Controlling the Internal Structure of Giant Unilamellar Vesicles by Means of Reversible Temperature Dependent Sol−Gel Transition of Internalized Poly(<i>N</i>-isopropyl acrylamide)

Jesorka, Aldo; Markström, Martin; Orwar, Owe

doi:10.1021/la047822k

Cited by 43 publications

(49 citation statements)

References 30 publications

(51 reference statements)

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“…Particularly notable is work in which pH-and ion-sensitive polymeric hydrogels coated with lipid bilayers were used to mimic secretory granules; these structures released drug molecules upon electroporation of the membrane (19). Thermoresponsive hydrogels have been microinjected into preformed GVs and GV networks, where they display characteristic sol-gel transitions (20). These hydrogel experiments were largely aimed at drug delivery but are also interesting in the present context in that their transitions are reversible, and the gel matrix mimics certain aspects of intracellular organization such as impeded diffusion.…”

mentioning

confidence: 99%

Dynamic microcompartmentation in synthetic cells

Long

Jones

Helfrich

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

233

271

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An experimental model for cytoplasmic organization is presented. We demonstrate dynamic control over protein distribution within synthetic cells comprising a lipid bilayer membrane surrounding an aqueous polymer solution. This polymer solution generally exists as two immiscible aqueous phases. Protein partitioning between these phases leads to microcompartmentation, or heterogeneous protein distribution within the ''cell'' interior. This model cytoplasm can be reversibly converted to a single phase by slight changes in temperature or osmolarity, such that local protein concentrations can be manipulated within the vesicle interior.aqueous phase separation ͉ intracellular organization ͉ vesicle T he interior of living cells is a crowded milieu of macromolecules, cytoskeletal filaments, and organelles. Even in cytoplasmic regions not separated by obvious barriers such as lipid membranes, differences in local composition are common. This phenomenon, referred to as microcompartmentation, is thought to have profound implications for cell function (1, 2). Understanding its role in living cells has been complicated by the lack of an experimental model system in which hypotheses could be tested. Even the mechanism(s) by which microcompartmentation is maintained remain unclear. Several possibilities have been proposed, including specific targeting and processes driven by macromolecular crowding, such as multiprotein complex formation, binding to intracellular surfaces, or phase separation (3). Aqueous phase separation occurs readily in bulk solutions of macromolecules even at much lower weight percents than are present in living cells (2). Thus, the question has been posed as to whether cytoplasm can exist without undergoing phase separation (4). Phase separation, and the accompanying partition of solutes between phases, could account for microcompartmentation of macromolecules, metabolites, and ions. Thus far, the complexity of living cells has precluded direct testing of the phase separation hypothesis. † We have encapsulated a poly(ethylene glycol) (PEG)͞dextran aqueous two-phase system (ATPS) within lipid vesicles to construct synthetic cells capable of dynamic protein and nucleic acid microcompartmentation. Substantial local variations in protein concentration can be maintained in the absence of intervening membranous barriers within these ATPS-containing vesicles. Our synthetic cytoplasm is promising as an experimental model for intracellular organization in general and demonstrates that aqueous phase separation is a viable mechanism for microcompartmentation.This work represents a bottom-up approach to understanding cell biology, in contrast to the top-down approach often adopted in biochemistry and perhaps best exemplified by efforts to generate the ''minimal cell'' through gene disruption in already simple organisms (6). Experimental model systems such as this one enable us to begin to test hypotheses in cell biology such as that of cytoplasmic phase separation. An analogy is lipid bilayer models of cell membrane...

