italy
| | - Bing-Jie Ni
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia.
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Islam MZ, Hossain SI, Deplazes E, Saha SC. Concentration-dependent cortisone adsorption and interaction with model lung surfactant monolayer. MOLECULAR SIMULATION 2022. [DOI: 10.1080/08927022.2022.2113397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Affiliation(s)
- Mohammad Zohurul Islam
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney, Ultimo, Australia
| | - Sheikh I. Hossain
- School of Life Sciences, University of Technology Sydney, Ultimo, Australia
| | - Evelyne Deplazes
- School of Life Sciences, University of Technology Sydney, Ultimo, Australia
| | - Suvash C. Saha
- School of Mechanical and Mechatronic Engineering, University of Technology Sydney, Ultimo, Australia
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Sofińska K, Lupa D, Chachaj-Brekiesz A, Czaja M, Kobierski J, Seweryn S, Skirlińska-Nosek K, Szymonski M, Wilkosz N, Wnętrzak A, Lipiec E. Revealing local molecular distribution, orientation, phase separation, and formation of domains in artificial lipid layers: Towards comprehensive characterization of biological membranes. Adv Colloid Interface Sci 2022; 301:102614. [PMID: 35190313 DOI: 10.1016/j.cis.2022.102614] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/28/2022] [Accepted: 02/01/2022] [Indexed: 01/01/2023]
Abstract
Lipids, together with molecules such as DNA and proteins, are one of the most relevant systems responsible for the existence of life. Selected lipids are able to assembly into various organized structures, such as lipid membranes. The unique properties of lipid membranes determine their complex functions, not only to separate biological environments, but also to participate in regulatory functions, absorption of nutrients, cell-cell communication, endocytosis, cell signaling, and many others. Despite numerous scientific efforts, still little is known about the reason underlying the variability within lipid membranes, and its biochemical significance. In this review, we discuss the structural complexity of lipid membranes, as well as the importance to simplify studied systems in order to understand phenomena occurring in natural, complex membranes. Such systems require a model interface to be analyzed. Therefore, here we focused on analytical studies of artificial systems at various interfaces. The molecular structure of lipid membranes, specifically the nanometric thickens of molecular bilayer, limits in a major extent the choice of highly sensitive methods suitable to study such structures. Therefore, we focused on methods that combine high sensitivity, and/or chemical selectivity, and/or nanometric spatial resolution, such as atomic force microscopy, nanospectroscopy (tip-enhanced Raman spectroscopy, infrared nanospectroscopy), phase modulation infrared reflection-absorption spectroscopy, sum-frequency generation spectroscopy. We summarized experimental and theoretical approaches providing information about molecular structure and composition, lipid spatial distribution (phase separation), organization (domain shape, molecular orientation) of lipid membranes, and real-time visualization of the influence of various molecules (proteins, drugs) on their integrity. An integral part of this review discusses the latest achievements in the field of lipid layer-based biosensors.
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8
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Róg T, Girych M, Bunker A. Mechanistic Understanding from Molecular Dynamics in Pharmaceutical Research 2: Lipid Membrane in Drug Design. Pharmaceuticals (Basel) 2021; 14:1062. [PMID: 34681286 PMCID: PMC8537670 DOI: 10.3390/ph14101062] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 11/17/2022] Open
Abstract
We review the use of molecular dynamics (MD) simulation as a drug design tool in the context of the role that the lipid membrane can play in drug action, i.e., the interaction between candidate drug molecules and lipid membranes. In the standard "lock and key" paradigm, only the interaction between the drug and a specific active site of a specific protein is considered; the environment in which the drug acts is, from a biophysical perspective, far more complex than this. The possible mechanisms though which a drug can be designed to tinker with physiological processes are significantly broader than merely fitting to a single active site of a single protein. In this paper, we focus on the role of the lipid membrane, arguably the most important element outside the proteins themselves, as a case study. We discuss work that has been carried out, using MD simulation, concerning the transfection of drugs through membranes that act as biological barriers in the path of the drugs, the behavior of drug molecules within membranes, how their collective behavior can affect the structure and properties of the membrane and, finally, the role lipid membranes, to which the vast majority of drug target proteins are associated, can play in mediating the interaction between drug and target protein. This review paper is the second in a two-part series covering MD simulation as a tool in pharmaceutical research; both are designed as pedagogical review papers aimed at both pharmaceutical scientists interested in exploring how the tool of MD simulation can be applied to their research and computational scientists interested in exploring the possibility of a pharmaceutical context for their research.
