Search

Implant-associate infection (IAI) is a major cause of failure of bone implant materials, and one of the significant challenges in clinical managements. A synergistic coating strategy combining montmorillonite (MMT) sustained release, adsorption of bacteria and gentamicin (GS) bactericidal is proposed herein to tackle infection issues. Surface morphology, microstructure and chemical composition of the samples were investigated using SEM, XRD, FT-IR and XPS. Electrochemical experiments and immersion experiments reveal that corrosion resistance of Mg samples with GS/MMT coatings was higher than that of bare Mg alloy substrate in DMEM solution. In vitro studies demonstrated that the GS/MMT coating had a significant inhibitory effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The viability of MC3T3-E1 cells was 92.7% after a co-culturing for 72 h. After a subcutaneous transplantation of 90 days, the survival rate was 100% for GS/MMT-coated Mg alloy specimens with no infection at the implantation sites and no toxic damage to liver, kidney and local muscles pathological sections. This study provides a novel method for the preparation of sustained-release antimicrobial coatings on biodegradable Mg alloys as promising candidates for orthopedic implant materials.

Background: bones and muscles originated together from the mesoderm during embryogenesis, and they can influence each other through mechanical stimulations and chemical signals. The sclerostin (SOST) is secreted from mature osteocytes. Here, we used a bird model to illustrate the potential roles of SOST on duck myoblasts to verify the hypothesis that SOST might play functions in coordinating the development of bones and muscles. Methods and Results: Firstly, a recombinant adenovirus vector carrying duck SOST was constructed. Then, the adenovirus-mediated duck SOST was transfected into duck myoblasts. The results revealed by CCK-8 showed that the cell proliferation of myoblasts was inhibited after 12 h, 36 h, and 48 h treatment by transfection of SOST. The labeling rates of EdU positive cells in the Ad-duSOST group were significantly lower than the Ad-NC group (P

To develop high-performance non-precious metal-based electrocatalysts for oxygen reduction reaction (ORR) is an urgent demand. We herein report an ingenious strategy to develop highly selective and competitive precious metal-free ORR electrocatalyst Co/CoO/SnO encapsulated in N-rich mesoporous carbon (CCS@NPC) nanocubes, via a simple one-step introduction of all functional components. Atomically mixed composites with significantly enhanced catalytic activity were obtained by adopting amorphous mesoporous ternary metal oxides CoSnO3 nanocubes as precursor and template. The synergistic effect of the triphase nanohybrids (Co, CoO & SnO) anchored in nitrogen-doped mesoporous carbon nanocubes promoted the catalytic reactions, owning to the anisotropic morphology, great heterojunction interfaces, and structural stability. The large-scale prepared CCS@NPC exhibited excellent electrocatalytic activity toward ORR with an admirable onset potential (1.01 V) and diffusion-limited current density (5.88 mA cm−2). The CCS@NPC showed stronger stability (20 h) and higher methanol tolerance with the concentration up to 8.0 M, compared to that of commercial Pt/C.

Salmonella is a foodborne pathogen that has contributed to numerous food safety accidents worldwide, making it necessary to detect contamination at an early stage. A pair of specific primers based on the invA gene of Salmonella was designed for PCR. Target double-stranded DNA (dsDNA) from PCR was purified and denatured at high temperature to obtain target single-stranded DNA (ssDNA). Two carboxyfluorescein-labeled hairpin probes (H1-FAM and H2-FAM) were designed with complementary portions to the ssDNA sequence so that binding could trigger H1-FAM and H2-FAM hybridization chain reaction (HCR) to produce a long dsDNA complex. In this study, graphene oxide (GO) was used in the development of a homogeneous fluorescence detection platform for Salmonella. Using this HCR-GO assay platform, Salmonella detection was completed in 3.5 h. Salmonella was reliably and specifically detected with a limit of detection (LOD) of 4.2 × 101 cfu/mL in pure culture. Moreover, this new HCR-GO assay platform was successfully applied to the detection of Salmonella in artificially contaminated milk with a LOD of 4.2 × 102 cfu/mL.

