Ruichun Luo

Stem cell spheroids, as an advanced platform in cell therapy, have shown great potential for improving therapeutic efficacy through enhanced cell–cell and cell–microenvironment interactions. Meanwhile, zinc-based biomaterials are attracting increasing attention for their biological functions. However, their roles in modulating stem cell spheroids remain largely unclear. In this study, we synthesized zinc-doped urchin-like hydroxyapatite (Zn-uHA) via a hydrothermal method and verified its long-term antibacterial activity. Utilizing microwell array technology, we conducted 3D cell culture of human dental pulp stem cells (hDPSCs) with Zn-uHA, thereby achieving high-throughput and precise fabrication of 3D hDPSCs/Zn-uHA hybrid stem cell spheroids. Compared with pure cell spheroids, hDPSCs/Zn ₃ -uHA hybrid spheroids demonstrated significantly enhanced cell migration and osteogenic differentiation, with osteogenesis-related gene expression upregulated 2.7-fold. In vivo studies further confirmed that the hybrid cell spheroids exhibited favorable biocompatibility, with no evident inflammatory response or immune rejection, and enabled prolonged retention at the implantation site. Additionally, they significantly promoted neovascularization and new bone formation. These findings suggest that Zn-uHA-integrated stem cell spheroids represent a promising strategy for enhancing both antibacterial and osteogenic performance, offering potential applications in bone tissue engineering, particularly in infection-prone clinical scenarios such as orthopedics and dentistry.

2D transition metal dichalcogenides (TMDs) exhibit remarkable properties that are strongly influenced by their atomic structures, as well as by various types of defects and interfaces that can be precisely engineered and controlled. These features make 2D TMDs and TMD‐based materials highly promising for a wide range of applications in electronics, optoelectronics, magnetism, spintronics, catalysis, energy, etc. By providing a comprehensive approach to understand the structure–property–functionality relationship in materials at the atomic scale, electron microscopy, and spectroscopy techniques have emerged as invaluable tools for studying both the static characteristics and dynamic evolutions of 2D TMDs. In this review, the primary focus lies in exploring intrinsic and artificial structures in TMDs and their heterostructures, along with their corresponding properties, through cutting‐edge aberration‐corrected scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). Additionally, recent advancements in the field of in situ visualization and manipulation of 2D TMDs using electron beams are highlighted. It is anticipated that the up‐to‐date overview provided, along with a glimpse into the future development of STEM‐based techniques, will make a substantial contribution to advancing research on 2D materials.

The structures and properties of van der Waals (vdW) heterojunctions between semiconducting two-dimensional transition-metal dichalcogenides (2D TMDs) and conductive metals, such as gold, significantly influence the performances of 2D-TMD based electronic devices. Chemical vapor deposition is one of the most promising approaches for large-scale synthesis and fabrication of 2D TMD electronics with naturally formed TMD/metal vdW interfaces. However, the structure and chemistry of the vdW interfaces are less known. Here we report the interfacial reconstruction between TMD monolayers and gold substrates. The participation of sulfur leads to the reconstruction of Au {001} surface with the formation of a metastable Au₄S₄ interfacial phase which is stabilized by the top MoS₂ and WS₂ monolayers. Moreover, the enhanced vdW interaction between the reconstructed Au₄S₄ interfacial phase and TMD monolayers results in the transition from n-type TMD-Au Schottky contact to p-type one with reduced energy barrier height.