Electrochemical and colorimetric dual-signal detection of Staphylococcus aureus enterotoxin B based on AuPt bimetallic nanoparticles loaded Fe-N-C single atom nanocomposite

Sensitive detection of Staphylococcus aureus enterotoxin B(SEB)is of importance for preventing food poisoning from threatening human health.In this work,an electrochemical and colorimetric dual-signal detection assay of SEB was developed.The probe(Ab2/AuPt@Fe-N-C)was bound to SEB captured by Ab1,where the Ab2/AuPt@Fe-N-C triggered methylene blue degradation and resulted in the decrease of electrochemical signal.Furthermore,the probe catalyzed the oxidation of 3,3’,5,5’-tetramethyl biphenyl to generate a colorimetric absorbance at 652 nm.Once the target was captured and formed a sandwich-like complex,the color changed from colorless to blue.SEB detection by colorimetric and electrochemical methods showed a linear relationship in the concentration ranges of 0.0002-10.0000 and 0.0005-10.0000 ng/mL,with limits of detection of 0.0667 and 0.1670 pg/mL,respectively.The dual-signal biosensor was successfully used to detect SEB in milk and water samples,which has great potential in toxin detection in food and the environment.

One stone two birds:electrochemical and colorimetric dual-mode biosensor based on copper peroxide/covalent organic framework nanocomposite for ultrasensentive norovirus detection

Norovirus(NoV)is regarded as one of the most common causes of foodborne diarrhea in the world.It is urgent to identify the pathogenic microorganism of the diarrhea in short time.In this work,we developed an electrochemical and colorimetric dual-mode detection for NoV based on the excellent dual catalytic properties of copper peroxide/COF-NH_(2)nanocomposite(CuO_(2)@COF-NH_(2)).For the colorimetric detection,NoV can be directly detected by the naked eye based on CuO_(2)@COF-NH_(2)as a laccase-like nonazyme using“peptide-NoV-antibody”recognition mode.The colorimetric assay displayed a wide and quality linear detection range from 1 copy/mL to 5000 copies/mL of NoV with a low limit of detection(LOD)of 0.125 copy/mL.For the electrochemical detection of NoV,CuO_(2)@COF-NH_(2)showed an oxidation peak of copper ion from Cu^(+)to Cu^(2+)using“peptide-NoV-antibody”recognition mode.The electrochemical assay showed a linear detection range was 1-5000 copies/mL with a LOD of 0.152 copy/mL.It's worthy to note that this assay does not need other electrical signal molecule,which provide the stable and sensitive electrochemial detection for NoV.The electrochemical and colorimetric dual-mode detection was used to detect NoV in foods and faceal samples,which has the potential for improving food safety and diagnosing of NoV-infected diarrhea.

Peripheral carbazole units-decorated MR emitter containing B−N covalent bond for highly efficient green OLEDs with low roll-off

Boron−nitrogen doped multiple resonance(BN-MR)emitters,characterized by B−N covalent bonds,offer distinctive advantages as pivotal building blocks for facile access to novel MR emitters featuring narrowband spectra and high efficiency.However,there remains a scarcity of exploration concerning synthetic methods and structural derivations to expand the library of novel BN-MR emitters.Herein,we present the synthesis of a BN-MR emitter,tCz[B−N]N,through a one-pot borylation reaction directed by the amine group,achieving an impressive yield of 94%.The emitter is decorated by incorporating two 3,6-di-tbutylcarbazole(tCz)units into a B−N covalent bond doped BN-MR parent molecule via para-C−π−D and para-N−π−D conjugations.This peripheral decoration strategy enhances the reverse intersystem crossing process and shifts the emission band towards the pure green region,peaking at 526 nm with a narrowband full-width at half maximum(FWHM)of 41 nm.Consequently,organic light emitting diodes(OLEDs)employing this emitter achieved a maximum external quantum efficiency(EQEmax)value of 27.7%,with minimal efficiency roll-off.Even at a practical luminance of 1000 cd·m^(−2),the device maintains a high EQE value of 24.6%.

Synthesis and electrochemical performance of a novel nano sized Sn_2SbNi composite

Chemical reduction method was employed to prepare nano-sized Sn2SbNi alloy composites used as anode material for rechargeable lithium ion batteries.This strategy was adopted to combine the virtues of both active/inactive and active/active alloys to fabricate a Sn2SbNi alloy powder with two active components and one inactive component.The two active components can realize the high capacity feature of electrode and can make the volume change of electrode take place in a stepwise manner due to the different lithiation potentials of two active components,leading to a stable cycling performance.Sn2SbNi alloy provides a reversible specific capacity over 640 mA·h/g with an excellent cyclic ability.The Sn-Sb-Ni alloy composite material shows to be a good candidate anode material for the lithium ion batteries.

