Abio/bio hybrids, which incorporate biocatalysts that promote efficient and selective material conversions under mild conditions into existing catalytic reactions, have attracted considerable attention for developing new catalytic systems. This study constructed a H2-forming biocathode based on a carbon material combined with whole-cell biocatalysis of genetically-engineered‒hydrogenase-overproducing Escherichia coli for the photoelectrochemical water splitting for clean H2 production. Low-cost and abundant carbon materials are generally not suitable for H2-forming cathode due to their high overpotential for proton reduction; however, the combination of the reduction of an organic electron mediator on the carbon electrode and the H2 formation with the reduced mediator by the redox enzyme hydrogenase provides a H2-forming cathodic reaction comparable to that of the noble metal electrode. The present study demonstrates that the recombinant E. coli whole cell can be employed as a part of the H2-forming biocathode system, and the biocathode system wired with TiO2 photoanode can be a photoelectrochemical water-splitting system without external voltage assistance under natural pH. The findings of this study expand the feasibility of applications of whole-cell biocatalysis and contribute to obtaining solar-to-chemical conversions by abio/bio hybrid systems, especially for low-cost, noble-metal-free, and clean H2 production.
Monthly Archives: September 2023
Engineering Coordination Environment of Cobalt Center in Molecular Catalysts for Improved Photocatalytic CO2 Reduction
By regulating the coordination heteroatoms, we designed three Co(II)-based molecular catalysts with coordination microenvironments of [CoN3O]ClO4, [CoN4]ClO4, and [CoN3S]ClO4. Impressively, due to the slightly different coordination environments around Co(II) center, [CoN3O]ClO4 shows better photocatalytic activity for CO2 reduction to CO, 1.28 and 1.65 times higher than that of [CoN4]ClO4, and [CoN3S]ClO4, respectively.
Comprehensive Summary
The creation of effective and inexpensive catalysts is essential for photocatalytic CO2 reduction. Homogeneous molecular catalysts, possessing definite crystal structures, are desirable to study the relationship between catalytic performance and coordination microenvironment around catalytic center. In this report, we elaborately developed three Co(II)-based molecular catalysts with different coordination microenvironments for CO2 reduction, named [CoN3O]ClO4, [CoN4]ClO4, and [CoN3S]ClO4, respectively. The optimal [CoN3O]ClO4 photocatalyst has a maximum TON of 5652 in photocatalytic reduced CO2 reduction, which is 1.28 and 1.65 times greater than that of [CoN4]ClO4 and [CoN3S]ClO4, respectively. The high electronegativity of oxygen in L1 (N,N-bis(2-pyridylmethyl)-N-(2-hydroxybenzyl)amine) provides the Co(II) catalytic centers with low reduction potentials and a more stable *COOH intermediate, which facilitates the CO2-to-CO conversion and accounts for the high photocatalytic activity of [CoN3O]ClO4. This work provides researchers new insights in development of catalysts for photocatalytic CO2 reduction.
A Nearly 20‐Year Journey to Success of Azvudine for Antiviral Therapy
The drug discovery campaign of Azvudine starts from 2′-deoxynucleoside, followed by extensive modifications. Azvudine receives approval from China and Russia for treating COVID-19 and represents a novel anti-HIV agent approved in China.
Comprehensive Summary
Modified nucleosides, particularly those with 4'-modifications, are significant nucleosides used in antiviral treatments. The drug discovery campaign of Azvudine starts from 2′-deoxynucleoside, followed by extensive modifications, such as introducing the 4’-position substitutions, a 2’-β-fluoro atom, and changing the nucleobases. Azvudine acts potently toward various HIV-1 strains by inhibiting HIV-1 reverse transcription and preventing Vif-induced A3G degradation, representing the first-in-class dual-acting antiviral agent. In July 2021, the NMPA conditionally approved Azvudine as an adjunct therapy for adult patients with high levels of HIV-1 virus load when combined with NRTIs or NNRTIs. Azvudine is capable of inhibiting SARS-CoV-2, as well as its variants, including Alpha, Beta, Delta, and Omicron. Clinical trials have revealed its real-world effectiveness among hospitalized severely or critically ill COVID-19 patients or those with pre-existing conditions. On July 25th, 2022, the NMPA granted conditional authorization approving Azvudine as China's first domestic oral anti-COVID-19 agent. Generally, Azvudine at therapeutic doses is safe and well-tolerated in clinical settings. Azvudine got approval from the National Health Commission and National Administration of Traditional Chinese Medicine on August 9th to be used in the "Diagnosis and Treatment Program for Novel Coronavirus Pneumonia (Ninth Edition)" for treating common COVID-19 adult patients. On August 12th, 2022, it was also approved by the National Healthcare Security Administration to be added to the list of medical reimbursements. Of note, the achievements related to Azvudine were indexed in the China Basic Research Development Report in Thirty-Five of 2022. Azvudine was also approved on January 5th, 2023, to be used in the "Diagnosis and Treatment Program for Novel Coronavirus Pneumonia (Tenth Edition)" for treating COVID-19 patients. In February 2023, the Ministry of Health of the Russian Federation approved the usage of Azvudine among individuals infected with SARS-CoV-2.
