In Situ Growth of Columnar PEG on PEDOT and Its Antifouling Properties.

The antifouling properties of conductive polymers have received extensive attention for biosensor and bioelectronic applications. Polyethylene glycol (PEG) is a well-known antifouling material, but the controlled regulation of the surface topography of PEG without a template remains a challenge. Here, we show a columnar structure antifouling conductive polymer brush with enhanced antifouling properties and considerable conductivity. The method involves synthesizing the 3,4-ethylenedioxythiophene monomer modified with azide (EDOT-N3), the electropolymerization of PEDOT-N3, and the in situ growth of PEG polymer brushes on PEDOT through double-click reactions. The resultant columnar structure polymer brush exhibits high electrical conductivity (3.5 Ω·cm2), ultrahigh antifouling property, electrochemical stability (capacitance retention was 93.8% after 2000 cycles of CV scans in serum), and biocompatibility.

Polyoxometalate functionalized magnetic metal-organic framework with multi-affinity sites for efficient enrichment of phosphopeptides.

The reasonable design of metal-organic framework (MOF)-derived nanomaterial has important meaning in increasing the enrichment efficiency in the study of protein phosphorylation. In this work, a polyoxometalate (POM) functionalized magnetic MOF nanomaterial (Fe3O4@MIL-125-POM) was designed and fabricated. The nanomaterial with multi-affinity sites (unsaturated metal sites and metal oxide clusters) was used for the enrichment of phosphopeptides. Fe3O4@MIL-125-POM had high-efficient enrichment performance towards phosphopeptides (selectivity, a mass ratio of bovine serum albumin/α-casein/ß-casein at 5000:1:1; sensitivity, 0.1 fmol; satisfactory repeatability, ten times). Furthermore, Fe3O4@MIL-125-POM was employed to enrich phosphopeptides from non-fat milk digests, saliva, serum, and A549 cell lysate. The enrichment results illustrated the great potential of Fe3O4@MIL-125-POM for efficient identification of low-abundance phosphopeptides.

Sensitive detection of infectious disease utilizing carbon Sphere@Fe3O4 micromotor combined with graphene field-effect transistor.

BACKGROUND: Rapid on-site detection of infectious diseases is considerably essential for preventing and controlling major epidemics and maintaining social and public safety. However, the complexity of the natural environment in which infectious disease pathogens exist severely disrupts the performance of on-site detection, and rapid detection can become meaningless because of the cumbersome sample pretreatment process. RESULT: Herein, a new detection platform based on a carbon sphere@Fe3O4 micromotor (CS@Fe3O4) in combination with a graphene field-effect transistor (GFET) was designed and used for the on-site detection of SARS-CoV-2 coronavirus pathogens. The CS@Fe3O4 micromotor, surface-modified with anti-SARS-CoV-2 coronavirus antibody, could move at a velocity of 79.4 µm/s in a solution containing hydrogen peroxide (H2O2) and exhibited capture rates of 67.9% and 36.2% for the SARS-CoV-2 pathogen in phosphate buffered saline (PBS) and soil solutions, respectively. After magnetic field separation, the captured micromotor was used for GFET detection, with detection limits of 4.6 and 15.6 ag/mL in PBS and soil solutions, respectively. SIGNIFICANCE AND NOVELTY: This detection platform can be employed to avoid complex sample pretreatment procedures and achieve rapid on-site detection of SARS-CoV-2 coronavirus pathogens in complex environments. This study introduces a novel approach for the on-site detection of infectious diseases.

Cobalt Phthalocyanine-Modified Magnetic Metal-Organic Frameworks for Specific Enrichment of Phosphopeptides.

For mass spectrometry (MS)-based phosphoproteomics studies, sample pretreatment is an essential step for efficient identification of low-abundance phosphopeptides. Herein, a cobalt phthalocyanine-modified magnetic metal-organic framework (MOF) (Fe3O4@MIL-101-CoPc) was prepared and applied to enrich phosphopeptides before MS analysis. Fe3O4@MIL-101-CoPc exhibited an excellent magnetic response (74.98 emu g-1) and good hydrophilicity (7.75°), which were favorable for the enrichment. Fe3O4@MIL-101-CoPc showed good enrichment performance with high selectivity (1:1:5000), sensitivity (0.1 fmol), reusability (10 circles), and recovery (91.3%). Additionally, the Fe3O4@MIL-101-CoPc-based MS method was able to successfully detect 827 phosphopeptides from the A549 cell lysate, demonstrating a high enrichment efficiency (89.3%). This study promotes the application of postfunctionalized MOFs for phosphoproteomics analysis.