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Affiliation(s)
- Tomasz Róg
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland;
| | - Mykhailo Girych
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland;
| | - Alex Bunker
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00014 Helsinki, Finland;
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9
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Zaborowska M, Dziubak D, Matyszewska D, Bilewicz R. Surface and electrochemical properties of lipid raft model membranes and how they are affected by incorporation of statin. Electrochim Acta 2021. [DOI: 10.1016/j.electacta.2021.138514] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Interaction of isolinderanolide E obtained from Nectandra oppositifolia with biomembrane models. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183690. [PMID: 34224703 DOI: 10.1016/j.bbamem.2021.183690] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 06/24/2021] [Accepted: 06/28/2021] [Indexed: 01/07/2023]
Abstract
A long-tail lactone, named isolinderanolide E, was obtained from Nectandra oppositifolia and incorporated in Langmuir monolayers of dipalmitoyl-phosphoethanolamine (DPPE) as a model of microbial membranes. The compound was dissolved in chloroform and mixed with DPPE to provide mixed solutions spread on the air-water interface. After solvent evaporation, mixed monolayers were formed, and surface pressure-area isotherms, dilatational rheology, Brewster angle microscopy (BAM), and infrared spectroscopy were employed to characterize the prodrug-membrane interactions. Isolinderanolide E expanded DPPE monolayers, denoting repulsive interactions. At 30 mN/m, the monolayer presented higher viscoelastic and in-plane elasticity parameters and an increased ratio of all-trans/gauche conformers of the alkyl chains, confirming molecular order. Morphology of the monolayer was analyzed by BAM, which revealed a more homogeneous distribution of Isolinderanolide E along the DPPE monolayer than the prodrug directly spread at the interface, which tends to aggregate. A molecular model proposing the molecular orientation of the amphiphilic drug is presented and explained by the distortion of the alkyl chains as well as by viscoelastic changes. In conclusion, the prodrug changes the thermodynamic, rheological, morphological, and structural properties of the DPPE monolayer, which may be essential to understand, at the molecular level, the action of bioactives in selected membrane models.
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Vignoli Muniz GS, Souza MC, Duarte EL, Lamy MT. Comparing the interaction of the antibiotic levofloxacin with zwitterionic and anionic membranes: Calorimetry, fluorescence, and spin label studies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183622. [PMID: 33865809 DOI: 10.1016/j.bbamem.2021.183622] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/30/2021] [Accepted: 03/31/2021] [Indexed: 11/30/2022]
Abstract
The present work compares the interaction of the antibiotic levofloxacin (LVX) with zwitterionic and anionic liposomes composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DPPG), respectively. By using differential scanning calorimetry (DSC), and with spin labels incorporated into liposomes at two different depths of the bilayers, we investigated the changes induced on the membrane by increasing concentrations of LVX. Further information was obtained using intrinsic LVX fluorescence. Under the conditions used here, all techniques evinced that LVX has little affinity for DPPC zwitterionic membrane. Opposite to that, LVX exhibits a considerable affinity for anionic bilayers, with membrane partition constants Kp = (3.3 ± 0.5) × 102 and (4.5 ± 0.3) × 102, for gel and fluid DPPG membranes, respectively. On binding to DPPG, LVX seems to give rise to the coexistence of LVX -rich and -poor domains on DPPG membranes, as detected by DSC. At the highest LVX concentration used (20 mol%), DSC trace shows an increase in the cooperativity of DPPG gel-fluid transition, also detected by spin labels as an increase in the bilayer packing. Moreover, LVX does not induce pore formation in either DPPG or POPG vesicles. Considering the possible relevance of LVX-membrane interaction for the biological and toxicological action of the antibiotic, the findings discussed here certainly contribute to a better understanding of its action, and the planning of new drugs.
