Rational Design of Mixed Matrix Membranes Modulated by Trisilver Complex for Efficient Propylene/Propane Separation.

The application of membrane-based separation processes for propylene/propane (C3 H6 /C3 H8 ) is extremely promising and attractive as it is poised to reduce the high operation cost of the established low temperature distillation process, but major challenges remain in achieving high gas selectivity/permeability and long-term membrane stability. Herein, a C3 H6 facilitated transport membrane using trisilver pyrazolate (Ag3 pz3 ) as a carrier filler is reported, which is uniformly dispersed in a polymer of intrinsic microporosity (PIM-1) matrix at the molecular level (≈15 nm), verified by several analytical techniques, including 3D-reconstructed focused ion beam scanning electron microscropy (FIB-SEM) tomography. The π-acidic Ag3 pz3 combines preferentially with π-basic C3 H6 , which is confirmed by density functional theory calculations showing that the silver ions in Ag3 pz3 form a reversible π complex with C3 H6 , endowing the membranes with superior C3 H6 affinity. The resulting membranes exhibit superior stability, C3 H6 /C3 H8 selectivity as high as ≈200 and excellent C3 H6 permeability of 306 Barrer, surpassing the upper bound selectivity/permeability performance line of polymeric membranes. This work provides a conceptually new approach of using coordinatively unsaturated 0D complexes as fillers in mixed matrix membranes, which can accomplish olefin/alkane separation with high performance.

Covalent organic framework-based electrochemical aptasensors for the ultrasensitive detection of antibiotics.

We designed and synthesized a novel covalent organic framework (COF) by condensation polymerization of 1,3,6,8-tetrakis(4-formylphenyl)pyrene and melamine through imine bonds (represented by Py-M-COF). The basic characterizations revealed that the Py-M-COF not only exhibited an extended π-conjugation framework, a large specific surface area (495.5 m2 g-1), big pore cavities, and nanosheet-like structure but also possessed rich functional groups, such as CË­C, CË­N, CË­O, and NH2. These features endowed the Py-M-COF with high charge carrier mobility, further improving the strong immobilization of DNA aptamer strands via π-π stacking interaction and electrostatic interaction. As such, the Py-M-COF-based electrochemical aptasensors are ultrasensitive in detecting different antibiotics, including enrofloxacin (ENR) and ampicillin (AMP), yielding extremely low detection limits of 6.07 and 0.04 fg mL-1 (S/N = 3) toward ENR and AMP, respectively, along with other excellent sensing performances. This biosensing platform based on Py-M-COF has potential applications for the sensitive detection of antibiotics or other analytes by replacing the corresponding aptamers.

Chemical structure of hollow carbon spheres and polyaniline nanocomposite.

In this data article, the chemical data of hollow carbon spheres and polyaniline (HCS@PANI) nanocomposite are presented for the research article entitled "Novel electrochemical biosensor based on core-shell nanostructured composite of hollow carbon spheres and polyaniline for sensitively detecting malathion" (He et al., 2018) [1]. The data includes chemical structure and components obtained by Raman spectra, X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption and desorption isotherms.

Cu x O@DNA sphere-based electrochemical bioassay for sensitive detection of Pb2.

The paper describes a one-step synthetic method to chemically reduce cupric sulfate by ascorbic acid in the presence of DNA strands to directly produce Cu x O@DNA spheres. The DNA strands act as template to assist the preparation of Cu x O, and also are capable of specifically binding  Pb(II) ions. The Cu x O@DNA spheres possess high specific surface area and strong bioaffinity. They can be directly employed as platform for detecting Pb2+ sensitively. Electrochemical impedance spectroscopy data showed that the assay exhibits high sensitivity and a wide linear analytical range that extends from 0.1 to 100 nM, and the detection limit is 6.8 pM at a signal-to-noise ratio of 3. The assay is selective, acceptably reproducible, stable, and well feasible for the detection of Pb2+ in blood serum. Graphical abstract Schematic presentation of the preparation of DNA-templated Cu x O spheres (Cu x O@DNA) for use in electrochemical detection of Pb2+. The assay exhibits detection limit of 6.8 pM, high selectivity, acceptable reproducibility, stability, and good applicability for Pb2+ detection.

Syntheses, Characterization and Crystal Structures of Schiff Base Zinc(II) Complexes with Antibacterial Activity.

Two polynuclear zinc(II) complexes, [Zn2(L1)2(OH2)2] (1) and [ZnL2(µ1,1-N3)]n (2), where L1 is the dianionic form of N,N'-bis(3,5-difluoro-2-hydroxybenzylidene)-1,3-diaminopropane, and L2 is the monoanionic form of 2-[(2-dimethylaminoethylimino)methyl]-4,6-difluorophenol, have been prepared and structurally characterized by elemental analyses, IR and UV-Vis spectroscopy, as well as single-crystal X-ray diffraction. In complex 1, the Zn atom is in octahedral coordination, with the donor atoms of the Schiff base ligands L1 and one water O atom. In complex 2, the Zn atom is in trigonal-bipyramidal coordination, with the three donor atoms of the Schiff base ligand L2 and two azido N atoms. The complexes have strong antibacterial activity against B. subtilis and S. aureus.

