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Multi-module dCas9 engineering systems have been developed for controllable transcriptional manipulation such as chemical- or light-induced systems. However, there is still a need for a separate module that can be used for internal control over the CRISPR-dCas9 system. Here, we describe a multi-module CRISPR-dCas9 system in which a separate structured RNA was applied as a programmable component that could control dCas9-based gene regulation and achieved a higher activation efficiency than dCas9-VPR that is traditionally used. By introducing a microRNA sensor, we generated a dCas9-based transcriptional regulation platform that responded to endogenous microRNAs and allowed controllable activation of endogenous genes. Moreover, we applied the platform to selectively identify HCT116 cells in a cell mixture. This work provides a flexible platform for efficient and controllable gene regulation based on CRISPR-dCas9.

Herbal medicines often contain bioactive polysaccharides.

The emergence of synthetic biology has opened new avenues in constructing cell-assembly biosystems with specific gene expression and function. The phenomena of cell spreading and detachment during tissue development and cancer metastasis are caused by surface tension, which in turn results from differences in cell-cell adhesion mediated by the dimerization of cadherin expressed on the cell surface. In this study, E- and P-cadherin plasmids were first constructed based on the differential adhesion hypothesis, then they were electroporated into K562 cells and HEK293T cells, respectively, to explore the process of cell migration and assembly regulated by cadherins. Using this approach, some special 3D cell functional components with a phase separation structure were fabricated successfully. Our work will be of potential application in the construction of self-assembling synthetic tissues and organoids.

End modification of the toehold domain or near to it using fluorophore dyes or quenchers can significantly modulate the kinetics of the toehold-mediated strand displacement reaction (TMSDR) by almost two orders of magnitude. The labels at the end of the signal strand impede the TMSDR, while those at the end of the toehold domain of the substrate strand accelerate the TMSDR kinetics.

The incorporation of heavy atoms into molecular backbone is an extremely straightforward strategy for fine-tuning the optoelectronic properties of organic semiconductors. However, it is rarely studied in n-type small molecules. Herein, by selenium substitution of NDI3HU-DTYM2, two Se-decorated core-expanded naphthalene diimides (NDI) derivatives DTYM-NDI3HU-DSYM ( 1 ) and NDI3HU-DSYM2 ( 2 ) were synthesized. In comparison with the reference S-containing compound NDI3HU-DTYM2, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of 1 and 2 were fine-tuned with ∆HOMO of about 0.2 eV, ∆LUMO of 0.1 eV and the narrowed HOMO-LUMO gaps. More surprisingly, the as-spun organic thin film transistors (OTFTs) based on 1 and 2 both showed µ e,sat values as high as 1.0 cm2 V−1 s−1, which are 2-fold higher than that of NDI3HU-DTYM2 with the same device structure and measurement conditions. In addition, the single crystal OFET devices based on Se-containing compound NDI2BO-DSYM2 showed a high µ e,sat value of 1.30 cm2 V−1 s−1. The molecular packing of NDI2BO-DSYM2 in single crystals (two-dimensional supramolecular structure formed by intermolecular Se···Se interactions) is quite different from that of a S-containing compound NDI-DTYM2 (one dimensional supramolecular structure formed by intermolecular π-π stacking). Therefore, the Se substitution can cause dramatic change about molecular stacking model, giving rise to high n-type OTFT performance. Our results demonstrated an effective strategy of the heavy atom effect for designing novel organic semiconductors.

The use of low-intensity NIR light to operate molecular switches offers several potential advantages including enhanced penetration into bulk materials, in particular biological tissues, and reduced radiation damage due to the limited photon energies. The latter, however, pose a challenge for designing reasonably bistable systems. We have developed a general design strategy for direct one-photon NIR photoswitches based on negative photochromic dihydropyrenes carrying opposing strong donor-acceptor substituents either along the long axis of the molecule or across it. Thus, two series of 2,7- and 4,9-disubstituted dihydropyrenes were synthesized, and their photothermal properties investigated as a function of the type, strength, and position of the attached donor and acceptor substituents as well as the polarity of the environment. By shifting the excitation wavelength deep into the NIR, both NIR one-photon absorption cross-section and photoisomerization efficiency could be maximized while retaining a reasonable thermal stability of the metastable cyclophanediene isomer. Thus, the lowest optical transition was shifted beyond 900 nm, the NIR cross-section was enhanced by two orders of magnitude, and the thermal half-lives vary between milliseconds and hours. These unique features open up ample opportunities for noninvasive, optically addressable materials and material systems.

The serious shuttle effect, low conductivity, and large volume expansion have been regarded as persistent obstacles for lithium sulfur (Li-S) batteries in its practical application. Carbon materials, such as graphene, are considered as promising cathode hosts to alleviate those critical defects and be possibly coupled with other reinforcement methods to further improve the battery performance. However, the open structure of graphene and the weak interaction with sulfur species restrict its further development for hosting sulfur. Herein, a rational geometrical design of hierarchical porous graphene-like bubbles (PGBs) as a cathode host of the Li-S system was prepared by employing magnesium oxide (MgO) nanoparticles as templates for carbonization, potassium hydroxide (KOH) as activation agent, and car tal pitch as a carbon source. The synthesized PGBs owns a very thin carbon layer around 5 nm that can be comparable to graphite nanosheets. Its high content of mesoporous and interconnected curved structure can effectively entrap sulfur species and impose restrictions on their diffusion and shuttle effect, leading to a much stable electrochemical performance. The reversible capacity of PGBs@S 0.3 C still can be maintained at 831 mAh g−1 after 100 cycles and 512 mAh g−1 after 500 cycles.

Lithium–sulfur (Li–S) batteries are seriously constrained by the diffusion and crossover of intermediary product polysulfides and their further reductions on the anode surface. Although carbon-based interlayers have been widely used to inhibit the detrimental shuttle effect in Li–S batteries, the weak physical adsorption of pure carbon materials for trapping polysulfides still leads to low recycle efficiency of active species and short cycle life for cells. Herein, we report a cyclized-polyacrylonitrile-cast carbon nanofiber (CP@CNF) film as an interlayer in Li–S batteries. By exploiting the CP@CNF interlayer, the batteries assembled with bare sulfur cathodes deliver superior rate capability and cycle stability. The reversible capacity could be maintained at 710 mA h g−1 after 200 cycles at 0.3C and a capacity of 560 mA h g−1 can be obtained even at a 2C rate. The improved performances are attributed to both the abundant pyridine groups in the cyclized polyacrylonitrile matrix, which can entrap polysulfides by strong interatomic attraction, and the three-dimensional porous conductive network composed of the carbon nanofiber skeleton and conjugated polymer matrix, giving rise to highly effective transfer pathways for electrons and ions.

Current research has demonstrated the presence of sub parts per billion levels of Sudan dye in paprika fruits during the vegetation process, which is difficult to understand on the basis of the conventional concept of cross-contamination or malicious addition. Detailed surveys on Sudan dyes I-IV in paprika fruits, soils, and agronomic materials used from seven fields of Xinjiang (China) were conducted to investigate the natural contamination. Results revealed that Sudan dyes II-IV were never detected and that Sudan I existed in almost all samples except for the mulching film and irrigation water. The higher total amount of Sudan I in soils, pesticides, and fertilizers compared to coated seeds indicated the combination of Sudan I-contaminated soils and application of Sudan I-containing agronomic materials constitutes a major source of 0.18-2.52 μg/kg levels of Sudan I in fruits during the growth period. The study offers a more reasonable explanation for the previously observed Sudan I in paprika fruits.