Construction of Multi-Enzyme Integrated Catalysts for Deracemization of Cyclic Chiral Amines.

Multi-enzyme cascade catalysis has become an important technique for chemical reactions used in manufacturing and scientific study. In this research, we designed a four-enzyme integrated catalyst and used it to catalyse the deracemization reaction of cyclic chiral amines, where monoamine oxidase (MAO) catalyses the enantioselective oxidation of 1-methyl-1,2,3,4-tetrahydroisoquinoline (MTQ), imine reductase (IRED) catalyses the stereo selective reduction of 1-methyl-3,4-dihydroisoquinoline (MDQ), formate dehydrogenase (FDH) is used for the cyclic regeneration of cofactors, and catalase (CAT) is used for decomposition of oxidative reactions. The four enzymes were immobilized via polydopamine (PDA)-encapsulated dendritic organosilica nanoparticles (DONs) as carriers, resulting in the amphiphilic core-shell catalysts. The hydrophilic PDA shell ensures the dispersion of the catalyst in water, and the hydrophobic DON core creates a microenvironment with the spatial confinement effect of the organic substrate and the preconcentration effect to enhance the stability of the enzymes and the catalytic efficiency. The core-shell structure improves the stability and reusability of the catalyst and rationally arranges the position of different enzymes according to the reaction sequence to improve the cascade catalytic performance and cofactor recovery efficiency.

Resin-Immobilized Palladium Acetate and Alcohol Dehydrogenase for Chemoenzymatic Enantioselective Synthesis of Chiral Diarylmethanols.

The enantioselective synthesis of chiral diarylmethanols is highly desirable in synthetic chemistry and the pharmaceutical industry, but it remains challenging, especially in terms of green and sustainable production. Herein, a resin-immobilized palladium acetate catalyst was fabricated with high activity, stability, and reusability in Suzuki cross-coupling reaction of acyl halides with boronic acids, and the coimmobilization of alcohol dehydrogenase and glucose dehydrogenase on resin supports was also conducted for asymmetric bioreduction of diaryl ketones. Experimental results revealed that the physicochemical properties of the resins and the immobilization modes played important roles in affecting their catalytic performances. These two catalysts enabled the construction of a chemoenzymatic cascade for the enantioselective synthesis of a series of chiral diarylmethanols in high yields (83-90%) and enantioselectivities (87-98% ee). In addition, the asymmetric synthesis of the antihistaminic and anticholinergic drugs (S)-neobenodine and (S)-carbinoxamine was also achieved from the chiral diarylmethanol precursors, demonstrating the synthetic utility of the chemoenzymatic cascade.

Modularization of Immobilized Multienzyme Cascades for Continuous-Flow Enantioselective C-H Amination.

Multienzyme cascades (MECs) have gained much attention in synthetic chemistry but remain far from being a reliable synthetic tool. Here we report a four-enzyme cascade comprising a cofactor-independent and a cofactor self-sustaining bienzymatic modules for the enantioselective benzylic C-H amination of arylalkanes, a challenging transformation from bulk chemicals to high value-added chiral amines. The two modules were subsequently optimized by enzyme co-immobilization with microenvironmental tuning, and finally integrated in a gas-liquid segmented flow system, resulting in simultaneous improvements in enzyme performance, mass transfer, system compatibility, and productivity. The flow system enabled continuous C-H amination of arylalkanes (up to 100 mM) utilizing the sole cofactor NADH (0.5 mM) in >90 % conversion, achieving a high space-time yield (STY) of 3.6 g ⋅ L-1 ⋅ h-1, which is a 90-fold increase over the highest value previously reported.

16S rRNA gene sequencing and machine learning reveal correlation between drug abuse and human host gut microbiota.

