The regeneration of tooth enamel, the hardest biological tissue, remains a considerable challenge because its complicated and well-aligned apatite structure has not been duplicated artificially. We herein reveal that a rationally designed material composed of calcium phosphate ion clusters can be used to produce a precursor layer to induce the epitaxial crystal growth of enamel apatite, which mimics the biomineralization crystalline-amorphous frontier of hard tissue development in nature. After repair, the damaged enamel can be recovered completely because its hierarchical structure and mechanical properties are identical to those of natural enamel. The suggested phase transformation–based epitaxial growth follows a promising strategy for enamel regeneration and, more generally, for biomimetic reproduction of materials with complicated structure.
Spider silk fibers (SSF) have a hierarchical structure composed of proteins with highly repetitive sequences and biomineralization is sophisticated in hierarchical organic-inorganic constructions. By using inorganic hydroxyapatite (HAP) and organic polyvinyl alcohol (PVA) to simulate the rigid crystalline and flexible amorphous protein blocks of SSF, respectively, biomimetic mineralization is herein attempted for the large-scale preparation of SSF-like macrofibers with a hierarchical ordered structure, a superhigh tensile strength of 949 ± 38 MPa, a specific toughness of 296 ± 12 J g −1 , and a stretch ability of 80.6%. The hybrid macrofibers consist of microfibers, and their outstanding performance (e.g., extreme tolerance to temperatures ranging from −196 to 80 °C and superior ability to inhibit the transverse growth of cracks) is attributed to the hierarchical arrangement as well as the organic-inorganic integrated structure within the oriented mineralized polymer chains. The biomineralization-inspired technique provides a promising tactic that can be used to synthesize functional organicinorganic fibers that are structurally complex and, furthermore, industrially manufacture SSF-like artificial fibers with a supertoughness.
Rhesus D (RhD) is one of the most important immunogenic antigens on red blood cells (RBCs). However, the supply of RhD-negative blood frequently faces critical shortages in clinical practice, and the positive-to-negative transition of the RhD antigen remains a great challenge. Here, we developed an alternative approach for sheltering the epitopes on RhD-positive RBCs using a surface-anchored framework, which is flexible but can achieve an optimal shield effect with minimal physicochemical influence on the cell. The chemical framework completely obstructed the RhD antigens on the cell surface, and the assessments of both blood transfusion in a mouse model and immunostimulation with human RhD-positive RBCs in a rabbit model confirmed the RhD-epitope stealth characteristics of the engineered RBCs. This work provides an efficient methodology for improving the cell surface for universal blood transfusion and generally indicates the potential of rationally designed cell surface engineering for transfusion and transplantation medicine.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.