7 research outputs found

    Synthesis of One-Component Nanostructured Polyion Complexes via Polymerization-Induced Electrostatic Self-Assembly

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    Nanostructured polyion complexes (PICs) are expected to serve as novel platforms to stabilize and deliver drugs, proteins, and nucleic acids. Yet, traditional self-assembly suffers from lack of scale-up and reproducibility. Particularly for one-component PICs, only spheres are available to date. Here, we report an efficient and scalable strategy to prepare one-component low-dimensional PICs. It involves visible-light-mediated RAFT iterative polymerization of opposite-charge monomers at 25% w/w solids in water at 25 °C. Sphere-film-vesicle transition and charge-/medium-tunable shape selectivity are reported. One-component PIC nanowire, ultrathin film, vesicle, tube, and surface-charged vesicle are easily prepared, and vesicle-polymerization is fulfilled, using this new strategy. This strategy provides a general platform to prepare one-component low-dimensional PICs with tailorable morphologies and high reproducibility on commercially viable scale under eco-friendly conditions

    Use of Polyion Complexation for Polymerization-Induced Self-Assembly in Water under Visible Light Irradiation at 25 °C

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    Polyion complexation (PIC) as the driving force of polymerization-induced self-assembly (PISA), that is, PIC–PISA, is explored. Reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization of NH<sub>3</sub><sup>+</sup>-monomer 2-aminoethylacrylamide hydrochloride (AEAM) can be achieved in water under visible light irradiation at 25 °C, using nonionic poly2-hydroxypropylmethacrylamide (PHPMA) macromolecular chain transfer agent in the presence of anionic poly­(sodium 2-acrylamido-2-methylpropanesulfonate) (PAMPS) PIC-template. Sphere-to-network transition occurs, owing to the PIC of PAMPS with growing chains upon reaction close to isoelectric point (IEP); thereafter, the increase of electrostatic repulsion promotes the split of networks and the rupture of spheres into fragments. Therefore, the free-flowing solution becomes viscous liquid and free-standing physical gel, and then back into viscous and free-flowing liquid. Such a PIC–PISA is appealing for gene delivery because the size and surface charge are variable on demand and at high solids

    Autocatalytic Self-Sorting in Biomimetic Polymer

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    Autocatalytic self-sorting in the biomimetic poly­(cystamine methacrylamide hydrochloride) (PCysMA) is presented, whose units comprise lysine-mimetic alkyl­ammonium ions and cystine-mimetic alkyl disulfide spacers. The block copolymer with poly­(2-hydroxy­propyl­methacrylamide) was synthesized directly by RAFT in acidic water under visible light irradiation at 25 °C. Disulfide exchange can be initiated by the terminal thiolates as generated by alkalization-induced aminolysis. 65–67% CysMA units sort into hydrophobic polymer disulfides and water-soluble cystamine at pH 10.5. Moreover, intermediate reactions occur in the presence of copper ions, i.e., Cu­(II)–NH<sub>2</sub> coordination, aminolysis, NH<sub>2</sub>-to-SH substitution, and cupric-to-cuprous reduction in metal centers, thus autocatalytic self-sorting with essentially 100% conversion at pH 8.8. UV–vis spectroscopy, <sup>1</sup>H NMR, atomic absorption spectroscopy, and elemental analysis confirmed this ideal self-sorting. Dynamic light scattering and atomic force microscopy identified supramolecular-to-supracolloidal self-assembly with concomitant release of cystamine molecules and intermediate cuprous complexes. Such a self-sorting underlines an amazing prospect for the use of a single polymer to achieve artificial reaction complexity, hierarchy, and metabolic process, with minimal synthetic efforts

    Synthesis of Hydrogen-Bonded Pore-Switchable Cylindrical Vesicles via Visible-Light-Mediated RAFT Room-Temperature Aqueous Dispersion Polymerization

