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Multiple drug resistance (MDR) bacterial strains are responsible by 1.2 million of human deaths all over the world. The pathogens possess efficient enzymes which are able to mitigate the toxicity of reactive oxygen species (ROS) produced by some antibiotics and the host immune cells. Among them, the bacterial peroxiredoxin alkyl hydroperoxide reductase C (AhpC) is able to decompose efficiently several kinds of hydroperoxides. To decompose their substrates AhpC use a reactive cysteine residue (peroxidatic cysteine—CysP) that together with two other polar residues (Thr/Ser and Arg) comprise the catalytic triad of these enzymes and are involved in the substrate targeting/stabilization to allow a bimolecular nucleophilic substitution (SN2) reaction. Additionally to the high efficiency the AhpC is very abundant in the cells and present virulent properties in some bacterial species. Despite the importance of AhpC in bacteria, few studies aimed at using natural compounds as inhibitors of this class of enzymes. Some natural products were identified as human isoforms, presenting as common characteristics a bulk hydrophobic moiety and an α, β-unsaturated carbonylic system able to perform a thiol-Michael reaction. In this work, we evaluated two chemically related natural products: 1,4-dihydroxy-2-(3',7'-dimethyl-1'-oxo-2'E,6'-octadienyl) benzene (C1) and 4-hydroxy-2-(3',7'-dimethyl-1'-oxo-2'E,6'-octadienyl) benzoic acid (C2), both were isolated from branches Piper crassinervium (Piperaceae), over the peroxidase activity of AhpC from Pseudomonas aeruginosa (PaAhpC) and Staphylococcus epidermidis (SeAhpC). By biochemical assays we show that although both compounds can perform the Michael addition reaction, only compound C2 was able to inhibit the PaAhpC peroxidase activity but not SeAhpC, presenting IC50 = 20.3 μM. SDS-PAGE analysis revealed that the compound was not able to perform a thiol-Michael addition, suggesting another inhibition behavior. Using computer-assisted simulations, we also show that an acidic group present in the structure of compound C2 may be involved in the stabilization by polar interactions with the Thr and Arg residues from the catalytic triad and several apolar interactions with hydrophobic residues. Finally, C2 was not able to interfere in the peroxidase activity of the isoform Prx2 from humans or even the thiol proteins of the Trx reducing system from Escherichia coli (EcTrx and EcTrxR), indicating specificity for P. aeruginosa AhpC. [ABSTRACT FROM AUTHOR]

Laccase-catalyzed coloration toward wool was carried out and the K/S of wool fabric dyed was much higher than raw wool, presenting a claybank color. On this basis, the reaction mechanism is elucidated using tyrosine, tryptophan and the mixture as substrates. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and LC-MS as well as FT-IR measurements were used to study the reactions. The results indicate that the laccase-catalyzed reaction of tyrosine monomer, tyrosine monomer and the mixture, respectively, generates free radicals, including phenoxy radical and benzene radicals, pyrrolidine radical. The coupling reaction can occur between two free radicals, and further the Michael addition reaction occurs between benzene radicals with monomer another tyrosine. In view of the tan polytyrosine and rufous polytryptophan, as well as the higher content of tyrosine than tryptophan, the oxidation coupling reaction of tyrosine residue predominates over that of tryptophan residue in the process of laccase-catalyzed coloration toward wool. [ABSTRACT FROM AUTHOR]

Michael addition reactions are highly useful in organic synthesis and are commonly accomplished using organocatalysts. However, the corresponding biocatalytic Michael additions are rare, typically lack synthetically useful substrate scope, and suffer from low stereoselectivity. Herein we report a biocatalytic nitro‐Michael addition, catalyzed by NahE, that proceeds with low catalyst loading at room temperature in moderate to excellent enantioselectivity and high yields. A series of β‐nitrostyrenes reacted with pyruvate in the presence of NahE to give, after oxidative decarboxylation, β‐aryl‐γ‐nitrobutyric acids in up to 99 % yield without need for chromatography, providing a simple preparative‐scale route to chiral GABA analogues. This reaction represents the first example of an aldolase displaying promiscuous Michaelase activity and opens the use of nitroalkenes in place of aldehydes as substrates for aldolases. [ABSTRACT FROM AUTHOR]

It is highly desirable to develop high-performance ratiometric fluorescent probes for SO2 derivative detection and realize their application in biological imaging. In this study, we report the rational design of a novel negative photochromic spiropyran derivative, spiro[azahomoadamantane-pyran] (MAHD-SP), with notable orange fluorescence in its stable ring-opened state without UV regulation. The unsaturated double bond of MAHD-SP underwent the Michael addition reaction of the SO2 derivative, making the fluorescence quenching of MAHD-SP obvious. Then, MAHD-SP, a fluorescent conjugated polymer PFO and a polymeric surfactant PEO113-b-PS49 were used to construct a ratiometric fluorescent polymeric nanoprobe (RFPN) via a coprecipitation method. The probe exhibited high sensitivity and selectivity for the ratiometric detection of SO2 derivatives in pure aqueous solutions. Moreover, the good biocompatibility of RFPN can be used to visualize exogenous and endogenous SO2 derivative generation in living cells. [ABSTRACT FROM AUTHOR]

Different Chiral Ionic Liquids (CIL) based on L-proline have been developed. Simple and efficient synthetic methodologies are used, allowing preparation in good yields for twelve novel CILs using L-proline as a cation or anion combined with suitable counter-ions. A detailed physical and chemical characterization of the CILs was performed to evaluate the influence of counter-ions on the final properties. The most promissory CILs were tested as efficient chiral catalysts in IL media for asymmetric Michael addition reactions of ketones and aldehydes to nitro-olefins. Similar or even better conversions and enantioselectivities (ee up to 95%) compared to the original L-proline were achieved. Additionally, a good product extraction performance using supercritical CO2 processes was obtained. [ABSTRACT FROM AUTHOR]

As the clinical demand for blood‐contacting materials increases, higher requirements are placed on their physicochemical properties, durability and hemocompatibility in vivo. In this work, a multiple functionalized material was developed through a facile modification process. Herein, polycarbonate urethane (PCU) surface was co‐modified with polyethylene glycol (PEG) and bivalirudin (BVLD). PCU provides excellent physical and mechanical properties, PEG and BVLD, especially BVLD, enable the surface with outstanding anticoagulant capacity. Specifically, PCU surface was first treated with hexamethylene diisocyanate to introduce active isocyanate groups onto the surface, followed by hydroxy‐PEG grafting to improve the hydrophilicity. Finally, BVLD was immobilized on the surface via Michael addition reaction to improve antithrombotic properties. Attenuated total reflection Fourier transforms infrared spectroscopy and UV spectrophotometers were used to confirm the modified surfaces. The hydrophilicity was characterized by static water contact angle measurement, the morphology of the modified surfaces was observed by scanning electron microscopy. Blood compatibility of the modified surfaces was characterized by the hemolysis rate, platelet adhesion assay and cell culture test. The results showed that the BVLD immobilized surface has excellent anticoagulant properties, good fibrin‐bound thrombin inhibition, and good resistance against non‐specific adhesion of proteins. Hence, the co‐modification with PEG and BVLD was proved an encouraging strategy for improving hemocompatibility. [ABSTRACT FROM AUTHOR]