Carbon nanodots based on L-arginine (L-Arg) were developed for enhanced nitric oxide (NO) gas therapy for cancer. The L-Arg-based carbon nanodots (Arg-dots) produced high levels of NO in the tumor environment rich in endogenous H2O2. In vitro cell experiments revealed that the Arg-dots could kill tumor cells (including human breast cancer cell line MCF-7, female gastric cancer cell line BGC-823, male lung cancer cell line A549, and female leukemic cell line K562) but did not affect the activity of normal cells (human normal lung epithelial cell line BEAS-2B). The Arg-dots produced twice the amount of NO for an equivalent amount of L-Arg. Theoretical calculations showed that the carbonization structure of the Arg-dots promoted significantly more electrons toward the guanidinium groups of L-Arg and boosted the adsorption of H2O2 molecules. In vitro and in vivo investigations confirmed that the Arg-dots reduced the multidrug resistance (MDR) effect of the tumor cells (MCF-7/ADR cells) and produced a combined antitumor efficacy with traditional chemotherapeutic drugs (adriamycin [ADR]). The fluorescence property (quantum yield, 6.88%) allows the Arg-dots to be used as a suitable fluorescent probe for fluorescence imaging of tumor cells. The ultra-small size of the Arg-dots (diameter: ca. 2.5 nm) enables them not only to penetrate deep tumors and provide enhanced antitumor activity but also to be removed through kidney filtration and have a renal clearance property. Statement of significance Nitric oxide (NO), which serves as a biological messenger, can be used in gas therapy for cancer. The development of a safe and efficient NO cancer therapy is, however, challenging because of the low NO release amount and poor tumor specificity of most NO donors. Many efforts have been made to overcome these drawbacks, but solving both these limitations through a single approach has been seldom achieved. In the present work, carbon nanodots (Arg-dots) from L-arginine were used for gas therapy of cancer. The Arg-dots produced NO in the H2O2-rich tumor environment. Theoretical calculations were consistent with the mechanism of enhanced NO release amount. The Arg-dots also reduced the multidrug resistance effect in cancer chemotherapy. In vivo and in vitro toxicity assessments confirmed that the Arg-dots have excellent biosafety.

As the high-power density and environmentally friendly energy resources, proton exchange membrane fuel cells (PEMFCs) have a promising future in portable power generation. Herein, the hybrid Nafion membranes of ionic hydrogen-bonded organic frameworks (iHOFs) for PEMFC applications are demonstrated. By adjusting the position of sulfonic groups on naphthalene disulfonic acid compounds, four iHOFs with different types of hydrogen bonds were synthesized successfully based on 1,1'-diamino-4,4'-bipyridylium and naphthalene disulfonic acid. The formation of hydrogen bond interactions between amino and sulfonate groups provides a rich hydrogen bond network, which makes such iHOFs have high conductivity, and the maximum value is 2.76 × 10-3 S·cm-1 at 100 °C and 98% RH. Besides, composite membrane materials were obtained by mixing Nafion and iHOFs, and the maximum proton conductivity values can achieve 1.13 × 10-2 S·cm-1 for 6%-iHOF-3/Nafion and 2.87 × 10-3 S·cm-1 for 6%-iHOF-4/Nafion membranes at 100 °C under 98% RH. Through the H2/O2 fuel cell performance test by using iHOF/Nafion as the solid electrolyte, the maximum power and current density values of hybrid membranes are 0.36 W·cm-2 and 1.10 A·cm-2 for 6%-iHOF-3/Nafion and 0.42 W·cm-2 and 1.20 A·cm-2 for 6%-iHOF-4/Nafion at 80 °C and 100% RH. This work provides a practicable approach for establishing high-performance proton exchange hybrid membranes by doping high proton-conducting iHOFs into the Nafion matrix.

As a crucial component of redox flow batteries (RFBs), porous electrode provides active sites for redox reaction to realize electrochemical energy conversion. The coupling reaction kinetics and mas...

The crown-shaped organotriphosphonate-modified 36-molybdenum cluster (NH4)18Na7H11[Zn(H2O)TeMo6O21{N(CH2PO3)3}]6·23H2O (1) has been synthesized, which is the largest zinc-containing organophosphonate-based polyoxometalate to date. Compound 1 was prepared in buffer solution (pH 5.5) with heptamolybdate and amino trimethylene phosphonic acid (ATMP) as the organic ligand. The polyanion constructed from a hexmeric assembly of [Zn(H2O){TeMo6O21}{N(CH2PO3)3}]6- subunits has been fully investigated by a few characterization methods. In this work, we discovered that 1 exhibited reversible photochromism and it changed from white to reddish brown upon UV irradiation. In addition, compound 1, as a catalyst, can oxidize sulfides to sulfoxides, showing a high yield/conversion and a good selectivity.

