Fully Floatable Mortise-and-Tenon Architecture for Synergistically Photo/Sono-Driven Evaporation Desalination and Plastic-Enabled Value-Added Co-Conversion of H2O and CO2.

Establishing an advanced ecosystem incorporating freshwater harvesting, plastic utilization, and clean fuel acquisition is profoundly significant. However, low-efficiency evaporation, single energy utilization, and catalyst leakage severely hinder sustainable development. Herein, a nanofiber-based mortise-and-tenon structural Janus aerogel (MTSJA) is strategically designed in the first attempt and supports Z-scheme catalysts. By harnessing of the upper hydrophilic layer with hydrophilic channels embedding into the hydrophobic bottom layer to achieve tailoring bottom wettability states. MTSJA is capable of a fully-floating function for lower heat loss, water supply, and high-efficiency solar-to-vapor conversion. Benefiting from the ultrasonic cavitation effect and high sensitivity of materials to mechanical forces, this is also the first demonstration of synergistic solar and ultrasound fields to power simultaneous evaporation desalination and waste plastics as reusable substrates generating fuel energy. The system enables persistent desalination with an exceptional evaporation rate of 3.1 kg m-2 h-1 and 82.3% efficiency (21 wt.% NaCl solution and 1 sun), and realizes H2, CO, and CH4 yields with 16.1, 9.5, and 3 µmol h-1 g-1, respectively. This strategy holds great potential for desalination and plastics value-added transformation toward clean energy and carbon neutrality.

Sculpting Mesoscopic Helical Chirality into Covalent Organic Framework Nanotubes from Entirely Achiral Building Blocks.

The diversification of chirality in covalent organic frameworks (COFs) holds immense promise for expanding their properties and functionality. Herein, we introduce an innovative approach for imparting helical chirality to COFs and fabricating a family of chiral COF nanotubes with mesoscopic helicity from entirely achiral building blocks for the first time. We present an effective 2,3-diaminopyridine-mediated supramolecular templating method, which facilitates the prefabrication of helical imine-linked polymer nanotubes using unprecedented achiral symmetric monomers. Through meticulous optimization of crystallization conditions, these helical polymer nanotubes are adeptly converted into imine-linked COF nanotubes boasting impressive surface areas, while well preserving their helical morphology and chiroptical properties. Furthermore, these helical imine-linked polymers or COFs could be subtly transformed into corresponding more stable and functional helical ß-ketoenamine-linked and hydrazone-linked COF nanotubes with transferred circular dichroism via monomer exchange. Notably, despite the involvement of covalent bonding breakage and reorganization, these exchange processes overcome thermodynamic disadvantages, allowing mesoscopic helical chirality to be perfectly preserved. This research highlights the potential of mesoscopic helicity in conferring COFs with favourable chiral properties, providing novel insights into the development of multifunctional COFs in the field of chiral materials chemistry.

Biomimetic Natural Silk Nanofibrous Microspheres for Multifunctional Biomedical Applications.

Silk nanofibrils (SNFs) extracted from natural silkworm silk represent a class of high-potential protein nanofiber material with unexplored biomedical applications. In this study, a SNF-assembled microsphere with extracellular matrix (ECM)-mimicking architecture and high specific surface area was developed. The SNFs were exfoliated from silkworm silks through an all-aqueous process and used as the building blocks for constructing the microspheres. Inspired by the structure and bioactive composition of ECM, hyaluronic acid (HA) was used as a bio-glue to regulate SNF assembly. With the assistance of HA, the SNF microspheres with stable fluffy nanofibrous structures were synthesized through electrospray. The biomimetic structure and nature derived composition endow the microspheres with excellent biocompatibility and enhanced osteogenic differentiation-inducing ability to mesenchymal stem cells. As proof of versatility, the SNF microspheres were further functionalized with other molecules and nanomaterials. Taking the advantages of the excellent blood compatibility and modifiability from the molecular level to the nanoscale of SNF microspheres, we demonstrated their versatile applications in protease detection and blood purification. On the basis of these results, we foresee that this natural silk-based nanofibrous microsphere may serve as a superior biomedical material for tissue engineering, early disease diagnosis, and therapeutic devices.

Physically crosslinked silk fibroin/hyaluronic acid scaffolds.

Combining the properties of natural protein and polysaccharide is a promising strategy to generate bioactive biomaterials with controlled structure. Here, a new method of preparing water-insoluble silk fibroin/hyaluronic acid (SF/HA) scaffolds with tunable performances using an all-aqueous process is reported. Freezing-induced assembly was used to form silk I crystallization in the SF/HA blends. Silk I crystallization enhanced the stability of SF/HA scaffolds in water by forming silk I crystal networks to entrap blended HA without chemical cross-linking. Increasing HA content significantly enhanced the flexibility and water binding capacity of porous scaffolds, but high amount of HA reduced the water-stability of porous scaffolds due to insufficient silk I crystal cross-links. The enzymatic degradation behavior of the SF/HA scaffolds was investigated, revealing that the regulation ability of HA in the SF scaffolds. This novel nonchemically cross-linked protein/polysaccharide scaffold may be useful for soft tissue engineering due to excellent biocompatibility and tunable performances.

Cu(II) ion loading in silk fibroin scaffolds with silk I structure.

Metal ions play important roles in the diverse biochemical reactions associated with many cell signalling pathways. The modification of biomaterials with metal ions may offer a promising approach to stimulate cellular activity for improving tissue regeneration. Here, copper ion loading as a potential therapeutic agent in silk fibroin (SF) scaffolds was investigated. Freezing-annealing was used to induce silk I crystallization for forming water-insoluble SF scaffolds. Cu(II) ions were entrapped into SF scaffolds with different ratios by forming silk I crystal networks when copper chloride dihydrate was less than 5.0 wt%, producing water-stable materials. Moreover, it was found that copper ion chelation further enhanced SF stability when a low amount copper chloride was loaded. Increasing copper chloride content weakened silk I crystallization and Cu(II) ion chelation, rendering SF scaffolds unstable in water. Above 5.0 wt% copper chloride dihydrate, silk I crystallization was prevented. Finally, silk I scaffold with 1.5 wt% copper chloride dihydrate showed the strongest water-stability and highest loading efficiency. The results provide valuable data for understanding the effect of metal ions in freezing-induced SF crystallization, and also offer options for preparing novel Cu(II)-functionalized SF scaffolds.