Over the past few years, there has been increasing evidence highlighting the strong connection between gut microbiota and overall well-being of the host. This has led to a renewed emphasis on studying and addressing substance use disorder from the perspective of brain-gut axis. Previous studies have suggested that alcohol, food, and cigarette addictions are strongly linked to gut microbiota and faecal microbiota transplantation or the use of probiotics achieved significant efficacy. Unfortunately, little is known about the relationship between drug abuse and gut microbiota. This paper aims to reveal the potential correlation between gut microbiota and drug abuse and to develop an accurate identification model for drug-related faeces samples by machine learning. Faecal samples were collected from 476 participants from three regions in China (Shanghai, Yunnan, and Shandong). Their gut microbiota information was obtained using 16S rRNA gene sequencing, and a substance use disorder identification model was developed by machine learning. Analysis revealed a lower diversity and a more homogeneous gut microbiota community structure among participants with substance use disorder. Bacteroides, Prevotella_9, Faecalibacterium, and Blautia were identified as important biomarkers associated with substance use disorder. The function prediction analysis revealed that the citrate and reductive citrate cycles were significantly upregulated in the substance use disorder group, while the shikimate pathway was downregulated. In addition, the machine learning model could distinguish faecal samples between substance users and nonsubstance users with an AUC = 0.9, indicating its potential use in predicting and screening individuals with substance use disorder within the community in the future.

Direct Asymmetric Reductive Amination of Alkyl (Hetero)Aryl Ketones by an Engineered Amine Dehydrogenase.

The direct asymmetric reductive amination of heteroaryl ketones has been a long-standing synthetic challenge. Here we report the engineering of an amine dehydrogenase (AmDH) from Jeotgalicoccus aerolatus for the asymmetric synthesis of chiral α-(hetero)aryl primary amines in excellent conversions (up to 99 %) and enantioselectivities (up to 99 % ee). The best AmDH variant (Ja-AmDH-M33 ) exhibited high activity and specificity toward alkyl (hetero)aryl ketones, even for those bearing a bulky alkyl chain. An efficient directed evolution approach based on molecular docking was implemented to enlarge the active pocket with a more hydrophobic entrance, which is responsible for the high activity. The Ja-AmDH-M33 was also used for preparative-scale synthesis of pharmaceutically relevant amines and a key intermediate of chiral pincer ligands, which highlighted its practical application in synthetic chemistry.

High-Throughput Zwitterion-Modified MoS2 Membranes: Preparation and Application in Dye Desalination.

Although loose nanofiltration membranes have been extensively studied for dye desalination, high-throughput membranes with antifouling and antibacterial properties are still highly needed. In this study, a zwitterion-modified molybdenum disulfide (MoS2) dual-layer loose nanofiltration membrane was prepared with the integration of antibacterial, antifouling, and high-flux properties. To be specific, MoS2 nanosheets were loaded on a polyacrylonitrile ultrafiltration membrane through pressure-assisted self-assembly. Then, poly (sulfobetaine methacrylate) (PSBMA) was coated on the surface of the MoS2 membrane via a simple polydopamine (PDA)-assisted one-step codeposition to prepare PSBMA/PDA/MoS2 nanofiltration membranes. Elemental and morphological analyses confirmed the formation of the MoS2 layer and PSBMA/PDA coating. In addition, the effect of the PSBMA amount and codeposition time on surface properties and membrane performances was investigated. Under optimum conditions, the as-prepared membrane showed excellent water permeance of 262 LMH/bar with good dye rejection (99.8% for methylene blue) and salt permeability, as well as excellent antifouling and antibacterial properties benefiting from the synergy of PSBMA/PDA coating layers and MoS2 layers.

Combinations of Multiple Neuroimaging Markers using Logistic Regression for Auxiliary Diagnosis of Alzheimer Disease and Mild Cognitive Impairment.

BACKGROUND: Multiple neuroimaging modalities have been developed providing various aspects of information on the human brain. OBJECTIVE: Used together and properly, these complementary multimodal neuroimaging data integrate multisource information which can facilitate a diagnosis and improve the diagnostic accuracy. METHODS: In this study, 3 types of brain imaging data (sMRI, FDG-PET, and florbetapir-PET) were fused in the hope to improve diagnostic accuracy, and multivariate methods (logistic regression) were applied to these trimodal neuroimaging indices. Then, the receiver-operating characteristic (ROC) method was used to analyze the outcomes of the logistic classifier, with either each index, multiples from each modality, or all indices from all 3 modalities, to investigate their differential abilities to identify the disease. RESULTS: With increasing numbers of indices within each modality and across modalities, the accuracy of identifying Alzheimer disease (AD) increases to varying degrees. For example, the area under the ROC curve is above 0.98 when all the indices from the 3 imaging data types are combined. CONCLUSION: Using a combination of different indices, the results confirmed the initial hypothesis that different biomarkers were potentially complementary, and thus the conjoint analysis of multiple information from multiple sources would improve the capability to identify diseases such as AD and mild cognitive impairment.

