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In recent years, magnetic particle spectroscopy (MPS) has become a highly sensitive and versatile sensing technique for quantitative bioassays. It relies on the dynamic magnetic responses of magnetic nanoparticles (MNPs) for the detection of target analytes in the liquid phase. There are many research studies reporting the application of MPS for detecting a variety of analytes including viruses, toxins, nucleic acids, and so forth. Herein, we report a modified version of the MPS platform with the addition of a one-stage lock-in design to remove the feedthrough signals induced by external driving magnetic fields, thus capturing only MNP responses for improved system sensitivity. This one-stage lock-in MPS system is able to detect as low as 781 ng multi-core Nanomag50 iron oxide MNPs (micromod Partikeltechnologie GmbH) and 78 ng single-core SHB30 iron oxide MNPs (Ocean NanoTech). We first demonstrated the performance of this MPS system for bioassay-related applications. Using the SARS-CoV-2 spike protein as a model, we have achieved a detection limit of 125 nM (equal to 5 pmole) for detecting spike protein molecules in the liquid phase. In addition, using a streptavidin-biotin binding system as a proof-of-concept, we show that these single-core SHB30 MNPs can be used for Brownian relaxation-based bioassays while the multi-core Nanomag50 cannot be used. The effects of MNP amount on the concentration-dependent response profiles for detecting streptavidin were also investigated. Results show that by using a lower concentration/ amount of MNPs, concentration-response curves shift to a lower concentration/amount of target analytes. This lower concentration-response indicates the possibility of improved bioassay sensitivities by using lower amounts of MNPs.

The past decade has seen tremendous progress in the synthesis and surface functionalization of iron oxide nanoparticles (IONPs) for a variety of biomedical applications. However, there is still a g...

Recently, zero-dimensional (0D) metal halides have made remarkable achievements in the field of optoelectronics due to their diverse structures and optical performances. Here, we report 0D (TBA)2Cu2I4 (TBA+ = tetrabutylammonium cation) single crystals (SCs), which shows a dual-emission band at 473 and 699 nm and a bright cool-white emission with a high photoluminescence quantum yield (PLQY) of 72.5% at room temperature (RT). The temperature-dependent emission spectra and Raman spectra show that a dual self-trapped exciton (STE) is present in this compound, and the external thermal energy can effectively regulate the population of STEs in the two emitting states, and thus the emission color can be changed from blue at a low temperature (78 K) to a cool-white emission at RT. More specifically, (TBA)2Cu2I4 SCs possess high anti-water stability, and can maintain highly efficient emission even if immersed in water for 24 hours. Also noteworthily, the high thermal stability, air stability and photostability of this component have also been proved.

Low-dimensional organic–inorganic hybrid metal halides have drawn intense attention due to their flexible structures and outstanding optical properties. However, the toxicity of lead halides hinders their future application in optoelectronic devices. Herein, we report a zero-dimensional (0D) lead-free compound of (TPA)2SbCl5 (TTA+ = tetrapropylammonium cation) single crystals (SCs), which crystallizes in a triclinic system with P symmetry. Interestingly, (TPA)2SbCl5 exhibits a single broad orange emission band at 610 nm under low-energy excitation (e.g., 375 nm) with a high photoluminescence quantum yield (PLQY) of 95.3%, while it shows a dual-band emission profile with an additional narrow emission band at 466 nm at high-energy excitation (e.g., 300 nm), which is formed by the transformation of the doublet of spin–orbit interactions into two individual STEs. The Raman spectra supplied clear evidence for the self-trapped exciton (STE) with clear multiphonon modes in (TPA)2SbCl5, which reflects its strong nonlinear electron–phonon coupling. The emission mechanism for the temperature-dependent dual emission can be attributed to the radiative transitions of singlet STEs and triplet STEs in [SbCl5]2− clusters. Moreover, a white-light-emitting diode (WLED) was also fabricated by mixing (TPA)2SbCl5 with green (Ba2SiO4:Eu2+) and blue (BaMgAl10O17:Eu2+) phosphors, which exhibited CIE coordinates of (3.48, 3.50), a correlated color temperature (CCT) of 4900 K, and a color rendering index (CRI) of 93.2. Our achievements illustrate that the lead-free compound of (TPA)2SbCl5 has great potential in solid-state lighting.