Enrichment of Phosphopeptides Based on Zirconium Phthalocyanine-Modified Magnetic Nanoparticles.

Highly selective extraction of phosphopeptides is necessary before mass spectrometry (MS) analysis. Herein, zirconium phthalocyanine-modified magnetic nanoparticles were prepared through a simple method. The Fe-O groups on Fe3O4 and the zirconium ions on phthalocyanine had a strong affinity for phosphopeptides based on immobilized metal ion affinity chromatography (IMAC). The enrichment platform exhibited low detection limit (0.01 fmol), high selectivity (α-/ß-casein/bovine serum albumin, 1/1/5000), good reusability (10 circles), and recovery (91.1 ± 1.1%) toward phosphopeptides. Nonfat milk, human serum, saliva, and A549 cell lysate were employed as actual samples to assess the applicability of the enrichment protocol. Metallo-phthalocyanine will be a competitive compound for designing highly efficient adsorbents and offers a new approach to phosphopeptide analysis.

Exploring the Performance Improvement for CO2 Chemical Fixation in Zn/ZnMg-MOFs.

A new 3D zinc-based metal-organic framework {[Zn7L2(DMF)3(H2O)(OH)2]·5DMF}n (1) (H6L = 5,5',5″-(methylsilanetriyl) triisophthalic acid) was constructed with an organosilicon-based linker, where H6L is a tetrahedral structure furnished with rich -COO- chelating sites for Zn(II) immobilization. Compound 1 exhibited two types of irregular one-dimensional channels and a three-dimensional skeleton with large specific surface area, making it a promising catalytic platform. Moreover, by incorporation of the second metal ion into the inorganic node of framework 1, isomorphic bimetallic MOF ZnMg-1 was successfully synthesized. ZnMg-1 demonstrated enhanced catalytic activity compared to 1 under identical conditions. Contrast experiments and theoretical calculations indicate that bimetallic active sites play a facilitating role in the chemical fixation of epoxides and CO2. It indicated that efficient chemical fixation of CO2 to cyclic carbonates was obtained over isomorphic MOF catalysts 1 and ZnMg-1.

Zirconium-rich magnetic polyoxometalate-based metal-organic framework: Tailored for phosphopeptide analysis from lung cancer A549 cells.

Polyoxometalate-based metal-organic frameworks (POMOFs) have become a promising affinity material for separation and enrichment. The analysis of protein phosphorylation represents a challenge for the development of efficient enrichment materials. Here, a novel zirconium-rich magnetic POMOF was successfully designed and prepared for the enrichment of phosphopeptides. The binding affinity of the nanomaterial partly came from Fe-O clusters in the MOF. The Lewis acid-base interactions between V-O clusters and zirconium ions in V10O28-Zr4+ and phosphate groups in phosphopeptides further strengthened the enrichment ability. The zirconium-rich magnetic POMOF was employed to capture phosphopeptides from non-fat milk, human saliva, and serum. Additionally, 748 unique phosphopeptide peaks were detected from the tryptic digests of lung cancer A549 cell proteins with a high specificity (86.9 %). POMOFs will become an active competitor for the design of protein affinity materials and will provide a new approach for phosphopeptide analysis.

Preparation of high-efficiency titanium ion immobilized magnetic graphite nitride nanocomposite for phosphopeptide enrichment.

BACKGROUND: Protein phosphorylation has been implicated in life processes including molecular interaction, protein structure transformation, and malignant disease. An in-depth study of protein phosphorylation may provide vital information for the discovery of early biomarkers. Mass spectrometry (MS)-based techniques have become an important method for phosphopeptide identification. Nevertheless, direct detection remains challenging because of the low ionization efficiency of phosphopeptides and serious interference from non-phosphopeptides. There is a great need for an efficient enrichment strategy to analyze protein phosphorylation prior to MS analysis. RESULTS: In this study, a novel nanocomposite was prepared by introducing titanium ions into two-dimensional magnetic graphite nitride. The nanocomposite was combined with immobilized metal ion affinity chromatography (IMAC) and anion-exchange chromatography mechanisms for phosphoproteome research. The nanocomposite had the advantages of a large specific surface (412.9 m2 g-1), positive electricity (175.44 mV), and excellent magnetic property (35.7 emu g-1). Moreover, it presented satisfactory selectivity (α-casein:ß-casein:bovine serum albumin = 1:1:5000), a low detection limit (0.02 fmol), great recyclability (10 cycles), and high recovery (92.8%). The nanocomposite demonstrated great practicability for phosphopeptides from non-fat milk, human serum, and saliva. Further, the nanocomposite was applied to enrich phosphopeptides from a more complicated specimen, A549 cell lysate. A total of 890 phosphopeptides mapping to 564 phosphoproteins were successfully detected with nano LC-MS. SIGNIFICANCE: We successfully designed and developed an efficient analysis platform for phosphopeptides, which includes protein digestion, phosphopeptide enrichment, and MS detection. The MS-based enrichment platform was further used to analyze phosphopeptides from complicated bio-samples. This work paves the way for the design and preparation of graphite nitride-based IMAC materials for phosphoproteome analysis.

