Protein–polymer nanoreactors for medical applications

Palivan, Cornelia G.; Fischer-Onaca, Ozana; Delcea, Mihaela; Itel, Fabian

doi:10.1039/c1cs15240h

Cited by 163 publications

(161 citation statements)

References 260 publications

(362 reference statements)

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“…Certain small molecules used in bacterial QS, such as N-(3-oxo-hexanoyl)-L-homoserine lactone, could pass through vesicle membranes (30) and the oil phase surrounding emulsion droplets (29), thus facilitating intercellular communication. Channel proteins could be used to allow transport of other signaling species across vesicle membranes (32), and stomatocytes with large openings would also freely exchange a wide range of materials with the external fluid (33). Hence, the necessary components for experimentally realizing our system are available.…”

Section: Discussionmentioning

confidence: 99%

Synthetic quorum sensing in model microcapsule colonies

Shum

Balazs

2017

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

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Biological quorum sensing refers to the ability of cells to gauge their population density and collectively initiate a new behavior once a critical density is reached. Designing synthetic materials systems that exhibit quorum sensing-like behavior could enable the fabrication of devices with both self-recognition and selfregulating functionality. Herein, we develop models for a colony of synthetic microcapsules that communicate by producing and releasing signaling molecules. Production of the chemicals is regulated by a biomimetic negative feedback loop, the "repressilator" network. Through theory and simulation, we show that the chemical behavior of such capsules is sensitive to both the density and number of capsules in the colony. For example, decreasing the spacing between a fixed number of capsules can trigger a transition in chemical activity from the steady, repressed state to largeamplitude oscillations in chemical production. Alternatively, for a fixed density, an increase in the number of capsules in the colony can also promote a transition into the oscillatory state. This configuration-dependent behavior of the capsule colony exemplifies quorum-sensing behavior. Using our theoretical model, we predict the transitions from the steady state to oscillatory behavior as a function of the colony size and capsule density.quorum sensing | repressilator | microcapsules Q uorum sensing (QS) refers to the ability of organisms in a population to assess the number and density of individuals present, allowing a specific behavior to be initiated only when a critical threshold in the population size and density is reached. QS plays a vital role in the life cycle of bacteria (1, 2), yeast (3, 4), and slime molds (5, 6), as well as social insects (7). In microorganisms, QS is based on chemical signaling among individuals in a colony. Bacteria (1, 8), for example, produce and secrete signaling molecules, which diffuse into the surrounding medium where they can be detected by other cells in the population. Through regulatory networks, the signaling molecule acts as an autoinducer; the rate of production of the autoinducer increases with its concentration. When the cell density is low, the concentration of the signaling molecule is low, and production is maintained at a low, basal rate. The cells are considered to be in the "off" QS state. When the population density is high, each cell detects a high concentration of the signaling molecule resulting from the collective production of many nearby neighbors. The cells are switched "on," increasing production of the signaling molecule and activating further metabolic pathways that are triggered by QS. Hence, spatially separated cells interact through regulatory networks, which coordinate the collective behavior of the colony.An intriguing challenge in both synthetic biology and materials science is to design man-made systems that exhibit behavior analogous to QS, i.e., sensing and responding to the system size and density. Such synthetic QS abilities could provide a route to ...

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Section: Discussionmentioning

confidence: 99%

Synthetic quorum sensing in model microcapsule colonies

Shum

Balazs

2017

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

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“…Applications of protein-polymer hybrid materials are drug/gene-delivery, bio-sensing, bio-imaging as well as creating materials for electronic devices and functional membranes. 17,[347][348][349] The established bioconjugation strategies can improve stability, solubility, biocompatibility and interfacial activity of a protein. 17,350 The activity of proteins is often preserved to a high degree in hybrid materials.…”

Section: Bionanoparticlesmentioning

confidence: 99%

Surface-initiated controlled radical polymerizations from silica nanoparticles, gold nanocrystals, and bionanoparticles

