Biomimetic Scaffolds for Tissue Engineering

Biomimetic scaffolds mimic important features of the extracellular matrix (ECM) architecture and can be finely controlled at the nano‐ or microscale for tissue engineering. Rational design of biomimetic scaffolds is based on consideration of the ECM as a natural scaffold; the ECM provides cells with a variety of physical, chemical, and biological cues that affect cell growth and function. There are a number of approaches available to create 3D biomimetic scaffolds with control over their physical and mechanical properties, cell adhesion, and the temporal and spatial release of growth factors. Here, an overview of some biological features of the natural ECM is presented and a variety of original engineering methods that are currently used to produce synthetic polymer‐based scaffolds in pre‐fabricated form before implantation, to modify their surfaces with biochemical ligands, to incorporate growth factors, and to control their nano‐ and microscale geometry to create biomimetic scaffolds are discussed. Finally, in contrast to pre‐fabricated scaffolds composed of synthetic polymers, injectable biomimetic scaffolds based on either genetically engineered‐ or chemically synthesized‐peptides of which sequences are derived from the natural ECM are discussed. The presence of defined peptide sequences can trigger in situ hydrogelation via molecular self‐assembly and chemical crosslinking. A basic understanding of the entire spectrum of biomimetic scaffolds provides insight into how they can potentially be used in diverse tissue engineering, regenerative medicine, and drug delivery applications.     

Capillary Network‐Like Organization of Endothelial Cells in PEGDA Scaffolds Encoded with Angiogenic Signals via Triple Helical Hybridization

Survival of tissue engineered constructs after implantation depends on proper vascularization. The differentiation of endothelial cells into mature microvasculature requires dynamic interactions between cells, scaffold, and growth factors, which are difficult to recapitulate in artificial systems. Previously, photocrosslinked poly(ethylene glycol) diacrylate (PEGDA) hydrogels displaying collagen mimetic peptides (CMPs), dubbed PEGDA‐CMP, that can be further conjugated with bioactive molecules via CMP‐CMP triple helix hybridization were reported. Here, it is shown that a bifunctional peptide featuring pro‐angiogenic domain mimicking vascular endothelial growth factor (VEGF) and a collagen mimetic domain that can fold into a triple helix conformation can hybridize with CMP side chains of the PEGDA‐CMP hydrogel, which results in presentation of insoluble VEGF‐like signals to endothelial cells. Presentation of VEGF‐like signals on the surface of micropatterned scaffolds in this way transforms cells from a quiescent state to elongated and aligned phenotype suggesting that this system could be used to engineer organized microvasculature. It is also shown that the pro‐angiogenic peptide, when applied topically in combination with modified dextran/PEGDA hydrogels, can enhance neovascularization of burn wounds in mice demonstrating the potential clinical use of CMP‐mediated matrix‐bound bioactive molecules for dermal injuries.     

Formation of Embryoid Bodies with Controlled Sizes and Maintained Pluripotency in Three‐Dimensional Inverse Opal Scaffolds

Embryoid bodies (EBs) are aggregates of cells derived from embryonic stem (ES) cells, which can serve as a good model system to investigate molecular and cellular interactions in the earliest stages of embryo development. Current methods for producing EBs mainly rely on the use of hanging drops or suspensions in non‐tissue culture treated plates, microwells, and spinner flasks. The capability of these methods is limited in terms of size uniformity and distribution as well as scalability. Here, a new platform based on three‐dimensional alginate inverse opal scaffolds with uniform pores is presented, where uniform EBs with controllable sizes could be produced in the pores and then recovered after disintegration of the scaffolds. The size of the EBs could be readily controlled by varying the culture time and/or by using scaffolds with different pore sizes. The EBs maintained their viability and undifferentiated state, and they were able to differentiate into specific lineages upon stimulation.     

校内实习走产学研的路子

阐述了校内生产实习结合工程教学走产学研的路子，并以“数字式温度测量调节仪的研制”，开拓加强学生实践训练和研制能力探索。     

Tailoring Precursor Chemistry Enabled Room Temperature-Processed Perovskite Films in Ambient Air for Efficient and Stable Solar Cells with Improved Reproducibility

The perovskite solar cells (PSCs) are promising for commercialization and practical application. However, high-quality perovskite films are normally fabricated in inert gas-filled glovebox, followed by thermal annealing, which is energy-consuming and thus not cost-effective. In this study, a simple manufacturing strategy is demonstrated to fabricate the highly-crystalline perovskite films in ambient air (a relative humidity of over ≈50%) at room temperature via blade-coating without the subsequent thermal–annealing. The perovskite precursor chemistry is tailored by solvent engineering via employing 2-methoxyethanol, which can strongly coordinate with ammonium halide species, thus forming highly uniform small-sized colloids and facilitating the homogeneous nucleation and rapid crystallization of perovskite films even at room temperature. The resultant PSCs fabricated with ambient-processed, annealing-free MAPbI₃ perovskite films exhibit a champion efficiency up to 19.16% with negligible hysteresis and improved reproducibility, which is on par with the high-temperature annealed counterparts fabricated in N₂, and represented one of the highest reported efficiencies for the room-temperature processed PSCs in ambient air. The unencapsulated devices show extended lifespan over 1000 h with nearly no efficiency loss.