Self-Assembly and Hierarchies in Pyridine-Containing Homopolymers and Block Copolymers with Hydrogen-Bonded Cholesteric Side-Chains

Flexible Block Copolymer Metamaterials Featuring Hollow Ordered Nanonetworks with Ultra-High Porosity and Surface-To-Volume Ratio

By utilizing bicontinuous and nanoporous ordered nanonetworks, such as double gyroid (DG) and double diamond (DD), metamaterials with exceptional optical and mechanical properties can be fabricated through the templating synthesis of functional materials. However, the volume fraction range of DG in block copolymers is significantly narrow, making it unable to vary its porosity and surface-to-volume ratio. Here, the theoretically limited structural volume of the DG phase in coil-coil copolymers is overcome by enlarging the conformational asymmetry through the association of mesogens, providing fast access to achieving flexible structured materials of ultra-high porosities. The new materials design, dual-extractable nanocomposite, is created by incorporating a photodegradable block with a solvent-extractable mesogen (m) into an accepting block, resulting in a new hollow gyroid (HG) with the largely increased surface-to-volume ratio and porosity of 77 vol%. The lightweight HG exhibits a low refractive index of 1.11 and a very high specific reduced modulus, almost two times that of the typical negative gyroid (porosity≈53%) and three times that of the positive gyroid (porosity≈24%). This novel concept can significantly extend the DG phase window of block copolymers and the corresponding surface-to-volume ratio, being applicable for nanotemplate-synthesized nanomaterials with a great gain of mechanical, catalytic, and optoelectronic properties.

Poly(vinylpyridine)-Containing Block Copolymers for Smart, Multicompartment Particles

Multicompartment particles generated by the self-assembly of block copolymers (BCPs) have received considerable attention due to their unique morphologies and functionalities. A class of important building blocks for multicomponent particles...

Mitochondria-targeted vitamin E succinate delivery for reversal of multidrug resistance

Inducing mitochondrial malfunction is an appealing strategy to overcome tumor multidrug resistance (MDR). Reported here a versatile mitochondrial-damaging molecule, vitamin E succinate (VES), is creatively utilized to assist MDR reversal of doxorubicin hydrochloride (DOX·HCl) via a nanovesicle platform self-assembled from amphiphilic polyphosphazenes containing pH-sensitive 1H-benzo-[d]imidazol-2-yl) methanamine (BIMA) groups. Driven by multiple non-covalent interactions, VES is fully introduced into the hydrophobic membrane of DOX·HCl-loaded nanovesicles with loading content of 23.5%. The incorporated VES also offers robust anti-leakage property toward DOX·HCl under normal physiological conditions. More importantly, upon release within acidic tumor cells, VES can target mitochondria and result in various dysfunctions including excessive generation of reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨ_m) loss, and inhibited adenosine triphosphate (ATP) synthesis, which contribute to cell apoptosis and insufficient energy supply for drug efflux pumps. Consequently, the killing-effect of DOX·HCl is significantly enhanced toward drug resistant cancer cells at the optimal mass ratio of DOX·HCl to VES. Further in vivo antitumor investigation on nude mice bearing xenograft drug-resistant human chronic myelogenous leukemia K562/ADR tumors verifies the extremely enhanced anti-tumor efficacy of the dual drug-loaded nanovesicle with the tumor inhibition rate (TIR) of 82.38%. Collectively, this study provides a s safe, facile and promising strategy for both precise drug delivery and MDR eradication to improve cancer therapy.

Enhanced thermomechanical property of a self-healing polymer via self-assembly of a reversibly cross-linkable block copolymer

Introduction of a self-healable block copolymer increases the mechanical property whilst maintaining self-healing efficiency.

Design of pH-Sensitive Nanovesicles via Cholesterol Analogue Incorporation for Improving in Vivo Delivery of Chemotherapeutics

pH-responsive polymersomes have emerged as promising nanocarriers for antitumor drugs to realize their fast release and action in a weakly acidic microenvironment of tumor cells. Herein, however, we designed a remarkably pH-responsive polymersome self-assembled from amphiphilic benzimidazole-based polyphosphazenes via the incorporation of cholesteryl hemisuccinate (CholHS), a type of cholesteric molecule, into the polymersome bilayers to inhibit the drug release during blood circulation. Actually, unwanted premature drug leakage before arriving at the acidic tumor site has become a serious problem for polymersomes encapsulating water-soluble drugs, especially when the drug loading is at a high level, thus limiting the therapeutic efficacy. In this study, polymersomes displayed high loading capability of doxorubicin hydrochloride as 12.83%. More importantly, CholHS incorporation decreased the membrane permeability of the polymersome and effectively retarded the cargo release under physiological conditions but induced the fast drug-release rate at pH 5.5, demonstrating a more remarkably acid-responsive release behavior when compared to that of the CholHS-free polymersomes. Further in vivo investigations including pharmacokinetic and antitumor activity studies verified the extended circulation time and enhanced antitumor efficacy of the drug-loaded CholHS-incorporated polymersomes.

