A multifunctional azobenzene-based polymeric adsorbent for effective water remediation

The efficient removal of trace carcinogenic organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs) and ionic dyes, from water is an important technical challenge. We report a highly effective recyclable multifunctional azobenzene (AZ)-based silica-supported polymeric adsorbent which can simultaneously remove both PAHs and anionic dyes from water to below parts per billion (ppb) level based on multiple interactions such as the hydrophobic effect, [pi]–[pi] stacking and electrostatic interactions, thus providing a new strategy for designer water remediation materials

Polymer/TiO₂ Hybrid Vesicles for Excellent UV Screening and Effective Encapsulation of Antioxidant Agents

Presented in this paper is a hybrid polymer/titanium dioxide (TiO₂) vesicle that has excellent UV-screening efficacy and strong capacity to encapsulate antioxidant agents. Poly­(ethylene oxide)-<i>block</i>-poly­(2-(dimethylamino)­ethyl methacrylate)-<i>block</i>-polystyrene (PEO-<i>b</i>-PDMAEMA-<i>b</i>-PS) triblock terpolymer was synthesized by atom transfer radical polymerization (ATRP) and then self-assembled into vesicles. Those vesicles showed excellent UV-screening property due to the scattering by vesicles and the absorption by PS vesicle membrane. The selective deposition of solvophobic tetrabutyl titanate in the PDMAEMA shell and the PS membrane of the vesicles led to the formation of polymer/TiO₂ hybrid vesicles, resulting in an enhanced UV-screening property by further reflecting and scattering UV radiation. The vesicles can effectively encapsulate antioxidant agents such as ferulic acid (up to 57%), showing a rapid antioxidant capability (within 1 min) and a long-lasting antioxidant effect

Asymmetrical Polymer Vesicles with a “Stealthy” Outer Corona and an Endosomal-Escape-Accelerating Inner Corona for Efficient Intracellular Anticancer Drug Delivery

The efficient intracellular drug delivery is an important challenge due to the slow endocytosis and inefficient drug release of traditional delivery vehicles such as symmetrical polymer vesicles, which have the same coronas on both sides of the membrane. Presented in this paper is a noncytotoxic poly­(ethylene oxide)-<i>block</i>-poly­(caprolactone)-<i>block</i>-poly­(acrylic acid) (PEO₁₁₃-<i>b</i>-PCL₁₃₂-<i>b</i>-PAA₁₅) triblock copolymer vesicle with an asymmetrical structure. The biocompatible exterior PEO coronas are designed for stealthy drug delivery; The pH-responsive interior PAA chains are designed for rapid endosomal escape and enhanced drug loading efficiency. The hydrophobic PCL vesicle membrane is for biodegradation. Such asymmetrical polymer vesicle showed high doxorubicin (DOX) loading efficiency and good biodegradability under extracellular enzymatic conditions. Compared with three traditional symmetrical vesicles prepared from PEO₁₁₃-<i>b</i>-PCL₁₁₀, PEO₄₃-<i>b</i>-PCL₉₈-<i>b</i>-PAA₂₅, and PAA₂₁-<i>b</i>-PCL₇₅ copolymers, the DOX-loaded asymmetrical PEO₁₁₃-<i>b</i>-PCL₁₃₂-<i>b</i>-PAA₁₅ polymer vesicles exhibited rapid endocytosis rate and much faster endosomal escape ability, demonstrating promising potential applications in nanomedicine

Probing into Homopolymer Self-Assembly: How Does Hydrogen Bonding Influence Morphology?

Self-assembly of amphiphilic homopolymers composed of both hydrophilic and hydrophobic components in each repeating unit is burgeoning in recent years due to their facile synthesis compared to block copolymers. However, ordered homopolymer nanostructures are very limited, and solid TEM evidence for the formation of vesicles and other complex morphologies is necessary to address the mechanistic insights of homopolymer self-assembly. Presented in this article are the studies on the morphological transition, the structure analysis, and the formation mechanism of homopolymer self-assembly. First, a series of amphiphilic homopolymers, poly­(2-hydroxy-3-phenoxypropyl acrylate) (PHPPA) with various molecular weights (MWs) have been designed and synthesized by the reversible addition–fragmentation chain transfer (RAFT) process. Second, upon simply changing the homopolymer’s chain length or cosolvents during self-assembly, a wide range of new homopolymer-based nanostructures can be obtained, such as large compound micelles (LCMs), simple vesicles, large compound vesicles (LCVs), and hydrated large compound micelles (HLCMs) as a result of different intensity of inter/intra-polymer hydrogen bonding in the homopolymer self-assemblies. Moreover, micrometer-sized branched cylinders are formed by premixing PHPPA₃₆ and PHPPA₁₀₃ homopolymers, which is not observed by self-assembly of PHPPA₃₆ and PHPPA₁₀₃ individually. Third, we claim that the structures of homopolymer self-assemblies are much different from their block copolymer analogues due to homopolymer’s fuzzy hydrophobic and hydrophilic domains compared to block copolymer’s distinct ones. We confirm that the structure of micelle core or vesicle membrane (alike to each other in nature) consists of both hydrophilic and hydrophobic moieties, which is different from block copolymer micelles or vesicles with hydrophobic cores or membranes. Also, a dye encapsulation experiment is employed to identify and distinguish a new nanostructure, HLCMs, from LCMs. Our study has provided a new perspective on homopolymer self-assembly