Three-dimensional numerical simulations of rotating detonation engines (RDEs) are reported with stoichiometric hydrogen/air mixtures using Navier-Stokes equations with non-slip walls. The effects o...

Magnetic nanoparticles (MNPs) have been extensively used in drug/gene delivery, hyperthermia therapy, magnetic particle imaging (MPI), magnetic resonance imaging (MRI), magnetic bioassays, and so forth. With proper surface chemical modifications, physicochemically stable and nontoxic MNPs are emerging contrast agents and tracers for in vivo MRI and MPI applications. Herein, we report the high magnetic moment, irregularly shaped γ′-Fe4N nanoparticles for enhanced hyperthermia therapy and T2 contrast agent for MRI application. The static and dynamic magnetic properties of γ′-Fe4N nanoparticles are characterized by a vibrating sample magnetometer (VSM) and a magnetic particle spectroscopy (MPS) system, respectively. Compared to the γ-Fe2O3 nanoparticles, γ′-Fe4N nanoparticles show at least three times higher saturation magnetization, which, as a result, gives rise to the stronger dynamic magnetic responses as proved in the MPS measurement results. In addition, γ′-Fe4N nanoparticles are functionalized with an oleic acid layer by a wet mechanical milling process. The morphologies of as-milled nanoparticles are characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), and nanoparticle tracking analyzer (NTA). We report that with proper surface chemical modification and tuning on morphologies, γ′-Fe4N nanoparticles could be used as tiny heating sources for hyperthermia and contrast agents for MRI applications with minimum dose.

In this study, the molecularly imprinted nano-polymer of minocycline was polymerized on the surface of a metal organic framework material to synthesize a novel composite. This composite was used as absorbent to develop a dispersive solid phase microextraction method for extraction of 7 tetracyclines in chicken muscle followed by determination with ultra performance liquid chromatography. The composite achieved high absorption capacities (2200–3000 ng/mg) and high recoveries (> 92%) for the 7 tetracyclines, and could be reused for 8 times. Due to the high enrichment factors (18–37), the limits of detection for the 7 drugs were in the range of 0.2–0.6 ng/g, and the limits of quantification were in the range of 0.5–2.0 ng/g. The recoveries of the 7 drugs from standard-fortified blank chicken muscle sample were in the range of 69.6–94.7%. Therefore, this method could be used as a practical tool for multi-detection of the residues of tetracyclines in meat.

Multichromophoric systems with efficient photoinduced excited-state processes are important for the conversion of solar energy in artificial photosynthesis. However, a low molecular absorption coefficient of these multichromophoric systems in the near-infrared region limits their power conversion efficiency in organic solar cells. It is critical to design molecules with a broad absorption range in the whole spectral region, to better harvest solar energy, and to reveal their important multiple-step photophysical processes for the design of organic solar cells. Here, we investigate a novel compound having three chromophores, namely two near-by N,N'-bis(1-pentyl)hexyl-3,4,9,10-perylenebiscarboximide (PDI) units linked to a zinc porphyrin core side by side (in the form of PDI-ZnPor-PDI), which absorbs solar energy ranging from the ultraviolet (UV) to near-infrared regions. The photophysical behavior of PDI-ZnPor-PDI in both film and solution forms, has been investigated using steady-state and transient spectroscopy measurements. Charge-transfer species and triplet excited-state species are observed, the excited-state evolutions of which are monitored using molecular vibrations as probes. These observations support the idea that PDI-ZnPor-PDI on photoexcitation generates the radical anion and triplet species of the PDI unit (PDI˙- and 3PDI*). Our results demonstrate the effect of solid film state on the photophysical properties in such multichromophoric system, and are valuable for guiding the design and utilization of novel near-infrared electron donors or acceptors for use in organic solar cells.