Divergent Asymmetric Total Synthesis of Mulinane Diterpenoids.

A concise, divergent, asymmetric total syntheses of mulinane diterpenoids has been achieved. Specifically, a new strategy was developed featuring a key intramolecular Friedel-Crafts reaction to construct the chiral fused 5-6-6 tricyclic motif, followed by sequential Birch reduction, conjugate methylation, and homologation/ring-expansion reactions to furnish the desired 5-6-7 tricyclic skeleton bearing five contiguous stereocenters. With this efficient strategy, seven mulinane diterpenoids and two analogues were synthesized via late-stage functional modification or functionalization in 8.6-20 % overall yields and 11-15 steps.

A Proline-Based Artificial Enzyme That Favors Aldol Condensation Enables Facile Synthesis of Aliphatic Ketones via Tandem Catalysis.

A proline-based artificial enzyme is prepared by grafting the l-proline moieties onto the surface of bovine serum albumin (BSA) protein through atom transfer radical polymerization (ATRP). The artificial enzyme, the BSA-PolyProline conjugate, prefers to catalyze the formation of unsaturated ketones rather than ß-hydroxy ketones in the reaction between acetone and aldehydes, which is difficult to achieve in free-proline catalysis. The altered reaction selectivity is ascribed to the locally concentrated l-proline moieties surrounding the BSA molecule, indicating a microenvironmental effect-induced switching of the reaction mechanism. Taking advantage of this selectivity, we used this artificial enzyme in conjunction with a natural enzyme, old yellow enzyme 1 (OYE1), to demonstrate a simple synthesis of different aliphatic ketones from acetone and aldehydes via tandem catalysis.

Asymmetric α-benzylation of cyclic ketones enabled by concurrent chemical aldol condensation and biocatalytic reduction.

Chemoenzymatic cascade catalysis has emerged as a revolutionary tool for streamlining traditional retrosynthetic disconnections, creating new possibilities for the asymmetric synthesis of valuable chiral compounds. Here we construct a one-pot concurrent chemoenzymatic cascade by integrating organobismuth-catalyzed aldol condensation with ene-reductase (ER)-catalyzed enantioselective reduction, enabling the formal asymmetric α-benzylation of cyclic ketones. To achieve this, we develop a pair of enantiocomplementary ERs capable of reducing α-arylidene cyclic ketones, lactams, and lactones. Our engineered mutants exhibit significantly higher activity, up to 37-fold, and broader substrate specificity compared to the parent enzyme. The key to success is due to the well-tuned hydride attack distance/angle and, more importantly, to the synergistic proton-delivery triade of Tyr28-Tyr69-Tyr169. Molecular docking and density functional theory (DFT) studies provide important insights into the bioreduction mechanisms. Furthermore, we demonstrate the synthetic utility of the best mutants in the asymmetric synthesis of several key chiral synthons.

Integrating Au Catalysis and Engineered Amine Dehydrogenase for the Chemoenzymatic Synthesis of Chiral Aliphatic Amines.

Direct synthesis of aliphatic amines from alkynes is highly desirable due to its atom economy and high stereoselectivity but still challenging, especially for the long-chain members. Here, a combination of Au-catalyzed alkyne hydration and amine dehydrogenase-catalyzed (AmDH) reductive amination was constructed, enabling sequential conversion of alkynes into chiral amines in aqueous solutions, particularly for the synthesis of long-chain aliphatic amines on a large scale. The production of chiral aliphatic amines with more than 6 carbons reached 36-60 g/L. A suitable biocatalyst [PtAmDH (A113G/T134G/V294A)], obtained by data mining and active site engineering, enabled the transformation of previously inactive long-chain ketones at high concentrations. Computational analysis revealed that the broader substrate scope and tolerance with the high substrate concentrations resulted from the additive effects of mutations introduced to the three gatekeeper residues 113, 134, and 294.

Molecular Engineering and Morphology Control of Covalent Organic Frameworks for Enhancing Activity of Metal-Enzyme Cascade Catalysis.

