Optical Manipulation and Fusion of Liposomes as Microreactors

Kulin, S. A.; Kishore, Rani; Helmerson, Kristian; Locascio, Laurie E.

doi:10.1021/la0344433

Cited by 89 publications

(80 citation statements)

References 23 publications

(34 reference statements)

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“…Optical manipulation was performed on a Zeiss Axiovert 100 inverted microscope, which was modified to include optical tweezers that can be moved across the field of view, and an optical scalpel (30). The trapping light is from a continuous-wave, ytterbium fiber laser (IPG Photonics, Oxford, Fig.…”

Section: Methodsmentioning

confidence: 99%

Stable and robust polymer nanotubes stretched from polymersomes

Reiner

Wells

Kishore

et al. 2006

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

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We create long polymer nanotubes by directly pulling on the membrane of polymersomes using either optical tweezers or a micropipette. The polymersomes are composed of amphiphilic diblock copolymers, and the nanotubes formed have an aqueous core connected to the aqueous interior of the polymersome. We stabilize the pulled nanotubes by subsequent chemical crosslinking. The cross-linked nanotubes are extremely robust and can be moved to another medium for use elsewhere. We demonstrate the ability to form networks of polymer nanotubes and polymersomes by optical manipulation. The aqueous core of the polymer nanotubes together with their robust character makes them interesting candidates for nanofluidics and other applications in biotechnology.cross-link ͉ optical tweezers ͉ nanofluidics ͉ vesicles N anotubes are among the most promising structures in nanotechnology. Carbon nanotubes are already finding applications in composite materials requiring high strength-to-weight ratio, and many more applications are expected in the near future (1). Nanotubes also can naturally occur in biology. Transport of genetic material from phage viruses to bacteria can occur via protein nanotubes (2), and phospholipid nanotubes between live cells, purported to be a conduit for intercellular organelle transport, were recently observed (3). The use of nanotubes for transport of biological molecules is particularly exciting, with potentially significant applications in biotechnology. Gold nanotubules in polymer membranes have been used to separate small biological molecules on the basis of molecular size (4) and DNA fragments according to base recognition. Experiments on the movement of DNA in nanofabricated structures (5, 6) showed that new transport mechanisms occur when spatial confinement in one or more dimensions is less than the radius of gyration. Similar effects also have been observed with DNA fragments passing through multiwalled carbon nanotubes (7). All of these nanotubular structures have an interior aqueous environment suitable for biological molecules, but with the exception of ref. 6, the length of an individual channel is only on the order of 1 m.Extremely long, water-filled nanotubes can be formed from self-assembling amphiphilic molecules. For example, phospholipids can spontaneously form nanotubes under appropriate conditions (8). Vesicle membranes composed of self-assembled amphiphilic molecules can exhibit both elastic and viscoelastic properties, which, under the application of a localized force, can result in the formation of a nanotube. Pioneering work by Evans et al. (9) demonstrated the formation of phospholipid nanotubes by using a micropipette to pull on phospholipid vesicle (liposome) membranes. More recently, Orwar and coworkers (10) adopted the technique of Evans to create elaborate networks of liposomes interconnected by phospholipid nanotubes and demonstrated transport through these networks. Similarly, optical tweezers have been used to create phospholipid nanotubes by pulling directly on membranes of ...

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Section: Methodsmentioning

confidence: 99%

Stable and robust polymer nanotubes stretched from polymersomes

Reiner

Wells

Kishore

et al. 2006

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

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“…Secondly, the approximation of the sphere was too rough for these crystalline deposits, if the particle was not dense or spherical and was ellipsoidal, flat, or cubic. However, the size had no effect on the estimation of mass magnetic susceptibility, as noticed in equation (2). Therefore, the estimated value of mass magnetic susceptibility is reliable.…”

Section: Magnetic Susceptibility Measurement By Atmospheric Magnetophmentioning

confidence: 97%

“…Therefore, the separation and analysis of a single microparticle is necessary to elucidate the function of microparticles in real systems. To perform them, nondestructive and noninvasive measurement techniques for the properties of an 'individual' single microparticle are extensively required in different research fields, such as biology, environmental chemistry, and medical science [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Magnetic susceptibility measurement of single iron/cobalt carbonyl microcrystal by atmospheric magnetophoresis

Suwa

Oshino

Watarai

et al. 2008

Science and Technology of Advanced Materials

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In this study, the use of an innovative atmospheric magnetophoresis, which enables us to measure the mass magnetic susceptibility and mass of a microparticle simultaneously, was demonstrated. Using this technique, we determined the magnetic susceptibility of a crystalline deposit of iron/cobalt carbonyl, mainly composed of Fe 2 (CO) 9 , which was prepared photochemically from a gaseous mixture of iron pentacarbonyl (Fe(CO) 5 ) and cobalt tricarbonyl nitrosyl (Co(CO) 3 NO). The mass magnetic susceptibility and the characteristic relaxation time of the microcrystal were (7.0 ± 1.9) × 10 −9 m 3 kg −1 and (5.6 ± 2.2) × 10 −4 s, respectively. The observed magnetic susceptibility shows that the microparticle was paramagnetic. Assuming that the density was equal to that of Fe 2 (CO) 9 (2.1 × 10 3 kg m −3 ) and that the shape of the particle was spherical, a hydrodynamic radius of 4.7 µm and a mass of 0.91 ng were observed. It was suggested that Co was incorporated in Fe 2 (CO) 9 .

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“…An important condition for successful fusion-initiated reactions is to stimulate the vesicles in order to obtain an effective fusion event since vesicle fusion is inefficient in the absence of external stimuli. Fusion can be induced artificially by means of membrane stress (Cohen et al, 1982;Shillcock et al, 2005), ions or organic reagents (Estes et al, 2006;Neil et al, 1993;Lentz, 2007;Haluska et al, 2006;Kunishima et al, 2006), DNA (Stengel et al, 2007), proteins (Jahn et al, 2006;Peters et al, 1999 and summary by Walde et al, 2001), laser beams (Steubing et al, 1991;Weber et al, 1992;Kulin et al, 2003) or electric fields (Strömberg et al, 2000). The last one is termed electrofusion.…”

Section: Electrofusion Protocolmentioning

confidence: 99%