Due to the effects of electron correlation and spin–spin coupling, pure transition metal compounds rarely produce luminescence and ferromagnetism. In this work, the Pb-free perovskite materials, C8H20N2MnBr4 and C4H10NMnBr3 with high luminescence yields, were obtained via a simple mechanochemical process. In C8H20N2MnBr4 powders, MnBr42− coordinated with two pyrrolidine molecules to form an independent mononuclear structure in a crystal, with paramagnetic properties and a strong emission band at 520 nm due to the lowest d–d crystal field radiation transition for individual Mn(II) ions. In C4H10NMnBr3 powders, MnX64− octahedra, coordinated with a much smaller amount of pyrrolidine molecules than that in C8H20N2MnBr4, formed edge-sharing linear chains of Mn-ion octahedra with a much smaller Mn–Mn distance, which produced emission bands at 628 nm due to the ferromagnetic coupling of Mn pairs or clusters. Influenced by the modification in the local crystal structure by incorporated pyrrolidine molecules, the microcrystals in these two powders exhibited different phase transition temperatures and varied lifetimes in their photoluminescence besides their emission colors. By controlling the processing time of mechanochemical reactions and pyrrolidine amount, the pyrrolidine insertion into the lattice of this transition metal halide can be adjusted to be completely realized, which provides a very simple way to change the ligand from a halide ion to an organic molecule, which regulates the Mn–Mn distance in the lattice, modifying the electronic correlation and spin coupling, thereby obtaining new manganese perovskite compounds with both strong luminescence and clear ferromagnetic properties.

In this work, the structural fluctuations and vibrational energy transfer dynamics in a supramolecular homodimer model, which is composed of 2-(9-anthracene)ureido-6-(1-undecyl)-4[1H]-pyrimidinone (UPAn) with quadruple intermolecular and single intramolecular hydrogen bonds (HBs), have been examined using ultrafast two-dimensional infrared (2D IR) and steady-state IR spectroscopies. A less structurally fluctuating intermolecular HB is found between the pyrimidinone C═O and ureido N-H groups. However, a larger structurally fluctuating intramolecular HB is suggested by the equilibrium and dynamical line-shape measurements of the ureido C═O stretch. Further, dynamical time-dependent 2D IR diagonal and off-diagonal signals show that intra- and intermolecular vibrational energy transfer processes occur on the picosecond timescale, where the latter is more efficient due to intermolecular hydrogen bonding interaction and through-space interaction.

ObjectiveThe objective of this study was to measure the effect of micromagnetic stimulation (μMS) on hippocampal neurons, by using single microcoil (μcoil) prototype,MagneticPen(MagPen). MagPen will be used to stimulate the CA3 region magnetically and excitatory post synaptic potential (EPSP) response measurements will be made from the CA1 region. The threshold for micromagnetic neurostimulation as a function of stimulation frequency of the current driving the μcoil will be demonstrated. Finally, the optimal stimulation frequency of the current driving the μcoil to minimize power will be estimated.ApproachA biocompatible, watertight, non-corrosive prototype, MagPen was built, and customized such that it is easy to adjust the orientation of the μcoil and its distance over the hippocampal tissue in anin vitrorecording setting. Finite element modeling (FEM) of the μcoil design was performed to estimate the spatial profiles of the magnetic flux density (in T) and the induced electric fields (in V/m). The induced electric field profiles generated at different values of current applied to the μcoil can elicit a neuron response, which was validated by numerical modeling. The modeling settings for the μcoil were replicated in experiments on rat hippocampal neurons.Main resultsThe preferred orientation of MagPen over the Schaffer Collateral fibers was demonstrated such that they elicit a neuron response. The recorded EPSPs from CA1 region due to μMS at CA3 region were validated by applying tetrodotoxin (TTX). Application of TTX to the hippocampal slice blocked the EPSPs from μMS while after prolonged TTX washout, a partial recovery of the EPSP from μMS was observed. Finally, it was interpreted through numerical analysis that increasing frequency of the current driving the μcoil, led to a decrease in the current amplitude threshold for micromagnetic neurostimulation.SignificanceThis work reports that micromagnetic neurostimulation can be used to evoke population EPSP responses in the CA1 region of the hippocampus. It demonstrates the strengthfrequency curve for μMS and its unique features related to orientation dependence of the μcoils, spatial selectivity and stimulation threshold related to distance dependence. Finally, the challenges related to μMS experiments were studied including ways to overcome them.

