Self-Reinforced MOF-Based Nanogel Alleviates Osteoarthritis by Long-Acting Drug Release.

Intra-articular injection of drugs is an effective strategy for osteoarthritis (OA) treatment. However, the complex microenvironment and limited joint space result in rapid clearance of drugs. Herein, a nanogel-based strategy is proposed for prolonged drug delivery and microenvironment remodeling. Nanogel is constructed through the functionalization of hyaluronic acid (HA) by amide reaction on the surface of Kartogenin (KGN)-loaded zeolitic imidazolate framework-8 (denoted as KZIF@HA). Leveraging the inherent hydrophilicity of HA, KZIF@HA spontaneously forms nanogels, ensuring extended drug release in the OA microenvironment. KZIF@HA exhibits sustained drug release over one month, with low leakage risk from the joint cavity compared to KZIF, enhanced cartilage penetration, and reparative effects on chondrocytes. Notably, KGN released from KZIF@HA serves to promote extracellular matrix (ECM) secretion for hyaline cartilage regeneration. Zn2+ release reverses OA progression by promoting M2 macrophage polarization to establish an anti-inflammatory microenvironment. Ultimately, KZIF@HA facilitates cartilage regeneration and OA alleviation within three months. Transcriptome sequencing validates that KZIF@HA stimulates the polarization of M2 macrophages and secretes IL-10 to inhibit the JNK and ERK pathways, promoting chondrocytes recovery and enhancing ECM remodeling. This pioneering nanogel system offers new therapeutic opportunities for sustained drug release, presenting a significant stride in OA treatment strategies.

Emulsion Interfacial Synthesis of Polymer/Inorganic Janus Particles.

We report a method to prepare polymer/inorganic Janus particles by transferring self-assembled membranes of copolymers such as PS- b-PAA at an emulsion interface when the amine-capped particles such as paramagnetic Fe3O4@SiO2 core/shell particles are preferentially adsorbed by specific interactions. While the particles are protected, the exposed side can be further modified to conjugate aldehyde-capped polyethylene oxide (PEO). Both connections become robust by covalent bonds. The hydrophilic PEO and hydrophobic PS chains are distinctly compartmentalized onto the opposite sides of the Fe3O4@SiO2 particles. As a magnetic responsive solid surfactant, the stabilized emulsions can be driven with a magnet for directional movement and coalescence with increasing magnetic strength. This method can be extended to other Janus particles with tunable organic materials and solid particles.

Particle Mold Synthesis of Block Copolymer Janus Nanomaterials.

A particle mold synthesis of 2D Janus nanomaterials is proposed by crosslinking of copolymer self-assembled monolayers confined within the mold domains. Onto the silica (SiO2 ) particle surface, mold domains with functional groups such as imidazole are generated. The model copolymer of polyacrylic acid-block-polystyrene (PAA-b-PS) can be preferentially absorbed onto the domains via electrostatic interactions, forming a self-assembled monolayer. In a cosolvent such as tetrahydrofuran (THF), the crosslinking occurs within the whole of the PAA side. A Janus disc is thus achieved after detachment from the particle upon breaking the specific interaction. In a poor solvent, the crosslinking slowly occurs from the periphery, giving Janus nanorings. The rings evolve into discs with further crosslinking. The mold particles can be recycled to synthesize the same 2D Janus materials.

Responsive Janus Cage Reactor.

A Janus silica cage was synthesized by selectively grafting an ionic liquid (IL) and poly-N-isopropylacrylamide (PNIPAM) (lower critical solution temperature (LCST)≈32 °C) onto the exterior and interior sides of the mesoporous SiO2 shell. The paramagnetic core inside the cavity is responsible for magnetic collection. The PW12 O40 3- anion is further conjugated onto the IL side by anion exchange. The Janus cage acts as a thermal-responsive reactor for catalytic oxidization of dibenzothiophene (DBT) in the presence of H2 O2 . The sulfide in the model oil can be completely decomposed at 25 °C, whilst the oxidative products are more dissoluble in water and preferentially captured inside the Janus cage. The Janus cage reactor could be regenerated at high temperature above 32 °C after releasing the products.