The aim was to develop a nanoscale drug delivery system with enzyme responsive and acid sensitive particle size and intelligent degradation aiming to research the inhibitory effect on breast cancer. The delivery system addressed the problems of tissue targeting, cellular internalization, and slow drug release at the target site, which could improve the efficiency of drug delivery and provide a feasible therapeutic approach for breast cancer. The acid sensitive functional material DSPE-PEG2000-dyn-PEG-R9 was synthesized by Michael addition reaction. Then, the berberine plus baicalin intelligent micelles were prepared by thin-film hydration. Subsequently, we characterized the physical and chemical properties of berberine plus baicalin intelligent micelles, evaluated its anti-tumor effects in vivo and in vitro. The target molecule was successfully synthesized, and the intelligent micelles showed excellent chemical and physical properties, delayed drug release and high encapsulation efficiency. In vitro and in vivo experiments also confirmed that the intelligent micelles could effectively target tumor sites, penetrate tumor tissues, enrich in tumor cells, inhibit tumor cell proliferation, inhibit tumor cell invasion and migration, and induce tumor cell apoptosis. Berberine plus baicalin intelligent micelles have excellent anti-tumor effects and no toxicity to normal tissues, which provides a new potential drug delivery strategy for the treatment of breast cancer. [ABSTRACT FROM AUTHOR]

A chromone‐based Michael reaction using water as solvent and nucleophile was firstly developed to derivatize chromone via a multicomponent reaction (MCR) cascade sequence in absence of metal catalyst. A series of versatile enaminodiones was synthesized and further successfully transferred into two different pyrazoles with the same starting material under facile and mild condition by a pH control of the preferred isomer. [ABSTRACT FROM AUTHOR]

In this work, a green-electrochemical synthesis was applied to catechol oxidation (1) to o-benzoquinone (2) using cyclic voltammetry and potential controlled coulometry. Encouraging results were obtained in the presence of semicarbazide (3) as a nucleophile in an ethanol/phosphate buffer mixture (pH 7.0). The pH, number of cycles, and scan rate were studied. The results indicate that the generated o-benzoquinone (2) participates in a Michael addition reaction with nucleophilic hydrazide via the ECEC mechanism to form a new triazinone adduct. The obtained results showed that a novel heterocyclic triazinone (9) product functionalized with hydroxyl and amide groups had been synthesized with a 68% yield. After purification, the product has been characterized by IR, UV-visible, GC/MS, 1H, and 13C NMR. The green-electrochemical synthesis approach produced novel organics with excellent purities and yields while being environmentally friendly and free of hazardous reagents. [ABSTRACT FROM AUTHOR]

In order to improve the bioavailability of curcumin, studies have been undertaken to prepare the so-called monocarbonyl analogs of curcumin (MACs) and assess their biological activity. These analogs contain an electrophilic α,β-unsaturated carbonyl moiety (Michael acceptor). Several key biological processes are connected/controlled with thiol alkylation (glutathione, cysteine, cysteine peptide residues). The most likely reaction is the Michael addition between the α,β-unsaturated acceptor and a corresponding thiol. 2,6-Bisarylidenecyclohexanone and 3,5-bisarylidenepiperidin-4-one scaffolds offer convenient tunability of electrophilicity and redox properties of the Michael acceptor by the introduction of various substituents. In this study, several MACs were prepared by Claisen-Schmidt condensation reaction, and their reactivity with 2-(dimethylamino)ethanethiol was evaluated. For this purpose, based on the UV-Vis spectra of the analogs and thiol(s), a proper method for spectrophotometric evaluation of their reactivity with 2-(dimethylamino)ethanethiol was optimized. The relative reactivity of the analogs was 7 > 2 > 5 > 4 > 1 ≈ 6. The developed method is simple, and it can be extended to assess the reactivity of other MACs. [ABSTRACT FROM AUTHOR]

Polydopamine (PDA) depositions, inspired by mussel foot adhesive proteins, represent a versatile method for preparing separation membranes. However, PDA-based nanofiltration membranes are limited by the long preparation time and moderate flux. This work modulated PDA deposition processes with a spiro-piperazine (SPIP) molecule containing two secondary amine groups and a quaternary ammonium salt. The SPIP could be covalently inserted into PDA coating structures via Michael addition reaction to accelerate the deposition process of PDA and reduce its aggregation. In addition, the rigid and spiro configuration of SPIP molecules provides higher fractional free volume and leads to looser and more uniform structures in the PDA coating. As such, water permeance of PDA/SPIP membranes is 73 L m(2 h(1 bar(1, 4.6 times improved compared with PDA control membranes, while the dye rejection (>99% for Congo red) is maintained high. These results demonstrate that SPIP is an effective molecule for the structure and performance engineering of mussel-inspired PDA nanofiltration membranes. [ABSTRACT FROM AUTHOR]

Glutathione S-transferases (GSTs) are important type-II detoxification enzymes that protect DNA and proteins from damage and are often used as protein tags for the expression of fusion proteins. In the present work, octa-aminopropyl caged polyhedral oligomeric silsesquioxane (OA–POSS) was prepared via acid-catalyzed hydrolysis of 3-aminopropyltriethoxysilane and polymerized on the surface of graphene oxide (GO) through an amidation reaction. Glutathione (GSH) was then modified to GO–POSS through a Michael addition reaction to obtain a GSH-functionalized GO–POSS composite (GPG). The structure and characteristics of the as-prepared GPG composite were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravity analysis, and surface charge analysis. The specific binding interactions between glutathione and GST gave GPG favorable adsorption selectivity towards GST, and other proteins did not affect GST adsorption. The adsorption behavior of GST on the GPG composite conformed to the Langmuir isotherm model, and the adsorption capacity of GST was high up to 364.94 mg g−1 under optimal conditions. The GPG-based solid-phase adsorption process was applied to the extraction of GST from a crude enzyme solution of pig liver, and high-purity GST was obtained via SDS-PAGE identification. [ABSTRACT FROM AUTHOR]

The structurally simplified trans-4-hydroxy-L-prolinamide derivatives are prepared as the efficient organocatalysts for Michael-type asymmetric reactions. Their catalytic behaviors are evaluated in the asymmetric Michael addition of aldehydes to nitroolefins with （S）-1，1'-bi-2-naphthol as the co-catalyst. Excellent diastereoand enantioselectivities（respectively up to >99/1 and 99%), as well as high yields（up to 96%）are achieved even at the catalyst loading of as low as 0. 5%~1%（molar percent）. This study provides a facile method to develop the low-cost and highly efficient organocatalyst system for the asymmetric Michael addition reactions. [ABSTRACT FROM AUTHOR]

A series of novel waterborne photosensitive resins were prepared successfully with poly(propylene oxide) bis(2-aminopropyl ether), tricyclodecane dimethanol diacrylate, 2-isocyanatoethyl acrylate, and hydrochloric acid by Michael addition reaction. The results show that with the increasing double bonds content, the double bonds conversion increases from 78.7, 85.6 to 92.8% in the photopolymerization, respectively, and the gel content of the UV-cured film increases from 48.05, 69.10 to 83.28%. In addition, the glass transition temperature and tensile strength of the UV-cured film follow the same increasing trend. Moreover, the content of hydrochloride has a great influence on the hydrophilicity of the waterborne photosensitive resins. The studies indicated that as the hydrochloride content decreases, the surface water contact angle of the UV-cured film increases from 10.8, 22.9 to 51.5°, and water absorption decreases from 26.55, 16.20 to 11.06%, respectively. Moreover, the waterborne photosensitive resins exhibited a high printing accuracy together with a good effect of washing and are promising for 3D printing [ABSTRACT FROM AUTHOR]

