One-dimensional (1D) conductive nanowire is one of the most important components for the development of nanosized electronic devices, sensors, and energy storage units. Great progresses have been made to prepare the 1D-conducting polymeric nanofibers by the low concentration process or the synthesis with hard or soft templates. However, it still remains as a great challenge to prepare polymeric nanofibers with narrow dispersity, high aspect ratio, and good processibility. With the rod-like tobacco mosaic virus as the template, 1D-conducting polyaniline and polypyrrole nanowires can be readily prepared via a hierarchical assembly process. This synthesis discloses a unique way to produce composite fibrillar materials with controlled morphology and great processibility, which can promote many potential applications including electronics, optics, sensing, and biomedical engineering.
A thermo-responsive poly{γ-2-[2-(2-methoxyethoxy)ethoxy]ethoxy-ε-caprolactone}-b-poly(γ-octyloxy-ε-caprolactone) (PMEEECL-b-POCTCL) diblock copolymer was synthesized by ring-opening polymerization using tin octanoate (Sn(Oct)(2)) catalyst and a fluorescent dansyl initiator. The PMEEECL-b-POCTCL had a lower critical solution temperature (LCST) of 38 °C, and it was employed to prepare thermally responsive micelles. Nile Red and Doxorubicin (DOX) were loaded into the micelles, and the micellar stability and drug carrying ability were investigated. The size and the morphology of the cargo-loaded micelles were determined by DLS, AFM, and TEM. The Nile-Red-loaded polymeric micelles were found to be stable in the presence of both fetal bovine serum and bovine serum albumin over a 72 h period and displayed thermo-responsive in vitro drug release. The blank micelles showed a low cytotoxicity. As comparison, the micelles loaded with DOX showed a much higher in vitro cytotoxicity against MCF-7 human breast cancer cell line when the incubation temperature was elevated above the LCST. Confocal laser scanning microscopy was used to study the cellular uptake and showed that the DOX-loaded micelles were internalized into the cells via an endocytosis pathway.
One-dimensional (1D) polyaniline/tobacco mosaic virus (TMV) composite nanofibers and macroscopic bundles of such fibers were generated via a self-assembly process of TMV assisted by in-situ polymerization of polyaniline on the surface of TMV. At near-neutral reaction pH, branched polyaniline formed on the surface of TMV preventing lateral association. Therefore, long 1D nanofibers were observed with high aspect ratios and excellent processibility. At a lower pH, transmission electron microscopy (TEM) analysis revealed that initially long nanofibers were formed which resulted in bundled structures upon long-time reaction, presumably mediated by the hydrophobic interaction because of the polyaniline on the surface of TMV. In-situ time-resolved small-angle X-ray scattering study of TMV at different reaction conditions supported this mechanism. This novel strategy to assemble TMV into 1D and 3D supramolecular composites could be utilized in the fabrication of advanced materials for potential applications including electronics, optics, sensing, and biomedical engineering.
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