Cerium ions immobilized magnetic graphite nitride decorated with L-Alanyl-L-Glutamine as new chelator for enrichment of phosphopeptides.

Cerium ions immobilized magnetic graphite nitride material have been prepared using L-Alanyl-L-Glutamine as the new chelator. The resulting Fe3O4/g-C3N4-L-Ala-L-Gln-Ce4+, as an immobilized metal ion affinity chromatography (IMAC) sorbent, was reusable. This is due to the strong coordination interaction between L-Alanyl-L-Glutamine and cerium ions. After a series of characterizations, the magnetic nanocomposite showed high surface area, good hydrophilicity, positive electricity, and magnetic response. Fe3O4/g-C3N4-L-Ala-L-Gln-Ce4+ had high sensitivity (0.1 fmol), selectivity (α-/ß-casein/bovine serum albumin, 1:1:5000), and good recyclability (10 cycles). A total of 647 unique phosphopeptides mapped to 491 phosphoproteins were identified from A549 cell lysate by nano LC-MS analysis.

Effective Enrichment of Phosphopeptides Using Magnetic Polyoxometalate-Based Metal-Organic Frameworks.

In this study, magnetic polyoxometalate-based metal-organic frameworks (Fe3O4-POMOFs) were designed and applied to the enrichment of phosphopeptides. Thanks to the abundant metal oxide and metal ion sites, the material had a strong affinity for phosphopeptides. Simultaneously, the high amount of amino and guanidyl groups provided hydrophilicity and positive charge for phosphopeptide capture. By coupling with MS detection, the established platform possessed good reusability, high sensitivity (0.01 fmol), and high selectivity (α-casein/ß-casein/bovine serum albumin = 1:1:5000). Furthermore, the method was successfully used for the detection of phosphopeptides in nonfat milk, human serum, saliva, and A549 cell lysate, showing great potential for practical application.

NiCoP/g-C3N4 Nanocomposites-Based Electrochemical Immunosensor for Sensitive Detection of Procalcitonin.

Herein, an ultra-sensitive and facile electrochemical biosensor for procalcitonin (PCT) detection was developed based on NiCoP/g-C3N4 nanocomposites. Firstly, NiCoP/g-C3N4 nanocomposites were synthesized using hydrothermal methods and then functionalized on the electrode surface by π-π stacking. Afterward, the monoclonal antibody that can specifically capture the PCT was successfully linked onto the surface of the nanocomposites with a 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS) condensation reaction. Finally, the modified sensor was employed for the electrochemical analysis of PCT using differential Pulse Voltammetry(DPV). Notably, the larger surface area of g-C3N4 and the higher electron transfer capacity of NiCoP/g-C3N4 endow this sensor with a wider detection range (1 ag/mL to 10 ng/mL) and an ultra-low limit of detection (0.6 ag/mL, S/N = 3). In addition, this strategy was also successfully applied to the detection of PCT in the diluted human serum sample, demonstrating that the developed immunosensors have the potential for application in clinical testing.

Activating Octahedral Center in Co-Doped NiFe2 O4 via Bridging Amorphous MoSx for Electrocatalytic Water Oxidation: A Case for eg Orbital Regulation in Spinel Oxide.

Moderate eg filling for octahedral metal cations (MOh ) is strongly correlated with the electrocatalytic water oxidation performance in the oxides system. Here, the eg fillings of NiOh and FeOh in NiFe2 O4 -based spinel are controllably regulated by introducing an external radical of catalytically inactive MoSx as an electron acceptor via a novel ultrasonic anchored pyrolysis strategy. The electron occupied in eg orbit of MOh emigrates with the amount of MoS hanging on the apical of octahedral sites, and results in a salutary transition from high to medium eg occupancy state, as confirmed by the X-ray absorption spectroscopy and X-ray photoelectron spectroscopy. In addition, benefiting from the abundant unsaturated S atoms in amorphous MoSx , the MOh at the surface furthest activates and consequently shows a superior water oxidation performance. Density functional theory also reveals that the eg fillings of Ni and Fe decrease to 1.4 and 1.2 after MoSx modification, which can effectively reduce the free energy of the OOH* intermediates in the oxygen evolution reaction process. This work opens an avenue for further releasing the electrocatalytic activity of octahedral sites through bridging external phases with rational electron-capturing/donating capability.