Aptamer-Templated Silver Nanoclusters Embedded in Zirconium Metal-Organic Framework for Bifunctional Electrochemical and SPR Aptasensors toward Carcinoembryonic Antigen.

This study reported a novel biosensor based on the nanocomposite of zirconium metal-organic framework (Zr-MOF, UiO-66) embedded with silver nanoclusters (Ag NCs) using the carcinoembryonic antigen (CEA)-targeted aptamer as template (AgNCs@Apt@UiO-66). The synthesized AgNCs@Apt@UiO-66 nanocomposite not only possesses good biocompatibility, active electrochemical performance, and strong bioaffinity, but also can be dispersed to form two-dimensional nanocomposite with nanoscale thickness. As such, the use of the AgNCs@CEA-aptamer enables AgNC@Apt@UiO-66 with sensitive and selective detection capacity of trace CEA, further concurrently being exploited as scaffold for surface plasmon resonance spectroscopy (SPR) and electrochemical biosensors. The results showed that the proposed electrochemical AgNC@Apt@UiO-66-based aptasensor exhibits high sensitivity with a low detection limit (LOD) of 8.88 and 4.93 pg·mL-1 deduced from electrochemical impedance spectroscopy and differential pulse voltammetry, respectively, within a broad linear range of the CEA concentration (0.01-10 ng·mL-1). Meanwhile, the developed SPR biosensor exhibited a slightly high LOD of 0.3 ng·mL-1 within the CEA concentration of 1.0-250 ng·mL-1. Both the electrochemical and SPR aptasensors displayed high selectivity, good reproducibility, stability, acceptable regenerability, and applicability in real human serum samples. These results proved that the proposed aptamer-targeted Zr-MOF nanocomposite can be utilized in multiple-functionally biosensing, further promoting the potential application of Zr-MOF-related nanomaterials in clinical diagnosis.

Aptasensor Based on Hierarchical Core-Shell Nanocomposites of Zirconium Hexacyanoferrate Nanoparticles and Mesoporous mFe3O4@mC: Electrochemical Quantitation of Epithelial Tumor Marker Mucin-1.

A novel nanostructured hierarchical core-shell nanocomposite of zirconium hexacyanoferrate (ZrHCF) and a mesoporous nanomaterial composed of Fe3O4 and carbon nanospheres (denoted as ZrHCF@mFe3O4@mC) was prepared and used as a novel platform for an aptasensor to detect the epithelial tumor marker mucin-1 (MUC1) sensitively and selectively. The prepared ZrHCF@mFe3O4@mC nanocomposite exhibited good chemical functionality, water stability, and high specific surface area. Therefore, large amounts of aptamer molecules resulted in high sensitivity of the developed electrochemical aptasensor toward traces of MUC1. The constructed sensor also showed a good linear relationship with the logarithm of MUC1 concentration in the broad range of 0.01 ng·mL-1 to 1.0 µg·mL-1, with a low detection limit of 0.90 pg·mL-1. The fabricated ZrHCF@mFe3O4@mC-based aptasensor exhibited not only high selectivity because of the formation of aptamer-MUC1 complex but also good stability, acceptable reproducibility, and applicability. The proposed novel strategy based on a newly prepared hierarchical core-shell nanocomposite demonstrated outstanding biosensing performance and presents potential applications in biomedical fields.

Carbon-based nanocomposites with aptamer-templated silver nanoclusters for the highly sensitive and selective detection of platelet-derived growth factor.

We synthesized two kinds of carbon-based nanocomposites of silver nanoclusters (AgNCs). An aptamer for targeted platelet-derived growth factor-BB (PDGF-BB) detection was used as the organic phase to produce AgNCs@Apt, three dimensional reduced graphene oxide@AgNCs@Aptamer (3D-rGO@AgNCs@Apt), and graphene quantum dots@AgNCs@Aptamer (GQD@AgNCs@Apt) nanocomposites. The formation mechanism of the developed nanocomposites was described by detailed characterizations of their chemical and crystal structures. Subsequently, the as-synthesized nanoclusters containing aptamer strands were applied as the sensitive layers to fabricate a novel electrochemical aptasensor for the detection of PDGF-BB, which may be directly used to determine the target protein. Electrochemical impedance spectra showed that the developed 3D-rGO@AgNCs@Apt-based biosensor exhibited the highest sensitivity for PDGF-BB detection among three kinds of fabricated aptasensors, with an extremely low detection limit of 0.82pgmL-1. In addition, the 3D-rGO@AgNCs@Apt-based biosensor showed high selectivity, stability, and applicability for the detection of PDGF-BB. This finding indicated that the AgNC-based nanocomposites prepared by a one-step method could be used as an electrochemical biosensor for various detection procedures in the biomedical field.

Protein-templated cobaltous phosphate nanocomposites for the highly sensitive and selective detection of platelet-derived growth factor-BB.

