Synthesis and Assembly of Laccase-Polymer Giant Amphiphiles by Self-Catalyzed CuAAC Click Chemistry

Covalent coupling of hydrophobic polymers to the exterior of hydrophilic proteins would mediate unique macroscopic assembly of bioconjugates to generate amphiphilic superstructures as novel nanoreactors or biocompatible drug delivery systems. The main objective of this study was to develop a novel strategy for the synthesis of protein-polymer giant amphiphiles by the combination of copper-mediated living radical polymerization and azide–alkyne cycloaddition reaction (CuAAC). Azide-functionalized succinimidyl ester was first synthesized for the facile introduction of azide groups to proteins such as albumin from bovine serum (BSA) and laccase from <i>Trametes versicolor</i>. Alkyne-terminal polymers with varied hydrophobicity were synthesized by using commercial copper wire as the activators from a trimethylsilyl protected alkyne-functionalized initiator in DMSO under ambient temperature. The conjugation of alkyne-functionalized polymers to the azide-functionalized laccase could be conducted even without additional copper catalyst, which indicated a successful self-catalyzed CuAAC reaction. The synthesized amphiphiles were found to aggregate into spherical nanoparticles in water and showed strong relevance to the hydrophobicity of coupled polymers. The giant amphiphiles showed decreased enzyme activity yet better stability during storage after chemical modification and self-assembly. These findings will deepen our understanding on protein folding, macroscopic self-assembly, and support potential applications in bionanoreactor, enzyme immobilization, and water purification

Nitrogen-Coordinated Boroxines Enable the Fabrication of Mechanically Robust Supramolecular Thermosets Capable of Healing and Recycling under Mild Conditions

The fabrication of mechanically robust polymeric materials capable of self-healing and recycling remains challenging because the mobility of polymer chains in such polymers is very limited. In this work, mechanically robust supramolecular thermosets capable of healing physical damages and recycling under mild conditions are fabricated by trimerization of bi-(ortho-aminomethyl-phenylboronic acid)- and tri-(ortho-aminomethyl-phenylboronic acid)-terminated poly­(propylene glycol) oligomers (denoted as Bi-PBA-PPG and Tri-PBA-PPG, respectively). The resultant supramolecular thermosets are cross-linked by dynamic covalent bonds of nitrogen-coordinated boroxines. The mechanical properties of the supramolecular thermosets can be systematically tailored by varying the ratios between Tri-PBA-PPG and Bi-PBA-PPG, which changes the cross-linking density of nitrogen-coordinated boroxines and the topology of the supramolecular thermosets. The mechanically strongest supramolecular thermosets with a molar ratio of Tri-PBA-PPG to Bi-PBA-PPG being 1:2 have a glass transition temperature of ∼36 °C, a tensile strength of ∼31.96 MPa, and a Young’s modulus of ∼298.5 MPa. The high reversibility of nitrogen-coordinated boroxines and the flexibility of poly­(propylene glycol) chains enable the supramolecular thermosets with the strongest mechanical strength to be highly efficiently healed at 55 °C and recycled under a pressure of 4 MPa at 60 °C to regain their original mechanical strength and integrity

Nitrogen-Coordinated Boroxines Enable the Fabrication of Mechanically Robust Supramolecular Thermosets Capable of Healing and Recycling under Mild Conditions

