The Selective Detection of Cyantraniliprole Insecticides Using Molecularly Imprinted Polymers Coupled with an Acetylcholinesterase Inhibition-Based Biosensor

Cyantraniliprole is one of the anthranilic diamide insecticides widely used in the agriculture sector. Due to its low toxicity and relatively fast degradation, there is need for a sensitive determination method for its residues. Nowadays, there is growing interest in the development of enzyme-based biosensors. The major drawback is the non-specific binding of many insecticides to the enzyme. This work employs Molecularly imprinted polymers (MIPs) to increase enzyme specificity and eliminate the organic solvent effect on the enzyme activity. The synthesized Cyan-Molecularly imprinted polymers (Cyan-MIP) possesses high affinity and selectivity toward cyantraniliprole. Acetylcholinesterase assay characteristics including enzyme concentration, substrate concentration, DTNB concentration, and acetonitrile concentration were optimized. Under optimal experimental conditions, the developed MIP-Acetylcholinesterase (MIP-AchE) inhibition-based sensor provides better precision than the AchE inhibition-based sensor with a wide linear range (15–50 ppm), limit of detection (LOD) 4.1 ppm, and limit of quantitation (LOQ) 12.6 ppm. The sensor was successfully applied for cyantraniliprole determination in spiked melon, giving satisfactory recoveries.     

Advances in polymer-based cell encapsulation and its applications in tissue repair

Cell microencapsulation is a more widely accepted area of biological encapsulation. In most cases, it involves fixing cells in polymer scaffolds or semi-permeable hydrogel capsules, providing the environment for protecting cells, allowing the exchange of nutrients and oxygen, and protecting cells against the attack of the host immune system by preventing the entry of antibodies and cytotoxic immune cells. Hydrogel encapsulation provides a three-dimensional (3D) environment similar to that experienced in vivo, so it can maintain normal cellular functions to produce tissues similar to those in vivo. Embedded cells can be genetically modified to release specific therapeutic products directly at the target site, thereby eliminating the side effects of systemic treatments. Cellular microcarriers need to meet many extremely high standards regarding their biocompatibility, cytocompatibility, immunoseparation capacity, transport, mechanical, and chemical properties. In this article, we discuss the biopolymer gels used in tissue engineering applications and the brief introduction of cell encapsulation for therapeutic protein production. Also, we review polymer biomaterials and methods for preparing cell microcarriers for biomedical applications. At the same time, in order to improve the application performance of cell microcarriers in vivo, we also summarize the main limitations and improvement strategies of cell encapsulation. Finally, the main applications of polymer cell microcarriers in regenerative medicine are summarized.     

Fluorinated End‐Groups in Electrolytes Induce Ordered Electrolyte/Anode Interface Even at Open‐Circuit Potential as Revealed by Sum Frequency Generation Vibrational Spectroscopy

Fluorine‐based additives have a tremendously beneficial effect on the performance of lithium‐ion batteries, yet the origin of this phenomenon is unclear. This paper shows that the formation of a solid‐electrolyte interphase (SEI) on the anode surface in the first five charge/discharge cycles is affected by the stereochemistry of the electrolyte molecules on the anode surface starting at open‐circuit potential (OCP). This study shows an anode‐specific model system, the reduction of 1,2‐diethoxy ethane with lithium bis(trifluoromethane)sulfonimide, as a salt on an amorphous silicon anode, and compares the electrochemical response and SEI formation to its fluorinated version, bis(2,2,2‐trifluoroethoxy) ethane (BTFEOE), by sum frequency generation (SFG) vibrational spectroscopy under reaction conditions. The SFG results suggest that the ? CF₃ end‐groups of the linear ether BTFEOE change their adsorption orientation on the a‐Si surface at OCP, leading to a better protective layer. Supporting evidence from ex situ scanning electron microscopy and X‐ray photoelectron spectroscopy depth profiling measurements shows that the fluorinated ether, BTFEOE, yields a smooth SEI on the a‐Si surface and enables lithium ions to intercalate deeper into the a‐Si bulk.     

