Papers by Rejhana Kolasinac
Membrane fusion is an essential process for life. It is simply a merging of two membranes into on... more Membrane fusion is an essential process for life. It is simply a merging of two membranes into one, and it can occur between two cells [1], between cell organelles [2-4], or two artificial membranes (lipid vesicles) [5,6], as well as between a cell and an artificial membrane [7-12]. Membrane fusion is significant from numerous points of view, such as trafficking within a cell [4,13-15] and between cells [13], for the mixing of genetic information between organisms [1] and the sculpting of tissues during development [16]. Usually, a fusion between two membranes is induced by some external mediators like proteins, peptides, and viruses, but it can happen without any inducers as it will be discussed later. There are some commonly accepted steps for fusion: membrane aggregation, close apposition of the membranes to fuse, transient destabilization of the bilayers, and mixing of the components to allow two membranes to become one. Studies on mediated membrane fusion, such as viral fusion, have implicated specific membrane proteins as promoters through bilayer destabilization [17]. The access of viruses, including numerous human pathogens, into the host cell, relies on the fusion between the viral and the host cell membranes [13, 18-21], which may signal the end of the organism's life. However, there are different life processes based on membrane fusion, such as the fusion process mediated by the SNARE proteins [13, 22-25]. Additionally, the benefits of membrane fusion are appreciated to the highly efficient and controlled delivery of important molecules like in controlled protein and nucleic acid delivery. Based on in vitro experiments, a non-mediated fusion between membranes (lipid bilayers) requires energy input, hence even a close and prolonged contact of two membranes may not harvest the fusion under physiological conditions (reviewed in [26]). In theory, any fusion that does not require specialized mediator denote a "spontaneous" fusion [27]. Nevertheless, it has been shown recently that liposomes, such as self-assembled lipid vesicles, can fuse with the cell membrane without any external inducer [9], and because of this special property, they are called fusogenic liposomes. 2.1.5. Additional material used for the work a) The material used for the preparation of liposomes 2-(4-(2-Hydroxyethyl)-1-Piperazinyl) Ethansulfonsäure (HEPES) Sigma-Aldrich, Taufkirchen, Germany Balls stainless steel unhardened 1.000 mm N0-Material 1.4301-Quality G100
Nanomaterials, Jul 17, 2019
Lipid-based nanoparticles, also called vesicles or liposomes, can be used as carriers for drugs o... more Lipid-based nanoparticles, also called vesicles or liposomes, can be used as carriers for drugs or many types of biological macromolecules, including DNA and proteins. Efficiency and speed of cargo delivery are especially high for carrier vesicles that fuse with the cellular plasma membrane. This occurs for lipid mixture containing equal amounts of the cationic lipid DOTAP and a neutral lipid with an additional few percents of an aromatic substance. The fusion ability of such particles depends on lipid composition with phosphoethanolamine (PE) lipids favoring fusion and phosphatidyl-choline (PC) lipids endocytosis. Here, we examined the effects of temperature, ionic strength, osmolality, and pH on fusion efficiency of cationic liposomes with Chinese hamster ovary (CHO) cells. The phase state of liposomes was analyzed by small angle neutron scattering (SANS). Our results showed that PC containing lipid membranes were organized in the lamellar phase. Here, fusion efficiency depended on buffer conditions and remained vanishingly small at physiological conditions. In contrast, SANS indicated the coexistence of very small (~50 nm) objects with larger, most likely lamellar structures for PE containing lipid particles. The fusion of such particles to cell membranes occurred with very high efficiency at all buffer conditions. We hypothesize that the altered phase state resulted in a highly reduced energetic barrier against fusion.
International Journal of Molecular Sciences, Jan 24, 2018
Cationic liposomes are frequently used as carrier particles for nucleic acid delivery. The most p... more Cationic liposomes are frequently used as carrier particles for nucleic acid delivery. The most popular formulation is the equimolar mixture of two components, a cationic lipid and a neutral phosphoethanolamine. Its uptake pathway has been described as endocytosis. The presence of an aromatic molecule as a third component strongly influences the cellular uptake process and results in complete membrane fusion instead of endocytosis. Here, we systematically varied all three components of this lipid mixture and determined how efficiently the resulting particles fused with the plasma membrane of living mammalian cells. Our results show that an aromatic molecule and a cationic lipid component with conical molecular shape are essential for efficient fusion induction. While a neutral lipid is not mandatory, it can be used to control fusion efficiency and, in the most extreme case, to revert the uptake mechanism back to endocytosis.