Non-syndromic inherited defects of tooth dentin are caused by two classes of dominant negative/gain-of-function mutations in dentin sialophosphoprotein (DSPP): 5′ mutations affecting an N-terminal targeting sequence and 3′ mutations that shift translation into the − 1 reading frame. DSPP defects cause an overlapping spectrum of phenotypes classified as dentin dysplasia type II and dentinogenesis imperfecta types II and III. Using CRISPR/Cas9, we generated a Dspp−1fs mouse model by introducing a FLAG-tag followed by a single nucleotide deletion that translated 493 extraneous amino acids before termination. Developing incisors and/or molars from this mouse and a DsppP19L mouse were characterized by morphological assessment, bSEM, nanohardness testing, histological analysis, in situ hybridization and immunohistochemistry. DsppP19L dentin contained dentinal tubules but grew slowly and was softer and less mineralized than the wild-type. DsppP19L incisor enamel was softer than normal, while molar enamel showed reduced rod/interrod definition. Dspp−1fs dentin formation was analogous to reparative dentin: it lacked dentinal tubules, contained cellular debris, and was significantly softer and thinner than Dspp+/+ and DsppP19L dentin. The Dspp−1fs incisor enamel appeared normal and was comparable to the wild-type in hardness. We conclude that 5′ and 3′ Dspp mutations cause dental malformations through different pathological mechanisms and can be regarded as distinct disorders.

Carbon materials have taken an important role in supercapacitor applications due to their outstanding features of large surface area, low price, and stable physicochemical properties. Considerable research efforts have been devoted to the development of novel synthesis strategy for the preparation of porous carbon materials in recent years. In particular, molten salt strategy represents an emerging and promising method, whereby it has shown great potential in achieving tailored production of porous carbon. It has been proved that the molten salt-assisted production of carbon via the direct carbonization of carbonaceous precursors is an effective approach. Furthermore, with the incorporation of electrochemical technology, molten salt synthesis of porous carbon has become flexible and diversiform. Here, this review focuses on the mainstream molten salt synthesis strategies for the production of porous carbon materials, which includes direct molten salt carbonization process, capture and electrochemical conversion of CO2 to value-added carbon, electrochemical exfoliation of graphite to graphene-based materials, and electrochemical etching of carbides to new-type carbide-derived carbon materials. The reaction mechanisms and recent advances for these strategies are reviewed and discussed systematically. The morphological and structural properties and capacitive performances of the obtained carbon materials are summarized to reveal their appealing points for supercapacitor applications. Moreover, the opportunities and challenges of the molten salt synthesis strategy for the preparation of carbon materials are also discussed in this review to provide inspiration to the future researches.

Background: Facet joint degeneration (FJD), which is also called facet joint syndrome (FJS), has become one of the most commonly seen etiological factors for lumbago. Cartilage lesion triggered by lumbar facet joint (LFJ) degeneration might be related to mitochondrial impairment, but the its underlying mechanism remains unclear. Materials and methods: The endplate chondrocytes were induced by hydrogen peroxide (H2O2) to mimic the pathological conditions of oxidative stress. Enzyme linked immunosorbent assay (ELISA) were used for the evaluation of reactive oxygen species (ROS). Adenosine-triphosphate (ATP) level was assessed using ATP detection, along with the detection the expression of cytochrome C in mitochondria (mito-cyt c) and in cell cytoplasm (cyto-cyt c) and cleaved caspase 3 by Western blot analysis. TUNEL assay was conducted for the measurement of cell apoptosis in endplate chondrocytes. Reverse transcription-polymerase chain reaction (RT-qPCR) was used to verify the expression of heat shock protein 22 (HSP22) and the transfection efficiency of HSP22 interference plasmid. Results: It was found that H2O2 promoted the mitochondrial dysfunction, ROS generation and cell apoptosis in endplate chondrocytes. Moreover, HSP22 was down-regulated in H2O2-induced endplate chondrocytes, and interference of HSP22 decreased the ROS production, increased the ATP level and promoted the cell apoptosis, resulting in the enhanced impairment of endplate chondrocytes. Additionally, mitochondrial ROS inhibitor (Mito-TEMPO) ameliorated the injury effects of HSP22 silencing in the H2O2-induced endplate chondrocytes. Conclusion: In conclusion, HSP22 inhibits oxidative stress-induced endplate chondrocyte apoptosis by regulating mitochondrial pathway, possibly providing novel guidance direction for the treatment of LFJ degeneration.