A facile, efficient, and simple one‐pot multi‐component protocol for the synthesis of pyrano[2,3‐c] pyrazoles has been developed using a cheap and readily available copper catalyst under moderate reaction conditions. Target products are obtained from aromatic aldehyde via Knoevenagel condensation and Michael addition reactions. Functional group tolerance and reaction mechanisms have also been examined in this methodology. In addition, we have also evaluated the anti‐cancer activity of the target products and we have attempted this method for practical utility purposes also. [ABSTRACT FROM AUTHOR]

The evolution of modern catalytic methodologies for asymmetric organic synthesis, including transition metal and organocatalysis, is briefly considered. The results of the authors' research group comprise the development of convenient, efficient, and reusable metal-free amine-containing catalysts (aminocatalysts) for manufacturing enantiomerically enriched organic compounds. The efficiency of the obtained catalysts is demonstrated for asymmetric aldol reactions, Michael reactions, and domino reactions, including green chemistry processes. The applicability of the developed catalysts and processes for the synthesis of natural product analogs and the most active enantiomers of clinically used drugs is demonstrated. [ABSTRACT FROM AUTHOR]

Ni(II) complex of the Schiff base of the chiral auxiliary (S)-2- N -(N ′-benzylprolyl)aminobenzophenone (BPB) and dehydroalanine as the initial complex in the addition reaction was investigated. The obtained four new derivatives of α-alanine were investigated as inhibitors of aldose reductase. Only one of them: (S)-2-amino-3-[(4-methylbenzyl)amino]propanoic acid showed activity. It becomes a reason for studying the patterns of biological activity of the structure of α-amino acids. The results of docking analysis indicated that (S)-2-amino-3-[(4-methylbenzyl)amino]propanoic acid demonstrated the ability to form bonds with different functional groups of the enzyme which let us assume that some amino acids of nonfunctional groups, such as Trp20 of ALR2, can play a key role in inhibitor–enzyme interactions. [ABSTRACT FROM AUTHOR]

The Michael addition reaction between dithiomalondianilide (N,N′-diphenyldithiomalondiamide) and arylmethylidene Meldrum's acids, accompanied by subsequent heterocyclization, was investigated along with factors affecting the mixture composition of the obtained products. The plausible mechanism includes the formation of stable Michael adducts which, under the studied conditions, undergo further transformations to yield corresponding N-methylmorpholinium 4-aryl-6-oxo-3-(N-phenylthio-carbamoyl)-1,4,5,6-tetrahydropyridin-2-thiolates and their oxidation derivatives, 4,5-dihydro-3H-[1,2]dithiolo[3,4-b]pyridin-6(7H)-ones. The structure of one such product, N-methylmorpholinium 2,2-dimethyl-5-(1-(2-nitrophenyl)-3-(phenylamino)-2-(N-phenylthiocarbamoyl)-3-thioxopropyl)-4-oxo-4H-1,3-dioxin-6-olate, was confirmed via X-ray crystallography. [ABSTRACT FROM AUTHOR]

In this work, the enantioselective total synthesis of (–)-quinine has been accomplished in a pot-economical manner using five reaction vessels. In the first pot, reactions involve the diphenylprolinol silyl ether-mediated Michael reaction, aza-Henry reaction, hemiaminalization, and elimination of HNO2 (five reactions), affording a chiral tetrahydropyridine with excellent enantioselectivity. In the second pot, five reactions proceed with excellent diastereoselectivity to afford a trisubstituted piperidine with the desired stereochemistry. A further five reactions are carried out in the last one-pot sequence. Syntheses of quinine have fascinated organic chemists for over a hundred years. Here, the authors developed an organocatalyst-mediated pot-economical enantioselective total synthesis using five reaction vessels. [ABSTRACT FROM AUTHOR]

Various aminoalkyl substituted triazines have been synthesised and their activity as organocatalyst has been studied in Michael addition reactions of β-diketones to nitrostyrenes. All the catalysts are found to be effective towards the addition reaction and highest performance is achieved with the catalyst having long chain alkyl group. The effect of base and solvent has also been investigated, and the condition has been optimized with triethylamine as the base and chlorobenzene as the solvent for excellent yields. The reaction is highly remarkable since the catalyst under study is readily available and inexpensive compared to other organocatalyst known for the reaction. [ABSTRACT FROM AUTHOR]

Renal ischemia–reperfusion injury (IRI) is a common prerequisite of acute renal injury (AKI) that involves the entire system and induces critical illness. The C domain of insulin-like growth factor-1 (IGF-1C) plays an important role in promoting angiogenesis and enhancing the inflammatory response. However, given the shortcomings of its short half-life and poor stability, the application of IGF-1C is restricted. In the present study, IGF-1C nanoparticles (NP-IGF-1C) were constructed by combining 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[maleimide (polye thyleneglycol)](DSPE-PEG-MAL) and IGF-1C through a Michael addition reaction to evaluate the effects of NP-IGF-1C on preventing IRI. In vitro studies have shown that NP-IGF-1C is not cytotoxic and protects cells from oxidative damage. The renal enrichment and biocompatibility of NP-IGF-1C were determined in vivo by connecting fluorescent molecules to NP-IGF-1C for in vivo imaging and pathological staining of important organs. After IRI, renal function decreased, and inflammatory cell infiltration, oxidative stress and apoptosis increased. As expected, NP-IGF-1C reversed these changes, indicating that NP-IGF-1C played a protective role in the process of IRI, which may be mediated by its antioxidant, anti-inflammatory and antiapoptotic activities. [ABSTRACT FROM AUTHOR]

Cartilage damage is a common injury. Currently, tissue engineering scaffolds with composite seed cells have emerged as a promising approach for cartilage repair. Polyethylene glycol (PEG) hydrogels are attractive tissue engineering scaffold materials as they have high water absorption capacity as well as nontoxic and nutrient transport properties. However, PEG is fundamentally bio-inert and lacks intrinsic cell adhesion capability, which is critical for the maintenance of cell function. Cell adhesion peptides are usually added to improve the cell adhesion capability of PEG-based hydrogels. The suitable cell adhesion peptide can not only improve cell adhesion capability, but also promote chondrogenesis and regulate the immune microenvironment. To improve the interactions between cells and PEG hydrogels, we designed cysteine-arginine-glycine-aspartic acid (CRGD), a cell adhesion peptide covalently cross-linked with PEG hydrogels by a Michael addition reaction, and explored the tissue-engineering hydrogels with immunomodulatory effects and promoted chondrogenic differentiation of mesenchymal stem cells (MSCs). The results indicated that CRGD improved the interaction between peripheral blood mesenchymal stem cells (PBMSCs) and PEG hydrogels. PEG hydrogels modified with 1 mM CRGD had the optimal capacity to promote chondrogenic differentiation, and CRGD could induce macrophage polarization towards the M2 phenotype to promote tissue regeneration and repair. PEG-CRGD hydrogels combined with PBMSCs have the potential to be suitable scaffolds for cartilage tissue engineering. [ABSTRACT FROM AUTHOR]