Metal-enzyme integrated catalysts (MEICs) that combine metal and enzyme offer great potential for sustainable chemoenzymatic cascade catalysis. However, rational design and construction of optimal microenvironments and accessible active sites for metal and enzyme in individual nanostructures are necessary but still challenging. Herein, Pd nanoparticles (NPs) and Candida antarctica lipase B (CALB) are co-immobilized into the pores and surfaces of covalent organic frameworks (COFs) with tunable functional groups, affording Pd/COF-X/CALB (X = ONa, OH, OMe) MEICs. This strategy can regulate the microenvironment around Pd NPs and CALB, and their interactions with substrates. As a result, the activity of the COF-based MEICs in catalyzing dynamic kinetic resolution of primary amines is enhanced and followed COF-OMe > COF-OH > COF-ONa. The experimental and simulation results demonstrated that functional groups of COFs modulated the conformation of CALB, the electronic states of Pd NPs, and the affinity of the integrated catalysts to the substrate, which contributed to the improvement of the catalytic activity of MEICs. Further, the MEICs are prepared using COF with hollow structure as support material, which increased accessible active sites and mass transfer efficiency, thus improving catalytic performance. This work provides a blueprint for rational design and preparation of highly active MEICs.

Bacteria-based cascade in situ near-infrared nano-optogenetically induced photothermal tumor therapy.

Rationale: Optogenetically engineered facultative anaerobic bacteria exhibit a favorable tendency to colonize at solid tumor sites and spatiotemporally-programmable therapeutics release abilities, attracting extensive attention in precision tumor therapy. However, their therapeutic efficacy is moderate. Conventional photothermal agents with high tumor ablation capabilities exhibit low tumor targeting efficiency, resulting in significant off-target side effects. The combination of optogenetics and photothermal therapy may offer both tumor-targeting and excellent tumor-elimination capabilities, which unfortunately has rarely been investigated. Herein, we construct a bacteria-based cascade near-infrared optogentical-photothermal system (EcNαHL-UCNPs) for enhanced tumor therapy. Methods: EcNαHL-UCNPs consists of an optogenetically engineered Escherichia coli Nissle 1917 (EcN) conjugated with lanthanide-doped upconversion nanoparticles (UCNPs), which are capable of locally secreting α-hemolysin (αHL), a pore-forming protein, in responsive to NIR irradiation. Anti-tumor effects of EcNαHL-UCNPs were determined in both H22 and 4T1 tumors. Results: The αHL not only eliminates tumor cells, but more importantly disrupts endothelium to form thrombosis as an in situ photothermal agent in tumors. The in situ formed thrombosis significantly potentiates the photothermic ablation of H22 tumors upon subsequent NIR light irradiation. Besides, αHL secreted by EcNαHL-UCNPs under NIR light irradiation not only inhibits 4T1 tumor growth, but also suppresses metastasis of 4T1 tumor via inducing the immune response. Conclusion: Our studies highlight bacteria-based cascade optogenetical-photothermal system for precise and effective tumor therapy.

Immobilization of cross-linked enzymes aggregates on hierarchical covalent organic frameworks: Highly stable chemoenzymatic nanoreactor for asymmetric synthesis of optically active halohydrins.

Organometallic catalyst is extensively applied for the non-enzymatic regeneration of nicotinamide adenine dinucleotide (phosphate) cofactors, but suffering from the mutual inactivation with the enzymes in one pot. The spatially separated immobilization of organometallic catalyst and enzymes on suitable carriers not only can reduce their mutual inhabitation but also can enhance their reusability. Here in this work, we present a hierarchical porous COFs (HP-TpBpy) that incorporated with [(Cp*RhCl2]2 to generate the metalized COF, Rh-HP-TpBpy. The obtained Rh-HP-TpBpy exhibited superior performance in nicotinamide adenine dinucleotide (NADH) and nicotinamide adenine dinucleotide phosphate (NADPH) regeneration using formate as the hydride donor, significantly outperforming the natural formate dehydrogenases in cofactor preference toward NADP+. Subsequently, the Lactobacillus fermentum short-chain dehydrogenase/reductase 1 (LfSDR1) was then cross-linked into enzyme aggregates (CLEA) and immobilized on hierarchical Rh-HP-TpBpy, achieving the integrated chemoenzymatic catalyst, LfSDR1@Rh-HP-TpBpy, which can catalyze the chemoenzymatic reduction of halogenated aryl ketones and give the corresponding optically active halohydrins with high conversion and enantiomeric excess (ee) value up to 99 %. The LfSDR1@Rh-HP-TpBpy also exhibits largely enhanced stability compared with the free LfSDR1 and the CLEAs-LfSDR1, enabling its excellent reusability.

