7 research outputs found
Synthesis of One-Component Nanostructured Polyion Complexes via Polymerization-Induced Electrostatic Self-Assembly
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
Polyion
complexation (PIC) as the driving force of polymerization-induced
self-assembly (PISA), that is, PICâPISA, is explored. Reversible
additionâfragmentation 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 polyÂ(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 PICâPISA 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
Autocatalytic self-sorting in the
biomimetic polyÂ(cystamine methacrylamide
hydrochloride) (PCysMA) is presented, whose units comprise lysine-mimetic
alkylÂammonium ions and cystine-mimetic alkyl disulfide spacers.
The block copolymer with polyÂ(2-hydroxyÂpropylÂmethacrylamide)
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.
65â67% 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., CuÂ(II)âNH<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. UVâvis 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
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 (âŒ25â85)
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
lâHistidine Salt-Bridged Monomer Preassembly and Polymerization-Induced Electrostatic Self-Assembly
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 âsalt-bridged homo-PISAâ
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
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
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