Hydrogen bonding interactions affect the hierarchical self-assembly and secondary structures of comb-like polypeptide supramolecular complexes displaying photoresponsive behavior

Hierarchical lamellae-within-lamellae structure for the PTyr/AzoPy-C16 supramolecular complex, featuring long-range-ordered lamellae arising from the PTyr within lamellae arising from AzoPy-C16 units oriented in a perpendicular manner.

Phase behaviors of side chain liquid crystalline block copolymers

The microphase separation of side chain liquid crystalline (SCLC) block copolymers was studied using dissipative particle dynamics (DPD) simulations.

Nanostructures on graphene using supramolecule and supramolecular nanocomposites

Nanopatterning and functionalizing of graphene is often required to tune or enhance its unique physical properties. However, complex processes are needed to overcome the chemical incompatibilities between the patterning template, the functional small molecules or nanoparticles, and the underlying graphene. We present a block copolymer (BCP)-based supramolecular thin film as a versatile platform for the generation of periodic patterns of small molecules and ordered assemblies of nanoparticles on top of a graphene substrate without chemical modification of any components. The present approach opens opportunities to readily pattern and functionalize graphene, and to investigate the structure-property correlations of graphene/nanoparticle and graphene/small molecule composite materials.

Thermally reversible aggregation of Gold nanoparticles in polymer nanocomposites through hydrogen bonding

The ability to tune the state of dispersion or aggregation of nanoparticles within polymer-based nanocomposites, through variations in the chemical and physical interactions with the polymer matrix, is desirable for the design of materials with switchable properties. In this study, we introduce a simple and effective means of reversibly controlling the association state of nanoparticles based on the thermal sensitivity of hydrogen bonds between the nanoparticle ligands and the matrix. Strong hydrogen bonding interactions provide excellent dispersion of gold nanoparticles functionalized with poly(styrene-r-2-vinylpyridine) [P(S-r-2VP)] ligands in a poly(styrene-r-4-vinyl phenol) [P(S-r-4VPh)] matrix. However, annealing at higher temperatures diminishes the strength of these hydrogen bonds, driving the nanoparticles to aggregate. This behavior is largely reversible upon annealing at reduced temperature with redispersion occurring on a time-scale of ~30 min for samples annealed 50 °C above the glass transition temperature of the matrix. Using ultraviolet-visible absorption spectroscopy (UV-vis) and transmission electron microscopy (TEM), we have established the reversibility of aggregation and redispersion through multiple cycles of heating and cooling.

Bioinspired assembly of functional block-copolymer nanotemplates

A new concept on bioinspired assembly of functional diblock copolymers, capable of forming different microstructures through nucleobase-induced supramolecular interactions, has been explored. In this paper, a new series of uracil-functionalized poly(ε-caprolactone)-b-(4-vinylbenzyl uracil)s (PCL-b-PVBU) have been prepared which exhibit a high self-complementary ability in solution and solid states owing to the formation of uracil–uracil pairs by induced hierarchical self-assembly. The ordered morphologies of PCL-b-PVBU diblock copolymers changed from a lamellar, hexagonally packed cylinder to a sphere with respect to the content of the hydrogen bond segment. Moreover, we further show that the PCL segment could be easily extracted by enzymatic degradation, leading to a cylinder porous structure of long-range order, which gives a facile method for the fabrication of uracil-functionalized nanotemplates. In addition, bio-complementary PCL-b-PVBU/9-hexadecyladenine (AC16) hierarchical supramolecular complexes formed through strong cooperative hydrogen bonding between the uracil group of PVBU and the adenine group of A-C16. When the mixing ratios of PCL-b-PVBU/AC16 differ from the stoichiometric ratio, these complexes self-assemble into well-ordered lamellar and hexagonal structures; the changing morphology at different AC16 loadings reveals that the molecular structures of the PCL-b-PVBU/AC16 complexes are readily tailored.