Reaction Mechanism,Synthesis and Characterization of Urea-glyoxal(UG) Resin

The reaction mechanism of glyoxal （G） with urea （U） under weak acid condition was theoretically investigated at PW91/DNP/COSMO of quantum chemistry using density functional theory （DFT） method. The results show that the addition reaction of G with U under the conditions mainly involves the reactions of U with protonated glyoxal （p-G）, protonated 2,2-dihy- droxyacetaldehyde （p-G 1） and protonated bis-hemdiol （p-G2） to form two important carbocation reactive intermediates of C-p-UG and C-p-UG1, and two important hydroxyl compounds of UG and UG1. These compounds play important roles in the formation of UG resin. According to the result of quantum chemical calculation, UG resin was synthesized successfully under weak acid conditions. The UG resin was characterized by matrix assisted laser desorption ionization time of flight mass spectrometry （MALDI-TOF-MS）, ultraviolet and visible spectroscopy （UV-vis）, Fourier transform infrared spectroscopy （FT1R） and nuclear magnetic resonance spectroscopy （13CNMR and 1HNMR）. These instrumental analytical results agree with each other and further confirm the addition reaction pathway of glyoxal with urea proposed by quantum chemical calculation.

Experimental Research of Concrete with Steel Slag Powder and Zeolite Powder

In order to increase use ratio of steel slag solid waste,the concrete containing steel slag powder and zeolite powder as admixtures was prepared by using the orthogonal test method.The effects of water-binder ratio,sand ratio,steel slag powder content and zeolite powder on working properties,mechanical strength and chloride ion permeability of the concrete was studied.It was found that the early strength of the concrete had a decrease with the mixing of steel slag and zeolite powders,but its later strength approached to pure concrete.Moreover,the physical filling and pozzolanic activity of the admixtures increased the density of the concrete,resulting in the improvement of the durability of the concrete by the migration speed of Cl−reducing.The optimum mix ratio of C40 steel slag powder-zeolite powder concrete is obtained,and which had the slump of 220 mm,the 3 d,7 d and 28 d compressive strengths of 27.8 MPa,37.5 MPa and 48.4 MPa,the 6 h electric flux of 950 C and the diffusion coefficient of 1.65×10−12 m2/s.

Acute and Sub-chronic Toxicity of Indole Alkaloids Extract from Leaves of Alstonia scholaris (L.) R. Br. in Beagle Dogs

Alstonia scholaris(L.)R.Br.,an evergreen tropical plant rich in indole alkaloids with significant physiological activity,is traditionally used to treat respiratory diseases in China.This study was conducted to establish the toxicity profile of the alkaloid extract(TA)of A.scholaris leaves in non-rodents.After oral administration of a single dose(4 g/kg.bw),a num-ber of transient symptoms,such as unsteady gait,drooling,emesis,and reddening of peri-oral mucosa,were observed,but no treatment-related mortality.A sub-chronic toxicity study with a range of doses of TA(20,60 and 120 mg/kg.bw)was conducted for a 13-week treatment period,followed by 4-week recovery observation.Except for emesis and drooling in majority of animals in 120 mg/kg.bw treatment group,no clinical changes were observed in TA-treated animals.Data from electrocardiography,bone marrow,urine,fecal,hematology and clinical chemistry analyses were comparable between TA-treated and control animals.No significant differences in the relative organ weights and histopathological characteristics were evident between the TA-treated and control groups.Accordingly,the non-observed-adverse-effect-level(NOAEL)of TA was established as 120 mg/kg.bw.Our results add further knowledge to the safety database for indole alkaloid extracts from A.scholaris with potential utility as novel drug candidates.

Synthesis of a Novel Aromatic Diamino-bridged Bis(β-cyclodextrin) and its Inclusion Complexation with Dyes Molecules

A novel brideed bis（β-cvclodextrin）, 4, 4＇-diaminodiphenyl ether-bfiged-bis （6-aimino-6-deoxv-β-cyclodextrin） 3, has been synthesized and its inclusion complexation behavior with three linear＇guest dyes （AR, NR and MB ） has been investigated by. means of fluorescence spectrometry. The-result obtained demonstrated that the novel bridged bis（β-cyclodextnn） showed much higher affinities towards guest dyes than native β-cyclodextrin.

