High-Performance Solution-Processed 2D P-Type WSe2 Transistors and Circuits through Molecular Doping.

Semiconducting ink based on 2D single-crystal flakes with dangling-bond-free surfaces enables the implementation of high-performance devices on form-free substrates by cost-effective and scalable printing processes. However, the lack of solution-processed p-type 2D semiconducting inks with high mobility is an obstacle to the development of complementary integrated circuits. Here, a versatile strategy of doping with Br2 is reported to enhance the hole mobility by orders of magnitude for p-type transistors with 2D layered materials. Br2 -doped WSe2 transistors show a field-effect hole mobility of more than 27 cm2  V-1  s-1 , and a high on/off current ratio of ≈107 , and exhibits excellent operational stability during the on-off switching, cycling, and bias stressing testing. Moreover, complementary inverters composed of patterned p-type WSe2 and n-type MoS2 layered films are demonstrated with an ultra-high gain of 1280 under a driving voltage (VDD ) of 7 V. This work unveils the high potential of solution-processed 2D semiconductors with low-temperature processability for flexible devices and monolithic circuitry.

Production of a novel quercetin glycoside through metabolic engineering of Escherichia coli.

Most flavonoids exist as sugar conjugates. Naturally occurring flavonoid sugar conjugates include glucose, galactose, glucuronide, rhamnose, xylose, and arabinose. These flavonoid glycosides have diverse physiological activities, depending on the type of sugar attached. To synthesize an unnatural flavonoid glycoside, Actinobacillus actinomycetemcomitans gene tll (encoding dTDP-6-deoxy-L-lyxo-4-hexulose reductase, which converts the endogenous nucleotide sugar dTDP-4-dehydro-6-deoxy-L-mannose to dTDP-6-deoxytalose) was introduced into Escherichia coli. In addition, nucleotide-sugar dependent glycosyltransferases (UGTs) were screened to find a UGT that could use dTDP-6-deoxytalose. Supplementation of this engineered strain of E. coli with quercetin resulted in the production of quercetin-3-O-(6-deoxytalose). To increase the production of quercetin 3-O-(6-deoxytalose) by increasing the supplement of dTDP-6-deoxytalose in E. coli, we engineered nucleotide biosynthetic genes of E. coli, such as galU (UTP-glucose 1-phosphate uridyltransferase), rffA (dTDP-4-oxo-6-deoxy-d-glucose transaminase), and/or rfbD (dTDP-4-dehydrorahmnose reductase). The engineered E. coli strain produced approximately 98 mg of quercetin 3-O-(6-deoxytalose)/liter, which is 7-fold more than that produced by the wild-type strain, and the by-products, quercetin 3-O-glucose and quercetin 3-O-rhamnose, were also significantly reduced.