Sugar-Breathing Glycopolymersomes for Regulating Glucose Level

Diabetes mellitus is a chronic, life-threatening illness that affects people of every age and ethnicity. It is a long-term pain for those who are affected and must regulate their blood glucose level by frequent subcutaneous injection of insulin every day. Herein, we propose a noninsulin and antidiabetic drug-free strategy for regulating blood glucose level by a nanosized “sugar sponge” which is a lectin-bound glycopolymersome capable of regulating glucose due to the dynamic recognition between the lectin and different carbohydrates. The glycopolymersome is self-assembled from poly­(ethylene oxide)-<i>block</i>-poly­[(7-(2-methacryloyloxyethoxy)-4-methylcoumarin)-<i>stat</i>-2-(diethylamino)­ethyl methacrylate-<i>stat</i>-(α-d-glucopyranosyl)­ethyl methacrylate] [PEO-<i>b</i>-P­(CMA-<i>stat</i>-DEA-<i>stat</i>-GEMA)]. The lectin bound in the glycopolymersome has different affinity for the glucose in the blood and the glucosyl group in the glycopolymersome. Therefore, this sugar sponge functions as a glucose storage unit by dynamic sugar replacement: The lectin in the sugar sponge will bind and store the glucose from its surrounding solution when the glucose concentration is too high and will release the glucose when the glucose concentration is too low. In vitro, this sugar-breathing behavior is characterized by a remarkable size change of the sugar sponge due to the swelling/shrinkage at high/low glucose levels, which can be used for blood sugar monitoring. In vivo, this sugar sponge showed an excellent antidiabetic effect for type I diabetic mice within 2 days upon one dose, which is much longer than traditional long-acting insulin. Overall, this concept of “controlling sugar levels with sugar” opens new avenues for regulating the blood glucose level without the involvement of insulin or other antidiabetic drugs

Preparation and Mechanism Insight of Nuclear Envelope-like Polymer Vesicles for Facile Loading of Biomacromolecules and Enhanced Biocatalytic Activity

The facile loading of sensitive and fragile biomacromolecules, such as glucose oxidase, hemoglobin, and ribonucleic acid (RNA), <i>via</i> synthetic vehicles directly in pure aqueous media is an important technical challenge. Inspired by the nucleus pore complex that connects the cell nucleus and the cytoplasm across the nuclear envelope, here we describe the development of a kind of polymeric nuclear envelope-like vesicle (NEV) to address this problem. The NEV is tailored to form the polymer pore complex (70 nm, similar to a nucleus pore complex) within the vesicle membrane based on nanophase segregation, which is confirmed <i>via</i> fluorescence spectrometry and dynamic light scattering (DLS) during self-assembly. This pH-triggered polymer pore complex can mediate the transportation of biomacromolecules across the vesicle membrane. Moreover, the NEVs facilitate the natural consecutive enzyme-catalyzed reactions <i>via</i> the H⁺ sponge effect. This simple strategy might also be extended for mimicking other synthetic cell organelles

Dually Gated Polymersomes for Gene Delivery

An ideal gene carrier requires an excellent gating system to efficiently load, protect, deliver, and release environmentally sensitive nucleic acids on demand. Presented in this communication is a polymersome with a “boarding gate” and a “debarkation gate” in the membrane to complete the above important missions. This dually gated polymersome is self-assembled from a block copolymer, poly­(ethylene oxide)-<i>block</i>-poly­[<i>N</i>-isopropylacrylamide-<i>stat</i>-7-(2-methacryloyloxyethoxy)-4-methylcoumarin-<i>stat</i>-2-(diethylamino)­ethyl methacrylate] [PEO-<i>b</i>-P­(NIPAM-<i>stat</i>-CMA-<i>stat</i>-DEA)]. The hydrophilic PEO chains form the coronas of the polymersome, whereas the temperature and pH-sensitive P­(NIPAM-<i>stat</i>-CMA-<i>stat</i>-DEA) block forms the dually gated heterogeneous membrane. The temperature-controlled “boarding gate” can be opened at room temperature for facile encapsulation of siRNA and plasmid DNA into polymersomes directly in aqueous solution. The “debarkation gate” can be triggered by proton sponge effect for intracellular release. Biological studies confirmed the successful encapsulation of siRNA and plasmid DNA, efficient in vitro and in vivo gene transfection, and the expression of green fluorescent protein (GFP) from GFP-encoding plasmid, suggesting that this kind of polymersome with a dual gating system can serve as an excellent biomacromolecular shuttle for gene delivery and other biological applications