Chiral primary α-amino amides, consisting of an adjacent enamine bonding site (Bronsted base site), a hydrogen bonding site (Bronsted acid site), and flexible bulky substituent groups to modify the steric factor, are proving to be extremely valuable bifunctional organocatalysts for a wide range of asymmetric organic transformations. Primary α-amino amides are less expensive alternatives to other primary amino organocatalysts, such as chiral diamines and cinchona-alkaloid-derived primary amines, as they are easy to synthesize, air-stable, and allow for the incorporation of a variety of functional groups. In recent years, we have demonstrated the catalytic use of simple primary α-amino amides and their derivatives as organocatalysts for the aldol reaction, Strecker reaction, Michael tandem reaction, allylation of aldehydes, reduction of N-Aryl mines, opening of epoxides, hydrosilylation, asymmetric hydrogen transfer, and N-specific nitrosobenzene reaction with aldehydes. [ABSTRACT FROM AUTHOR]

A series of 3-hydroxy-fluorene-2-carboxylate compounds were prepared from Michael addition of acetoacetate to 2-benzylideneindan-l-one followed by Robinson annulation and aromatization. In this reaction, we were able to isolate two Robinson annulation products and characterize them. This sequential reaction could proceed without the isolation of intermediates to give the desired products directly in reasonable yields. [ABSTRACT FROM AUTHOR]

Chalcone is an interesting scaffold found in the structure of many naturally occurring molecules. Medicinal chemists are commonly interested in designing new chalcone‐based structures because of having the α, β‐unsaturated ketone functional group, which allows these compounds to participate in Michael's reaction and create strong covalent bonds at the active sites of the targets. Some studies have identified several natural chalcone‐based compounds with the ability to inhibit the severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus proteases. A few years after the advent of the coronavirus disease 2019 pandemic and the publication of many findings in this regard, there is some evidence that suggests chalcone scaffolding has great potential for use in the design and development of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) inhibitors. Artificial placement of this scaffold in the structure of optimized anti‐SARS‐CoV‐2 compounds can potentially provide irreversible inhibition of the viral cysteine proteases 3‐chymotrypsin‐like protease and papain‐like protease by creating Michael interaction. Despite having remarkable capabilities, the use of chalcone scaffold in drug design and discovery of SARS‐CoV‐2 inhibitors seems to have been largely neglected. This review addresses issues that could lead to further consideration of chalcone scaffolding in the structure of SARS‐CoV‐2 protease inhibitors in the future. [ABSTRACT FROM AUTHOR]

Etherification of cellulose is of significant importance to construct cellulose-based materials. However, the homogeneous and controllable etherification of cellulose is difficult to achieve. Herein, we systematically demonstrated that mild, rapid and efficient etherification of cellulose was realized in tetra-n-butylphosphonium hydroxide ([P4,4,4,4]OH) aqueous solution, including Williamson etherification reaction, Michael addition reaction, and hydroxyalkylation reaction. A series of cellulose ethers with different substituents and degrees of substitution (DS) were easily and controllably synthesized, including ethyl cellulose, cyanoethyl cellulose, hydroxypropyl cellulose and quaternized cellulose. More interestingly, both the Williamson etherification and hydroxyalkylation reaction were conducted in 15 min at 25–60 °C which are rapid and efficient. The DS and performance of the resultant cellulose ethers were regulated over a wide range by changing the reaction conditions. The solvent [P4,4,4,4]OH aqueous solution could be successfully recovered after a three-steps process of extraction with CHCl3, anion exchange and concentration. [ABSTRACT FROM AUTHOR]

To improve interfacial adhesion to rubber matrix, a lower cost surface modification strategy of ultrahigh molecular weight polyethylene (UHMWPE) fiber was proposed by replacing expensive dopamine with the two‐component system of catechol/tetraethylenepentamine (CAT/TEPA) and then depositing nano zinc oxide (ZnO NPs). By Michael addition reaction or Schiff base reaction between CAT and TEPA, the CAT/TEPA layer was coated on the fiber surface, and further served as a secondary functional platform to realize ZnO NPs deposition through coordination. The surface morphology, chemical structure and composition, wettability and thermal property of the UHMWPE fibers were investigated to evaluate the process and effect of the surface modification. The results of the single‐filament tensile test indicated that the tensile strength of the UHMWPE fibers has no deterioration after the modification treatment. In comparison with the original fiber, the pull‐out test showed that the highest interface adhesion between the modified UHMWPE fibers and rubber matrix increased by 80.4%. Additionally, it was found that the appropriate zinc ion concentration played an important role in the modification effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • For the first time, a detailed study on fluorescent Mn 3 O 4 Quantum dots synthesis and characterization is reported. • The material exhibits excellent Catechol-oxidase mimicking activity demonstrating excellent enzyme kinetic parameters. • Dopamine sensor is developed using Mn 3 O 4 nanozymes with promising sensing parameters and LoD is obtained as 18 nM. • The quenching mechanism behind proposed Dopamine sensor has been studied and explained in detail. The development of multifunctional semi-conductor nano-enzymes has attained significant interest recently, due to their ease in fabrication, cost-effectiveness, and wide range of applications. In this work, we report the synthesis of ammine-functionalized Mn 3 O 4 quantum dots (Mn 3 O 4 QDs) with excellent luminescence properties. These QDs have been developed via the reduction of permanganate using L-cysteine through a simple, facile one-step bottom-up approach. The steady-state enzyme kinetic studies revealed the superior Catechol-Oxidase mimic activity of the Mn 3 O 4 QDs with a Michaelis-Menten constant (K m) of 133.19 µM, and maximum reaction velocity (V max) of 69.40 µMs−1. Due to this superior enzymatic activity, dopamine (DA) gets easily oxidized into DA-quinone and eventually polymerized to form polydopamine. Schiff base/Michael addition reaction between nucleophilic ammine on the surface of QDs and the aromatic chain makes the probe and analyte come closer and leads to the formation of a charge transfer complex, resulting in fluorescence quenching of QDs. This fluorescence quenching has been quantified to develop a turn-off sensor for DA. The sensing characteristics are highly selective and sensitive towards DA with a detection limit of 18 nM. The synthesised Mn 3 O 4 QDs with superior enzyme-mimicking properties have tremendous potential as fluorescent probes in imaging and health care applications. [ABSTRACT FROM AUTHOR]

