Photo Cleavable Thioacetal Block Copolymers for Controlled Release

We present a new light cleavable polymer containing o-nitrobenzene thioacetal groups in the main chain. By conjugation to a PEG block, we synthesized block copolymers capable of forming nanoparticles in aqueous solution. We studied drug encapsulation and release using the model drug Nile Red. Irradiation with UV-A light (365 nm) leads to efficient degradation of the polymers and associated burst release of the payload. Unlike other thioacetal and thioketal polymers, these polymers are stable to reactive oxygen species (ROS), preventing non-triggered release. Moreover, the nanocarriers showed low cytotoxicity in cell viability experiments

A Fuel-Driven Chemical Reaction Network Based on Conjugate Addition and Elimination Chemistry

Here, we propose a new chemical reaction network for fuel-driven transient formation of covalent bonds, based on redox-controlled conjugate addition and elimination chemistry. By investigating the separate reactions making up the cycle, we find that the bond formation, breaking and regeneration processes can be realized. At present, substantial side reactivity prevents achieving repeated operation of a full cycle in a single system. If such obstacles would be overcome, this chemical reaction network could be a valuable addition to the toolbox for out-of-equilibrium systems chemistry

Synergistically assembled RGO/Si3N4 whiskers hybrid aerogels to endow epoxy composites with excellent thermal and tribological performance

Abstract Epoxy resin (EP) composites with satisfactory thermal and tribological performance are highly required for engineering moving components. However, the simple addition of fillers leaded to the serious filler agglomeration and limited promotion in tribological properties. In this work, we constructed a new kind of three-dimensional (3D) reduced graphene oxide (RGO)/Si3N4 hybrid aerogel for EP composites, which was prepared by a facile hydrothermal self-assembly method followed by freeze-drying technique. As a result, the dispersibility of Si3N4 whiskers was greatly improved through wrapping of polydopamine—polyethyleneimine copolymer (PDA—PEI) copolymer and physical spacing of 3D skeleton. Furthermore, benefiting from the synergistic effect of RGO and Si3N4@PDA—PEI in the thermal network, the thermal conductivity of RGO/Si3N4 hybrid aerogel (GSiA)—EP increased by 45.4% compared to that of the neat EP. In addition, the friction coefficient and wear rate of GSiA—EP decreased by 83.7% and 35.8%, respectively. This work is significant for opening a tribological performance enhancement strategy though constructing 3D hybrid architecture

Efficacy and Safety of Immunosuppressive Therapy for PBC–AIH Overlap Syndrome Accompanied by Decompensated Cirrhosis: A Real-World Study

Aim. To explore the efficacy and safety of immunosuppressive therapy for the treatment of primary biliary cirrhosis-autoimmune hepatitis (PBC-AIH) overlap syndrome accompanied by decompensated cirrhosis. Methods. A cohort study was performed to evaluate the usefulness of immunosuppressive therapy in this unique group. This cohort study was performed between October 2013 and June 2017 and included 28 biopsy-proven patients diagnosed according to the Paris criteria. The therapies included ursodeoxycholic acid (UDCA) alone (N=14) or in combination with immunosuppression (IS) therapy (N=14). The primary endpoints were biochemical remission, liver-related adverse events, transplant-free survival, and drug side-effects. Results. The frequency of biochemical remission for the AIH features was significantly higher in the UDCA+IS group than in the UDCA-only group (60.0 versus 9.1%, P=0.024) after 12 months of therapy but not after 3 and 6 months (28.6 versus 0%, P=0.165; 35.7 versus 7.1%, P=0.098). The rates of liver-related adverse events were lower in the combined group (2/14 versus 9/14, P=0.018). The Kaplan-Meier estimate showed that the transplant-free survival was distinct between the two groups (P=0.019). In the UDCA+IS group, mild and transient leukopenia occurred in two patients receiving azathioprine (AZA), and an infection was observed in one patient receiving mycophenolate mofetil (MMF). Conclusions. PBC-AIH patients with decompensated cirrhosis receiving a combination of UDCA and immunosuppressors presented with higher biochemical remission rates and experienced fewer liver-related adverse events, implying that the combined treatment might be a better therapeutic option for strictly defined decompensated PBC-AIH overlap syndrome

Super-Transparent Soil for In Situ Observation of Root Phenotypes

Transparent soil (TS) presents immense potential for root phenotyping due to its ability to facilitate high-resolution imaging. However, challenges related to transparency, mechanical properties, and cost hinder its development. Herein, we introduce super-transparent soil (s-TS) prepared via the droplet method using low acyl gellan gum and hydroxyethyl cellulose crosslinked with magnesium ions. The refractive index of the hydroxyethyl cellulose solution (1.345) closely aligns with that of water (1.333) and the low acyl gellan gum solution (1.340), thereby significantly enhancing the transmittance of hydrogel-based transparent soil. Optimal transmittance (98.45%) is achieved with polymer concentrations ranging from 0.8 to 1.6 wt.% and ion concentrations between 0.01 and 0.09 mol·L−1. After 60 days of plant cultivation, s-TS maintains a transmittance exceeding 89.5%, enabling the detailed visualization of root growth dynamics. Furthermore, s-TS exhibits remarkable mechanical properties, withstanding a maximum compressive stress of 477 kPa and supporting a maximum load-bearing depth of 186 cm. This innovative approach holds promising implications for advanced root phenotyping studies, fostering the investigation of root heterogeneity and the development of selective expression under controlled conditions

Self-propelled supramolecular nanomotors with temperature-responsive speed regulation

Self-propelled catalytic micro- and nanomotors have been the subject of intense study over the past few years, but it remains a continuing challenge to build in an effective speed-regulation mechanism. Movement of these motors is generally fully dependent on the concentration of accessible fuel, with propulsive movement only ceasing when the fuel consumption is complete. Here we report a demonstration of control over the movement of self-assembled stomatocyte nanomotors via a molecularly built, stimulus-responsive regulatory mechanism. A temperature-sensitive polymer brush is chemically grown onto the nanomotor, whereby the opening of the stomatocytes is enlarged or narrowed on temperature change, which thus controls the access of hydrogen peroxide fuel and, in turn, regulates movement. To the best of our knowledge, this represents the first nanosized chemically driven motor for which motion can be reversibly controlled by a thermally responsive valve/brake. We envision that such artificial responsive nanosystems could have potential applications in controllable cargo transportation

Stomatocyte in Stomatocyte: A New Shape of Polymersome Induced via Chemical-Addition Methodology

Accurate control of the shape transformation of polymersome is an important and interesting challenge that spans across disciplines such as nanomedicine and nanomachine. Here, we report a fast and facile methodology of shape manipulation of polymersome via out-of-equilibrium polymer self-assembly and shape change by chemical addition of additives. Due to its increased permeability, hydrophilicity, and fusogenic properties, poly­(ethylene oxide) was selected as the additive for bringing the system out of equilibrium via fast addition into the polymersome organic solution. A new shape, stomatocyte-in-stomatocyte (sto-in-sto), is obtained for the first time. Moreover, fast shape transformation within less than 1 min to other relevant shapes such as stomatocyte and large compound vesicles was also obtained and accurately controlled in a uniform dispersion. This methodology is demonstrated as a general strategy with which to push the assembly further out of equilibrium to generate unusual nanostructures in a controllable and fast manner