In vitro generation of functional gametes is a promising approach for treating infertility, although faithful replication of meiosis has proven to be a substantial obstacle to deriving haploid gamete cells in culture. Here we report complete in vitro meiosis from embryonic stem cell (ESC)-derived primordial germ cells (PGCLCs). Co-culture of PGCLCs with neonatal testicular somatic cells and sequential exposure to morphogens and sex hormones reproduced key hallmarks of meiosis, including erasure of genetic imprinting, chromosomal synapsis and recombination, and correct nuclear DNA and chromosomal content in the resulting haploid cells. Intracytoplasmic injection of the resulting spermatid-like cells into oocytes produced viable and fertile offspring, showing that this robust stepwise approach can functionally recapitulate male gametogenesis in vitro. These findings provide a platform for investigating meiotic mechanisms and the potential generation of human haploid spermatids in vitro.

Upon fertilization, drastic chromatin reorganization occurs during preimplantation development . However, the global chromatin landscape and its molecular dynamics in this period remain largely unexplored in humans. Here we investigate chromatin states in human preimplantation development using an improved assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) . We find widespread accessible chromatin regions in early human embryos that overlap extensively with putative cis-regulatory sequences and transposable elements. Integrative analyses show both conservation and divergence in regulatory circuitry between human and mouse early development, and between human pluripotency in vivo and human embryonic stem cells. In addition, we find widespread open chromatin regions before zygotic genome activation (ZGA). The accessible chromatin loci are readily found at CpG-rich promoters. Unexpectedly, many others reside in distal regions that overlap with DNA hypomethylated domains in human oocytes and are enriched for transcription factor-binding sites. A large portion of these regions then become inaccessible after ZGA in a transcription-dependent manner. Notably, such extensive chromatin reorganization during ZGA is conserved in mice and correlates with the reprogramming of the non-canonical histone mark H3K4me3, which is uniquely linked to genome silencing. Taken together, these data not only reveal a conserved principle that underlies the chromatin transition during mammalian ZGA, but also help to advance our understanding of epigenetic reprogramming during human early development and in vitro fertilization.

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Photoreduction of CO 2 to fuels offers a promising strategy for managing the global carbon balance using renewable solar energy. But the decisive process of oriented photogenerated electron delivery presents a considerable challenge. Here, we report the construction of intermolecular cascaded π-conjugation channels for powering CO 2 photoreduction by modifying both intramolecular and intermolecular conjugation of conjugated polymers (CPs). This coordination of dual conjugation is firstly proved by theoretical calculations and transient spectroscopies, showcasing alkynyl-removed CPs blocking the delocalization of electrons and in turn delivering the localized electrons through the intermolecular cascaded channels to active sites. Therefore, the optimized CPs (N-CP-D) exhibiting CO evolution activity of 2247 μmol g −1 h −1 and revealing a remarkable enhancement of 138-times compared to unmodified CPs (N-CP-A).

Spatially ordered embryo-like structures self-assembled from blastocyst-derived stem cells can be generated to mimic embryogenesis in vitro. However, the assembly system and developmental potential of such structures needs to be further studied. Here, we devise a nonadherent-suspension-shaking system to generate self-assembled embryo-like structures (ETX-embryoids) using mouse embryonic, trophoblast and extra-embryonic endoderm stem cells. When cultured together, the three cell types aggregate and sort into lineage-specific compartments. Signaling among these compartments results in molecular and morphogenic events that closely mimic those observed in wild-type embryos. These ETX-embryoids exhibit lumenogenesis, asymmetric patterns of gene expression for markers of mesoderm and primordial germ cell precursors, and formation of anterior visceral endoderm-like tissues. After transplantation into the pseudopregnant mouse uterus, ETX-embryoids efficiently initiate implantation and trigger the formation of decidual tissues. The ability of the three cell types to self-assemble into an embryo-like structure in vitro provides a powerful model system for studying embryogenesis.

Two‐dimensional (2D) materials, benefitting from their unique planar structure and various appealing electronic properties, have attracted much attention for novel electronic and optoelectronic applications. As a basis for practical devices, the study of micro/nano‐2D material arrays based on coupling effects and synergistic effects is critical to the functionalization and integration of 2D materials. Moreover, micro/nano‐2D material arrays are compatible with traditional complementary metal oxide semiconductor (CMOS) electronics, catering well to high‐integration, high‐sensitivity, and low‐cost sensing and imaging systems. This review presents some recent studies on 2D material arrays in sequence from their novel preparations to high‐integration applications as well as explorations on dimension tuning. A first focus is on various typical fabrication methods for 2D material arrays, including photolithography, 2D printing, seeded growth, van der Waals epitaxial growth, and self‐assembly. Then, the applications of 2D material arrays, such as field effect transistors, photodetectors, pressure sensors, as well as flexible electronic devices of photodetectors and strain sensors, are elaborately introduced. Furthermore, the recent burgeoning exploration of mixed‐dimensional heterostructure arrays including 0D/2D, 1D/2D, and 3D/2D is discussed. Ultimately, conclusions and an outlook based on the current developments in this promising field are presented.

It is a rapidly developed subject in expanding the fundamental properties and application of two‐dimensional (2D) materials. The weak van der Waals interaction in 2D materials inspired researchers to explore 2D heterostructures (2DHs) based broadband photodetectors in the far‐infrared (IR) and middle‐IR regions with high response and high detectivity. This review focuses on the strategy and motivation of designing 2DHs based high‐performance IR photodetectors, which provides a wide view of this field and new expectation for advanced photodetectors. First, the photocarriers' generation mechanism and frequently employed device structures are presented. Then, the 2DHs are divided into semimetal/semiconductor 2DHs, semiconductor/semiconductor 2DHs, and multidimensional semi‐2DHs; the advantages, motivation, mechanism, recent progress, and outlook are discussed. Finally, the challenges for next‐generation photodetectors are described for this rapidly developing field.

The performance of donor–acceptor (D–A) conjugated polymer-based photocatalyts for solar hydrogen production is severely limited by poor charge mobility and weak reactive sites. Here, a series of D–A conjugated polymers with electronegative fluorine atoms on the backbone is presented and the influence of fluorination on charge transfer and catalytic site activity is investigated. Theoretical calculation reveals that sequential fluorination on the A unit benzothiadiazole will activate the catalytic site, and the photocatalytic H2 generation process could be illustrated by a proton-coupled electron-transfer mechanism. Two series of fluorinated polymers were synthesized, and accelerated charge transfer was also verified. Among them, linear B-FOBT-1,4-E and porous B-FOBT-1,3,5-E with simultaneous electron-donating CH3O– and electron-withdrawing F-substitution show a H2 evolution rate that is 3.1 and 28.8 times higher than that of nonfluorinated counterparts, respectively, and the apparent quantum yield of 5.7% at 420 nm is obtained for B-FOBT-1,4-E. The results provide reciprocal understanding of the activation nature of substituent-regulating polymers.