Stable and robust polymer nanotubes stretched from polymersomes

Abstract

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 ...

Reshaping Elastic Nanotubes via Self-Assembly of Surface-Adhesive Nanoparticles

“…Furthermore, it should be possible to reversibly switch nanoparticle self-assembly on and off in experiments -for instance by tuning temperature, or by exploiting electrostatic or depletion interactions. Controlling nanotube shape may be relevant to applications of tubular nanomaterials [17][18][19], of bioactive nanotubes [20], and in microfluidics [21]. We believe that experimental systems in which the here described coupling between nanoparticle self-assembly and nanotube deformation occurs can be readily realized.…”

In-vitro nanodiagnostic platform through nanoparticles and DNA-RNA nanotechnology

“…In the studies of the synthesis of polymer-based nanotubes, Reiner et al (2006) literally pull the membranes off polymersomes, which are polymer vesicles composed of amphiphilic diblock copolymer. The pulled nanotubes are stabilized by chemical cross-linking and are demonstrated to be extremely robust.…”

“…Rice and Whitehead (1965) published a seminal paper on the theory behind fluidics physics in a nanoscale capillary which resulted in the Fig. 1 a An inorganic nanotube microfluidic device for single DNA molecular sensing (Fan et al 2005); b the creation of polymer nanotube-vesicle networks (scale bar, 10 μm) (Reiner et al 2006); c DNA sequencing by using a nanopore (Branton et al 2008) derivation of the following equation for the radial distribution of the velocity of a liquid, vz(r) as follows:…”

Capable Cross-links: Polymersomes Reinforced with Catalytically Active Metal–Ligand Bonds

“…18 One example of the chemical versatility of vesicle forming polymers is the number of ways devised to cross-link these structures. Covalent systems are well-known and include disulfide bonds, 19 free radical cross-linking of polymer sidechain groups by redox couples, 20,21 and polymers with reactive side-chain groups. 22−24 These cross-linking systems can be used to increase vesicle robustness, allowing for swelling and controlled release of encased solutes, 23,25,26 and gating of reagent flow.…”