RSC Advances, 2022
Fusogenic liposomes have been widely used for molecule delivery to cell membranes and cell interi... more Fusogenic liposomes have been widely used for molecule delivery to cell membranes and cell interior. However, their physicochemical state is still little understood. We tested mechanical material behavior by micropipette aspiration of giant vesicles from fusogenic lipid mixtures and found that the membranes of these vesicles are fluid and under high mechanical tension even before aspiration. Based on this result, we developed a theoretical framework to determine the area expansion modulus and membrane tension of such pre-tensed vesicles from aspiration experiments. Surprisingly high membrane tension of 2.1 mN m À1 and very low area expansion modulus of 63 mN m À1 were found. We interpret these peculiar material properties as the result of a mechanically driven phase transition between the usual lamellar phase and an, as of now, not finally determined three dimensional phase of the lipid mixture. The free enthalpy of transition between these phases is very low, i.e. on the order of the thermal energy.
International Journal of Molecular Sciences, 2021
Liposomes are highly biocompatible and versatile drug carriers with an increasing number of appli... more Liposomes are highly biocompatible and versatile drug carriers with an increasing number of applications in the field of nuclear medicine and diagnostics. So far, only negatively charged liposomes with intercalated radiometals, e.g., 64Cu, 99mTc, have been reported. However, the process of cellular uptake of liposomes by endocytosis is rather slow. Cellular uptake can be accelerated by recently developed cationic liposomes, which exhibit extraordinarily high membrane fusion ability. The aim of the present study was the development of the formulation and the characterization of such cationic fusogenic liposomes with intercalated radioactive [131I]I− for potential use in therapeutic applications. The epithelial human breast cancer cell line MDA-MB-231 was used as a model for invasive cancer cells and cellular uptake of [131I]I− was monitored in vitro. Delivery efficiencies of cationic and neutral liposomes were compared with uptake of free iodide. The best cargo delivery efficiency (~...
RSC Advances
The lipid moiety of fusogenic liposomes is in a mixed phase state whose thermodynamic equilibrium... more The lipid moiety of fusogenic liposomes is in a mixed phase state whose thermodynamic equilibrium depends on membrane tension.
Journal of the Serbian Chemical Society, 2021
A large series of disubstituted fulleropyrrolidines was synthesized and analyzed by the cyclic vo... more A large series of disubstituted fulleropyrrolidines was synthesized and analyzed by the cyclic voltammetry. The three main groups of target compounds differ by a flexible N-chain, while their further diversity was achieved by the introduction of various rigid, aryl substituents at pyrrolidine carbon. Some dialkyl analogues were designed for comparison, as well. A standard [3+2]-cycloaddition of in situ generated azomethine ylides to C60 afforded a variety of disubstituted fulleropyrrolidines. Furthermore, a set of dumbbell-shaped di(fulleropyrrolidine) derivatives containing rigid fumaryl or isophthaloyl diamide platform was prepared in aim to investigate a long-range effect of the second fulleropyrrolidine moiety on electrochemical properties. All compounds were fully characterized by comparative analysis of spectral data, while examination of electrochemical properties was performed on representative samples, distinguished by main structural subunits. All compounds expressed quite...
International journal of molecular sciences, Jan 24, 2018
Cationic liposomes are frequently used as carrier particles for nucleic acid delivery. The most p... more Cationic liposomes are frequently used as carrier particles for nucleic acid delivery. The most popular formulation is the equimolar mixture of two components, a cationic lipid and a neutral phosphoethanolamine. Its uptake pathway has been described as endocytosis. The presence of an aromatic molecule as a third component strongly influences the cellular uptake process and results in complete membrane fusion instead of endocytosis. Here, we systematically varied all three components of this lipid mixture and determined how efficiently the resulting particles fused with the plasma membrane of living mammalian cells. Our results show that an aromatic molecule and a cationic lipid component with conical molecular shape are essential for efficient fusion induction. While a neutral lipid is not mandatory, it can be used to control fusion efficiency and, in the most extreme case, to revert the uptake mechanism back to endocytosis.
Proceedings of The 20th International Electronic Conference on Synthetic Organic Chemistry, 2016
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Papers by Rejhana Kolasinac