Sesquiterpenoids and 2-(2-Phenylethyl)chromone Derivatives from the Resinous Heartwood of Aquilaria sinensis

One novel spirolactone,aquilarisinolide(1),three new sesquiterpenoids,(2R,4S,5R,7R)-2-hydroxyeremophila-9,11-dien-8-one(2),(1R,4S,5S,7R,11R)-13-hydroxyepidaphnauran-9-en-8-one(3),and(4R,5S,7R,8S,10S,13R)-8,13-dihydroxyrotunda-1,11-dien-3-one(4),together with 13 known compounds(5-17)were isolated from the resinous heartwood of Aquilaria sinensis(Thymelaeaceae).The structures of the new compounds were elucidated based on the analysis of NMR and MS data and theoretical calculations their ECD spectra.The isolated compounds were evaluated for their protective activities against PC12 cell injury induced by corticosterone(CORT)and 1-methyl-4-phenylpyridine ion(MPP+),as well as inhibitory activities against BACE1.Compound 4,5,6-dihydroxy-2-(2-phenylethyl)chromone(5),daphnauranol B(7),6-methoxy-2-[2-(3-methyoxyphenyl)ethyl]chromone(10),isoagarotetrol(14),and 1-hydroxy-1,5-diphenylpentan-3-one(16)showed significant protective effects on CORT-induced injury in PC12 cells at a concentration of 20μM(P<0.001).Isoagarotetrol(14)showed a significant protective effect on MPP+-induced injury in PC12 cells at a concentration of 20μM(P<0.001),while compound 4 showed a moderate activity(P<0.01).The BACE1-inhibitory activities of all tested compounds were very weak with less than 30%inhibition at a concentration of 20μM.

Acute and Chronic Toxicity of Indole Alkaloids from Leaves of Alstonia scholaris (L.) R. Br. in Mice and Rats

Alstonia scholaris(L.)R.Br.(Apocynaceae)is an evergreen tree that has been used to treat lung diseases.In this study,the toxicity profile of indole alkaloids from leaves of A.scholaris was investigated.In acute toxicity tests,mice were adminis-tered total alkaloids(TA)and five indole alkaloids.In a chronic toxicity test,rats were continuously administered TA(50,100,and 300 mg/kg bw)for 13 weeks,followed by a 4-week recovery.A single administration of TA affected the behavior of mice,and at 12.8 g/kg bw,prone position,shortness of breath,wheezing,and convulsion were observed.The half-lethal dose(LD50)in mice was 5.48 g/kg bw,almost 2740 times the clinical dose in humans.Among the five indole alkaloids,the maximum tolerance dose in mice ranged from 0.75 to 4 g/kg bw.The TA-treated rats did not die and showed no adverse effects or dose-dependent changes in weight or food and water consumption,despite fluctuations in hematological and bio-chemical parameters compared with historical data.Furthermore,both gross and histopathological observations revealed no abnormalities in any organ.With daily oral administration to rats,the non-observed-adverse-effect-level of TA was 100 mg/kg bw.The results indicate that TA is safe for clinical use.

A Pair of 3D Homochiral Coordination Polymers with Open Channels Constructed by Lactic Acid Derivative Ligands and In-situ Formed Anions

With the help of in-situ formed CH_3COO- anion, a pair of 3D homochiral coordination polymers with open channels were constructed by the assembly of lactic acid derivative ligands, 1.4-DIB ligands and Cd（II） ions, namely [Cd3（（R）-CIA）2（CH3CO2）_2（1.4-DIB）2（H2O）2]·x（Guest）（1-D） and [Cd3（（S）-CIA）2（CH3CO2）2（1.4-DIB）2（H2O）2]·x（Guest）（1-L）. They contain 1D interesting ladder-like Cd-（R）-CIA（3-） chains and exhibit SHG-active behavior and photoluminescent property.