Heteroatom Structural Engineering of Conjugated Porous Polymers Enhances Photocatalytic Nicotinamide Cofactor Regeneration.

Photocatalysis is an eco-friendly method to regenerate nicotinamide (NADH) cofactors, which is essential for biotransformation over oxidoreductases. Organic polymers exhibit high stability, biocompatibility and functional designability as photocatalysts, but still suffering from rapid charge recombination. Herewith the heteroatom structural engineering of donor-π-acceptor (D-π-A) conjugated porous polymers were conducted to promote charge transfer and photocatalytic NADH regeneration. The electron delocalization of polymer photocatalysts can be readily tuned by changing the electron density of the donor unit, leading to faster charge separation and better photocatalytic performance. The optimum sulfur-doped polymer exhibits the highest NADH regeneration yield of 47.4 % in 30 min and 94.1 % in 4 h, which can drive the biocatalytic C=C bond reduction of 2-cyclohexen-1-one by ene-reductase, giving the corresponding cyclohexanone yield of 96.7 % in 10 h. Moreover, the oxygen-doped polymer, from biomass derived 2,5-diformylfuran, exhibits comparable photocatalytic activity to the sulfur-doped CPP, suggesting the potential of furan as alternative donor unit to thiophene.

Construction of an Immunity and Ferroptosis-Related Risk Score Model to Predict Ovarian Cancer Clinical Outcomes and Immune Microenvironment.

BACKGROUND: Ovarian cancer (OV) is a severe and common gynecological disease. Ferroptosis can regulate the progression and invasion of tumors. The immune system is a decisive factor in cancer. The present study aimed to use gene expression data to establish an immunity and ferroptosis-related risk score model as a prognostic biomarker to predict clinical outcomes and the immune microenvironment of OV. METHODS: Common gene expression data were searched from the Gene Expression Omnibus and The Cancer Genome Atlas databases. Immunity-related genes and ferroptosis-related genes were searched and downloaded from the ImmPort and FerrDb databases, followed by the analysis of the overall survival of patients with OV and the identification of genes. Subsequently, the status of the infiltration of immune cells and the association between immune checkpoints and risk score were assessed. RESULTS: A total of 10 prognostic genes (C5AR1, GZMB, IGF2R, ISG20, PPP3CA, STAT1, TRIM27, TSHR, RB1, and EGFR) were included in the immunity and ferroptosis-related risk score model. The high-risk group had a higher infiltration of immune cells. The risk score, an independent prognostic feature of OV was negatively associated with each immune checkpoint. The risk score may thus help to predict the response to immunotherapy. CONCLUSIONS: The immunity and ferroptosis-related risk score model is an independent prognostic factor for OV. The established risk score may help to predict the response of patients to immunotherapy.

Engineered baicalein-decorated zinc phosphates for synergistic alleviation of inflammatory bowel disease by repairing the mucosal barrier and relieving oxidative stress.

Orally administered baicalein-decorated zinc phosphates (ZnBM) were engineered for mucosal barrier improvement and intestinal inflammation relief. ZnBM with a size of 1.78 µm comprised 5.58 wt% baicalein and 13.17 wt% zinc. The incorporation of baicalein endowed ZnBM with excellent radical scavenging activities. ZnBM exhibited good stability with negligible zinc release in PBS solution for 2 days, and 32.82% of the zinc could reach the gut. In addition, ZnBM polarized macrophages into the anti-inflammatory M2 type and effectively scavenged intracellular reactive oxygen species (ROS) of lipopolysaccharide (LPS)-treated RAW264.7. Meanwhile, ZnBM effectively scavenged intracellular ROS of phorbol 12-myristate 13-acetate (PMA)-induced Caco-2 cells and exerted a reparative effect on the LPS-damaged Caco-2 monolayer, causing an obvious improvement of the barrier function. Reduced systemic exposure to FITC-dextran was observed to illustrate barrier restoration by ZnBM, which was achieved through upregulation of tight junction protein expression. Notably, the commonly used clinical drug 5-aminosalicylic acid is toxic to the liver and kidneys, and commercial ZnO caused the death of mice during treatment. Apparently, the therapeutic effect of ZnBM was significantly better than that of baicalein alone in chronic colitis. Overall, ZnBM exhibited outstanding therapeutic efficacy and is expected to treat colitis due to its effectiveness, biosecurity, facile preparation, and easy storage.

