Hollow Nanocapsules in Biomedical Imaging Applications

Dergunov, Sergey A.; Pinkhassik, Eugene

doi:10.1002/9781118873151.ch4

Cited by 7 publications

(4 citation statements)

References 98 publications

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“…Nanocapsule containing entrapped structures, such as molecules, nanoparticles, or supramolecular aggregates, represent an essential architecture for creating functional devices. We employed different strategies to create such hybrid structures, including capturing molecules or nanoparticles located in the aqueous core of the vesicles (Figure a), − assembling large structures via the ship-in-a-bottle approach (Figure b), , or loading molecules into prefabricated nanocapsules and locking them inside by changing the environment of nanopores. , …”

Section: Synthesis and Characterization Of Nanocapsules And Nanocapsu...mentioning

confidence: 99%

Building Functional Nanodevices with Vesicle-Templated Porous Polymer Nanocapsules

et al. 2018

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Conspectus Vesicle-templated nanocapsules offer a unique combination of properties enabled by robust shells with single-nanometer thickness containing programmed uniform pores capable of fast and selective mass transfer. These capsules emerged as a versatile platform for creating functional devices, such as nanoreactors, nanosensors, and containers for the delivery of drugs and imaging agents. Nanocapsules are synthesized by a directed assembly method using self-assembled bilayers of vesicles as temporary scaffolds. In this approach, hydrophobic building blocks are loaded into the hydrophobic interior of vesicles formed from lipids or surfactants. Pore-forming templates are codissolved with the monomers and cross-linkers in the interior of the bilayer. The polymerization forms a cross-linked shell with embedded pore-forming templates. Removal of the surfactant scaffold and pore-forming templates leads to free-standing nanocapsules with shells containing uniform imprinted nanopores. Development of reliable and scalable synthetic methods for the modular construction of capsules with tunable properties has opened the opportunity to pursue practical applications of nanocapsules. In this Account, we discuss how unique properties of vesicle-templated nanocapsules translate into the creation of functional nanodevices. Specifically, we focus the conversation on applications aiming at the delivery of drugs and imaging agents, creation of fast-acting and selective nanoreactors, and fabrication of nanoprobes for sensing and imaging. We present a brief overview of the synthesis of nanocapsules with an emphasis on recent developments leading to robust synthetic methods including the synthesis under physiological conditions and creation of biodegradable nanocapsules. We then highlight unique properties of nanocapsules essential for practical applications, such as precise control of pore size and chemical environment, selective permeability, and ultrafast transport through the pores. We discuss new motifs for catch and release of small molecules with porous nanocapsules based on controlling the microenvironment inside the nanocapsules, regulating the charge on the orifice of nanopores in the shells, and reversible synergistic action of host and guest forming a supramolecular complex in nanocapsules. We demonstrate successful creation of fast-acting and selective nanoreactors by encapsulation of diverse homogeneous and nanoparticle catalysts. Due to unhindered flow of substrates and products through the nanopores, encapsulation did not compromise catalytic efficiency and, in fact, improved the stability of entrapped catalysts. We present robust nanoprobes based on nanocapsules with entrapped sensing agents and show how the encapsulation resulted in selective measurements with fast response times in challenging conditions, such as small volumes and complex mixtures. Throughout this Account, we highlight the advantages of encapsulation and discuss the opportunities for future design of nanodevices.

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Section: Synthesis and Characterization Of Nanocapsules And Nanocapsu...mentioning

confidence: 99%

Building Functional Nanodevices with Vesicle-Templated Porous Polymer Nanocapsules

et al. 2018

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“…Hollow polymer nanocapsules have emerged as a viable platform for diverse practical applications, including nanoreactors, nanosensors, and containers for the delivery of drugs and imaging agents. − In particular, vesicle-templated nanocapsules have garnered special attention in recent years due to the combination of precisely controlled permeability, fast mass transfer, and excellent long-term stability. ,, In all of these applications, the shells of the nanocapsules play a crucial role. Vesicle-templated nanocapsules are formed by controlled polymerization and cross-linking of hydrophobic monomers placed in the hydrophobic interior of bilayers of spontaneously formed vesicles.…”