The rapid detection of pyrosulfites in food chemistry is crucial to food safety and health. Here, a coumarin-type ratiometric fluorescent probe was developed based on the Michael addition reaction to detect sodium pyrosulfite (Na 2 S 2 O 5). The probe exhibited high selectivity and fast response (t 1/2 = 6 s) to Na 2 S 2 O 5 and a low detection limit (26 nM). Because of its excellent ratiometric response performance, the probe was successfully applied to measure the amount of Na 2 S 2 O 5 in preserved fruits. Colour information analysis and formula calculations were performed to quickly determine the sodium pyrosulfite amount in an actual sample by using a smartphone. Therefore, the intelligent strategy of combining the sensing process and smartphone provides a convenient and efficient method for the fast monitoring of sodium metabisulfite in actual food. [Display omitted] • A coumarin-type ratiometric fluorescent probe was synthesized to detect Na 2 S 2 O 5. • The probe identified Na 2 S 2 O 5 with fast response time (t 1/2 = 6 s) and low detection limit (26 nM). • Using RGB analysis and formula application, the Na 2 S 2 O 5 content can be calculated. • Smartphone-based on-site detection of Na 2 S 2 O 5 in actual samples was achieved. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide (H 2 S) is considered one of the most important gaseous transmitters in the metabolic system, and the abnormal concentration of H 2 S is associated with a variety of diseases. Up to now, it is still a challenge to develop a portable assay for H 2 S even though the research about the detection of H 2 S is booming. Herein, a novel bifunctional dialdehyde-cellulose fluorescent probe DAC-DPD was prepared with high selectivity and sensitivity to H 2 S with colorimetric and fluorescent "turn-on" characteristics, and the limit of detection (LOD) of DAC-DPD for H 2 S was 0.831 μM. The sensing mechanism of DAC-DPD 's to H 2 S was a Michael addition reaction confirmed by HRMS, 1H NMR and density-functional theory (DFT) calculations. DAC-DPD can be used to detect H 2 S in red wine samples. In Addition, the prepared DAC-DPD embedded fluorescent membrane can be used as a reliable sensing platform for rapid detection of H 2 S. It provided a convenient and rapid detection material, simplifying the detection process of H 2 S, which is of great significance for the development of cellulose-based fluorescent smart material. [Display omitted] • A dialdehyde cellulose-based colorimetric and turn-on fluorescent probe DAC-DPD for H 2 S detection was prepared. • The fluorescent probe DAC-DPD exhibited a wide pH detection range and a short response time. • DAC-DPD can detect H 2 S in red wine sample. • The prepared DAC-DPD embedded fluorescent membrane can be used for the specific and portable detection of H 2 S. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new and facile tool for functionalized polymer. • The PPM is mild and rapid. • The PPM enlightened the produce of photoluminescent material. Post-polymerization modification (PPM) is a valuable strategy for achieving diversified functional polymers; nonetheless, the pursuit of achieving mild and efficient dual modification along the polymeric backbone remains as a challenge. In this work, the Michael addition reaction of acetoacetates and acrylates have been demonstrated as a robust PPM technique. The reversible addition-fragmentation chain transfer polymerization of commercially available 2-(acetoacetoxy)ethyl methacrylate provides a polymer scaffold with controlled molecular weight and acetoacetate groups. These pendant groups are capable of undergoing efficient double addition reactions with acrylates, leading to an increased density of functional moieties within the polymeric backbone. This PPM reaction exhibits unique advantages such as mild reaction conditions (at 40 °C), rapid kinetics (completion within 1 h), and high atom economy. Consequently, a series of polymers with tunable thermal stability, glass transition temperature, and hydrophilicity have been successfully synthesized. Applications have been demonstrated for both the synthesis of polymers exhibiting aggregation-induced luminescence and the preparation of luminescent materials with adjustable mechanical properties. This pioneering work unveils a robust post-polymerization modification technique, significantly advancing the synthesis of innovative functional polymers. [ABSTRACT FROM AUTHOR]

Nonspecific adsorption occurring on the surface of electrochemical sensors seriously affects the sensitivity and accuracy of sensing and is particularly prominent when applied to complex food matrices. Construction of antifouling sensing surfaces by modifying antifouling materials is a promising approach to address surface biofouling. In this study, a biomimetic phosphorylcholine (PC-SH) was synthesized by a simple Michael addition reaction with a hydrophilic zwitterion group and a thiol group. Poly(sodium- p -styrene sulfonate) (PSS)-doped poly(3,4-ethylenedioxythiophene) (PEDOT) and Au NPs were used as the conductive substrate. As a result, PC-SH effectively enhanced the hydrophilicity of the sensing surfaces, and the biomimetic phosphorylcholine-based antifouling surface showed excellent antifouling ability both in three single protein solutions (signal suppression as low as 0.9 %) and milk samples (signal suppression as low as 0.5 %). The constructed antifouling biosensor was able to sensitively detect TC with a low limit of detection of 8.8 pg mL−1. More importantly, the biomimetic phosphorylcholine-based antifouling biosensor achieved satisfactory recoveries (96.9–107.6 %) in milk with dilution treatment only, which effectively avoided cumbersome sample pre-treatment and proved its promising application for antibiotic monitoring in complex food matrices. • Biomimetic phosphorylcholine synthesized via a Michael addition reaction. • An antifouling sensing surface prepared by biomimetic phosphorylcholine. • An antifouling electrochemical biosensor with a low limit of detection for TC. • Sensitive detection of TC in milk only by dilution without other pre-treatments. [ABSTRACT FROM AUTHOR]

The resource of trace lead (Pb2+) from wastewater bearing intricate components is imperative for sustainable progression of the lead-acid battery industry. Herein, we fabricated a tannic acid-based covalent polymeric hydrogel (TA@PMAM) with antimicrobial properties and stability via facile Michael addition reaction. The incorporation of tannic acid (TA) through robust covalent bond leads to a stable porous 3D covalent polymer network with almost no loss of mechanical properties even after 20 compression cycles. Batch adsorption experiments of TA@PMAM revealed an extraordinary adsorption capacity of Pb2+(Qe =196.6 mg/g), achieving 87.2 % of Pb2+ adsorption within the first 5 min owing to porous structure, numerous adsorption sites and good hydrophilicity. Moreover, TA@PMAM demonstrated a strong affinity for Pb2+ in the presence of the interfere metal ions (Cu2+, Co2+, Mn2+ etc.) due to the carbonyl and phenolic hydroxyl that can specifically pair with Pb2+. Stable adsorption properties of TA@PMAM were confirmed in fixed bed column adsorption experiment using lead-acid batteries wastewater, retaining 79.56 % of initial adsorption capacity even after 10 times' reuse. Besides, TA@PMAM possesses a broad spectrum of antimicrobial properties. This study sheds novel light on the design and fabrication of adsorbent, which holds great potential for commercialization in recovering lead from battery industrial wastewater. [Display omitted] • Stable tannic acid-based covalent crosslinked 3D network is facilely fabricated. • High selectivity of Pb2+ is due to its specific pairing with carbonyl and hydroxyl. • TA@PMAM features anti-interference, reusability and broad-spectrum antimicrobial. • Calculations and cycling experiments confirm the robust attachment of TA. [ABSTRACT FROM AUTHOR]

A stereoselective synthesis of fused tricyclic framework of epi -parvistemonine A from D-glucono-δ-lactone is described. The synthetic strategic is based on the stereoselective construction of the 7-membered cyclic skeleton via a cross-metathesis reaction followed by a Michael type cyclization promoted by Tf 2 O. [Display omitted] • Stereoselective synthesis of the fused tricyclic framework of epi -parvistemonine A from D-glucono-δ-lactone. • Access to cis fused tricyclic via a Michael type cyclization mediated by Tf 2 O. • Synthetic approach under a protecting group-free fashion. • Formation of a 7-membered cyclic skeleton. [ABSTRACT FROM AUTHOR]