We synthesized novel Co3(PO4)2-based nanocomposites with 3D porous architectures via self-assembly; here, bovine serum albumin (BSA) and aptamer were used as organic phases to produce Co3(PO4)2@BSA and Co3(PO4)2@Apt nanocomposites, respectively. The formation mechanism of Co3(PO4)2-based nanocomposites was described based on characterizations of their physio-chemical performance, and the developed nanocomposites were applied as scaffold materials to construct a novel electrochemical aptasensor and detect platelet-derived growth factor-BB (PDGF-BB). The PDGF-BB targeting aptamer must be immobilized onto the Co3(PO4)2@BSA-modified electrode to detect PDGF-BB, whereas Co3(PO4)2@Apt-based aptasensor may be directly used to determine the target protein. Electrochemical impedance spectroscopy results showed that the developed Co3(PO4)2@BSA- and Co3(PO4)2@Apt-based aptasensors present highly sensitive detection ability toward PDGF-BB. Due to the special nanoflower structure, the Co3(PO4)2@BSA-based aptasensor features a detection limit of 3.7 pg mL(-1); while the limit of detection of the Co3(PO4)2@Apt-based aptasensor is 61.5 pg mL(-1), which is the possible bioactivity loss of the aptamer in Co3(PO4)2@Apt nanocomposite. The two detection limits obtained are still much lower than or comparable with those of previously reported aptasensors. The Co3(PO4)2@BSA- and Co3(PO4)2@Apt-based aptasensors showed high selectivity, stability, and applicability for detecting the desired protein. This finding indicates that the Co3(PO4)2-based nanocomposites could be used as an electrochemical biosensor for various detection procedures in the biomedical field.

Feasible electrochemical biosensor based on plasma polymerization-assisted composite of polyacrylic acid and hollow TiO2 spheres for sensitively detecting lysozyme.

A composite made of polyacrylic acid and hollow TiO2 spheres (TiO2@PPAA) was prepared by the plasma polymerization method and subsequently used as an electrode material for detecting lysozyme. The chemical structure, surface morphology, and electrochemical performance of the TiO2@PPAA composite were mainly affected by the plasma input power used during plasma polymerization. After optimizing plasma conditions, aptamer strands exhibited high adsorption affinity toward the surface of TiO2@PPAA composite via synergistic effects between TiO2 and PPAA. Electrochemical impedance spectroscopy results showed that the developed TiO2@PPAA aptasensor presents highly sensitive detection ability toward lysozyme; the limit of detection of the proposed aptasensor is 0.015 ng mL(-1) (1.04 pM) within the range of 0.05-100 ng mL(-1) in terms of 3σ value. The film further showed excellent selectivity toward lysozyme in the presence of interfering proteins, such as thrombin, bovine serum albumin, and immunoglobulin E. Thus, this aptasensing strategy might broaden the applications of plasma polymerized nanomaterials in the field of biomedical research and early clinical diagnosis.

An electrochemical aptasensor based on a TiO2/three-dimensional reduced graphene oxide/PPy nanocomposite for the sensitive detection of lysozyme.

A sensitive aptasensor based on a nanocomposite of hollow titanium dioxide nanoball, three-dimensional reduced graphene oxide, and polypyrrole (TiO2/3D-rGO/PPy) was developed for lysozyme detection. A lysozyme aptamer was easily immobilized onto the TiO2/3D-rGO/PPy nanocomposite matrix by assembling the aptamer onto graphene through simple π-stacking interactions and electrostatic interactions between PPy molecular chains and aptamer strands. In the presence of lysozyme, the aptamer on the adsorbent layer catches the target on the electrode interface, which generates a barrier for electrons and inhibits electron transfer, subsequently resulting in decreased electrochemically differential pulse voltammetric signals of a gold electrode modified with TiO2/3D-rGO/PPy. Using this strategy, a low limit of detection of 0.085 ng mL(-1) (5.5 pM) for detecting lysozyme was observed within the detection range of 0.1-50 ng mL(-1) (0.007-3.5 nM). The aptasensor also presents high specificity for lysozyme, which is unaffected by the coexistence of other proteins. Such an aptasensor opens a rapid, selective, and sensitive route to lysozyme detection. This finding indicates that the TiO2/3D-rGO/PPy nanocomposite could be used as an electrochemical biosensor for detecting proteins in the biomedical field.

DNA immobilization/hybridization on plasma-polymerized pyrrole.

The present work describes the fabrication and characterization of the conducting polymer coatings prepared by the continuous wave plasma polymerization and the applications as adhesion layers for studying DNA immobilization/hybridization. The stability of plasma polymerized pyrrole (ppPY) in the aqueous solution was characterized by ellipsometry. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to investigate polymer matrix properties and oligonucleotide/DNA binding interaction. The successful DNA immobilization on ppPY surfaces was found to depend on the macromolecular architecture of plasma polymerized films. The plasma polymers with similar thickness deposited at different input powers showed various comparable immobilization properties. The plasma-polymerized films prepared at the low input power showed a lower sensitivity toward DNA binding than those films deposited at the high input power. This result will be important to study plasma polymerized films as potential DNA biosensors in the future.