2015

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In recent years, core/shell nanohybrids containing a nanoparticle core and a distinct surrounding shell of polymer brushes have received extensive attention in nanoelectronics, nanophotonics, catalysis, nanopatterning, drug delivery, biosensing, and many others. From the large variety of existing polymerization methods on the one hand and strategies for grafting onto nanoparticle surfaces on the other hand, the combination of grafting-from with controlled radical polymerization (CRP) techniques has turned out to be the best suited for synthesizing these well-defined core/shell nanohybrids and is known as surface-initiated CRP. Most common among these are surface-initiated atom transfer radical polymerization (ATRP), surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, and surface-initiated nitroxide-mediated polymerization (NMP). This review highlights the state of the art of growing polymers from nanoparticles using surface-initiated CRP techniques. We focus on mechanistic aspects, synthetic procedures, and the formation of complex architectures as well as novel properties. From the vast number of examples of nanoparticle/polymer hybrids formed by surface-initiated CRP techniques, we present nanohybrid formation from the particularly important and most studied silica nanoparticles, gold nanocrystals, and proteins which can be regarded as bionanoparticles

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“…2 Block copolymers offer a promising way to achieve inner structures in the 10−100 nm length scale thanks to the possibility to control their microphase separation. 3 The microphase-separated structures can take the form of, for example, alternating lamellae, hexagonally packed cylinders, or spheres in face-centered cubic lattice.…”

Section: ■ Introductionmentioning

confidence: 99%

Hierarchical Structures of Hydrogen-Bonded Liquid-Crystalline Side-Chain Diblock Copolymers in Nanoparticles

et al. 2012

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Here we show that it is possible to control the overall morphology as well as hierarchical microstructure of lamellae-forming block copolymers within nanoparticles by altering side-chain content and processing temperature. We used cholesteryl hemisuccinate (CholHS) as hydrogen-bonded side chains and poly(styrene)-block-poly(4-vinylpyridine) (PS−P4VP) as backbone to produce submicrometer particles with the aerosol method. With CholHS-to-P4VP repeat unit ratio of 0.25 and 0.50, we obtained onion-like particles with either single CholHS layers sandwiched between P4VP rich lamellae or smectic P4VP(CholHS) layers perpendicular to the polymer domain interfaces. When the fraction of CholHS was increased to 0.75, the onion-like structure broke down due to increased splay deformation energy of the liquid crystalline P4VP(CholHS) domains. The onion-like structure could be re-established, however, when the particles were produced at a higher temperature which made the CholHS molecules partially soluble into the PS phase. Because of the reversible nature of the hydrogen bonds, it was possible to selectively remove the CholHS side chains from the particles. ■ INTRODUCTIONSubmicrometer-sized particles with inner structures have promising applications for instance as templates for porous materials 1 or as microenvironments for chemical reactions. 2 Block copolymers offer a promising way to achieve inner structures in the 10−100 nm length scale thanks to the possibility to control their microphase separation. 3 The microphase-separated structures can take the form of, for example, alternating lamellae, hexagonally packed cylinders, or spheres in face-centered cubic lattice. The morphology depends on the relative volumes of the polymer blocks and the strength of their mutual interactions. The block with the lowest surface energy typically concentrates on the surface of the material. 4−6 This controls the final microphase-separated structure of block copolymer in particles whose radius is smaller than the coherence length of the structures. The surface-induced orientation results in spherically symmetric structures in spherical particles. For instance, computational studies predict that block copolymers with symmetric block volumes microphase separate into concentric shells of alternating domains. 7−12 The morphology can be described as "onion-like". However, if the size of the particles is incommensurate with the periodicity of the domains, more exotic morphologies can arise. 9,11,13 Since the early report by Thomas et al., 14 the onionlike morphology has been observed also experimentally in a number of works. 15−28 In particles prepared by the so-called good solvent-poor solvent method, the surface layer can be controlled by the choice of surfactants. 19 By further modifying the surface interactions, it is possible to turn the onion-like structures to "tulip-bulb"-like or even change the shape of the particles from spherical to prolate spheroidal with block copolymer lamellae stacked orthogonal to the long axis. 22 Stacked lamel...

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Protein–polymer nanoreactors for medical applications

Cited by 163 publications

References 260 publications

Synthetic quorum sensing in model microcapsule colonies

Synthetic quorum sensing in model microcapsule colonies

Surface-initiated controlled radical polymerizations from silica nanoparticles, gold nanocrystals, and bionanoparticles

Hierarchical Structures of Hydrogen-Bonded Liquid-Crystalline Side-Chain Diblock Copolymers in Nanoparticles

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