A facile plasma–liquid technique is designed and demonstrated for rapid and mass production of few-layered phosphorene.

As a layered nano-sheet material, layered graphitic carbon nitride (g-C₃N₄) has attracted attention in multifunctional photocatalytic applications. However, g-C₃N₄ is electrochemically inert consequently hampering electrochemical applications. In this work, low-temperature nitrogen plasma processing was conducted to modify g-C₃N₄ to enhance the electrocatalytic performance in the hydrogen evolution reaction (HER). The plasma produced significant morphological and chemical changes on the surface of g-C₃N₄ via active species, and nitrogen atoms were incorporated into the surface while the bulk properties did not change. The modification improved the surface hydrophilicity and electrocatalytic HER activity, as well as excellent stability in HER after 2000 cycles. Our results revealed that plasma treatment was a promising technique to improve the HER of carbon-based layered nano-sheet materials.

Dielectric barrier discharge (DBD) plasma surface modification has certain aging effect. This article studies the aging effect of plasma (DBD) on the surface modification of carbon fibers. The test results show that plasma (DBD) treatment reduces the impurity particles on the surface of carbon fibers and makes the surface texture coarser. In addition, there is no significant change. After plasma (DBD) treatment, the content of C–O–C, C–O and C=O on the surface of carbon fibers increased from 3.20%, 7.76% and 1.64% to 7.06%, 21.50 and 6.08%, respectively. This is due to the high-energy particle bombardment of the fiber surface, which forms activated carbon atoms on the surface. The free electrons of these activated carbon atoms combine with ionized oxygen in the air. However, with the passage of time, the content of C–O–C, C–O and C=O gradually decreases to 3.31%, 8.57% and 1.77%, respectively. This is because some functional groups formed on the treated carbon fiber surface are not firmly bound, and some of these functional groups containing O₂ groups will combine with surrounding substances through irreversible chemical oxidation reactions to produce CO₂, which leaves the carbon fiber surface as a gas. The treated carbon fibers will immediately become hydrophilic, and the water contact angle decreases from 148.71° to 0°. With the passage of time, the water contact angle gradually increases to 118.16°, and the hydrophobicity recovers.

This letter focuses on the streamer-to-spark transitions generated by microsecond pulsed discharges (±20 kV of amplitude, 150 μ s of pulse width) in deionized water to provide a quantitative insight into the underwater breakdown process. The discharge channel during underwater electrical breakdown is generally considered as a homogenous blackbody radiator by the arc model. However, we report an unsymmetrical structure of negative breakdown channel in water which shows great discrepancy from the frequently observed uniform structure. An improved two-stage analytical model is proposed to quantitatively estimate the parameter variations of the discharge channels, e.g. radius, temperature, pressure. The calculated results show that the discrepancy in parameters of different parts of negative discharge channel is tremendous. Specifically, during negative electrical breakdown, the region of discharge channel near ground electrode owns greatest values in characteristic parameters (e.g. T _max = 22 300 K, P _max = 0.145 GPa and v _max = 219 m s ⁻¹ ), which are far above the counterparts of main body of channel. By introducing field ionization and impact ionization mechanisms during the propagation of the streamer, we explain the rapid expansion of positive discharge channel and the regions of negative channel near the needle tip as well as the ground electrode. Besides, the deposited homocharges at the gas–liquid interface weaken the ionizations in main body of negative breakdown channel, and hence causing the formation of the unsymmetrical structure.

A carrier-free CRISPR/Cas9 ribonucleoprotein delivery strategy for genome editing mediated by a cold atmospheric plasma (CAP) is described. The CAP is promising in many biomedical applications due to efficient production of bioactive ionized species. The MCF-7 cancer cells after CAP exposure exhibit increased extracellular reactive oxygen and nitrogen species (RONS) and altered membrane potential and permeability. Hence, transmembrane transport of Ca²⁺ into the cells increases and accelerates ATP hydrolysis, resulting in enhanced ATP-dependent endocytosis. Afterwards, the increased Ca²⁺ and ATP contents promote the release of cargo into cytoplasm due to the enhanced endosomal escape. The increased membrane permeability also facilitates passive diffusion of foreign species across the membrane into the cytosol. After CAP exposure, the MCF-7 cells incubated with Cas9 ribonucleoprotein (Cas9-sgRNA complex, Cas9sg) with a size of about 15 nm show 88.9% uptake efficiency and 65.9% nuclear import efficiency via passive diffusion and ATP-dependent endocytosis pathways. The efficient transportation of active Cas9sg after the CAP treatment leads to 21.7% and 30.2% indel efficiencies in HEK293T and MCF-7 cells, respectively. This CAP-mediated transportation process provides a simple and robust alternative for the delivery of active CRISPR/Cas9 ribonucleoprotein. Additionally, the technique can be extended to other macro-biomolecules and nanomaterials to cater to different biomedical applications.