Miniaturized free-flow electrophoresis: production,optimization, and application using 3D printing technology

The increasing resolution of three-dimensional (3D) printing offers simplified access to, and development of, microfluidic devices with complex 3D structures. Therefore, this technology is increasingly used for rapid prototyping in laboratories and industry. Microfluidic free flow electrophoresis (μFFE) is a versatile tool to separate and concentrate different samples (such as DNA, proteins, and cells) to different outlets in a time range measured in mere tens of seconds and offers great potential for use in downstream processing, for example. However, the production of μFFE devices is usually rather elaborate. Many designs are based on chemical pretreatment or manual alignment for the setup. Especially for the separation chamber of a μFFE device, this is a crucial step which should be automatized. We have developed a smart 3D design of a μFFE to pave the way for a simpler production. This study presents (1) a robust and reproducible way to build up critical parts of a μFFE device based on high-resolution MultiJet 3D printing; (2) a simplified insertion of commercial polycarbonate membranes to segregate separation and electrode chambers; and (3) integrated, 3D-printed wells that enable a defined sample fractionation (chip-to-world interface). In proof of concept experiments both a mixture of fluorescence dyes and a mixture of amino acids were successfully separated in our 3D-printed μFFE device.     

Additive manufacturing for energy storage: Methods,designs and material selection for customizable 3D printed batteries and supercapacitors

Additive manufacturing and 3D printing in particular have the potential to revolutionize existing fabrication processes, where objects with complex structures and shapes can be built with multifunctional material systems. For electrochemical energy storage devices such as batteries and supercapacitors, 3D printing methods allows alternative form factors to be conceived based on the end use application need in mind at the design stage. Additively manufactured energy storage devices require active materials and composites that are printable, and this is influenced by performance requirements and the basic electrochemistry. The interplay between electrochemical response, stability, material type, object complexity and end use application are key to realising 3D printing for electrochemical energy storage. Here, we summarise recent advances and highlight the important role of methods, designs and material selection for energy storage devices made by 3D printing, which is general to the majority of methods in use currently.     

A novel strategy for fabrication,activation and cleaning of fully 3D printed flexible planar electrochemical platforms

In recent years, 3D printing of carbon-based conductive filaments has received growing attention for assembling electrodes to be used in a wide variety of electroanalytical devices and applications. Despite the large amount of work present in literature concerning the development of three-dimensional (3D) conductive structures, its potential as dry deposition method for assembling two-dimensional (2D) electrodes to be used in planar configuration is still largely unexplored. In fact, the possibility to rapidly change the geometry of the electrochemical circuits, associated with the reduction of waste and the absence of solvents, which are instead important components of ink and paste formulations, makes this strategy a valid green and efficient alternative to other deposition approaches such as screen-printing technology. We report here a rapid and solvent-free method for assembling fully 3D printed flexible planar electroanalytical platforms (3DEPs) to be used with microliters of liquid. At the same time, a novel protocol for the surface pre-treatment of 3D printed electrodes based on ultrasonication in aqueous NaOH solution followed by electrochemical activation using the same medium, is presented. In addition, the same procedure has proved to be efficient for cleaning the electrode surface after electrochemical passivation, thus confirming the validity of both time-efficient and environmentally-friendly assembling and activation/cleaning procedures developed which allow efficient and reusable electrodes to be produced. Finally, 3DEPs were tested by a proof-of-concept quantification of a commonly used food dye (Brilliant Blue, E-133) in commercial solutions used for homemade food coloring.     