Enveloped viruses such as SARS-CoV-2 frequently have a highly infectious nature and are considered effective natural delivery systems exhibiting high efficiency and specificity. Since simultaneously enhancing the activity and selectivity of lipopeptides is a seemingly unsolvable problem for conventional chemistry and pharmaceutical approaches, we present a biomimetic strategy to construct lipopeptide-based mimics of viral architectures and infections to enhance their antimicrobial efficacy while avoiding side effects. Herein, a surface-nanoengineered antimicrobial liposome (SNAL) is developed with the morphological features of enveloped viruses, including a moderate size range, lipid-based membrane structure, and highly lipopeptide-enriched bilayer surface. The SNAL possesses virus-like infection to bacterial cells, which can mediate high-efficiency and high-selectivity bacteria binding, rapidly attack and invade bacteria via plasma membrane fusion pathway, and induce a local “burst” release of lipopeptide to produce irreversible damage of cell membrane. Remarkably, viral mimics are effective against multiple pathogens with low minimum inhibitory concentrations (1.6–6.3 μg mL−1), high bactericidal efficiency of >99% within 2 h, >10-fold enhanced selectivity over free lipopeptide, 99.8% reduction in skin MRSA load after a single treatment, and negligible toxicity. This bioinspired design has significant potential to enhance the therapeutic efficacy of lipopeptides and may create new opportunities for designing next-generation antimicrobials., Graphical abstract Image 1

Calcium phosphate (CaP) has been widely used for bone defect repair due to good biocompatibility and osteoconductivity. Additive manufacture of calcium phosphate bioceramics with tailored architectures and improved mechanical properties has recently attracted great attention. Herein, calcium phosphate nanoparticles with the size of ∼89−164 nm were synthesized by the hydrothermal treatment of amorphous calcium phosphate (ACP) precursors at 180 °C for 24 h. Biofunctional elements including Mg, Sr and Zn have been doped into these calcium phosphate nanoparticles. Our results revealed that Mg2+ ions played critical roles in formation of whitlockite-type calcium phosphate (not hydroxyapatite) from ACP precursors. Moreover, gyroid scaffolds with bionic triply periodic minimal surface structures were fabricated using stereolithography printing of these calcium phosphate nanoparticles, which are likely used as biofunctional scaffolds for bone repair.

An efficient preparation and local coordination environment regulation of isolated single-atom sites catalysts (ISASC) for improved activity is still challenging. Herein, we develop a solid phase thermal diffusion strategy to synthesize Mn ISASC on highly uniform nitrogen-doped carbon nanotubes by employing MnO2 nanowires@ZIF-8 core-shell structure. Under high-temperature, the Mn species break free from core-MnO2 lattice, which will be trapped by carbon defects derived from shell-ZIF-8 carbonization, and immobilized within carbon substrate. Furthermore, the poly-dispersed Mn sites with two nitrogen-coordinated centers can be controllably renovated into four-nitrogen-coordinated Mn sites using NH3 treatment technology. Both experimental and computational investigations indicate that the symmetric coordinated Mn sites manifest outstanding oxygen reduction activity and superior stability in alkaline and acidic solutions. This work not only provides efficient way to regulate the coordination structure of ISASC to improve catalytic performance but also paves the way to reveal its significant promise for commercial application.

The high-valence inorganic metalloid element of silicon was used for doping perovskite type oxides Pr0.6Sr0.4Fe1-xSixO3-δ (PSFSix, x = 0−0.1), as the oxygen transport membranes (OTM) for thermochemical water splitting to hydrogen production, which were fabricated by sol-gel method successfully. The effects of Si doped on microstructure, thermal expansion, permeability, and stability were investigated systematically. Although the crystal structure does not change, the metal-oxygen average binging energy (ABE) and oxygen vacancy concentration at room temperature increase after Si4+ doped. Furthermore, the phase transition process is reduced below the operating temperature by silicon doped. Due to the increase of ABE, the oxygen vacancy concentration of PSF exceeds that of the Si-doping samples with the temperature elevated. This is why the oxygen permeation flux of Si-doping samples is gradually exceeded by PSF. The long-term stability of water splitting to hydrogen is enhanced because the Si-doping increases the chemical stability of samples in reducing atmosphere.