Evaluation of effectiveness of enhanced‐efficiency fertilizers as mitigation options for N2O and NO emissions from agricultural soils: meta‐analysis

Agricultural fields are an important anthropogenic source of atmospheric nitrous oxide (N₂O) and nitric oxide (NO). Although many field studies have tested the effectiveness of possible mitigation options on N₂O and NO emissions, the effectiveness of each option varies across sites due to environmental factors and field management. To combine these results and evaluate the overall effectiveness of enhanced‐efficiency fertilizers [i.e., nitrification inhibitors (NIs), polymer‐coated fertilizers (PCFs), and urease inhibitors (UIs)] on N₂O and NO emissions, we performed a meta‐analysis using field experiment data (113 datasets from 35 studies) published in peer‐reviewed journals through 2008. The results indicated that NIs significantly reduced N₂O emissions (mean: ?38%, 95% confidential interval: ?44% to ?31%) compared with those of conventional fertilizers. PCFs also significantly reduced N₂O emissions (?35%, ?58% to ?14%), whereas UIs were not effective in reducing N₂O. NIs and PCFs also significantly reduced NO (?46%, ?65% to ?35%; ?40%, ?76% to ?10%, respectively). The effectiveness of NIs was relatively consistent across the various types of inhibitors and land uses. However, the effect of PCFs showed contrasting results across soil and land‐use type: they were significantly effective for imperfectly drained Gleysol grassland (?77%, ?88% to ?58%), but were ineffective for well‐drained Andosol upland fields. Because available data for PCFs were dominated by certain regions and soil types, additional data are needed to evaluate their effectiveness more reliably. NIs were effective in reducing N₂O emission from both chemical and organic fertilizers. Moreover, the consistent effect of NIs indicates that they are potent mitigation options for N₂O and NO emissions.     

New peptide conjugates with 9-aminoacridine: synthesis and binding to DNA.

New peptides-9-aminoacridine conjugates with an ethylene diamine linker-have been synthesized (both solution and solid phase methods were used) and their interactions with DNA have been studied. The affinity of H-Phe-Gln-Gly-Ile(2)-NHCH(2)CH(2)NH-Acr conjugate and of its extended analogue containing 6-aminohexanoic acid to DNA were lower than that of a standard H-Gly-NHCH(2)CH(2)NH-Acr conjugate. The results fit well into our concept of peptide conjugates with lowered binding activity to DNA, which could be capable of unlimited extravascular distribution. Moreover, new structures could be potentially useful as the mild tuners of DNA interaction with strong bis-acridine binders.     

Synthesis and characterization of semi-interpenetrating polymer network microspheres of acrylamide grafted dextran and chitosan for controlled release of acyclovir

Semi-interpenetrating polymer network (IPN) microspheres of acrylamide grafted on dextran (AAm-g-Dex) and chitosan (CS) were prepared by emulsion-crosslinking method using glutaraldehyde (GA) as a crosslinker. The grafting efficiency was found to be 94%. Acyclovir, an antiviral drug with limited water solubility, was successfully encapsulated into IPN microspheres by varying the ratio of AAm-g-Dex and CS, % drug loading and amount of GA. Microspheres were characterized by FT-IR spectroscopy to assess the formation of IPN structure and to confirm the absence of chemical interactions between drug, polymer and crosslinking agent. Particle size was measured using laser light scattering technique. Microspheres with average particle sizes in the range of 265–388 μm were obtained. Differential scanning calorimetry (DSC) and X-ray diffraction (X-RD) studies were performed to understand the crystalline nature of drug after encapsulation into IPN microspheres. Acyclovir encapsulation of up to 79.6% was achieved as measured by UV spectroscopy. Both equilibrium and dynamic swelling studies were performed in 0.1 N HCl. Diffusion coefficients (D) and diffusional exponents (n) for water transport were determined using an empirical equation. In vitro release studies indicated the dependence of drug release rates on both the extent of crosslinking and amount of AAm-g-Dex used in preparing microspheres; the slow release was extended up to 12 h. The release rates were fitted to an empirical equation to compute the diffusional exponent (n), which indicated non-Fickian trend for the release of acyclovir.     