Development and visualization of level II,III features of latent fingerprints using some new 4-(4-substitutedphenyl)-6-(4-substitutedphenyl)-2-oxo-1,2-dihydropyridine-3-carbonitrile derivatives: Synthesis,characterization, optoelectronic and DFT studies

Organic dye compounds with luminescent properties are in demand to use in visualizing the latent fingerprints (LFPs) at crime spot investigation. Here, we synthesized some new 4-(4-substitutedphenyl)-6-(4-substitutedphenyl)-2-oxo-1,2-dihydropyridine-3-carbonitrile 4(a-d) and were confirmed using spectroscopic approaches. Optical properties were recorded in solvent media, where peaks were absorbed in ?300–400 nm of longer wavelength and emitted at ?467–574 nm in the blue region. Dual redox peak current was observed in Cyclic voltammetry at different scan rate and estimated redox onset potential, and energy molecules have been experimentally calculated. DFT studies have been carried out using Gaussian 09 software at the gaseous phase. From the results of theoretical investigations, compounds 4(a-d) showed higher photostability, chemical reactivity and good reactive sites. Also, synthesized compounds were used to determine the latent fingerprints with the help of powder dusting method. Level II and III features of LFPs are observed on porous/non-porous surfaces without optical hindrance and images were taken in normal and 365 nm UV light. From the above results, the synthesized compounds are efficient materials for forensic science applications.     

Dispersion corrected interaction of polar and nonpolar fluids confined within carbon nanotubes: Density functional theoretical analysis using Grimme's D3 scheme

The structural and flow characteristics of fluids within carbon nanotube (CNT) is dictated by the interaction of fluid molecules within the nanocavity of CNT. Therefore, in the present study, dispersion corrected density functional theory has been used to investigate the structure and interaction of polar and nonpolar molecules within CNT. The present study shows that there is profound effect on the interaction due to dispersion. The interaction energy of the confined water was found to be reduced with increasing distance of the water molecule from the wall of the CNT. The water is preferentially adsorbed over methane due to stronger interaction with CNT over methane. Further, water is preferentially adsorbed over methanol molecule when interaction is calculated without dispersion but after inclusion of dispersion interaction, the calculated results show that the methanol–CNT interaction is stronger than that of water molecule and hence preferentially adsorbed within the CNT as revealed from MD simulation. The present calculation reveals that that the effect of CNT confinement on the IR spectra of the single file water is quite considerable compared to the IR spectra of tetrahedral bulk water cluster. Therefore, the present results might be useful for the separation of polar molecule from nonpolar molecule during fabrication of CNT‐based filter and purification system.     

Synthesis and characterization of highly random copolymer of ϵ-caprolactone and D,L-lactide using rare earth catalyst

Highly random copolymers of ϵ-caprolactone (CL) and D ,L -lactide (LA) were synthesized by a new catalyst system, rare earth chloride–propylene oxide (PO) system. In the presence of propylene oxide, all rare earth chlorides tested are highly effective for the copolymerization. The influences of reaction conditions on the copolymerization catalyzed by the NdCl₃-5PO system have been investigated in detail. The reactivity ratios of ϵ-caprolactone and D ,L -lactide were determined and show that the copolymerization with this new rare earth catalyst is closer to ideal copolymerization than reported for other catalysts. The microstructure of copolymer analyzed by ¹³C-NMR shows that the monomer units in the copolymer is near to completely random distribution with a short average monomer sequence length. The DSC measurement confirms the high randomness of the chain structure. The mechanism studied by NMR indicates that the rare earth alkoxide generated by the reaction of rare earth chloride with propylene oxide initiates the copolymerization, and then proceeds via a “coordination-insertion” mechanism with acyl-oxygen bond cleavage of CL and LA. © 1996 John Wiley & Sons, Inc.     