In this study, the dihydropteroate synthase of Staphylococcus aureus was obtained, and its recognition mechanisms for 31 sulfonamide drugs were studied. Results showed that their core structure matched well with the binding pocket of para-aminobenzoic acid, and all the sulfonamide side chains were out of the binding pocket. Hydrogen bonds and hydrophobic interactions were the main intermolecular forces, and the key amino acids were Gly171 and Lys203. The binding sites in sulfonamide molecules were mainly around the para-aminobenzenesulfonamide part. This enzyme was used to develop a fluorescence polarization assay for detection of these drugs in chicken muscles. The change trends of half of inhibition concentrations and cross-reactivities for the 31 drugs were identical with the receptor-ligand affinities. The limits of detection were in the range of 2.0-38.5 ng/g, and one assay could be finished within several minutes. Therefore, this method could be used for multiscreening of sulfonamide residues in meat samples.

A lead-free compound, (TBAC)SnCl3 (TBAC = tetrabutylammonium chloride), with high anti-water stability was reported, which can be stable in water for 24 hours. Upon photoexcitation, this compound exhibits a green photoluminescence (PL) centered at 523 nm with a larger Stokes shift of 260 nm at room temperature (RT), stemming from self-trapped exciton (STE) emission.

In this study, nitrobenzene was used as dummy template to synthesize a type of specific molecularly imprinted microspheres for chloramphenicol, and 4-nitroaniline was coupled with three fluorophores to synthesize three fluorescent tracers. Then a competitive fluorescence method was developed on a conventional microplate for detection of chloramphenicol in chicken and pork samples. This method contained only one sample-loading step, so one assay was finished within 30 min. The IC50 was 1.8 ng/ml, and the limit of detection was 0.06 ng/g. The recoveries from chloramphenicol-fortified blank meat samples were in the range 67.5-96.2%. Furthermore, this method could be recycled three times. The detection results for some real meat samples were identical to that of a LC-MS/MS method. Therefore, this method could be used as a practical tool for routine screening for the residue of chloramphenicol in large number of meat samples.

The objective of this study is to report a molecularly imprinted polymer-based chemiluminescence method for determination of Sudan dyes. A dummy-template molecularly imprinted polymer capable of recognizing seven Sudan dyes was first synthesized and its recognition mechanism was studied by using computation simulation method. The polymer was coated in the wells of conventional microplate to prepare a chemiluminescence sensor and the assay process consisted of only one sample-loading step prior to signal acquisition. The optimized sensor was used to determine the seven dyes in egg yolk and the results were confirmed with a high performance liquid chromatography. Results showed that this sensor achieved ultrahigh sensitivity (1.0–5.0 pg/mL), rapid assay process (10 min) and satisfactory recovery (70.5%–92.2%). Furthermore, the sensor could be reused for 5 times. Therefore, this sensor could be used as a useful tool for screening the residues of Sudan dyes in egg.

We investigated spin-to-charge conversion in sputtered Bi43Se57/Co20Fe60B20 heterostructures with in-plane magnetization at room temperature. High spin-to-charge conversion voltage signals have been observed at room temperature. The transmission electron microscope images show that the sputtered bismuth selenide thin films are nanogranular in structure. The spin-pumping voltage decreases with an increase in the size of the grains. The inverse Edelstein effect length (λIEE) is estimated to be as large as 0.32 nm. The large λIEE is due to the spin-momentum locking and is further enhanced by quantum confinement in the nanosized grains of the sputtered bismuth selenide films. We also investigated the effect on spin-pumping voltage due to the insertion of layers of MgO and Ag. The MgO insertion layer has almost completely suppressed the spin-pumping voltage, whereas the Ag insertion layer has enhanced the λIEE by 43%.