Synthesis and Mechanism Insight of a Peptide-Grafted Hyperbranched Polymer Nanosheet with Weak Positive Charges but Excellent Intrinsically Antibacterial Efficacy

Antimicrobial resistance is an increasingly problematic issue in the world and there is a present and urgent need to develop new antimicrobial therapies without drug resistance. Antibacterial polymers are less susceptible to drug resistance but they are prone to inducing serious side effects due to high positive charge. Herein we report a peptide-grafted hyperbranched polymer which can self-assemble into unusual nanosheets with highly effective intrinsically antibacterial activity but weak positive charges (+ 6.1 mV). The hyperbranched polymer was synthesized by sequential Michael addition-based thiol–ene and free radical mediated thiol–ene reactions, and followed by ring-opening polymerization of <i>N</i>-carboxyanhydrides (NCAs). The nanosheet structure was confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM) studies. Furthermore, a novel “wrapping and penetrating” antibacterial mechanism of the nanosheets was revealed by TEM and it is the key to significantly decrease the positive charges but have a very low minimum inhibitory concentration (MIC) of 16 μg mL^–1 against typical Gram-positive and Gram-negative bacteria. Overall, our synthetic strategy demonstrates a new insight for synthesizing antibacterial nanomaterials with weak positive charges. Moreover, the unique antibacterial mechanism of our nanosheets may be extended for designing next-generation antibacterial agents without drug resistance

Multifunctional Homopolymer Vesicles for Facile Immobilization of Gold Nanoparticles and Effective Water Remediation

Homopolymers have been considered as a nonideal building block for creating well-defined nanostructures due to their fuzzy boundary between hydrophobic and hydrophilic moieties. However, this unique fuzzy boundary may provide some opportunities for fabricating functional nanomaterials. Presented in this paper is a pH-responsive multifunctional homopolymer vesicle based on poly[2-hydroxy-3-(naphthalen-1-ylamino)propyl methacrylate] (PHNA). This vesicle is confirmed to be an excellent supporter for gold nanoparticles (AuNPs) to facilitate the reduction reaction of 4-nitrophenol (4-NP). The pH-responsive vesicle membrane favors the effective embedding and full immobilization of AuNPs because it is kinetically frozen under neutral and basic environments, preventing AuNPs from aggregation. Meanwhile, there is a synergistic effect between the AuNPs and the supporter (PHNA vesicle). Due to the π–π interaction between the naphthalene pendants in every repeat unit of PHNA and the extra aromatic compounds, a substrate-rich (high concentration of 4-NP) microenvironment can be created around AuNPs, which can dramatically accelerate the AuNPs-catalyzed reactions. In addition, we proposed a method for more accurately determining the membrane thickness of rigid polymer vesicles from TEM images based on “stack-up” vesicles, which may overturn the measuring method commonly used by far. Moreover, proof-of-concept studies showed that those homopolymer vesicles may be used as a powerful adsorbent for effective water remediation to remove trace carcinogenic organic pollutants such as polycyclic aromatic hydrocarbons to below parts per billion (ppb) level at a very fast rate based on the π–π interaction between the naphthalene pendants in PHNA vesicle and polycyclic aromatic hydrocarbons. Overall, this multifunctional homopolymer vesicle provides an alternative insight on preparing effective recyclable AuNPs-decorated nanoreactor and powerful water remediation adsorbent

Efficient Removal of Polycyclic Aromatic Hydrocarbons, Dyes, and Heavy Metal Ions by a Homopolymer Vesicle

It is an important challenge to effectively remove environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs), dyes, and heavy metal ions at a low cost. Herein, we present a multifunctional homopolymer vesicle self-assembled from a scalable homopolymer, poly­(amic acid) (PAA), at room temperature. The vesicle can efficiently eliminate PAHs, cationic dyes, and heavy metal ions from water based on π–π stacking, hydrophobic effect, and electrostatic interactions with the pollutants. The residual concentrations of PAHs, cationic dyes, and heavy metal ions (such as Ni²⁺) in water are lower than 0.60 and 0.30 parts per billion (ppb) and 0.095 parts per million (ppm), respectively, representing a promising adsorbent for water remediation. Furthermore, precious metal ions such as Ag⁺ can be recovered into silver nanoparticles by <i>in situ</i> reduction on the membrane of PAA vesicles to form a silver nanoparticle/vesicle composite (Ag@vesicle) that can effectively catalyze the reduction of toxic pollutants such as aromatic nitro-compounds and be recycled for more than ten times