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    Analogous to cellulose, polymers whose monomer units possess both hydrogen donators and acceptors are generally insoluble in ambient water because of hydrogen bonding (HB). Herein we present stimuli-responsive long aqueous cylindrical vesicles (nanotubes) synthesized directly using HB-driven polymerization-induced self-assembly (PISA) under visible-light-mediated RAFT aqueous dispersion polymerization at 25 °C. The PISA undergoes an unprecedented film/silk-to-ribbon-to-vesicle transition and films/silks/ribbons formed at low DPs (∌25–85) of core-forming block in free-flowing aqueous solution. Pore-switchable nanotubes are synthesized by electrostatic repulsive perturbation of the HB association in anisotropic vesicular membranes via inserting minor ionized monomer units into the core-forming block. These nanotubes are synthesized at >35% solids, and tubular membranes are more sensitive than spherical counterparts in response to aqueous surroundings. This facile, robust, and general strategy paves a new avenue toward scale-up production of advanced intelligent nanomaterials

    l‑Histidine Salt-Bridged Monomer Preassembly and Polymerization-Induced Electrostatic Self-Assembly

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    Salt bridges are predominant in protein construction and stabilization, yet largely unexplored for polymer nanoparticle synthesis. We herein report the use of l-histidine salt bridges to drive monomer preassembly and two-dimensional electrostatic self-assembly in aqueous photo-RAFT polymerization. l-histidine salt bridges drive the monomer clustering nucleation, complex coacervation, and Coulombic stabilization, leading to the 2 nm ultrasmall clusters and coacervate droplets. Homopolymerization leads to a precision two-dimensional electrostatic self-assembly via a droplet-monolayer-multilayer transition, i.e., salt-bridged homo-polymerization-induced self-assembly (PISA). Block copolymerization does not disturb the “salt-bridged homo-PISA” mechanism. Enhanced Coulombic repulsion via seeded polymerization of charged monomers using as-achieved multilayer lamellae (seeds) yields supercharged 5 nm ultrathin monolayer lamellae with high colloidal stability upon dilution, salting, and long-term storage, urgently needed for bioapplications. This work opens up a new avenue to use amino acid salt bridges for PISA synthesis of biologically important, yet hitherto inaccessible, salt-resistant ultrathin polyelectrolyte complex nanomaterials

    Compartmentalization and Unidirectional Cross-Domain Molecule Shuttling of Organometallic Single-Chain Nanoparticles

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    Compartmentalization and unidirectional cross-domain molecule shuttling are omnipresent in proteins, and play key roles in molecular recognition, enzymatic reaction, and other living functions. Nanomachinery design emulating these biological functions is being considered as one of the most ambitious and challenging tasks in modern chemistry and nanoscience. Here, we present a biomimetic nanomachinery design using single-chain technology. Stepwise complex of the outer blocks of water-soluble linear ABC triblock terpolymer to copper ions yields dumbbell-shaped single-chain nanoparticle. A novel nanomachine capable of compartmentalization and unidirectional cross-domain molecule shuttling has been achieved upon ascorbic acid reduction, leading to synergistically donating/accepting copper centers between discrete double heads, overall dumbbell-to-tadpole configurational transition, and intake of oxidized ascorbic acid into reconstructed head. Subsequent air oxidation results in the inverse molecule shuttling and configurational transition processes. This is the first demonstration of biomimetic nanomachinery design that is capable of compartmentalization and unidirectional cross-domain molecule shuttling, exemplified simply using a new single-chain technology

    Controlled Mineralization of Calcium Carbonate on the Surface of Nonpolar Organic Fibers

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    Isotactic polypropylene (iPP) fiber, the surface of which is hydrophobic, can modulate the crystallization polymorphs of calcium carbonate (CaCO<sub>3</sub>) at the air/solution interface under mild conditions. The present results provide a novel perspective on controlling the crystallization of biominerals by an insoluble matrix, and they can shed new light on understanding the biomineralization process of CaCO<sub>3</sub> as it occurs in nature
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