[Display omitted] • Preparation of Au-Ag NCs was conducted for determination of acrylamide (ACM). • Stabilization of Au-Ag NCs was carried out using BSA. • The BSA@Au-Ag NCs probe exhibits dual-emissions at 630 nm and 405 nm after excitation at 320 nm. • Addition of cysteine quenched fluorescence of the probe. • In the presence of ACM, the fluorescence was restored due to the formation of thiol-ene Michael addition adducts. Dual-emissive gold and silver nanoclusters stabilized by bovine serum albumin (BSA@Au-Ag NCs) were engineered for the precise and sensitive estimation of acrylamide (ACM). The probe demonstrated emissions at 630 nm and 405 nm upon excitation at 320 nm. Decreasing the fluorescence of the probe at 630 nm was observed upon cysteine (Cys) addition while the emission band at 405 nm experienced a slight increase. The introduction of ACM into the probe led to the recovery of fluorescence at 630 nm, while the fluorescence at 405 nm remained largely unaffected. This selective response provides a ratiometric method for determining ACM. A linear relationship between the response ratio (F 630 /F 405) and ACM concentration was established in the range of 0.12–450 µM, with LOD of 0.03 µM. The fluorescent probe boasts several advantages, including a low LOD, robustness against interference, and reliability. Furthermore, the synthesized probe was deployed for detecting ACM in certain food matrices. The recovery percentages ranged from 96.5 to 102.6 %, with RSD between 2.98 and 4.87 %, thus affirming the potential practical applications of the fluorescent probe. [ABSTRACT FROM AUTHOR]

[Display omitted] • Green ZnO nanocatalyst was prepared using Celastruspaniulatus leaf extract as a green fuel. • ZnO characterized using PXRD, FT-IR, UV, SEM and TEM analysis. • Developed green ZnO nanocatalyst for the Synthesis of novel indole-4-hydroxy-chromen-2-ones. • Synthesized indole-4-hydroxy-chromen-2-ones derivatives characterized by Spectral Analysis. • The synthesised chrome compound 4f and 4g are active compounds against A549 cells. Zinc oxide (ZnO) nanoparticles have significant attention in the field of photocatalyst, super capacitor, battery and biomedicine due to their versatile potential and diverse applications. In the present study, ZnO was synthesized using Celastruspaniulatus leaf extract as a green fuel through combustion method. The morphological and structural studies of ZnO were characterized using XRD, FTIR, UV–Vis, SEM and TEM analysis. The PXRD pattern of ZnO as shown diffraction peaks of ZnO planes (1 0 0), (0 0 2), (1 0 2), (1 1 0), (1 0 3) and (1 1 2) are hexagonal Wurtzite ZnO structure. ZnO is formed in a discrete irregular hexagonal shape was confirmed by SEM analysis. The application of ZnO is achieved for the synthesis of (4-hydroxy3-(1 H -indol-3-yl)-phenyl-methyl-chromen-2-one) and its derivatives via Knoevenagel/Michael addition reaction. All synthesized compounds showed good yield and are characterized using 1H NMR, 13C NMR and ESI-MS spectral studies. The reusability of the ZnO catalyst is tested and documented. Some of the synthesized chromenone compounds show promising anticancer activity against A549 cells with less concentration. [ABSTRACT FROM AUTHOR]

The emission of venenous sulfur dioxide (SO 2) and its derivatives from industrial applications such as coking, transportation and food processing has caused great concern about public health and environmental quality. Probes that enable sensitivity and specificity to detect SO 2 derivatives play a crucial role in its regulations and finally mitigating its environmental and health impacts, but fluorescent probes that can accurately, rapidly and on-site detect SO 2 derivatives in foodstuffs and environmental systems rarely reported. Herein, a near-infrared (NIR) fluorescent probe (ZTX) for the ratiometric response of bisulfite (HSO 3 −) was designed and synthesized by regulating the structure of high-performance HSO 3 − fluorescent probe SL previously reported by us based on structural analyses, theoretical calculations and related literature reports. The Michael addition reaction between the electronic-deficient C=C bond and HSO 3 − destroys ZTX 's π-conjugation system and blocks its intramolecular charge transfer (ICT) process, resulting in a significant fading of the fuchsia solution and the bluish-purple fluorescence turned light blue fluorescence. Fluorescent imaging of HSO 3 − in live animals utilizing ZTX has been demonstrated. The quantitative analysis of HSO 3 − in food samples using ZTX via a smartphone has been also successfully implemented. Simultaneously, the ZTX -based test strips were utilized to quantificationally determine HSO 3 − in environmental water samples by a smartphone. Consequently, probe ZTX could provide a new method to understand the physiopathological roles of HSO 3 −, evaluate food safety and monitor environment, and is promising for broad applications. [Display omitted] • The fluorescence probe ZTX features NIR-emitting (849 nm), large Stokes shift (326 nm) and high biocompatibility. • The quantitative determination of HSO 3 − in environmental water and actual food sampleswere realized using ZTX combined with a smartphone. • Applications of ZTX in fluorescence imaging of HSO 3 − in vivo in mouse model are successfully demonstrated. [ABSTRACT FROM AUTHOR]

[Display omitted] • An efficient selective elimination of tetracyclines antibiotics was developed. • The interaction mechanism between tetracyclines and benzoquinone was confirmed. • Periodate exhibited superior degradation efficiency than other oxidants. • Remarkable resistance to natural water substances implied its potential applications. The binding behavior of tetracyclines (TCs) with natural organic matter and the subsequent induction of degradation in advanced oxidation processes has been underestimated. In this study, based on the specific oxidative effects of periodate, the selective degradation of TCs by periodate was achieved with benzoquinone (BQ) that induced poor stability intermediates. The periodate achieved the near complete degradation of TC with a trace concentration of BQ under the alkaline condition, with the k obs at 0.3090 min−1. The degradation experiments for twelve micropollutants revealed that the periodate/BQ system had a considerably efficient degradation only for TCs, and combined with the electron paramagnetic resonance (EPR) analysis, the minor involvement of reactive oxygen species during the degradation process was confirmed. The evident correlation between the observed k obs and the pre-mixing duration of TC with BQ demonstrated the dependence of the degradation process on intermediate generation. Furthermore, theoretical calculations revealed the reaction sites between the TC and BQ; the product identification and energy barrier of 18.94 kcal/mol further confirmed the interaction pathway through the Michael addition reaction. Moreover, based on the narrow energy gap (0.5350 eV) with the intermediate, only the periodate demonstrated efficient degradation of TC under alkaline conditions among the various oxidants. Little toxic iodine species were produced during the reaction, and the system exhibited resistance to natural water substances, such as anions and humic acid, highlighting its potential for application. In conclusion, the interaction mechanisms between TCs and BQ were elucidated in this research, and an efficient approach was proposed for eliminating residual TCs from aquatic environments and selective degradation from wastewater matrices. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) have attracted significant attention in recent years due to their interesting properties, such as photoluminescence, biocompatibility, excellent water dispersibility, as well as their potential applications in different fields. Despite these features, the complexity of their photoluminescent properties remains a subject of ongoing research and still presents unresolved questions. In this work, we investigated the preparation of various CDs from different low molecular mass starting materials containing carbon, nitrogen and/or sulfur, using hydrothermal carbonization as the preparation method. The CDs were characterized using various techniques, including TEM, FTIR, photoluminescence, UV–Vis, Raman and XPS. A detailed analysis of the initial reactions between the precursors was conducted, and our main results suggest that the optical properties of the CDs are related to fluorophores formed during the initial Michael condensation reactions between the precursors. This process produces molecular fluorescence, which plays a pivotal role in the photoluminescence properties of the nanoparticles. In addition, two of the obtained CDs were used as selective and sensitive probes for metal ions, achieving a detection limit of 0.58 μM and 0.55 μM. Finally, the findings described here can guide future works in fine-tuning the design of CDs with desired properties and different potential applications. • Carbon dots were prepared from different low molecular weight precursors. • Initial Michael condensation reactions lead to fluorophore formation. • Molecular fluorescence is important in the PL properties of the nanoparticles. • Efficient Michael condensation between carbon and nitrogen sources increases QY. • Two CDs used as selective and sensitive metal ion probes (LOD = 0.55 μM for Fe3+). [ABSTRACT FROM AUTHOR]