Unsupported nanoporous gold catalyst for highly selective hydroamination of alkynes.

An efficient and highly selective heterogeneous catalyst system for hydroamination of alkynes was developed using unsupported gold nanopores (AuNPore) for the first time. The AuNPore-catalyzed highly regioselective hydroamination of alkynes proceeded smoothly without any additive and solvent under mild conditions (rt-50 °C) to yield Markovnikov imines in satisfactory to excellent yields. No gold leached from AuNPore during the hydroamination of alkynes. Moreover, the catalyst was easily recovered and reused without any loss of catalytic activity. A one-pot, two-step procedure using a single AuNPore catalyst has been devised to produce secondary amines derived from readily available alkynes and anilines with high atom efficiency.

Design of two-dimensional molybdenum trioxide-immobilized magnetic graphite nitride nanocomposites with multiple affinity sites for phosphopeptide enrichment.

Here, two-dimensional magnetic graphite nitride nanosheets were synthesized, over which molybdenum trioxide was distributed evenly. The magnetic nanocomposite served as an enrichment platform for phosphopeptides based on metal oxide affinity chromatography and anion-exchange chromatography. Owing to the abundant affinity sites, positive electricity, and large surface area, the nanocomposite had high selectivity (α-casein/ß-casein/bovine serum albumin, 1:1:5000), sensitivity (0.1 fmol), quantitative recovery (91.3%), and good recyclability (10 cycles). The nanocomposite also showed good enrichment performance for phosphopeptides from non-fat milk, human serum, saliva, and A549 cell lysate. The results demonstrated the value of this material in phosphorylated proteomics.

Synthesis of Tetrahydrocarbazol-4-ones via Rh(III)-Catalyzed C-H Activation/Annulation of Arylhydrazines with Iodonium Ylides.

The rhodium(III)-catalyzed C-H activation followed by intramolecular annulation reactions between arylhydrazines and iodonium ylides under suitable conditions has been described. Tetrahydrocarbazol-4-ones are readily achieved with moderate to excellent yields. The synthetic protocol features a wide range of substrates with high functional group tolerance. The gram-scale reaction and derivatization of the product demonstrate the synthetic practicality and utilization of this method.

A Facile Fabrication of CdSe/ZnS QDs-Block Copolymer Brushes-Modified Graphene Oxide Nanohybrid with Temperature-Responsive Behavior.

In this paper, we described a straightforward one-step chemical method for the synthesis of semiconductor quantum dots(QDs)-block copolymer brushes functionalized graphene oxide(GO) fluorescence nanohybrids. The azobenzene-terminated block copolymer poly(N-isopropylacrylamid)-b-poly(styrene-co-5-(2-methacryoylethyloxymethyl)-8-quinolinol)(PNIPAM-b-P(St-co-MQ)) was modified on the surface of GO sheets via host-guest interactions between ß-cyclodextrin-modified GO and azobenzene moieties, and simultaneously CdSe/ZnS QDs were integrated on the block copolymer brushes through the coordination between 8-hydroxyquinoline units in the polymer brushes and CdSe/ZnS QDs. The resulting fluorescence nanohybrid exhibited dual photoluminescence at 620 nm and 526 nm, respectively, upon excitation at 380 nm and LCST-type thermo-responsive behavior which originated from the change in the PNIPAM conformation in the block copolymer brushes of GO sheets.

Layer-by-layer assembly of multilayered double hydroxides/polyoxometalate-coated magnetic nanoparticles for highly efficient phosphopeptide enrichment.

A layer-by-layer (LbL) assembly strategy was developed to prepare multilayered double hydroxide/polyoxometalate shell-coated magnetic nanoparticles. The introduction of functional shells not only offered abundant affinity sites of metal oxide and metal ions but also increased the surface area for the contact with targets. By combining the enrichment strategies of immobilized metal ion affinity chromatography and metal oxide affinity chromatography, the nanomaterial can capture phosphopeptides via a synergistic effect. The method presented a low detection limit of 0.1 fmol in combination with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis. The nanomaterial showed satisfactory selectivity (1:1:5000 M ratio of α-/ß-casein/bovine serum albumin), good recovery (92.07%), high adsorption capacity (117.6 mg g-1), and ten times reusability for capturing phosphopeptides.