What is the most favorite and original chemistry developed in your research group?
My favorite chemistries are always those that enable efficient access to drug molecules.
How do you get into this specific field? Could you please share some experiences with our readers?
The virus uses nucleosides as raw materials for replication. Learned from this biological process, I have been devoted to, for decades, synthesizing nucleoside mimics. Once attached to the 3'-hydroxy group of the virus RNA chain, these nucleoside analogs can effectively inhibit virus replication. Hard work pays off! We have developed a series of novel 4’-modified nucleosides, among which Azvudine has been officially approved for treating HIV in China and COVID-19 in both China and Russia. Notably, Azvudine is the first Chinese oral anti-COVID-19 agent. The experiences I would like to share with the readers are many, but emphases are placed on thinking critically and working enthusiastically.
How do you supervise your students?
I generally supervise students differently according to their aptitudes. For those keen on scientific work, I always suggest them learn from the literature, and practice makes perfect, think critically, and work with passion.
What is the most important personality for scientific research?
The personalities such as curiosity, creativity, persistence, and the ability to think critically and solve problems matter most for scientific research. Furthermore, what sets successful scientists apart is their passion for their work and their ability to persevere in facing challenges and setbacks.
Who influences you mostly in your life?
My Ph.D. supervisor profoundly fuels my passion for academia and, to some extent, reshapes my personality.
Aggregation‐Induced Emission‐Active Donor‐Substituted Aroyl‐S,N‐Ketene Acetals via Nucleophilic Amine Base Attack
It is all About That Base: Simply by switching the base it is possible to access both bis(aroyl-S,N-ketene acetals) as well as diethylamino-aroyl-S,N-ketene acetals. The latter show strong solid-state emission as well as outstanding aggregation-induced emission properties thus conveying a 53-fold increase in emission intensity.
Abstract
Donor-substituted aroyl-S,N-ketene acetals can be rapidly obtained by nucleophilic attack of triethylamine at the acid chloride with concomitant decarbonylation followed by addition-elimination reaction of in situ generated enamines. These potent chromophores exhibit intensive solid-state emission and pronounced AIE (aggregation-induced emission) characteristics with high quantum yields. By changing the base to diisopropylethylamine, enlarged aroyl-S,N-ketene acetal bi- and trichromophores are easily accessible.
Recent Expedition in Pd‐ and Rh‐Catalyzed C(Ar)−B Bond Formations and Their Applications in Modern Organic Syntheses
Transition metal-catalyzed borylation involves the incorporation of boron-containing fragment to organic molecules. Recent advancements of C(Ar)−B bond-forming reaction include the development of new catalyst systems and boron reagents that allow for efficient transformations, as well as more versatile applications in drug synthesis and materials sciences. Representative synthetic strategies have demonstrated the ability to synthesize complex molecules through the borylative pathway as a key synthetic step.
Abstract
Transition metal-catalyzed borylation has emerged as a powerful and versatile strategy for synthesizing organoboron compounds. These compounds have found widespread applications in various aspects, including organic synthesis, materials science, and medicinal chemistry. This review provides a concise summary of the recent advances in palladium- and rhodium-catalyzed borylation from 2013 to 2023. The review covers the representative examples of catalysts, substrates scope and reaction conditions, with particular emphasis on the development of catalyst systems, such as phosphine ligands, NHC-carbene, and more. The diverse array of borylative products obtained for further applications in Suzuki-Miyaura coupling, and other transformations, are also discussed. Future directions in this rapidly evolving field, with the goal of designing more efficient, selective borylation methodologies are highlighted, too.
Electrolysis of Direct Seawater: Challenges, Strategies, and Future Prospects
Comprehensive Summary
The use of renewable sources such as solar, ocean, geothermal, and wind energy to drive water electrolysis reactions to obtain green and clean hydrogen fuels is one of the important paths to achieve sustainable energy development. At present, most water electrolysis technologies need to conduct corresponding pre-processing, such as diluting water sources and purifying dehydration, which will greatly increase operating costs. The development of direct seawater electrolytic process can effectively solve the above problems. Here, we review the latest progress of the electrode materials and catalysts of the direct electrolysis process of seawater, and discuss how to design high activity and high-selective electrode materials for water electrolysis with familiar impurities (such as chloride, metal ions and biological organisms) existing in the future.