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mentioning

confidence: 99%

Dynamic microcompartmentation in synthetic cells

Long

Jones

Helfrich

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

233

271

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“…Larger nanogels (about 450 nm) are obtained from encapsulation of 20% dextran hydroyethylmethacrylate solution ( -Mn= 19000) inside vesicles obtained by phospholipids film hydration, followed by extru- sion. 37 Poly(ethylenedioxythiophene)/poly(styrenesulfonate) 13 and poly(N-isopropylacrylamide) 12,16 microgels, in conjunction with lipid bilayers, are obtained by injecting a polymer solution inside GUVs, followed by freeze-thaw cycles and electroporation. The vesicle diameters, in these latter cases, vary from 5 to 100 µm.…”

Section: Particle Characterizationmentioning

confidence: 99%

“…9 Alternatively, nanogels can be prepared by inclusion in reverse micelles of pre-formed polymers, followed by crosslinking. 10 Vesicles also can be used to obtain hydrogels nanoparticles, by monomer encapsulation followed by polymerization 11 or gelation of encapsulated polymers, generally induced by sol-gel temperature transitions 12 or ionic crosslinking, 13 typically without removal of the lipid bilayer. 14 These gel-like vesicles work as cell models, since they have elastic modulus comparable to that of cell cytoplasm 14 and are considered artificial cytoskeletons.…”

Section: Introductionmentioning

confidence: 99%

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Preparation of PVP hydrogel nanoparticles using lecithin vesicles

Bueno¹,

Catalani²,

Perez³

et al. 2010

Quím. Nova

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Recebido em 21/6/10; aceito em 20/8/10; publicado na web em 15/10/10 Hydrogels micro, sub-micro and nanoparticles are of great interest for drug encapsulation and delivery or as embolotherapic agents. In this work it is described the preparation of nano and sub-microparticles of pre-formed, high molecular weight and monomer free poly(N-vinyl-2-pyrrolidone) encapsulated inside the core of lecithin vesicles. The hydrogel particles are formed with a very narrow diameter distribution, of about 800 nm, and a moderate swelling ratio, of approximately 10.

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“…The internal and external solution composition as well as different lipid compositions (which can also include membrane proteins) can be used to tailor a reactor. Furthermore, polymers can be included to create crowded environments (32,33). Network topology can be controlled, too, and it is possible to use either static-or dynamic-shell networks (where the network geometry is changed during the course of a reaction).…”

Section: Chemical Reactions In Biomimetic Networkmentioning

confidence: 99%

Chemical Analysis in Nanoscale Surfactant Networks

Karlsson¹,

Ewing²,

Dommersnes³

et al. 2006

Anal. Chem.

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A lthough the "hard matter" physical sciences (e.g., microelectronics) and the "soft matter" biological sciences (e.g. cell biology and molecular biology) are two distinct areas of research, they are now progressively being combined to create new systems and devices with applications in analytical chemistry. Miniaturization is one of the important factors here: A major goal is to create devices that can operate with high sensitivity and resolution on length scales and time frames relevant to single-molecule studies. Using top-down strategies to fabricate ultrasmall structures is technologically challenging. Therefore, new bottom-up methods of nanoscale fabrication based on self-assembly and self-organization of biological or biomimetic materials are constantly being developed (1-6). The type of nanoscale engineering described in this article has, at least partly, been derived from our growing understanding of living cells, where many nanomechanical and chemical operations are based on controlled shape transitions in surfactant bilayer membranes that also carry proteins to support important functions. Biological cells have a staggering ability to parallel-process multiple chemical reactions and physical (e.g., transport) processes in nanometer-sized systems and to perform a great number of tasks based on single-molecule processes. Thus, nature has solved many engineering problems on small length scales and achieved truly nanoscale, complex chemical devices that can be used for computational, biophysical, synthetic, and analytical applications (7-11). The philosophy behind the work reviewed here is to produce human-made, biomimetic systems that imitate some key features of small biological systems with the overall goal of providing micro-and nanoscale devices that can perform complex chemical operations.

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Controlling the Internal Structure of Giant Unilamellar Vesicles by Means of Reversible Temperature Dependent Sol−Gel Transition of Internalized Poly(N-isopropyl acrylamide)

Cited by 43 publications

References 30 publications

Dynamic microcompartmentation in synthetic cells

Dynamic microcompartmentation in synthetic cells

Preparation of PVP hydrogel nanoparticles using lecithin vesicles

Chemical Analysis in Nanoscale Surfactant Networks

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