Monitoring photopolymerization reactions through thermal imaging: A unique tool for the real‐time follow‐up of thick samples, 3D printing,and composites

The ever increasing applications of photopolymers from historical thin (<50 µm) coatings to very deep samples (>1 cm) require the development of robust 4D monitoring strategies able to assess photopolymerization efficiencies (first dimension) as a function of time (second dimension) and position (third and fourth dimensions). Therefore, here, we demonstrated that thermal imaging is a valuable photopolymerization monitoring device showing: (a) very high response times (<1 s); (b) high repeatability of the measurement; (c) strong adaptability of the setup to various conditions (e.g., onto irregular surfaces or inside a real time Fourier transformed infrared spectrometer (RT‐FTIR)); (d) extremely deep photopolymerization follow‐ups (and subsequent rationalization) with good resolution in time and in space (real‐time thermal imaging microscopy experiments); (e) adaptability to applied materials. This monitoring strategy was found particularly robust when taking into account all the heat generating phenomena (i.e., direct heating from the lamp vs. temperature raised due to monomer conversion). As a result, we propose thermal imaging as the next reference monitoring system for the new ranges of thick and/or filled samples (e.g., 3D objects, composites) and/or applied photopolymerizations (e.g., 3D printing) more and more present in the literature. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 889–899     

Fused deposition modeling-based additive manufacturing (3D printing): techniques for polymer material systems

While the developments of additive manufacturing (AM) techniques have been remarkable thus far, they are still significantly limited by the range of printable, functional material systems that meet the requirements of a broad range of industries; including the health care, manufacturing, packaging, aerospace, and automotive industries. Furthermore, with the rising demand for sustainable developments, this review broadly gives the reader a good overview of existing AM techniques; with more focus on the extrusion-based technologies (fused deposition modeling and direct ink writing) due to their scalability, cost efficiency and wider range of material processability. It then goes on to identify the innovative materials and recent research activities that may support the sustainable development of extrusion-based techniques for functional and multifunctional (4D printing) part and product fabrication.     

Efficient synthesis of polycycles bearing prenylated, geranylated, and farnesylated citrans: application to 3′-prenylrubranine and petiolin D regioisomer

Efficient synthetic routes for biologically interesting polycycles with prenylated, geranylated, and farnesylated citrans were developed from several trihydroxybenzenes with prenyl, geranyl, and farnesyl groups on the benzene rings. Ethylenediamine diacetate-catalyzed cyclization by a domino aldol-type/electrocyclization/H-shift/hetero Diels-Alder reaction of prenylated, geranylated, and farnesylated trihydroxybenzenes with citral or trans,trans-farnesal provided a variety of tetracycles bearing prenylated, geranylated, and farnesylated citrans. The mechanistic pathway for regio- and stereochemistry of synthesized polycycles was described. As an application of this methodology, 3′-prenylrubranine and petiolin D regioisomer were first synthesized.     

An investigation of keto–enol tautomerism in N-vinyl-2-, and 3-pyrrolidinones using ab initio and density functional theory calculations

We investigated the protomeric tautomerism of N-vinyl-2-pyrrolidinone (NV2P) and N-vinyl-3-pyrrolidinone (NV3P) molecules, and considered the three neutral tautomers for NV2P (1a, 1b, 1c) and the five for NV3P (2a, 2b, 2c, 2d, 2e). Full geometry optimizations were carried out at the HF/6-31G**, HF/6-31+G** and B3LYP/6-31+G** levels in the gas phase and in water. Additionally, single-point MP2/6-31+G** calculations were performed on the HF/6-31+G** optimized geometries. The tautomerization processes in water (=78.54) were studied using the self-consistent reaction field theory. According to our estimations, the tautomerization of NV2P and NV3P molecules are not strongly influenced by the polar solvents, the improvement of the basis set quality and the electron correlation effects in the gas phase and in water. The calculated relative free energies (ΔG) predict that 1a and 2a are the energetically preferred tautomers in the gas phase and in water.     