The fabrication of mechanically robust polymeric materials capable of self-healing and recycling remains challenging because the mobility of polymer chains in such polymers is very limited. In this work, mechanically robust supramolecular thermosets capable of healing physical damages and recycling under mild conditions are fabricated by trimerization of bi-(ortho-aminomethyl-phenylboronic acid)- and tri-(ortho-aminomethyl-phenylboronic acid)-terminated poly­(propylene glycol) oligomers (denoted as Bi-PBA-PPG and Tri-PBA-PPG, respectively). The resultant supramolecular thermosets are cross-linked by dynamic covalent bonds of nitrogen-coordinated boroxines. The mechanical properties of the supramolecular thermosets can be systematically tailored by varying the ratios between Tri-PBA-PPG and Bi-PBA-PPG, which changes the cross-linking density of nitrogen-coordinated boroxines and the topology of the supramolecular thermosets. The mechanically strongest supramolecular thermosets with a molar ratio of Tri-PBA-PPG to Bi-PBA-PPG being 1:2 have a glass transition temperature of ∼36 °C, a tensile strength of ∼31.96 MPa, and a Young’s modulus of ∼298.5 MPa. The high reversibility of nitrogen-coordinated boroxines and the flexibility of poly­(propylene glycol) chains enable the supramolecular thermosets with the strongest mechanical strength to be highly efficiently healed at 55 °C and recycled under a pressure of 4 MPa at 60 °C to regain their original mechanical strength and integrity

Mechanically Robust yet Body-Temperature Self-Healable Polyurethane Elastomer via the Cross-Linking of Dynamic Boroxines

It has been a long-standing goal to develop self-healable polyurethane elastomers with desirable mechanical strength and toughness to satisfy the needs of practical applications. However, the conflict between mechanical strength and self-healing efficiency makes the development of such materials very challenging. Here, we have developed a mechanically robust and body-temperature self-healable polyurethane elastomer via the synergy of multiple dynamic reversible non- and covalent interactions in the polymer networks. The design selects flexible 1,4-butanediol bis(3-aminopropyl) ether (BBE) as the chain extender to endow the elastomer with toughness and chain flexibility to benefit its self-healing at body temperature. In addition, 4-formylphenylboronic acid (4-FPBA) was used to cross-link the polyurethane prepolymer to enhance the mechanical properties by the dehydration of phenylboronic acids. Therefore, the as-prepared boroxine cross-linked poly(urethane-urea) (PUUI-Boroxine) elastomer exhibited high mechanical strength and toughness of ∼49.2 MPa and ∼162.9 MJ m–3, respectively. Importantly, the damaged PUUI-Boroxine elastomer can be healed with a high healing efficiency of 91% at 37 °C for 15 h. The PUUI-Boroxine elastomer can also be solution reprocessed for at least three cycles with only a minimal decline in its mechanical properties. Finally, the PUUI-Boroxine elastomer can be employed to fabricate a body-temperature self-healable watchband. This work provides a facile strategy for the development of body-temperature self-healable polyurethane elastomers with outstanding mechanical strength and toughness

Near-Infrared Light-Stimulus-Responsive Film as a Sacrificial Layer for the Preparation of Free-Standing Films

It remains a challenge to fabricate sacrificial films that are stable in most of solvents and can be readily decomposed on demand. Here we report the fabrication of a near-infrared (NIR) light decomposable sacrificial film by layer-by-layer (LbL) assembly of UV-light-decomposable poly­((4-(2-bromoethoxy)-5-methoxy-2-nitrobenzyl acrylate) triethylammonium bromide) (PNBA-TEA), poly­(sodium 4-styrene-sulfonate) (PSS), branched polyethyleimine (bPEI), and lanthanide-doped upconversion nanoparticles (UCNPs). The [(PNBA-TEA/PSS)*2/(bPEI/UCNPs)*3]*2 films are stable in deposition solutions of various materials and decompose upon NIR light irradiation. In the [(PNBA-TEA/PSS)*2/(bPEI/UCNPs)*3]*2 films, UCNPs can convert NIR light into UV light, which can decompose PNBA-TEA. After immersing the NIR light-irradiated [(PNBA-TEA/PSS)*2/(bPEI/UCNPs)*3]*2 films in 0.1 M aqueous NaHCO3 solution, the disintegration of the entire films occurs because of the repulsive force between the negatively charged photoproduct of PNBA-TEA and PSS. LbL-assembled (PAH/PAA)*50 films deposited on top of the NIR-light-decomposable [(PNBA-TEA/PSS)*2/(bPEI/UCNPs)*3]*2 films can be conveniently released to produce large-area and defect-free (PAH/PAA)*50 free-standing films after NIR light irradiation and subsequent immersion in 0.1 M aqueous NaHCO3 solution. Because of the satisfactory stability and on-demand decomposable property, the [(PNBA-TEA/PSS)*2/(bPEI/UCNPs)*3]*2 films are promising as sacrificial layers for the fabrication of various free-standing films