Design of Gd3+-immobilized two-dimensional magnetic magadiite nanosheets for highly selective enrichment of phosphopeptides.

Exfoliated magadiite nanosheets embedded with Fe3O4 were constructed. Advantage was taken of the strong coordination between the silanol groups in magadiite nanosheets and the Gd3+ ion to prepare the final adsorbent, Gd3+-immobilized magnetic magadiite nanosheets. The adsorbent with two-dimensional (2D) morphology offered high surface area and abundant Gd3+ contents for phosphopeptides enrichment, on which Fe3O4 with positive electricity incorporated the magnetic properties. Combining with matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI TOF-MS), the method showed low detection limit (0.05 fmol). The feasibility of using the 2D nanocomposite for phosphopeptides enrichment was demonstrated using mixtures of ß-casein and bovine serum albumin (1:5000). The standard deviation of captured phosphopeptides in three repeated experiments were in the range 0.15-0.42 (< 0.5% RSD). Further evaluation revealed that the nanocomposite was capable of enriching phosphopeptides from non-fat milk, human saliva, and serum. A novel Gd3+-immobilized two-dimensional magnetic magadiite nanosheets-based enrichment platform was designed. The developed material was employed as the adsorbent for the selective enrichment of phosphopeptides by coupling with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The material was successfully applied to enrich phosphopetides from standard peptide mixtures, nonfat milk, human saliva, and serum.

Photocatalytic selective H2release from formic acid enabled by CO2captured carbon nitride.

The selective decomposition of formic acid (FA) traditionally needs to be carried out under high temperature with the noble metal-based catalysts. Meanwhile, it also encounters a separation of H2and CO2for pure H2production. The photocatalytic FA dehydrogenation under mild conditions can meet a growing demand for sustainable H2generation. Here, we reported a photocatalytic selective H2release from FA decomposition at low temperature for pure H2production by Pt/g-C3N4. Low-cost and easy-to-obtained urea was utilized to produce carbon nitride as the metal-free semiconductor photocatalyst, along with a photodeposition to obtain Pt/g-C3N4. The electrochemical evidences clearly demonstrate the photocatalytic activity of Pt/g-C3N4to produce H2and CO2in one-step FA decomposition. And, the impedance is the lowest under simulated solar light of 70 mW cm-2with a faster electron transfer kinetic. Under simulated solar light, H2production rate is up to 1.59 mmol · h-1· g-1for FA with concentration at 2.65 mol l-1, 1700 000 times larger than that under visible light and 1928 times under ultraviolet (UV) light. DFT calculations further elucidate that nitrogen (N) active site at the g-C3N4has an excellent adsorption towards CO2molecule capture. Then, H2molecules are selectively released to simultaneously separate H2and CO2in solution. Platinum (Pt) at Pt/g-C3N4as the catalytic site contributes into the acceleration of H2production.

Carbon nitride grafted waste-derived carbon as sustainable materials for lithium-sulfur batteries.

The synthesis of a sustainable material through carbon nitride (C3N4) chemically grafted on waste-derived carbon including carbonizing coals (PM), melamine-urea-formaldehyde resins (MUF-C-1100), and luffa cylindrical sponges (SG), respectively, and its application as sulfur cathode in lithium-sulfur (Li-S) batteries were demonstrated. The Li-S cell assembled by the sulfur (S) cathode with component from C3N4grafted coal-derived carbon (PM-CN) possesses a specific capacity of 1269.8 mA h g-1at 0.05 C. At 1 C, the initial specific capacity of PM cathode is only 380.0 mA h g-1, comparable to the PM-CN5 cathode of 681.9 mA h g-1, and PM-CN10 cathode of 580.7 mA h g-1, respectively. And, PM-CN 5 cathode presents the capacity retention of 75.9% with a coulomb efficiency (C.E.) of 97.3% after 200 cycles. The MUF-CN cathode gives a specific capacity of 1335.6 mA h g-1at 0.05 C, and the capacity retention of 66.7% with a C. E. of 93.6% after 300 cycles at 0.5 C. The SG-CN cathode had a specific capacity of 953.9 mA h g-1at 0.05 C, and capacity retention of 95.1% with a C. E. of 98.2% after 125 cycles at 1 C. The remarkable improved performances were mainly ascribed to the sustainable materials as S host with micro-meso pore and C3N4structure providing the strong affinity N sites to lithium polysulfides (LiPSs). This work provides an attractive approach for the preparation of sustainable materials by rational design of grafting C3N4to waste-derived carbons with functions as S cathode materials for high-performance Li-S batteries.