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Katrina Kratz,
Amrit Narasimhan, Ravisubhash Tangirala,
SungCheal Moon,
Ravindra Revanur,
Santanu Kundu,
Hyun Suk Kim,
Alfred J Crosby,
Thomas P Russell,
Todd Emrick,
German Kolmakov,
Anna C Balazs
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ABSTRACT: Nanoparticles have useful properties, but it is often important that they only start working after they are placed in a desired location. The encapsulation of nanoparticles allows their function to be preserved until they are released at a specific time or location, and this has been exploited in the development of self-healing materials and in applications such as drug delivery. Encapsulation has also been used to stabilize and control the release of substances, including flavours, fragrances and pesticides. We recently proposed a new technique for the repair of surfaces called 'repair-and-go'. In this approach, a flexible microcapsule filled with a solution of nanoparticles rolls across a surface that has been damaged, stopping to repair any defects it encounters by releasing nanoparticles into them, then moving on to the next defect. Here, we experimentally demonstrate the repair-and-go approach using droplets of oil that are stabilized with a polymer surfactant and contain CdSe nanoparticles. We show that these microcapsules can find the cracks on a surface and selectively deliver the nanoparticle contents into the crack, before moving on to find the next crack. Although the microcapsules are too large to enter the cracks, their flexible walls allow them to probe and adhere temporarily to the interior of the cracks. The release of nanoparticles is made possible by the thin microcapsule wall (comparable to the diameter of the nanoparticles) and by the favourable (hydrophobic-hydrophobic) interactions between the nanoparticle and the cracked surface.
Nature Nanotechnology 01/2012; 7(2):87-90. · 27.27 Impact Factor
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ABSTRACT: Ag(2) S nanocrystals (NCs) are embedded into a GeS(2) matrix while controlling the size, shape, and interparticle spacing of the Ag(2) S NCs. We demonstrate that the ionic and electronic properties of these inorganic nanocomposites can be systematically controlled by varying the diameter of the Ag(2) S NCs. We also observe an ionic conductivity enhancement relative to pure Ag(2) S and (GeS(2) )(0.5) (Ag(2) S)(0.5) glass.
Advanced Materials 12/2011; 24(1):99-103. · 13.88 Impact Factor
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ABSTRACT: Inorganic nanocomposites have been prepared by assembling colloidal nanocrystals and then replacing the organic ligands with precursors to an inorganic matrix phase. Separate synthesis and processing of the nanocrystal and matrix phases allows complete compositional modularity and retention of the superlattice morphologies for sphere (see scheme; top) or rod (bottom) assemblies.
Angewandte Chemie International Edition 03/2010; 49(16):2878-82. · 13.45 Impact Factor
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ABSTRACT: Using a hybrid computational approach, we simulate the behavior of nanoparticle-filled microcapsules that are propelled by an imposed shear to move over a substrate, which encompasses a microscopic crack. When the microcapsules become localized in the crack, the nanoparticles can penetrate the capsule's shell to bind to and fill the damaged region. Initially focusing on a simple shear flow, we isolate conditions where the microcapsules become arrested in the cracks and those where the capsules enter the cracks for a finite time but are driven to leave this region by the imposed flow. We also characterize the particle deposition process for these two scenarios, showing that the deposition is greater for the arrested capsules. We then determine the effect of utilizing a pulsatile shear flow and show that this flow field can lead to an effective "repair-and-go" system where the microcarriers not only deliver a high volume fraction of particles into the crack but also leave the fissure and, thus, can potentially repair additional damage within the system.
ACS Nano 02/2010; 4(2):1115-23. · 10.77 Impact Factor
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Jinbo He,
Zhongwei Niu, Ravisubhash Tangirala,
Jia-Yu Wang,
Xinyu Wei,
Gagandeep Kaur,
Qian Wang,
Günther Jutz,
Alexander Böker,
Byeongdu Lee,
Sai Venkatesh Pingali,
Pappannan Thiyagarajan,
Todd Emrick,
Thomas P Russell
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ABSTRACT: The oil/water interfacial assembly of tobacco mosaic virus (TMV) has been studied in situ by tensiometry and small-angle X-ray and neutron scattering (SAXS and SANS). TMV showed different orientations at the perfluorodecalin/water interface, depending on the initial TMV concentration in the aqueous phase. At low TMV concentration, the rods oriented parallel to the interface, mediating the interfacial interactions at the greatest extent per particle. At high TMV concentrations, the rods were oriented normal to the interface, mediating the interfacial interactions and also neutralizing inter-rod electrostatic repulsion. We found that the inter-rod repulsive forces between TMVs dominated the in-plane packing, which was strongly affected by the ionic strength and the bulk solution but not by the pH in the range of pH = 6-8.
Langmuir 06/2009; 25(9):4979-87. · 4.19 Impact Factor
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ABSTRACT: Amphiphilic, PEGylated gold nanoparticles, of approximately 2 nm average core diameter, were synthesized by reduction of hydrogen tetrachloroaurate in the presence of the ligand (1-mercaptoundec-11-yl)tetra(ethylene glycol). These PEGylated gold nanoparticles were found to assemble cleanly at the oil-water interface. This self-assembly process gave a microencapsulated oil phase, water as the continuous phase, and a monolayer of gold nanoparticles at the oil-water interface. The capsules could be cross-linked from the organic phase by reaction of the chain-end hydroxyl groups of the PEG ligands with suitable electrophiles such as terephthaloyl chloride.
Nano Letters 03/2007; 7(2):389-93. · 13.20 Impact Factor
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ABSTRACT: Interfacial segregation of nanoparticles on droplets, such as water droplets in oil, is achieved by mixing or shaking organic solutions of the nanoparticles with water. This typically results in the formation of droplets with a large distribution of sizes, ranging from 10 microm to greater than 200 microm in diameter. Here we describe the application of track-etch membranes to control the size of these nanoparticle-coated droplets. Passing nanoparticle-coated droplets through the membranes substantially reduces their size by breaking up the droplets during the extrusion process and reforming droplets of comparable size to the membrane pore diameter. When the nanoparticles used in these sizing procedures are covered with functional ligands, stabilization of the post-extrusion diameter is achieved by polymerization/cross-linking of the ligand periphery.
Langmuir 02/2007; 23(3):965-9. · 4.19 Impact Factor
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Journal of Polymer Science Part A Polymer Chemistry 07/2006; 44(17):5076 - 5086. · 3.92 Impact Factor
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Justin T Russell,
Yao Lin,
Alexander Böker,
Long Su,
Philippe Carl,
Heiko Zettl,
Jinbo He,
Kevin Sill, Ravisubhash Tangirala,
Todd Emrick,
Kenneth Littrell,
Pappannan Thiyagarajan,
David Cookson,
Andreas Fery,
Qian Wang,
Thomas P Russell
Angewandte Chemie International Edition 05/2005; 44(16):2420-6. · 13.45 Impact Factor
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Justin T. Russell,
Yao Lin,
Alexander Böker Dr,
Long Su,
Philippe Carl Dr,
Heiko Zettl,
Jinbo He,
Kevin Sill, Ravisubhash Tangirala,
Todd Emrick Professor,
Kenneth Littrell Dr,
Pappannan Thiyagarajan Dr,
David Cookson Dr,
Andreas Fery Dr,
Qian Wang Professor,
Thomas P. Russell Professor
Angewandte Chemie International Edition 03/2005; 44(16):2420 - 2426. · 13.45 Impact Factor