Symbiotic Antimicrobial Effects of Cellulose‐Based Bio‐Nanocomposite for Disease Management of Agricultural Crops
Abstract
In the present work, a bionanocomposite for plant crop protection was prepared by non-toxic biocompatible & biodegradable nanomaterials (Cellulose & TiO2) to utilize its synergistic effects against antimicrobial pathogens. The commercially available microcrystalline cellulose has been reduced to a nanometric scale regime using acid hydrolysis, while the standard TiO2 nano-powder of particle size ~20 nm has been used to prepare their nanocomposite (NC). The antibacterial studies via agar well diffusion method demonstrated that after 72 h of incubation, parent nanomaterials Ncell and TiO2 were not showing any activity against phytopathogens X. campestris pv. campestris, and Clavibacter while the nanocomposite's NC's were still effective depicting both bacteriostatic and bactericidal actions. However, the bacterial growth of biocontrol P. fluorescence was not affected by Ncell, TiO2 NPs and NC after 72 h of incubation. The antifungal testing results via poison food agar assay method suggest that the nanocomposite, along with Ncell and TiO2 NPs, exhibited strong inhibition of fungal growth of Phytophthora Spp at 0.125 mg/ml concentration while for F. graminearum, similar effect was observed at 0.25 mg/ml concentration. The nanocomposite has proved its potential by exhibiting longer & stronger synergistic effects against plant pathogens as a good antimicrobial agent for protection of agricultural crops.
A Homochiral Diphenylalanine Analog Based Mechanoresponsive Hydrogel: An Insight Towards Its Wound Healing Efficacy
Abstract
Deciphering the most promising strategy for the evolution of potential wound-healing therapeutics is one of the greatest challenging affairs to date. The development of peptide-based smart scaffolds with innate antimicrobial, anti-inflammatory, and antioxidant properties is an appealing way out. Aligned to the goal a set of Hydrogelators I–IV were developed utilizing the concept of chiral orchestration in diphenylalanine fragment, such that the most potent construct with all the bench marks namely mechanoresponsiveness, biocompatibility, consistent antimicrobial and antioxidant properties, could be fished out from the design. Interestingly, our in vitro Antifungal and Lipid peroxidation analysis identified the homochiral isomer Boc-δ-Ava-L-Phe-L-Phe-OH (Hydrogelator I), as an ideal candidate for the wound healing experiment, so we proceeded for the in vivo histopathological and antioxidant measurements in Wister rats. Indeed the wound images obtained from the different sets of animals on the 14th day of treatment demonstrated that with increased recovery time, hydrogelator I displayed a significant reduction in the lesion diameter compared to the marketed drug, and negative control. Even the histopathological measurements using H & E staining demonstrated diminished tissue destruction, neutrophil infiltration necrosis, and lymphatic proliferation in the hydrogelators, in comparison to others, backed by in vivo lipid peroxidation data. Overall our investigation certifies hydrogelator I as an effective therapeutic for managing the wound healing complication.
Synthesis towards Phainanoid F: Photo‐induced 6π‐Electrocyclization for Constructing Contiguous All‐Carbon Quaternary Centers
Photoinitiated 6π-electrocyclization was developed as an efficiently strategy to construct vicinal quaternary carbons. Combined with homoallylic elimination, the 13,30-cyclodammarane skeleton of phainanoid F was constructed.
Abstract
In this paper, we report an efficient strategy for synthesizing the DEFGH rings of phainanoid F. The key to the construction of the 13,30-cyclodammarane skeleton of the molecule was a photo-induced 6π-electrocyclization and a homoallylic elimination. Notably, this is a rare example of using electrocyclization reaction to simultaneously construct two vicinal quaternary carbons in total synthesis. The strategy outlined here forms the basis of our total synthesis of Phainanoid F, and it could also serve as a generally applicable approach for synthesizing other natural products containing similar 13,30-cyclodammarane skeletons.
Triphenylamine‐Based N,O‐Bidentate BF2‐Enolimine Initiator for Three‐Arm Star Polymethacrylates with Dual‐State Fluorescent Emission
Three-arm star polymethacrylates with dual-phase (solution and solid-state) fluorescent emission were synthesized via ATRP using a triphenylamine-derived organoboron complex TAPA-BKI-3Br as initiator.
Abstract
Three-arm star polymethacrylates with dual-phase (solution and solid-state) fluorescent emission have been synthesized via atom transfer radical polymerization (ATRP) using a triphenylamine-derived organboron complex (TAPA-BKI-3Br) as initiator. The as-synthesized three-arm star polymethacrylates exhibited bright emission in both solution and the solid states due to the highly twisted structure and intramolecular charge transfer (ICT) effect of TAPA-BKI core, as well as the steric effect and restriction of intramolecular motions from the polymer arms. And the polymer chains have an important influence on the photophysical behavior of the as-synthesized three-arm star polymethacrylates in the aggregated state.