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confidence: 99%

Unraveling the Single-Nanometer Thickness of Shells of Vesicle-Templated Polymer Nanocapsules

Richter

Dergunov

Kim

et al. 2017

J. Phys. Chem. Lett.

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Vesicle-templated nanocapsules have emerged as a viable platform for diverse applications. Shell thickness is a critical structural parameter of nanocapsules, where the shell plays a crucial role providing mechanical stability and control of permeability. Here we used small-angle neutron scattering (SANS) to determine the thickness of freestanding and surfactant-stabilized nanocapsules. Despite being at the edge of detectability, we were able to show the polymer shell thickness to be typically 1.0 ± 0.1 nm, which places vesicle-templated nanocapsules among the thinnest materials ever created. The extreme thinness of the shells has implications for several areas: mass-transport through nanopores is relatively unimpeded; pore-forming molecules are not limited to those spanning the entire bilayer; the internal volume of the capsules is maximized; and insight has been gained on how polymerization occurs in the confined geometry of a bilayer scaffold, being predominantly located at the phase-separated layer of monomers and cross-linkers between the surfactant leaflets.

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“…1,2 The encapsulation of indicator dyes has led to nanoprobes for sensing and imaging. 3,4,13,18,20 Encapsulation offered further benefits, such as improved stability of photosensitive molecules, and may lead to broader control of the properties of entrapped molecules due to the regulated microenvironment. 4,21−26 In these applications, the underlying technology is based on nanocontainers, or hybrid nanorattlelike structures, containing various molecules entrapped in the interior of a hollow nanocapsule with porous nanometer-thick shells.…”

Section: Introductionmentioning

confidence: 99%

“…Hollow polymer nanocapsules with entrapped molecules are increasingly used in the construction of diverse functional nanodevices. − The ability to imprint uniform nanopores in the shells of vesicle-templated nanocapsules permitted tunable size- and charge-selective permeability, which translated into devices taking advantage of the ability to retain entrapped molecules while providing unhindered communication with the environment. ,− For example, the entrapment of homogeneous catalysts produced fast-acting and selective nanoreactors. , The encapsulation of indicator dyes has led to nanoprobes for sensing and imaging. ,,,, Encapsulation offered further benefits, such as improved stability of photosensitive molecules, and may lead to broader control of the properties of entrapped molecules due to the regulated microenvironment. ,− In these applications, the underlying technology is based on nanocontainers, or hybrid nanorattle-like structures, containing various molecules entrapped in the interior of a hollow nanocapsule with porous nanometer-thick shells.…”

Section: Introductionmentioning

confidence: 99%

Controlling the Encapsulation of Charged Molecules in Vesicle-Templated Nanocontainers through Electrostatic Interactions with the Bilayer Scaffold

2017

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This work addresses the challenge of creating hollow nanocapsules with a controlled quantity of encapsulated molecules. Such nanocontainers or nanorattle-like structures represent an attractive platform for building functional devices, including nanoreactors and nanosensors. By taking advantage of the electrostatic attraction between oppositely charged cargo molecules and the surface of the templating bilayer of catanionic vesicles, formed by mixing single-tailed cationic and anionic surfactants, we were able to achieve a substantial increase in the local concentration of molecules inside the vesicle-templated nanocapsules. Control of electrostatic interactions through changes in the formulation of catanionic vesicles or the pH of the solution enabled fine tuning of the encapsulation efficiency in capturing ionic solutes. The ability to control the quantity of entrapped molecules greatly expands the application of nanocontainers in the creation of functional nanodevices.

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Hollow Nanocapsules in Biomedical Imaging Applications

Cited by 7 publications

References 98 publications

Building Functional Nanodevices with Vesicle-Templated Porous Polymer Nanocapsules

Building Functional Nanodevices with Vesicle-Templated Porous Polymer Nanocapsules

Unraveling the Single-Nanometer Thickness of Shells of Vesicle-Templated Polymer Nanocapsules

Controlling the Encapsulation of Charged Molecules in Vesicle-Templated Nanocontainers through Electrostatic Interactions with the Bilayer Scaffold

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