Pt-based alloy nanomaterials with nanodendrites (NDs) structures are efficient electrocatalysts for methanol oxidation reaction (MOR), however their durability is greatly limited by the issue of transition metals dissolution. In this work, a facile trace Ir-doping strategy was proposed to fabricate Ir-PtZn and Ir-PtCu alloy NDs catalysts in aqueous medium, which significantly improved the electrocatalytic activity and durability for MOR. The as-prepared Ir-PtZn/Cu NDs catalysts showed distinct dendrites structures with the averaged diameter of 4.1 nm, and trace Ir doping subsequently improved the utilization of Pt atoms and promoted the oxidation efficiency of methanol. The electrochemical characterizations further demonstrated that the obtained Ir-PtZn/Cu NDs possessed enhanced mass activities of nearly 1.23 and 1.28-fold higher than those of undoped PtZn and PtCu, and approximately 2.35 and 2.67-fold higher than that of Pt/C in acid medium. More excitingly, after long-term durability test, the proposed Ir-PtZn and Ir-PtCu NDs still retained about 88.9% and 91.6% of its initial mass activities, which further highlights the key role of Ir-doping in determining catalyst performance. This work suggests that trace Ir-doping engineering could be a promising way to develop advanced electrocatalysts toward MOR for direct methanol fuel cell (DMFC) applications.

The catalytic diastereo- and enantioselective syntheses of C2-symmetric axially chiral 1,4-dicarbonyl derivatives with 2,3-quaternary stereocenters were achieved by utilizing an organo-/iodine binary catalytic strategy. The reactions proceeded well under mild conditions without metals or strong bases.

The non-aqueous redox flow battery (NARFB) has received extensive attention in large-scale energy storage systems, but its electrochemical performance needs to be improved. In this study, electrode modification was performed by depositing non-noble metal chromium oxide on the surface of graphite felt by impregnation combined with high-temperature calcination. The results show that the graphite felt electrode decorated with Cr2O3 has a good electrocatalytic effect on the redox reaction of Fe(II)/Fe(III). In addition, the polarization curve test shows that the power density of the modified electrode reaches 11.22 mW·cm−2 (15% increment). In the charge–discharge cycle test, the NARFB assembled with the chromium oxide–modified electrode has an energy efficiency of 87.2%. This work provides a potential way to improve the performance of NARFB with deep eutectic solvent (DES) electrolytes.

A series of dense xCe0.85Pr0.15O2-δ (CP) -(100-x) Pr0.6Sr0·4Fe0·9Al0·1O3-δ (PSFA) (x = 30, 40, 50, 60, 70) dual-phase oxygen transport membranes were successfully synthesized by sol-gel method. The feasibility of xCP-(100-x) PSFA membranes for hydrogen production by thermochemical water splitting was explored by testing in the thermochemical stability, oxygen permeability, hydrogen production efficiency, and performance degradation mechanism of these membranes. The results show that the thermochemical stability of xCP-(100-x) PSFA membranes is improved with the CP content increasing. The oxygen permeation model demonstrates that appropriate CP content is beneficial to reduce the permeation resistance of xCP-(100-x) PSFA membranes, and the reaction of surface exchange plays a major role in the oxygen transport process at 925 °C. The formation of Fe(SiO3) and Sr3Fe2O7 on the sweep side leads to the decline in hydrogen production rate. The 60CP-40PSFA membrane showed the best comprehensive performance with a hydrogen production retention rate of 90% and a stable hydrogen production rate of 0.99 ml cm−2 min−1 in the 100-h test cycle.