Organic fast ion-conductor with ordered Li-ion conductive nano-pathways and high ionic conductivity for electrochemical energy storage

Solid electrolyte(SE)is the most crucial factor to fabricate safe and high-performance all-solid-state lithium-ion batteries.However,the most commonly reported SE,including solid polymer electrolyte(SPE)and inorganic oxides and sulfides,suffer problems of low ionic conductivity at room temperature for SPE and large interfacial impedance with electrodes for inorganic electrolytes.Here we for the first time demonstrate a novel ionic plastic crystal lithium salt solid electrolyte(OLiSSE)fast ion-conductor dilithium(1,3-diethyl-4,5-dicarboxylate)imidazole bromide with ordered Li-ion conductive nanopathways and an exceptional ionic conductivity of 4.4×10^(−3)Scm^(−1)at 30℃.The prepared OLiSSE exhibits apparent characters of typical ionic plastic crystals in the temperature range of−20 to 70℃,and shows remarkable thermal stability and electrochemical stability below 150℃ and 4.7 V,respectively.No lithium dendrite or short circuit behavior is detected for the Li|OLiSSE|Li cell after the galvanostatic charge-discharge test for 500 h.The fabricated Li|OLiSSE|LiFePO_(4) all-solid-state cell without using any separator and liquid plasticizer directly delivers an initial discharge capacity of 151.4 mAh g^(−1) at the discharge rate of 0.1 C,and shows excellent charge-discharge cycle stability,implying large potential application in the next generation of safe and flexible all-solid-state lithium batteries.

Density Functional Theory Study of Water Diffusion and Clustering on Pd(111)

The internal structures as well as adsorption and hopping energies of monomers, dimers, trimers, tetramers, pentamers and hexamers of water on Pd（111） have been studied by density functional theory （DFT） plane-wave pseudopotential method which performs the firstprinciples quantum-mechanical calculations to explore the properties of crystals and surfaces in materials. Based on the calculations, we suppose that their absorption is via one water molecule for monomers, dimmers and trimers, but three water molecules for pentamers and hexamers. Moreover, there is one water molecule bonding with Pd atom by O atom in pentamers and hexamers, which explains why pentamers and hexamers are stable. The binding energies of polymers may be used to explain why the trimer comes close to two nearby monomers to form a stable pentamer instead of tetramer. And the difference of mobility of small water clusters is due to their different hopping energies.

Irlactane and Tremulane Sesquiterpenes from the Cultures of the Medicinal Fungus Irpex lacteus HFG1102

A new irlactane-type,namely irlactin K(1),and 22 tremulane-type sesquiterpenes including fourteen previously undescribed ones,namely irpexolactins A-N(2-15),and a known irlactane-type sesquiterpenoid,were isolated from the fermentation broth of the medicinal fungus Irpex lacteus HFG1102.The structures of all the isolates were characterized by extensive spectroscopic methods,including 1D and 2D NMR and MS spectroscopic analysis.The absolute configurations of irlactin K and the known compound conocenol B(20)were established by single-crystal X-ray diffraction analysis.The vasorelaxant effects of irlactin K(1),irpexolactins A(2),C(4),K(12),and irlactam(22)were evaluated.

Chemistry and bioactivities of natural steroidal alkaloids

Steroidal alkaloids possess the basic steroidal skeleton with a nitrogen atom in rings or side chains incorporated as an integral part of the molecule.They have demonstrated a wide range of biological activities,and some of them have even been developed as therapeutic drugs,such as abiraterone acetate(Zytiga®),a blockbuster drug,which has been used for the treatment of prostate cancer.Structurally diverse natural steroidal alkaloids present a wide spectrum of biological activities,which are attractive for natural product chemistry and medicinal chemistry communities.This review comprehensively covers the structural classification,isolation and various biological activities of 697 natural steroidal alkaloids discovered from 1926 to October 2021,with 363 references being cited.

Synthesis and Anticancer Activity of 4b-Triazolepodophyllotoxin Glycosides

A series of novel 4b-triazole-podophyllotoxin glycosides were synthesized by utilizing the Click reaction.Evaluation of cytotoxicity against a panel of five human cancer cell lines(HL-60,SMMC-7721,A-549,MCF-7,SW480)using MTT assay shows that most of these compounds show weak cytotoxicity.It was observed that compound 16 shows the highest activity with IC50 values ranging from 2.85 to 7.28 lM,which is more potent than the control drugs etoposide and cisplatin against four of five cancer cell lines tested.Compound 16 is characterized with an a-D-galactosyl residue directly linked to the triazole ring and a 40-OH group on the E ring of the podophyllotoxin scaffold.HPLC investigation of representative compound indicates that incorporation of a sugar moiety seems to improve the chemical stability of the podophyllotoxin scaffold.