Fluorescence probes bearing malononitrile derivatives as electron withdrawing group have attracted the interests of many researchers during the past decades. Even for the similar fluorophore, the sensing mechanism and pathway could be much different and hard to predict. Thus, we designed a fluorescence probe consisting 2-(3,5,5-trimethylcyclohex-2-en-1-ylidene)malononitrile as the electron withdrawing group and thienocoumarin as fluorophore in order to investigate the possible superiority in designing related optical sensors. In our research, it is interesting to find that our probe has the different properties compared with the similar reported probe bearing the coumarin fluorophore. The novel fluorescent probe (CSO–CN) was demonstrated to be able to detect HSO 3 − ions and changes in viscosity with a good resistance to oxidizers. The probe offers high sensitivity (LOD = 0.149 μM) for detecting HSO 3 − via the Michael addition reaction. It also enables fluorescence emission at 483 nm and the tracking of viscosity alternation by impeding the twisted intramolecular charge transfer (TICT) mechanism. Besides, the dual-functional probe has effectively been utilized to monitor HSO 3 − level in living cells, zebrafish and real food samples. [Display omitted] • Thienocoumarin based fluorescence probes that could specific detect bisulfite and viscosity. • Rapid, highly sensitive and highly selective detections in aqueous solutions. • Probe is oxidizer-resistant. • Probe can be used for imaging bisulfite in biosystems and real foods. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design and synthesis of compound 1 (single nitro-substituent) and compound 2 (three nitro substituents). • Detection of cyanide in aqeous medium via hydrogen bonding in 1 , whereas Michael addition reaction in 2. • Change in the mode of binding of a specific analyte, merely by changing the number of un-reactive substituents. • Furthermore, a library of BIM compounds with different number of nitro groups at different positions (total 12) were designed for evaluation of anti-tubercular activity. • Detailed computational and docking studies for the cyanide detection mechanism and prediction of anti-tubercular activity of the BIM compounds. A pair of bisindolyl methane (BIM) compounds (1 and 2) were designed and their colorimetric response towards cyanide (CN−) ions were investigated in detail. In aqueous medium, the compound with single nitro-substituent (1) showed blue-shifted absorption maxima upon addition of cyanide ion, resulting in change in solution color from pink to yellow. On the contrary, the compound with three nitro functional groups (2), exhibited hypochromic shift along with initial, blue-shifted absorption maxima (color changed from pink to yellow to colourless). The mechanistic investigation indicated that the former observation could be attributed by cyanide-mediated hydrogen bonding interaction (or deprotonation), while the latter might be caused due to the Michael addition reaction. Interestingly, at alkaline pH, chemodosimetric interaction was observed with both the probe molecules. However, the rate of interaction was much faster for compound 2 than that observed for 1. A change in the mode of binding of a specific analyte, merely by changing the number of un-reactive substituents, is not much known in the literature. However, it will be extremely beneficial for future engineering of more efficient sensory systems. Furthermore, a library of BIM compounds with various number of nitro groups at different positions (total twelve) were synthesized for evaluation of anti-tubercular activity. Fortunately, some of the compounds were found to be as equally effective as the commercially available anti-tuberculosis drug, ethambutol (MIC: 1.56 µg/mL), whereas the compound 2 displayed a better anti-tubercular response (MIC: 0.78 µg/mL). This observation was further rationalized by docking studies with M. tuberculosis DprE1 in complex with the non-covalent inhibitor QN118. [ABSTRACT FROM AUTHOR]

The technique of utilizing structural color dyeing presents a sustainable and energy-conserving approach to textile dyeing. However, the coating with structural coloration always exhibited cracks and inadequate colorfastness attributed to the presence of capillary tension. In this study, we employed a hydrophilic silane called 3-aminopropyltriethoxysilane (KH550) to chemically modify the fabric. This method endowed the fabric with reactive amino groups, thereby augmenting the interfacial bonding strength between polydopamine (PDA)@SiO 2 @Ag+/Ag NPs and the fabric substrate through metal coordination and covalent bonds. Additionally, by utilizing catechol complexation, we successfully loaded Ag ions onto the PDA coating of composite microspheres. These Ag ions acted as linkers during self-assembly of microspheres. The active amino groups on the surface of chemically modified cotton fabric reacted with PDA at a specific temperature, resulting in the formation of robust covalent bonds simultaneously. The resulting fabric demonstrated excellent water resistance as well as efficient antibacterial and anti-static properties, which were confirmed through various mechanical tests such as washing, folding, and rubbing experiments. This research presents an innovative approach for creating durable structural colored fabrics with multifunctional properties based on metal coordination and covalent bonds that can be effectively applied in textile printing and dyeing. [Display omitted] • The PDA@SiO 2 @Ag+ microspheres assembled into amorphous photonic crystals (APCs) were dripped on the modified cotton fabric. • APCs were stabilized by metal coordinates of Ag+ with catechol groups from PDA of the surface of PDA@SiO 2 @Ag+ microspheres. • APCs reacted with -NH 3 on the surface of the modified cotton fabric with the Schiff base reaction or Michael addition. • The amorphous structural color fabric has durable antibacterial and antistatic properties after in-situ reduction of Ag+. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of new amino juglone derivatives was synthesized as antibacterial and or antibiotic adjuvant. • 3e showed a significant synergistic effect cloxacillin against clinically resistant S. aureus. • A structural characterization of 3e was carried out for the first time using X-ray diffraction. technic. • 3e did not show a cytotoxic activity on sheep red blood cells. 1,4-naphthoquinones hydroxyderivatives belong to an important class of natural products and have been known as a favored scaffold in medicinal chemistry due to their multiple biological properties. Juglone is one of the most important 1,4-naphthoquinone extracted from juglandaceae family showing a good antibacterial activity. In this study, we report the synthesis of aminojuglone derivatives through Michael addition reaction using Cerium (III) chloride heptahydrate (CeCl 3 ·7H 2 O) as catalyst. The synthesized aminojuglone derivatives were evaluated for their antibacterial properties against sensitive, clinical resistant Gram-positive and Gram-negative bacterial strains. Compound 3c showed a good antibacterial activity similar to cloxacillin (2 µg/mL) against the clinically resistant S.aureus. The antibiotic adjuvant activity of compounds was evaluated in combination with three clinically use antibiotics. The combination of compounds 3a , 3b , 3e , 3 h - 3 l , 3n and 3o with cloxacillin showed remarkable adjuvant activity against clinically resistant S. aureus (66-fold potentiation of cloxacillin activity). 3e is the only compound consistent with the concept of antibiotic adjuvant, presenting insufficient antibacterial activity (MIC > 128 µg/mL) and potentiate the activity of cloxacillin (66-fold) with synergistic effect. A structural characterization of 3e was carried out for the first time using X-ray diffraction technic. Moreover, compound 3e did not show a cytotoxic activity on sheep red blood cells. [ABSTRACT FROM AUTHOR]

