Zhihong Dong,Ying Zhu,Xuexi Zhang,Xinliang Zhang,Xueting Zhao,Jiefeng Pan
Covalent organic frameworks (COFs) are ideal materials for engineering molecular sieves membranes. Colloidal COFs play an important role in the preparation of defect-free COF membranes. Herein, we present the alkali-mediated approach to synthesize uncharged β -ketoenamine-linked COFs with high colloidal dispersibility that can serve as preferred membrane-forming materials. The colloidal β -ketoenamine-linked COFs are synthesized in the single solution-phase system and alkali is employed to regulate the reversible dynamic amine-aldehyde condensation process by directing the weak hydrogen bond networks. The colloidal COFs obtained from alkali-mediated synthesis exhibit promoted crystallinity and outstanding dispersity for membrane construction. Furthermore, the alkali-mediated synthesis approach is universal and suitable for synthesizing a series of colloidal β -ketoenamine-linked COFs without the limitations of charged monomers or frameworks. The colloidal COFs are further assembled into COF membranes by vacuum-assisted assembly. Thanks to the intrinsic regular pore structure of COFs, the COF membranes exhibit high permeability (58 L m −2 h −1 ·bar −1 ) and can achieve accurate screening of dye molecules. This work provides a facile and scalable synthesis strategy for uncharged colloidal COFs, and can be employed to develop COF membranes for on-demand molecule separation.
Severe damage to the uterine endometrium , which results in scar formation and endometrial dysfunction, eventually leads to infertility or pregnancy-related complications. No effective therapeutic treatment is currently available for such injuries owing to the structural complexity, internal environment, and function of the uterus. Three-dimensional (3D) bio-printing to engineer biomimetic structural constructs provides a unique opportunity for tissue regeneration . Herein, using 3D extrusion-based bioprinting (EBB), we constructed a bilayer endometrial construct (EC) based on a sodium alginate-hyaluronic acid (Alg-HA) hydrogel for functional regeneration of the endometrium. The upper layer of the 3D bio-printed EC is a monolayer of endometrial epithelial cells (EECs), while the lower layer has a grid-like microstructure loaded with endometrial stromal cells (ESCs). In a partial full-thickness uterine excision rat model, our bilayer EC not only restored the morphology and structure of the endometrial wall (including organized luminal/ glandular epithelium, stroma, vasculature and the smooth muscle layer), but also significantly improved the reproductive outcome in the surgical area after implantation (75%, 12/16, p < 0.01). Therefore, repair of the uterine endometrium using the developed 3D bio-printed bilayer EC may represent an effective regenerative treatment for severe endometrial injury. Statement of significance Achieving structural and functional recovery of the endometrium following severe injury is still a challenge. Here, we designed a 3D bio-printed endometrial construct (EC) to mimic the native bilayer structure and cellular components of the endometrium. The bio-printed EC consists of a dense upper layer with endometrial epithelial cells and a lower layer with endometrial stromal cells. In particular, the 3D bio-printed EC significantly improved the reproductive outcome in the surgical area (75%, 12/16) compared to that of the cell-loaded non-printed group (12.5%, 2/16). This study demonstrates that a biomimetic bilayer construct can facilitate endometrial repair and regeneration. Therefore, an endometrial cells-loaded 3D-bioprinted EC is a promising therapeutic option for patients suffering from severe endometrial damage.
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