It has been a long-lasting debate whether indigo undergoes excited-state proton transfer and how this contributes to its photostability. A prevailing point of view is that a sub-picosecond excited-state intramolecular single proton transfer occurs; however, it has been studied mostly under dilute solution conditions. In this work, excited-state structural dynamics of indigo oligomers formed at millimolar concentration in dimethyl sulfoxide is investigated using femtosecond visible pump spectroscopy, infrared and visible probe spectroscopies, and steady-state infrared and fluorescence spectroscopies. Experimental evidence indicates the presence of transient intermolecular electronic excited-state proton transfer, which is supported by quantum-chemistry computations. The formed enol species disappears with a time constant of 200-300 fs, followed by a relatively slow nonradiative relaxation to the electronic ground state. Our results reveal new photochemistry of indigo particularly in its oligomeric state.

In this study, a novel composite was synthesized by polymerizing the dummy-template molecularly imprinted microspheres on the surface of magnetic graphene. This composite was used as recognition reagent and energy acceptor to develop a platform for determination of chloramphenicol according to the principle of chemiluminescence resonance energy transfer. The light signal was induced with luminol H2O2 4-(imidazole-1-yl)phenol system, and the chemiluminescence intensity was positively correlated with the analyte concentration. The limit of detection for chloramphenicol in meat sample was 2.0 pg/g, and the recoveries from the standard fortified blank meat sample were in the range of 69.5%–97.3%. Furthermore, one single assay could be finished within 10 min, and the magnetic composite could be reused for at least thirty times. Therefore, this platform could be used as a rapid, simple, sensitive, accurate and recyclable tool for screening the residue of chloramphenicol in meat.

Magnetic nanoparticles (MNPs) have been extensively used as contrasts and tracers for bioimaging, heating sources for tumor therapy, carriers for controlled drug delivery, and labels for magnetic immunoassays. Here, we describe a MNP relaxation dynamics-based magnetic particle spectroscopy (MPS) method for the quantitative detection of molecular biomarkers. In MPS measurements, the harmonics of oscillating MNPs are recorded and used as a metric for the freedom of rotational motion, which indicates the bound states of the MNPs. These harmonics can be collected from microgram quantities of iron oxide nanoparticles within 10 seconds. Using a streptavidin-biotin binding system, we demonstrate the feasibility of using MPS to sense these molecular interactions, showing this method is able to achieve rapid, wash-free bioassays, and is suitable for future point-of-care (POC), sensitive, and versatile diagnosis., 24 pages, 8 figures, 2 schemes, 1 table

In this study, a homogeneous competitive immunoassay based on graphene and chemiluminescence resonance energy transfer was first reported to detect small molecule substance. A generic monoclonal antibody of phenothiazine drugs was coupled to graphene as the recognition element and energy acceptor. The composite, the HRP-labeled hapten and the analyte solution were added into the microplate wells to perform homogeneous competition. Then luminol-H2O2-4-(imidazol-1-yl)phenol system was added to initiate light emission, and the light signal was positive correlation with the analyte concentration. After optimization of several parameters, the method was used to determine the residues of 4 phenothiazines in pig urine. Results showed that one assay was finished within 10 min, and the limits of detection for the 4 drugs were in the range of 2.0–5.0 pg/mL. Their recoveries from the standards fortified blank urine sample were in the range of 81.5%–96.8%. Therefore, this method could be used as a simple, rapid, and sensitive tool for routine screening the residues of phenothiazines in pig urine.