Bottlebrush-Colloid Janus Nanoparticles.

A bottlebrush-colloid Janus nanoparticle (JNP) with a ball-and-stick structure is reported. A single poly(4-vinyl benzyl chloride) (PVBC) polymer chain was grafted onto the amine-capped Fe3O4@NH2 nanoparticle. pH-responsive 2-diethylaminoethyl methacrylate (DEAEMA) and water-soluble oligo(ethylene glycol) methacrylate (OEGMA) were sequentially grown from the PVBC backbone by ATRP, forming a core-shell bottlebrush. The synthesized PVBC208-g-(PDEAEMA13-b-POEGMA8)-Fe3O4@NH2 JNPs are dispersible in water and can be manipulated by a magnet. The Fe3O4 NPs with exposed -NH2 groups facilitate accumulation at acidic sites. Hydrophobic dyes can be loaded within the PDEAEMA at pH ≥ 7.5, while they are released at pH values below 6.8. The composite JNPs are promising as a guided pH-responsive delivery vector toward acidic solid tumors.

Ion-triggered calcium hydroxide microcapsules for enhanced corrosion resistance of steel bars.

Herein, we synthesized Ca(OH)2 microcapsules with ion-responsive shells composed of cross-linked poly-ionic liquids (CPILs). By exchanging PF6 - with Cl- in water, the hydrophobic poly-ionic liquids (PILs) on the shell are converted to hydrophilic channels. The encapsulated Ca(OH)2 can permeate through the hydrophilic channels and release OH-. Meanwhile, the Cl- content can be reduced. The release rate of Ca(OH)2 is influenced by the content of monomers and concentration of Cl- ions in water. SO4 2- can also trigger the release of Ca(OH)2 from the microcapsule. With these microcapsules, Q235 steel exhibited promising corrosion resistance in simulated seawater. These results indicate that encapsulation of corrosion inhibitors is highly desirable for enhanced corrosion resistance of steel bars and the proposed approach can be used to encapsulate various corrosion inhibitors and functional materials for a wide range of applications.

Coral-like Janus Porous Spheres.

A Janus porous sphere with a coral-like microstructure is prepared by stepwise dealloying a metallic alloy sphere and sequential modification (for example, using silanes and polymers). Nanoscale coral-like microstructure of the internal skeleton gives remarkable capillary force, thus accelerating the mass transportation. Starting from the outer layer of the sphere, stepwise dealloying can achieve different layers inwardly, thus introducing different composition and performance. As an example, poly(ethylene glycol)-poly(N-isopropylacrylamide) (PEG-PNIPAM)- and poly(ethylene glycol)-poly(N,N-diethylamino-2-ethylmethacrylate) (PEG-PDEAEMA)-responsive Janus porous spheres can quickly capture oil by simply changing temperature or pH. Similarly, release is also triggered.

Magnetic Hydrogels from Alkyne/Cobalt Carbonyl-Functionalized ABA Triblock Copolymers.

A series of alkyne-functionalized poly(4-(phenylethynyl)styrene)-block-poly(ethylene oxide)-block-poly(4-(phenylethynyl)styrene) (PPES-b-PEO-b-PPES) ABA triblock copolymers was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. PESn[Co2(CO)6]x-EO800-PESn[Co2(CO)6]x ABA triblock copolymer/cobalt adducts (10-67 wt % PEO) were subsequently prepared by reaction of the alkyne-functionalized PPES block with Co2(CO)8 and their phase behavior was studied by TEM. Heating triblock copolymer/cobalt carbonyl adducts at 120 °C led to cross-linking of the PPES/Co domains and the formation of magnetic cobalt nanoparticles within the PPES/Co domains. Magnetic hydrogels could be prepared by swelling the PEO domains of the cross-linked materials with water. Swelling tests, rheological studies and actuation tests demonstrated that the water capacity and modulus of the hydrogels were dependent upon the composition of the block copolymer precursors.