四种同构镧系金属有机框架的合成、结构和荧光传感Fe3+和盐酸环丙沙星

采用溶剂热法,以含氮四羧酸3,5-二(3'',5''-二羧苯)-1H-1,2,4-三唑(H₄BDT)为配体,成功合成了4种同构镧系金属有机框架(Ln-MOFs)：{[La₃(BDT)₂(HCOO)(H₂O)₅]·0.5H₂O·3DMF}_n(1)、{[Ce₃(BDT)₂(HCOO)(H₂O)₅]·3DMF}_n(2)、{[Pr₃(BDT)₂(HCOO)(H₂O)₅]·3DMF}_n(3)和{[Nd₃(BDT)₂(HCOO)(H₂O)₅]·3DMF}_n(4),并采用单晶X射线衍射、粉末X射线衍射、元素分析、热重、傅里叶换红外光谱、N₂吸附实验和荧光光谱对其进行表征。结果表明,这些Ln-MOFs均为单斜C2/m空间群晶体,是双核为无机建筑单元的三维介孔结构。其中2可选择性荧光检测Fe³⁺离子和盐酸环丙沙星药物分子,检测限分别为4.59和0.77 μmol·L^-1。     

3D Dendritic Nanostructure of Silver‐Array: Preparation,Growth Mechanism and Application in Nitrate Sensor

A 3D dendritic nanostructure of silver‐array (DSA) was prepared via electrodeposition on an interdigitated array (IDA) microelectrode. For preparation of this nanostructure, the optimal parameters such as deposition potential, deposition time, the electrode bandwidth and gap size were systematically investigated. It was found that the edge effect of the IDA microelectrode is a key factor for controlling the 3D dendritic growth of silver. Furthermore, the formation of the 3D dendritic morphology was discussed from the aspect of electrochemical nucleation theory and nonequilibrium growth dynamics to give a deep understanding of its growth mechanism. For its potential practical application, we showed that the as‐prepared 3D DSA nanomaterial exhibited high electrocatalytic reduction ability to nitrate in neutral solution and excellent performance for nitrate determination. An amperometric nitrate microsensor based on the 3D DSA was obtained.     

Facile Synthesis of Ultra‐wide Two Dimensional Bi2S3 Nanosheets: Characterizations,Properties and Applications in Hydrogen Peroxide Sensing and Hydrogen Storage

The ultra‐wide two dimensional Bi₂S₃ nanosheets (2D Bi₂S₃ Ns) as non‐toxic graphene‐like nanomaterials have been prepared through solvothermal decomposition of a single‐source precursor, Bi(S₂CNEt₂)₃, in ethylenediamine media for 2 h in 180 °C. The morphology, structure, properties and catalytic activity of prepared 2D Bi₂S₃ Ns were characterized with XRD, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV‐Visible spectroscopy, cyclic voltammetry (CV), amperometry, electrochemical charge/discharge technique and electrochemical impedance spectroscopy (EIS). The SEM image showed the 2D Bi₂S₃ Ns with a thickness of 15±4 nm and lengths of several micrometers is synthesized. The UV−Vis spectrum of 2D Bi₂S₃ Ns showed high sensitivity to visible‐near infrared light with its direct energy band gap of ≈1.22 eV. These Bi₂S₃ Ns showed high electron transfer ability and good electrochemical behavior and also exhibited electro‐catalytic activity toward the reduction‐oxidation of hydrogen peroxide. It is found that Bi₂S₃ Ns could detect H₂O₂ at wide linear concentration range (50.0 μM–8.0 mM) with detection limit 8 μM, using amperometry as measuring technique. Also the synthesized Bi₂S₃ Ns exhibited excellent electrochemical H₂ storage properties. As a result, based on above properties, the Bi₂S₃ Ns can be used as a valuable and useful nanomaterial for H₂ storage, high‐energy batteries, electrocatalytic fields and electrochemical sensing.     

Synthesis, Characterization and Crystal Structure of [Na2(APZC)2(μ-H2O)2(μ3-H2O)]n

The synthesis and spectroscopic properties of a Na^＋ complex with ligand 3-aminopyrazine-2-carboxylic acid were described. The resulting complex was characterized by elemental analysis, IR, UV-Vis, NMR spectroscopy and single crystal X-ray diffraction method. The title compound crystallizes in the triclinic system with space group . The crystalline structure of this compound consists of supramolecular architectures involving strong intramolecular N—H…O in pyrazine molecules and intermolecular O—H…N, O—H…O, and N—H…N hydrogen bonds between substituted pyrazine and water molecules.     