BACKGROUND Hepatocellular carcinoma (HCC) is the third leading cause of death from malignant tumors worldwide. More than 50% of HCC cases occur in China. The prognosis remains poor and overall efficacy is still unsatisfactory. Chemotherapy resistance is the most important reason for the poor outcome. Much progress has been made in the study of chemotherapy resistance of HCC; however, the specific mechanisms of progression of HCC have still only been partially established. Therefore, the mechanism of chemotherapy resistance in HCC requires more research. AIM To investigate the effect of miR-34a expression on the growth inhibition of HepG2 cells by doxorubicin. METHODS A recombinant lentiviral vector containing miR-34a was constructed and transfected into HepG2 cells. The expression of miR-34a was detected by reverse transcription-polymerase chain reaction (commonly known as RT-PCR) before and after transfection. Cells were exposed to 2 μM doxorubicin or phosphate-buffered saline before and after transfection. Cell viability in each group was detected by MTT assay, and cell cycle and apoptosis were detected by flow cytometry. Changes in expression levels of phospho (p)-p53, sirtuin (SIRT) 1, cyclin D1, cyclin-dependent kinase (CDK) 4, CDK6, BCL-2, multidrug resistance protein (MDR) 1/P glycoprotein (P-gp), and AXL were detected by Western blotting. RESULTS Recombinant lentiviral vector LV-hsa-mir-34a was successfully constructed by restriction endonuclease digestion and sequencing. RT-PCR showed that expression of miR-34a in HepG2 cells was significantly upregulated after transfection (P < 0.01). MTT assay showed that growth of HepG2 cells was inhibited after upregulation of miR-34a, and viability was significantly decreased after combined treatment with doxorubicin (P < 0.01). Flow cytometry showed that the number of HepG2 cells in G1 phase increased, and G1 phase arrest was more obvious after intervention with doxorubicin (P < 0.01). The apoptosis rate of HepG2 cells was increased after upregulation of miR-34a, and became more obvious after intervention with doxorubicin (P < 0.01). Western blotting showed that upregulation of miR-34a combined with treatment with doxorubicin caused significant changes in the expression levels of p-p53, SIRT1, cyclin D1, CDK4, CDK6, BCL-2, MDR1/P-gp and AXL proteins (P < 0.01). CONCLUSION MiR-34a may enhance the inhibitory effect of doxorubicin by downregulating MDR1/P-gp and AXL, which may be related to p53 expression.

This study explored the phenomenon of the detonation formation delay time in an RDE with an annular combustion chamber with an array of holes fueled with hydrogen. It was determined that the delay time increased when the combustor prefilling time increased. Due to the explosion, the interaction of the shock wave and the pressure wave in the combustor leads to an increase in pressure near the inlet wall surface, thereby impeding the gas feeding. The wavelet transformation was used to analyze the pressure time signal associated with the detonation wave, which was found to be better than the fast Fourier transform typically used. Moreover, the phenomenon of single–double–single wave transformation was observed, of which the underlying mechanism can be explained by an interactive-adjusting process. Also, the experiment captured the reinitiation phenomenon of detonations after a long period of time (around 300 ms) of extinction.

In this study, a molecularly imprinted polymer capable of recognizing 8 benzimidazoles was first synthesized. The computation simulation showed that the shape and size of used template were the main factors influencing its recognition ability. Then the polymer was used as recognition reagent to prepare a chemiluminescence sensor on conventional 96-well microplate. The sample solution and a HRP-labeled hapten were added into the microplate wells to perform competitive binding, and the light signal was initiated with 4-(imidazol-1-yl)phenol enhanced luminol-H2O2 system. The optimized sensor was used to determine the residues of 8 benzimidazoles in mutton and beef. Result showed that the sensor achieved ultrahigh sensitivity (limits of detection of 1.5–21 pg/mL), rapid assay process (18 min) and satisfactory recovery (65.8%–91.2%). Furthermore, this sensor could be reused for 4 times. Therefore, this sensor could be used as a rapid, simple, sensitive and durable tool for screening the residual benzimidazoles in meat.

We have investigated two solid-state phase transformations-nitriding of the ternary alloy FeCuB ribbons and martensitic phase transformation in the FeCuBN ribbons using x-ray diffraction, Auger Electron spectroscopy, and scanning electron microscopy. We also studied the diffusion kinetics of nitrogen in FeCuB ribbons and found the activation energy of N to diffuse in the FeCuB matrix and the diffusion coefficient of N at different temperatures. We investigated the evolution of the microstructure during nitriding process and found a layered growth of iron nitride in the FeCuB matrix. Finally, the martensitic phase transformation of the FeCuBN ribbons was also optimized, and the optimizing parameters for the martensitic phase transformation of FeCuB ribbons were reported.

