Highly selective detection of methanol in aqueous and ethanol medium based on hybrid ZnS:Mn2+quantum dots/N-methylpolypyrrole as a fluorescence switchable sensor

Enhanced Biosynthesis of d-Allulose from a d-Xylose-Methanol Mixture and Its Self-Inductive Detoxification by Using Antisense RNAs in Escherichia coli

d-Allulose, a C-3 epimer of d-fructose, has great market potential in food, healthcare, and medicine due to its excellent biochemical and physiological properties. Microbial fermentation for d-allulose production is being developed, which contributes to cost savings and environmental protection. A novel metabolic pathway for the biosynthesis of d-allulose from a d-xylose-methanol mixture has shown potential for industrial application. In this study, an artificial antisense RNA (asRNA) was introduced into engineered Escherichia coli to diminish the flow of pentose phosphate (PP) pathway, while the UDP-glucose-4-epimerase (GalE) was knocked out to prevent the synthesis of byproducts. As a result, the d-allulose yield on d-xylose was increased by 35.1%. Then, we designed a d-xylose-sensitive translation control system to regulate the expression of the formaldehyde detoxification operon (FrmRAB), achieving self-inductive detoxification by cells. Finally, fed-batch fermentation was carried out to improve the productivity of the cell factory. The d-allulose titer reached 98.6 mM, with a yield of 0.615 mM/mM on d-xylose and a productivity of 0.969 mM/h.

Highly selective and discriminative detection of small alcohols based on a dual-emission macrocyclic samarium complex

Lower alcohols (C1-C7) have a close relationship with our lives and some of them are harmful to our body's health. For example, liquor mixed with a tiny amount of methanol is harmful to our health. Much of this study is about identifying one or two low-level alcohols. How to detect low-level alcohol and high-throughput and distinguish between analogues of alcohol remains a tremendous challenge. In this study, a new large ring Schiff base Sm(III) complex (Sm-2r) is synthesized with a double emission matrix using the template method. Its dynamic imine bond (CN) and organic ligands (H₂L2_r) with molecular rotor properties can respond to changes in viscosity and polarity in external environments. The PCA method is used to turn the data matrix into a fingerprint spectrum to distinguish different alcohols (C1-C7). Sm-2r enables the quantization of cyclopropyl and glycerol. Linear ranges of cyclopropanol and glycerol are 0-9.0% and 0-3.0% (v/v), respectively. In addition, Sm-2r has an excellent ability to distinguish the mixtures of n-PrOH and i-PrOH, C₅H₉OH and C₆H₁₁OH, n-PeOH and n-HeOH, 1,3-PDO and 1,2-PDO, MeOH and EtOH, 1,2-EG and 1,2-PDO at different volume ratios. We have provided a way to distinguish alcohol species based on their molecular polarity and viscosity.

A donor-π-acceptor aggregation-induced emission compound serving as a portable fluorescent sensor for detection and differentiation of methanol and ethanol in the gas phase

The design strategy of aggregation-induced emission (AIE) fluorophores with donor-π-acceptor (D-π-A) conjugation structure has greatly contributed to the development of luminescent materials and devices, including volatile organic compounds (VOCs) sensors. In this work, a D-π-A fluorophore DEBAB was synthesized, showing both AIE and intramolecular charge transfer (ICT) properties as confirmed by spectroscopic data and quantum chemical calculations. Furthermore, there is notable emission-enhancement when DEBAB is exposed to small-molecule alcohols, such as methanol and ethanol. Based on this phenomenon, a portable film sensor was fabricated, capable of detecting methanol and ethanol in gas phase, with detection limit (DL) as low as 8.02 ppm. Our systematic investigation suggests that hydrogen-bonding may be formed between DEBAB and alcohols, intensifying the AIE efficacy while influencing the ICT process. This working mechanism is supported by density functional theory (DFT) calculations including electrostatic potential mapping and molecular total energy. In addition, a sensor array was fabricated on a cellulose paper strip, showing different levels of emission changing in response to alcohols. Thus the detection and differentiation of methanol and ethanol are enabled.

Integration of Cd:ZnS QDs into ZIF-8 for enhanced selectivity toward Cu2+ detection

Cd:ZnS QDs were integrated into ZIF-8 that could specifically interact with Cu²⁺ for enhanced selectivity toward Cu²⁺ detection.