In this study, a hyperbranched polymer (HBP) with a hydrophobic backbone and hydrophilic adhesive catechol side chains was synthesized through the Michael addition reaction between multi-vinyl monomers with dopamine. Underwater adhesion experiments demonstrated that HBP had rapidly strong adhesion. Using HBP as the wall material and lavender essential oil (LO) as the core material, catechol-hyperbranched nanocapsules (CHNPs) with good adhesion and acidic responsive properties were prepared by solvent evaporation method. Subsequently, ACFs with good wash resistance were prepared by impregnation and further introduction of Fe3+. After 25 washing cycles, the retention rate of LO in CF treated solely with CHNPs solution (CHNPs@CF) was only 9.7 %, whereas the retention rate increased to 17.8 % for CHNPs@CF treated with FeCl 3 solution (Fe3+/CHNPs@CF). The persistent adhesion of CHNPs on cotton fabrics (CF) is achieved by hydrogen bonding and Fe3+-catechol coordination bonding. These results confirm the significant potential of CHNPs in aromatic textile applications and it is expected to promote the diversified development of functional textiles. [Display omitted] • HBP imparts the shell layer of CHNPs with abundant catechol structures. • CHNPs exhibit a distinctive acidic response mechanism, sustained adhesive properties and outstanding biocompatibility. • CHNPs can be persistently attached to the cotton fabric by hydrogen and metal coordination bonds. • Cotton fabrics treated with CHNPs demonstrate remarkable washing resistance properties. [ABSTRACT FROM AUTHOR]

Therapeutic outcomes of local biomolecule delivery to the central nervous system (CNS) using bulk biomaterials are limited by inadequate drug loading, neuropil disruption, and severe foreign body responses. Effective CNS delivery requires addressing these issues and developing well-tolerated, highly-loaded carriers that are dispersible within local neural parenchyma. Here, we synthesized biodegradable trehalose-based polyelectrolyte oligomers using facile A2:B3:AR thiol-ene Michael addition reactions that form complex coacervates upon mixing of oppositely charged oligomers. Coacervates permit high concentration loading and controlled release of bioactive growth factors, enzymes, and antibodies, with modular formulation parameters that confer tunable release kinetics. Coacervates are cytocompatible with cultured neural cells in vitro and can be formulated to either direct intracellular protein delivery or sequester media containing proteins and remain extracellular. Coacervates serve as effective vehicles for precisely delivering biomolecules, including bioactive neurotrophins, to the mouse striatum following intraparenchymal injection. These results support the use of trehalose-based coacervates as part of therapeutic protein delivery strategies for CNS disorders. [ABSTRACT FROM AUTHOR]

The relationship between the mechanical forces associated with bowel movement and colonic mucosal physiology is understudied. This is partly due to the limited availability of physiologically relevant fecal models that can exert these mechanical stimuli in in vitro colon models in a simple-to-implement manner. In this report, we created a mucus-coated fecal surrogate that was magnetically propelled to produce a controllable sweeping mechanical stimulation on primary intestinal epithelial cell monolayers. The mucus layer was derived from purified porcine stomach mucins, which were first modified with reactive vinyl sulfone (VS) groups followed by reaction with a thiol crosslinker (PEG-4SH) via a Michael addition click reaction. Formation of mucus hydrogel network was achieved at the optimal mixing ratio at 2.5 % w/v mucin-VS and 0.5 % w/v PEG-4SH. The artificial mucus layer possessed similar properties as the native mucus in terms of its storage modulus (66 Pa) and barrier function (resistance to penetration by 1-μm microbeads). This soft, but mechanically resilient mucus layer was covalently linked to a stiff fecal hydrogel surrogate (based on agarose and magnetic particles, with a storage modulus of 4600 Pa). The covalent bonding between the mucus and agarose ensured its stability in the subsequent fecal sliding movement when tested at travel distances as long as 203 m. The mucus layer served as a lubricant and protected epithelial cells from the moving fecal surrogate over a 1 h time without cell damage. To demonstrate its utility, this mucus-coated fecal surrogate was used to mechanically stimulate a fully differentiated, in vitro primary colon epithelium, and the physiological stimulated response of mucin-2 (MUC2), interleukin-8 (IL-8) and serotonin (5HT) secretion was quantified. Compared with a static control, mechanical stimulation caused a significant increase in MUC2 secretion into luminal compartment (6.4 ×), a small but significant increase in IL-8 secretion (2.5 × and 3.5 × , at both luminal and basal compartments, respectively), and no detectable alteration in 5HT secretion. This mucus-coated fecal surrogate is expected to be useful in in vitro colon organ-on-chips and microphysiological systems to facilitate the investigation of feces-induced mechanical stimulation on intestinal physiology and pathology. [ABSTRACT FROM AUTHOR]

Herein, the functionalized N-doped carbon nanosheet (N@PCNs) was successfully achieved through pyrolysis of metal−organic framework (MOF) and then surface modification with anti-wear agent. Firstly, the N@PCNs was obtained via carbonization of copper pyridine coordination polymer-based MOFs. Then tannic acid (TA) cross-linked by polyethylenimine (PEI) via Michael addition was grafted on the N@PCNs surfaces. Finally, the anti-wear agent 2,5-dimercaptothiadiazole dimer (DTD) was grafted onto N@PCNs via Michael addition reaction with TA to obtain DTD-N@PCNs. The average COF of 500SN decreases to 0.110 from 0.195, accompanied by 69.3% reduction in wear volume with 1.00 wt% DTD-N@PCNs addition. The lubrication performance is ascribed to the formation of a stable protective film through DTD-N@PCNs facilitating tribochemical reactions, preventing direct contact of the ball-disc pairs. [Display omitted] • The functionalized N@PCNs was prepared through pyrolysis of copper-based MOFs and then surface modification with DTD. • The resultant DTD-N@PCNs exhibits improved anti-wear and friction reducing properties when used as a lubricant additive. • The lubrication performance was attributed to the polishing effect and mending effect of DTD-NN@PCNs, along with formation of a protective film. [ABSTRACT FROM AUTHOR]

The efficiency of an amino imidate organocatalyst was evaluated in the Michael reaction of ketones with nitroalkenes. tert-Butyl­ l-proline imidate was found to be a syn-selective catalyst, generating products with moderate to good enantioselectivities of up to 84% ee. The best substrates were found to be cyclic ketones and β-nitrostyrenes. The catalytic efficiency and enantioselectivity were enhanced by the addition of 10 mol% of benzoic acid.