In this work, an intensity-enhanced C≡C stretching infrared (IR) absorption is observed in hexakis[(trimethylsilyl)ethynyl]benzene (HTEB), whose IR transition dipole magnitude becomes comparable to that of a typical C═O stretch, and the enhancement is believed to be due to a joint effect of π-π conjugation and hyperconjugation associated with a terminal trimethylsilyl group. Using dynamical time-dependent two-dimensional infrared (2D IR) spectroscopy, a picosecond intramolecular energy redistribution process is observed between two nondegenerate C≡C stretching modes, whose symmetry breaking is attributed to a noncovalent halogen-bonding interaction between HTEB and solvent CH2Cl2. The rigid structure of HTEB and limited structural dynamics are also inferred from the insignificant initial spectral diffusion value extracted from the 2D IR spectra. This work provides the first nonlinear infrared investigation of the conventionally weak C≡C stretch. The methods outlined are particularly important for detailed understanding of the structure-related processes such as vibrational energy transfer in novel C≡C species containing materials such as graphdiyne.

Isoprenaline was used as the template to synthesize a molecularly imprinted polymer that was able to simultaneously recognize ten β-agonists. The simulation showed that the three-dimensiona...

A molecularly imprinted polymer (MIP) capable of recognizing five tetracyclines using minocycline as the template was synthesized for the first time. The MIP was employed as the recognition reagent to prepare a chemiluminescence sensor on a conventional microtiter plate. The light signal was initiated using the highly efficient bis(2,4,6-trichlorophenyl) oxalate-hydrogen peroxide-imidazole chemiluminescence system. After optimization of several appropriate factors, the sensor was employed to determine five tetracyclines in milk. The developed assay contained only one sample-loading step, so each measurement was completed within 12 min. The limits of detection for these analytes were in the range from 0.5 to 2.0 pg/mL, while the recoveries from the fortified milk samples were between 78.1 and 105%. In addition, the sensor was shown to be reusable for up to four measurements. Hence, this sensor has been demonstrated to be a simple, rapid, sensitive, and durable tool for the determination of tetracyc...

The microstructure of FeCuB ribbons (∼20 μm thick) was modified to fabricate α′′-Fe16N2 at a temperature as low as 160 °C. The ribbon samples were heat treated first at a temperature reaching 930 °C and then quenched down to room temperature. During the heat treatment, ribbon samples were oxidized, and hydrogen reduction was then conducted to remove the oxygen from the ribbon samples. The reduced ribbon samples had a porous structure, which improved the nitrogen diffusion efficiency and decreased the fabrication temperature of α′′-Fe16N2 down to 160 °C. It was demonstrated that the techniques for microstructure control in this method including oxidation and reduction helped obtain the α′′-Fe16N2 phase with high coercivity, thus manifesting this could be a promising technique for low-temperature nitridation on ribbons in general.

In this study, molecularly imprinted microspheres of a type capable of recognising amantadine and rimantadine were first synthesised, and three fluorescent tracers based on dansyl chloride, fluorescein isothiocyanate and 5-carboxytetramethylrhodamine were also synthesised. These reagents were used to develop and optimise a direct competitive fluorescence method on conventional 96-well microplate for detection of the two analytes. Results showed that this method achieved simple operation procedure, rapid assay process (30 min), high sensitivity (limits of detection 0.04-0.05 ng mL

Subtle changes in molecular structure often lead to significant differences in host-guest interactions, which result in different host-guest recognition capabilities and dynamics behaviours in complex formation. Herein, we reveal the influence of the guest substituents on host-guest molecular recognition by molecular dynamics (MD) simulation and density functional theory (DFT) approaches. The results suggest that the binding energy barrier of acyclic cucurbit[4]uril (ACB[4]) with opiate metabolites gradually decreases. The methyl group in morphine (MOR) and morphine-3-glucuronide (M3G) strengthens the hydrophobicity of the guest, while depressing the energy loss of the desolvation of polar groups (e.g. hydroxyl) inside the ACB[4] cavity. However, in M3G, the 3-glucuronide group located outside the ACB[4] host cavity effectively alleviates the unfavourable desolvation effect of the hydroxyl and increases the binding constant by two orders of magnitude (compared with normorphine (NMOR)). Our findings stressed the essentiality of the binding mode and intermolecular noncovalent interactions in the host-guest selective binding ability.