Data_Sheet_1_The Active Components of Sunflower (Helianthus annuus L.) Calathide and the Effects on Urate Nephropathy Based on COX-2/PGE2 Signaling Pathway and the Urate Transporter URAT1, ABCG2, and GLUT9.docx

The sunflower (Helianthus annuus L.) calathide is gradually used as an alternative treatment for hyperuricemia; nevertheless, evidence regarding its main components and therapeutic capacity for urate nephropathy is lacking. Identification of sunflower calathide aqueous extract (SCE) was rapidly done by UPLC-ESI-Q-Orbitrap, and 32 water-soluble compounds with a comprehensive score >80 were discovered. Besides, yeast extract was administrated to induce high UA levels and hyperuricemic renal injury. We found that SCE treatment not only decreased UA levels to a comparable degree as allopurinol and benzbromarone, but also reduced the BUN levels and participated in kidney injury repair induced by uric acid. Moreover, it regulated the expression of URAT1 and ABCG2, especially inhibiting the GLUT9 in the normal kidney. Results were multifacetedly evaluated with a view to suggesting a possible mechanism of action as compared with those of allopurinol and benzbromarone by western blotting, H&E staining, and immunohistochemistry. However, the H&E staining showed histological changes in model, benzbromarone, and allopurinol groups rather than SCE treatments, and at the same time, the uric acid was identified as a cause of renal damage. The antiinflammatory effects and the regulations of COX-2/PGE2 signaling pathway were revealed on the LPS-induced RAW264.7 cells, indicating that the SCE not only increased cellular proliferation but also downregulated the COX-2, PGE2, NO, and IFN-γ cytokines in the RAW264.7 cells. To conclude, the SCE acts on urate transporters and contributes to prevent urate nephropathy via alleviating inflammatory process involving COX-2/PGE2 signaling pathway. It is available to develop SCE as food supplemental applications for hyperuricemia and nephritic inflammation.</p

Chemically Recyclable Supramolecular Thermosets toward Strong and Reusable Hot-Melt Adhesives

Chemically recyclable thermosets are an ideal substitute for traditional thermosets in the development of a circular economy and sustainable environment. However, the development of efficient and easy-to-achieve chemical recycling strategies remains challenging. Herein, a series of supramolecular thermosets that can be chemically recycled under mild acid conditions at room temperature are fabricated by cross-linking the polyimine polymers with dynamic boroxines (PIx-Boroxine). By tailoring the molar content of boroxines, the PI1.2-boroxine can exhibit a tensile strength of ∼30.6 MPa, a tensile yield strength of 33.0 MPa, an elongation at break of ∼111.6%, and a Young’s modulus of ∼679.6 MPa. Because of the dynamic nature of boroxines and imine bonds, the PIx-boroxine supramolecular thermoset exhibits fast stress relaxation behavior, which enables them to have good reprocessing ability. These unique features can also guarantee the PIx-boroxine supramolecular thermosets to be a high-performance reusable hot-melt adhesive. The maximum lap shear strength of the PIx-Boroxine-based hot-melt adhesives in stainless steel bonding adhesive can reach ∼18.6 MPa, which is comparable to that of commercial hot-melt adhesives. Meanwhile, the PIx-Boroxine-based hot-melt adhesives can be reused at least 10 times with only a small amount of reduction in lap shear strength. More importantly, the PIx-boroxine supramolecular thermosets can be easily depolymerized in a 0.1 M HCl/H2O solution at room temperature. Further, the monomers can be easily and efficiently separated by a simple separation procedure. The recovered monomers can also be reused to fabricate new PIx-boroxine supramolecular thermosets without losing their mechanical properties. This work provides a new design strategy to develop high-performance thermosets with easy-to-achieve chemical recyclability, which will contribute to the sustainable development of modern society