Cation control of dimensionality in isothiocyanate coordination polymers constructed from conformationally flexible 3,3′-bipyridine tethers

Two isothiocyanate coordination polymers constructed from the conformationally flexible tethering ligand 3,3′-bipyridine (3,3′-bpy) and divalent metal cations have been prepared and characterized via single crystal X-ray diffraction, infrared spectroscopy and elemental analysis. [Co(NCS)₂(3,3′-bpy)₂] (1), wherein the isothiocyanate ligands are coordinated in a trans fashion, manifests stacked two-dimensional (2-D) rhomboid grid layered motifs. In contrast, [Ni(NCS)₂(3,3′-bpy)₂] (2) possesses a doubly interpenetrated adamantoid three-dimensional (3-D) network despite the presence of trans isothiocyanate ligands. Thus, a metal cation-based control of coordination polymer dimensionality has been revealed in this system, reflective of different donor dispositions allowed by the conformational flexibility of the exobidentate 3,3′-bpy ligand. The 3-D framework of 2 decomposes at a temperature ∼40 °C higher than the 2-D network of 1.     

Syntheses, crystal structures and photoluminescences of two (4,4) topological coordination networks derived from the flexible bipyridyl ligands

Two new 2D coordination polymers, [Ag₄(μ-4,4′-bpp)₃(1,3-bdc)₂]_n · 2nH₂O (1) and [Ag(μ-4,4′-bpp)₂ClO₄]_n(2) (4,4′-bpp = 2,2′-bis(4-pyridylmethyleneoxy)-1,1′-biphenylene; 1,3-bdc = 1,3-benzenedicarboxylate) have been synthesized using three-layer diffusion methods. Single-crystal X-ray analyses reveal that they are both extended grid networks of the (4,4) topology. In complex 1, a chain built by Ag(I) centers with T-shaped and linear geometries is further connected by the interesting ligand-unsupported Ag?Ag interactions as well as the conjugated π systems to form an interdigitated 2-D coordination network. The corrugated (4,4) sheets of 2 are packed in the ab planes and stacked along the c direction with the anions occupying the gaps in the squares.     

Hydrothermal synthesis and characterization of a new 1-D polymeric lanthanum ethylenediaminetetraacetate with less metal-aqua coordination: {[La(EDTA)(H2O)]2}n

A new lanthanum ethylenediaminetetraacetate (EDTA) coordination polymer, {[La(EDTA)(H₂O)]₂}_n (EDTA³⁻ = [(CH₂N)₂(CH₂COOH)(CH₂COO⁻)₃]), was hydrothermally prepared from LaCl₃ solution and ethylenediaminetetracetic acid at 448 K. The compound was characterized by elemental analysis, FTIR, TG-DTA, and X-ray crystallography. The structure consists of ladder-like chains of [La(EDTA)(H₂O)]₂ dimers bridged by O-C-O groups. Hydrothermal method successfully reduced the high number of La-aqua coordinations in known lanthanum EDTA to one giving rise to relatively compact structure. It has high thermal stability up to 550 K. Every EDTA ligand with COOH group is involved in eight La-O(N) bonds to three nine-coordinated La centers.     

One-dimensional coordination polymer and its hydrogen bonded 2D network generated from dimeric Ag(I) building units

A new dimeric silver(I) complex [Ag(PhPPy₂)(CH₃CN)]₂(ClO₄)₂ (1) (PhPPy₂ = bis(2-pyridyl)phenylphosphine) was synthesized by a direct reaction of [Ag(CH₃CN)₄]ClO₄ with ligand PhPPy₂. X-ray crystallographical studies revealed that in 1, two silver atoms are bridged by two PhPPy₂ ligands and bonded to each other. Each Ag(I) adopts a distorted trigonally bi-pyramidal geometry, and axially coordinated acetonitrile molecules are collinear with two silver atoms. By using 1 as a building block precursor, a 1D coordination polymer, [Ag₂(PhPPy₂)₂(1,3,5-C₆H₃(CO₂)₂(CO₂H))]_∞ (2) was prepared by replacing axially coordinated acetonitrile molecules in 1 with two carboxylate groups of a bridging ligand, 1,3,5-benzenetricarboxylate. In solid state, linear polymeric chains are oriented parallel to each other and interestingly interact by hydrogen bonding through their carboxylic/carboxylate groups to construct a novel wave-shaped 2D network. Both 1 and 2 exhibit similar photoluminescent properties in solid state at room temperature.