Genotoxicity and Safety Pharmacology Studies of Indole Alkaloids Extract from Leaves of Alstonia scholaris (L.) R. Br.

Indole alkaloids extract(IAAS)was prepared from leaves of Alstonia scholaris(L.)R.Br.,an evergreen tropical plant widely distributed throughout the world.This plant has been used historically by the Dai ethnic people of China to treat respiratory diseases.This study evaluated the genotoxicity and safety pharmacology of IAAS to support clinical use.The bacterial reverse mutation(Ames)test,in vitro mammalian chromosomal aberration test,and in vivo mammalian erythrocyte micronucleus(MN)test were performed to evaluate genotoxicity.Mice were administered IAAS(240,480,or 960 mg/kg bw)once orally to observe adverse central nervous system effects.Furthermore,beagle dogs were administered IAAS(10,30,60 mg/kg bw)once via the duodenum to evaluate its effects on the cardiovascular and respiratory systems.IAAS with or without S9-induced metabolic activation showed no genotoxicity in the Ames test up to 500μg/plate,in the mammalian chromosomal aberration test up to 710μg/mL,or in the MN test up to 800 mg/kg bw.No abnormal neurobehavioral effects were observed in mice following treatment with up to 960 mg/kg bw of IAAS.Moreover,blood pressure,heart rate,electrocardiogram parameters,and depth and rate of breathing in anesthetized beagle dogs did not differ among the IAAS doses or from the vehicle group.These data indicated that IAAS did not induce mutagenicity,clastogenicity,or genotoxicity,and no pharmaco-toxicological effects were observed in the respiratory,cardiovascular,or central nervous systems.Our results increased understanding of safety considerations associated with IAAS,and may indicate that IAAS is a possible drug candidate.

Anti-microbial Effects In Vitro and In Vivo of Alstonia scholaris

Alstonia scholaris could be used as a traditional medicinal plant in China for the treatment of acute respiratory,which might be caused by respiratory tract infections.The investigation tested the anti-infective effects of total alkaloids extract(TA)from leaves of A.scholaris,and as a result,TA inhibited herpes simplex virus type 1(HSV-1),respiratory syncytial virus(RSV)and influenza A virus(H1N1)in vitro respectively.In addition,the survival days of mice were prolonged,and the lung weights and mortality of mice were decreased significantly,after oral administrated TA in H1N1 and beta-hemolytic streptococcus infectious models in vivo respectively.The finding supported partly the traditional usage of A.scholaris in the treatment of respiratory infections.

Sesquiterpenoids and an ergosterol from cultures of the fungus Daedaleopsis tricolor

Four new bisabolane sesquiterpenoids daedatrins A-D(1-4),a cadinane sesquiterpene 12-hydroxy-α-cadinol(5),and a heptanorergosterane derivative daedatrin G(6)were isolated from cultures of the basidiomycete Daedaleopsis tricolor.Their structures were elucidated by spectroscopic methods including extensive 2D NMR techniques and X-ray crystallography.All the compounds showed no significant activity against five human cancer cell lines.

Tuning desolvation kinetics of in-situ weakly solvating polyacetal electrolytes for dendrite-free lithium metal batteries

The host structure of polymers significantly influences ion transport and interfacial stability of electrolytes,dictating battery cycle life and safety for solid-state lithium metal batteries.Despite promising properties of ethylene oxide-based electrolytes,their typical clamp-like coordination geometry leads to crowd solvation sheath and overly strong interactions between Li^(+)and electrolytes,rendering difficult dissociation of Li+and unfavorable solid electrolyte interface(SEI).Herein,we explore weakly solvating characteristics of polyacetal electrolytes owing to their alternately changing intervals between–O–coordinating sites in the main chain.Such structural asymmetry leads to unique distorted helical solvation sheath,and can effectively reduce Li^(+)-electrolyte binding and tune Li^(+)desolvation kinetics in the insitu formed polymer electrolytes,yielding anion-derived SEI and dendrite-free Li electrodeposition.Combining with photoinitiated cationic ring-opening polymerization,polyacetal electrolytes can be instantly formed within 5 min at the surface of electrode,with high segmental chain motion and well adapted interfaces.Such in-situ polyacetal electrolytes enabled more than 1300-h of stable lithium electrodeposition and prolonged cyclability over 200 cycles in solid-state batteries at ambient temperatures,demonstrating the vital role of molecular structure in changing solvating behavior and Li deposition stability for high-performance electrolytes.