Application of a 1H δ‐resolved 2D NMR experiment to the visualization of enantiomers in chiral environment,using sample spatial encoding and selective echoes

We present the application of a 2D broadband homodecoupled proton NMR experiment to the visualization of enantiomers. In a chiral environment, the existence of diastereoisomeric intermolecular interactions can yield—generally slight—variations of proton chemical shifts from one enantiomer to another. We show that this approach, which relies on a spatial encoding of the NMR sample, is particularly well suited to the analysis of enantiomeric mixtures, since it allows, within one single 2D experiment, to detect subtle chemical shift differences between enantiomers, even in the presence of several couplings. This sequence, which uses semiselective radio‐frequency (rf) pulses combined to a z‐field gradient pulse, produces different selective echoes in various parts of the sample. The resulting homonuclear decoupling provides an original δ‐resolved spectrum along the diagonal of the 2D map where it becomes possible to probe the chiral differentiation process through every proton site where the resulting variation in the chemical shift is detectable. We discuss the advantages and drawbacks of this approach, regarding other experiments which provide homodecoupled proton spectra. This methodology is applied to the observation of enantiomers of (1) ( ± )2‐methyl‐isoborneol coordinated to europium (III) tris[3‐(trifluoromethyl‐hydroxymethylene)‐(+)‐camphorate] in isotropic solution, and (2) ( ± )3‐butyn‐2‐ol dissolved in a chiral liquid‐crystal solvent, in order to show the robustness of this pulse sequence for a wide range of chiral samples. Copyright © 2009 John Wiley & Sons, Ltd.     

Unexpected detection of 3‐aroylbenzofuran side products in the preparation of 2‐arylbenzofurans: Identification,characterization, and comparison with chalcone's fragmentation patterns using EI/MSn

A gas chromatography‐mass spectrometry study of the intramolecular Wittig reaction revealed, together with the expected 2‐phenylbenzofuran, the formation of an unexpected side product that has not been reported until now. This study reports the identification of the by‐product, ie, the 3‐benzoyl‐2‐phenylbenzofuran, on the base of its mass spectrometric behaviour using a combination of electron ionization, exact mass measurement, multiple stage mass spectrometry, and labelled compounds. This study reports the common fragmentation pathways and discusses possible fragment structures of characteristic ions from a series of 3‐aroyl‐2‐arylbenzofuran derivatives obtained as by‐product under Wittig conditions. Emphasis is laid on the formation and structure investigation of the [M‐H]⁺ and [M‐OH]⁺ ions. Our results showed interesting analogies with the mass spectrometric behaviour of chalcones.     

Molecular transporters for peptides: delivery of a cardioprotective εPKC agonist peptide into cells and intact ischemic heart using a transport system, R7

Background: Recently, we reported a novel oligoguanidine transporter system, polyarginine (R₇), which, when conjugated to spectroscopic probes (e.g., fluorescein) and drugs (e.g., cyclosporin A), results in highly water-soluble conjugates that rapidly enter cells and tissues. We report herein the preparation of the first R₇ peptide conjugates and a study of their cellular and organ uptake and functional activity. The octapeptide ψεRACK was selected for this study as it is known to exhibit selective ε protein kinase C isozyme agonist activity and to reduce ischemia-induced damage in cardiomyocytes. However, ψεRACK is not cell-permeable.Results: Here we show that an R₇-ψεRACK conjugate readily enters cardiomyocytes, significantly outperforming ψεRACK conjugates of the transporters derived from HIV Tat and from Antennapedia. Moreover, R₇-ψεRACK conjugate reduced ischemic damage when delivered into intact hearts either prior to or after the ischemic insult.Conclusions: Our data suggest that R₇ converts a peptide lead into a potential therapeutic agent for the ischemic heart.     