For lithium-ion capacitors, electrode potential tuning has been widely regarded as an efficient technology to improve their performance where the anode is usually pre-lithiated for desired potentials. However, the attention on the cathode is quite rare which denies the further excavation of this promising strategy. Herein, we reported the precious regulation of the potential of a cathode made of nitrogen-doped carbon nanosheets to fully leverage the merit of the electrode materials and the electrolyte potential window. Specifically, the nitrogen-doped carbon nanosheets in the optimized potential range of 1.6–4.5 V vs Li/Li+ show a specific capacity of around 150 mA h g−1 at 0.2 A g−1, which is four-time higher than that of the typical activated carbon cathode without potential tuning, and could be stably cycled for over 10 000 cycles without obvious decay. After pairing with a pre-lithiated anode, the as-assembled lithium-ion capacitors based on such a cathode can lead to simultaneously optimize the specific capacitance and voltage window of the device that contributes to a 17-fold increase in energy density, large power density, and long-term stability. The simple and effective strategy demonstrated here may inspire an alternative avenue to regulate the real performance of hybrid energy storage devices.

DGAT2 (acyl CoA:diacylglycerol acyltransferase 2) is a key and rate-limiting enzyme that catalyzes the final step of triglyceride (TG) synthesis. In this study, hybrid tilapia were generated from Nile tilapia (♀) and blue tilapia (♂) crossing. The TG content levels in the liver of these tilapia were measured. The results showed that the TG content was higher in the hybrid tilapia. In addition, protein and mRNA expression levels in the tilapia livers were determined. Higher hepatic mRNA and protein expression of DGAT2 in the hybrid fish was found. A luciferase reporter assay with HEK293T cells revealed that miRNA-19a-5p targeted the 3'UTR of DGAT2, suggesting a direct regulatory mechanism. Using qRT-PCR, we found that DGAT2 mRNA levels had a negative correlation with miRNA-19a-5p expression in Nile tilapia and hybrid. Taken together, these findings provide evidence that miRNA-19a-5p is involved in TG synthesis in the regulation of lipid metabolism in tilapia.

C-terminally encoded peptides (CEPs) are small peptides, typically post-translationally modified, and highly conserved in many species. CEPs are known to inhibit plant growth and development, but the mechanisms are not well understood. In this study, 14 CEPs were identified in Setaria italica and divided into two groups. The transcripts of most SiCEPs were more abundant in roots than in other detected tissues. SiCEP3, SiCEP4, and SiCEP5 were also highly expressed in panicles. Moreover, expression of all SiCEPs was induced by abiotic stresses and phytohormones. SiCEP3 overexpression and application of synthetic SiCEP3 both inhibited seedling growth. In the presence of abscisic acid (ABA), growth inhibition and ABA content in seedlings increased with the concentration of SiCEP3. Transcripts encoding eight ABA transporters and six ABA receptors were induced or repressed by synthetic SiCEP3, ABA, and their combination. Further analysis using loss-of-function mutants of Arabidopsis genes functioning as ABA transporters, receptors, and in the biosynthesis and degradation of ABA revealed that SiCEP3 promoted ABA import at least via NRT1.2 (NITRATE TRANSPORTER 1.2) and ABCG40 (ATP-BINDING CASSETTE G40). In addition, SiCEP3, ABA, or their combination inhibited the kinase activities of CEP receptors AtCEPR1/2. Taken together, our results indicated that the CEP-CEPR module mediates ABA signaling by regulating ABA transporters and ABA receptors in planta.