Immobilization of Enzymes on Cyclodextrin-Anchored Dehiscent Mesoporous TiO2 for Efficient Photoenzymatic Hydroxylation.

A three-in-one heterogeneous catalyst (UPO@dTiO2-CD) was fabricated by grafting cyclodextrins (CDs) on the dehiscent TiO2 (dTiO2) surface and subsequently immobilizing unspecific peroxygenase (rAaeUPO), which exhibited double enhanced electron/mass transfer in photo-enzymatic enantioselective hydroxylation of the C-H bond. The tunable anatase/rutile phase ratio and dehiscent mesoporous architectures of dTiO2 and the electron donor feature and hydrophobic inner cavity of the CDs are independently responsible for accelerating both electron and mass transfer. The coordination of the photocatalytic and enzymatic steps was achieved by structural and compositional regulation. The optimized UPO@dTiO2-CD not only displayed high catalytic efficiency (turnover number and turnover frequency of rAaeUPO up to >65,000 and 91 min-1, respectively) but also exhibited high stability and reusability.

Asymmetric Hydrogenation of C = C Bonds in a SpinChem Reactor by Immobilized Old Yellow Enzyme and Glucose Dehydrogenase.

The application of immobilized enzymes in pharmaceutical and bulk chemical production has been shown to be economically viable. We demonstrate the exceptional performance of a method that immobilizes the old yellow enzyme YqjM and glucose dehydrogenase (GDH) on resin for the asymmetric hydrogenation (AH) of C = C bonds in a SpinChem reactor. When immobilized YqjM and GDH are reused 10 times, the conversion of 2-methylcyclopentenone could reach 78%. Which is because the rotor of the SpinChem reactor effectively reduces catalyst damage caused by shear force in the reaction system. When the substrate concentration is 175 mM, an 87% conversion of 2-methylcyclopentenone is obtained. The method is also observed to perform well for the AH of C = C bonds in other unsaturated carbonyl compounds with the SpinChem reactor. Thus, this method has great potential for application in the enzymatic production of chiral compounds.

Fabrication of Three-Dimensional ZnO: Ga@ITO@Ag SERS-Active Substrate for Sensitive and Repeatable Detectability.

Vertically aligned ZnO: Ga nanotowers can be directly synthesized on a glass substrate with a ZnO seed film via the chemical bath method. A novel heterostructure of ZnO: Ga@ITO@Ag nanotowers was subsequently deposited in the ITO layer and Ag nanoparticles via the facile two-step ion-sputtering processes on the ZnO: Ga nanotowers. The appropriate ion-sputtering times of the ITO layer and Ag nanoparticles can benefit the fabrication of ZnO: Ga@ITO@Ag nanotowers with higher surface-enhanced Raman scattering (SERS) enhancement in detecting rhodamine 6G (R6G) molecules. Compared with ZnO: Ga@Ag nanotowers, ZnO: Ga@ITO@Ag nanotowers exhibited a high SERS enhancement factor of 2.25 × 108 and a lower detection limit (10-14 M) for detecting R6G molecules. In addition, the ITO layer used as an intermediate layer between ZnO: Ga nanotowers and Ag nanoparticles can improve SERS enhancement, sensitivity, uniformity, reusability, detection limit, and stability for detecting amoxicillin molecules. This phenomenon shall be ascribed to the ITO layer exhibiting a synergistic Raman enhancement effect through interfacial charge transfer for enhancing SERS activity. As a result, ZnO: Ga@ITO@Ag nanotowers can construct a three-dimensional SERS substrate for potential applications in environmentally friendly and cost-effective chemical or drug detection.