Optimization of an α‐(Amino acid)‐N‐carboxyanhydride polymerization using the high vacuum technique: Examining the effects of monomer concentration,polymerization kinetics,polymer molecular weight,and monomer purity

l ‐Ornithine‐based poly(peptides) have been widely utilized in the field of drug delivery, however few studies have been conducted examining the details of polymerization. In this article, the effects of monomer concentration, polymerization kinetics, polymer molecular weight and monomer purity were investigated using l ‐carboxybenzyl (Cbz)‐ornithine as a model monomer. The mechanism of polymerization herein follows the normal amine mechanism to produce poly(peptides) having controlled molecular weights, known chain ends and a narrow polydispersity index (PDI). A preferred monomer concentration range was determined, which required minimal polymerization times and allowed for predictable and reproducible molecular weights with narrow PDIs. The impact of monomer purity on the polymerization was established and monomer purification conditions are reported, which produce high‐purity monomer after a single recrystallization. Additionally, the optimized polymerization conditions and monomer purification protocol were combined with a sequential monomer addition technique to produce high molecular weight poly(ornithine) with a narrow PDI and known chain ends. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1385–1391     

A novel series of M(II) complexes of 6‐methylpyridine‐2‐carboxylic acid with 4(5)methylimidazole: Synthesis,crystal structures, α‐glucosidase activity,density functional theory calculations and molecular docking

Novel complexes of 6‐methylpyridine‐2‐carboxylic acid and 4(5)methylimidazole, namely [Mn(6‐mpa)₂(4(5)MeI)₂] ( 1 ), [Zn(6‐mpa)₂(4(5)MeI)₂] ( 2 ), [Cd(6‐mpa)₂(4(5)MeI)₂] ( 3 ), [Co(6‐mpa)₂(4(5)MeI)₂] ( 4 ), [Ni(6‐mpa)₂(4(5)MeI)(OAc)] ( 5 ) and [Cu(6‐mpa)₂(4(5)MeI)] ( 6 ), were synthesized for the first time. The structures of complexes 1 – 4 and complexes 5 and 6 were determined using X‐ray diffraction and mass spectrometric techniques, respectively. The experimental spectral analyses for these complexes were performed using Fourier transform infrared and UV–visible techniques. The α‐glucosidase inhibition activity values (IC₅₀) of complexes 1 – 6 were identified in view of genistein reference compound. Moreover, the DFT/HSEh1PBE/6‐311G(d,p)/LanL2DZ level was used to obtain optimal molecular geometry and vibrational wavenumbers for complexes 1 – 6 . Electronic spectral behaviours and major contributions to the electronic transitions were investigated using TD‐DFT/HSEh1PBE/6‐311G(d,p)/LanL2DZ level with conductor‐like polarizable continuum model and SWizard program. Finally, in order to investigate interactions between the synthesized complexes ( 1 – 6 ) and target protein (template structure S. cerevisiae isomaltase), a molecular docking study was carried out.     

新型三维金属-有机配位聚合物的合成、结构与性能

在中温混合溶剂热条件下,分别用镉离子和锰离子与混合多羧酸和多氮配体合成出两个金属-有机配位聚合物[M6(TDC)6(hmt)2(DMF)6(H2O)3 ? (H2O)] (JUC-85a, JUC-85b) (M = Cd 或 Mn,TDC = 噻吩-2,5-二羧酸,hmt = 六次甲基四胺,DMF = N,N-二甲基甲酰胺, JUC = Jilin University China),并通过X射线单晶衍射、元素分析、热重分析、粉末X光衍射、拓扑结构分析和荧光分析对其结构、组成和性质进行了表征. 单晶衍射结果表明,化合物JUC-85a和JUC-85b是同构的三维开放骨架结构,具有一种从少见的(3,6)连接拓扑结构loh1. 同时,JUC-85a具有很好的荧光性质.