Tetracyclines and fluoroquinolones are common antibacterial drugs used in aquaculture, and their residues may pose a risk to human health. The low concentration of drug residues and complex matrixes such as fats and proteins in aquatic products necessitate the urgent development of efficient sample pretreatment methods. Solid phase extraction (SPE) is the most common sample pretreatment method, in which the core is an adsorbent. Compared with traditional SPE adsorbents, nanofiber mat (NFsM) has more interaction sites because of their large specific surface area. Furthermore, NFsMs modified with specific functional groups can significantly improve the extraction efficiency of tetracyclines and fluoroquinolones. Polydopamine (PDA) is spontaneously synthesized by the oxidative self-polymerization of dopamine-hydrochloride in alkaline solutions (pH>7.5). Because of its rich amino and catechol groups, PDA can form π-π stacking, electrostatic attraction, hydrophobic interaction, and hydrogen bonding interactions with target molecules. By exploiting the above advantages, polystyrene (PS) NFsM, as a template, was prepared by the electrostatic spinning method, and PDA-PS NFsM was obtained by functional modification of PDA through self-polymerization. Fourier transform infrared spectroscopy (FT-IR) and field-emission scanning electron microscopy (FESEM) were used to characterize the synthesized PS NFsM and PDA-PS NFsM. It was proved that PDA was successfully modified on the PS NFsM, with the SEM images revealing a rough outer core shell structure and an inner honeycomb structure. Subsequently, the handmade SPE column with PDA-PS NFsM was completed. A novel and efficient screening analytical method based on PDA-PS NFsM for the simultaneous determination of three tetracyclines (tetracycline (TET), chlortetracycline (CTC), and oxytetracycline (OTC)) and three fluoroquinolones (enrofloxacin (ENR), ciprofloxacin (CIP), and norfloxacin (NOR)) in fish by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established. The SPE procedure was optimized to develop an efficient method for sample preparation. Evaluate parameters including the amount of NFsM usage, ionic strength, flow rate of the sample solution, composition of eluent, and breakthrough volume were investigated. Only (20±0.1) mg of PDA-PS NFsM was sufficient to completely adsorb the targets, and the analytes retained on NFsM could be eluted by 1 mL of formic acid-ethyl acetate (containing 20% methanol) (1∶99, v/v). The residues were redissolved in 0.1 mL 10% methanol aqueous solution containing 0.2% formic acid. In addition, no adjustment of the pH and ionic strength of the sample solutions was required, and the breakthrough volume was 50 mL. The limits of detection (LODs) and limits of quantification (LOQs) of the six target compounds were measured at 3 times and 10 times the signal-to-noise ratio (S/N), respectively. The LODs and LOQs were 0.3-1.5 μg/kg and 1.0-5.0 μg/kg, respectively. The linear ranges of the six target compounds were LOQ-1000 μg/kg, and the coefficient of determination (R2) was greater than 0.999. To evaluate the accuracy and precision, blank spiked samples at three levels (low, medium, and high) were prepared for the recovery experiments, and each level with six parallel samples (n=6). The recoveries ranged from 94.37% to 102.82%, with intra-day and inter-day relative standard deviations of 2.38% to 8.06% and 4.10% to 9.10%, respectively. To evaluate the purification capacity of PDA-PS NFsM, the matrix effects before and after SPE were calculated and compared. Matrix effects before SPE were -12.98% to -38.68%. After the completion of SPEbased on PDA-PS NFsM, the matrix effect of each target analyte was significantly reduced to -2.15% to -7.36%, which proved the significant matrix removal capacity of PDA-PS NFsM. Finally, the practicality of this method was evaluated by using it to analyze real samples. This SPE method based on PDA-PS NFsM is efficient, practical, and environmentally friendly, and it has great potential for use in the routine monitoring of drug residues in fish.

The photocatalytic performances of water oxidation were usually carried out in two different systems, photosensitizer and non-photosensitizer systems. There is few report about the same catalyst used in two systems and therefore it is of great significant to compare its role of the same catalyst in two systems and explore its different reaction mechanisms. In this work, first 4 kinds of metallic Co microparticles were obtained by different reduction methods through hydrothermal processes, and Co@Co3O4 core-shell microparticles (1–4) were obtained from these metallic Co microparticles oxidized in air or in the reacting solution in situ. The core-shell structure of 1 was characterized by a series of analytical techniques. 1–4 exhibited excellent activities and stabilities in the [Ru(bpy)3]2+/S2O82−/light system when they were used as catalysts for the photocatalytic water oxidation. The maximum O2 evolution of 1 after 20 min’s illumination was 98.2 μmol, the O2 yield was 65.5%, the initial turnover frequency was 6.6 × 10−3, the initial quantum efficiency (ΦQY initial) was 15.0% higher than Co (8.3%), CoO (11.7%), Co2O3 (1.2%), Co3O4 (2.8%) and 5 (2.2%). Even after the sixth run, the catalytic activity of recovered 1 still remained 85.1% of initial activity. In addition, the photocatalytic performances of 1 in the [Ru(bpy)3]2+/S2O82−/light system and S2O82−/light system were compared for the first time. In the non-photosensitizer system, 1 shows bifunctional roles and acts as optical absorption center and active catalytic site, and oxygen evolution rate is lower and it takes longer time. In the photosensitizer system, 1 only acts as a catalyst, the photosensitizer enhances the light absorption and promotes water oxidation reaction with higher O2 yield and QE, meanwhile the photosensitizer brings the defect of high cost and instability into the system. Based on the results the two different reaction mechanisms were deeply discussed.