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Affiliation(s)
| | - Mariana C Souza
- Instituto de Física, Universidade de São Paulo, São Paulo, SP CEP 05508-090, Brazil
| | - Evandro L Duarte
- Instituto de Física, Universidade de São Paulo, São Paulo, SP CEP 05508-090, Brazil
| | - M Teresa Lamy
- Instituto de Física, Universidade de São Paulo, São Paulo, SP CEP 05508-090, Brazil.
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Waku T, Kasai A, Kobori A, Tanaka N. Investigation on the Interactions between Self-Assembled β-Sheet Peptide Nanofibers and Model Cell Membranes. Int J Mol Sci 2020; 21:ijms21249518. [PMID: 33327660 PMCID: PMC7765088 DOI: 10.3390/ijms21249518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/10/2020] [Accepted: 12/12/2020] [Indexed: 11/16/2022] Open
Abstract
Self-assembled peptide nanofibers (NFs) obtained from β-sheet peptides conjugated with drugs, including antigenic peptides, have recently attracted significant attention. However, extensive studies on the interactions of β-sheet peptide NFs with model cell membranes have not been reported. In this study, we investigated the interactions between three types of NFs, composed of PEG-peptide conjugates with different ethylene glycol (EG) lengths (6-, 12- and 24-mer), and dipalmitoylphosphatidylcholine (DPPC) Langmuir membranes. When increasing the EG chain length, those interactions significantly decreased considering measurements in the presence of the NFs of: (i) changes in surface pressure of the DPPC Langmuir monolayers and (ii) surface pressure-area (π-A) compression isotherms of DPPC. Because the observed trend was similar to the EG length dependency with regard to cellular association and cytotoxicity of the NFs that was reported previously, the interaction of NFs with phospholipid membranes represented a crucial factor to determine the cellular association and toxicity of the NFs. In contrast to NFs, no changes were observed with varying EG chain length on the interaction of the building block peptide with the DPPC membrane. The results obtained herein can provide a design guideline on the formulation of β-sheet peptide NFs, which may broaden its potential.
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13
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Structure of DPPC Monolayers at the Air/Buffer Interface: A Neutron Reflectometry and Ellipsometry Study. COATINGS 2020. [DOI: 10.3390/coatings10060507] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Langmuir monolayers of 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine, known as DPPC, at the air/water interface are extensively used as model systems of biomembranes and pulmonary surfactant. The properties of these monolayers have been mainly investigated by surface pressure–area isotherms coupled with different complementary techniques such as Brewster angle microscopy, for example. Several attempts using neutron reflectometry (NR) or ellipsometry have also appeared in the literature. Here, we report structural information obtained by using NR and ellipsometry on DPPC monolayers in the liquid condensed phase. On one side, NR can resolve the thickness of the aliphatic tails and the degree of hydration of the polar headgroups. On the other side, ellipsometry gives information on the refractive index and, therefore, on the physical state of the monolayer. The thickness and surface excess obtained by multiple-angle-of-incidence ellipsometry (MAIE) is compared with the results from NR measurements yielding a good agreement. Besides, a novel approach is reported to calculate the optical anisotropy of the DPPC monolayer that depends on the orientation of the aliphatic chains. The results from both NR and ellipsometry are also discussed in the context of the existing results for DPPC monolayers at the air/water interface. The differences observed are rationalized by the presence of buffer molecules interacting with phospholipids.
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