The "specific" interaction between metal cations (Na+, Ca2+, Mg2+, and Zn2+) and the charged COO- group, and the "non-specific" interaction between these cations and the peptide backbone of a zwitterionic trialanine (Ala3) in aqueous solutions were examined in detail, using linear infrared (IR) absorptions of the COO- symmetric stretching and the amide-II (mainly the C-N stretching) modes as IR probes. Different IR spectral changes in peak positions and intensities of the two IR probes clearly demonstrate their sensitivities to nearby cation distributions in distance and population. Quantum chemistry calculations and molecular dynamics simulations were used to describe the cation-peptide interaction picture. These combined results suggest that Na+ and Ca2+ tend to bind to the COO- group in the bidentate form, while Mg2+ and Zn2+ tend to bind to the COO- group in the pseudo-bridging form. The results also show that while all three divalent cations indirectly interact with the peptide backbone with large population, Ca2+ and Mg2+ can be sometimes distributed very close to the backbone. Such a non-specific cation interaction can be moderately sensed by the C-N stretching of the amide-II mode when cations approach the polar amide C[double bond, length as m-dash]O group, and is also influenced by the NH3+ charge group located at the N-terminus. The results suggest that the experimentally observed complication of the Hofmeister cation series shall be understood as a combined specific and non-specific cation-peptide interactions.

In recent years, high-moment magnetic nanoparticles (MNPs) such as FeCo are attracting intense interest for biomedical applications. The synthesized FeCo MNPs have the specific saturation magnetization up to 226 emu/g that is more than three times higher than that of iron oxide MNPs (~ 70–80 emu/g). Core-shell MNPs are also synthesized to enhance the functionality of high-moment MNPs. Shells like SiO2, Au, and Ag are used for these high-moment MNPs to improve biocompatibility. The sputtering-based gas-phase condensation approach to synthesize high-moment MNPs and core-shell nanostructures are reviewed. The applications of these high-moment MNPs such as magnetic hyperthermia, drug delivery, magnetic resonance imaging (MRI), and biosensing are summarized. The heating efficiency of magnetic hyperthermia and drug delivery could be significantly enhanced by using high-moment MNPs. MNPs with different crystallinity and shapes (such as cubic, spherical, triangular, and octahedral shapes) are also summarized due to their potential applications in MRI. High-moment MNPs could also provide more magnetic signals for giant magnetoresistance (GMR)-based biosensors, which are also reviewed. We believe that the high-moment MNPs are promising candidates for many bio-applications.

Topological insulator (TI) materials are exciting candidates for integration into next-generation memory and logic devices because of their potential for efficient, low-energy-consumption switching of magnetization. Specifically, the family of bismuth chalcogenides offers efficient spin-to-charge conversion because of its large spin-orbit coupling and spin-momentum locking of surface states. However, a major obstacle to realizing the promise of TIs is the thin-film materials' quality, which lags behind that of epitaxially grown semiconductors. In contrast to the latter systems, the Bi-chalcogenides form by van der Waals epitaxy, which allows them to successfully grow onto substrates with various degrees of lattice mismatch. This flexibility enables the integration of TIs into heterostructures with emerging materials, including two-dimensional materials. However, understanding and controlling local features and defects within the TI films is critical to achieving breakthrough device performance. Here, we report observations and modeling of large-scale structural defects in (Bi,Sb)$_2$Te$_3$ films grown onto hexagonal BN, highlighting unexpected symmetry-breaking rotations within the films and the coexistence of a second phase along grain boundaries. Using first-principles calculations, we show that these defects could have consequential impacts on the devices that rely on these TI films, and therefore they cannot be ignored.

In this report, we investigated the effects of carbon and microstructure of the precursor on the magnetic performances based on a developed method for bulk preparation to synthesize Fe–CN (Minnealloy) soft magnetic materials. The melt-spun ribbons of Fe1−xCx were obtained to improve the efficiency of the nitrogen diffusivity by introducing porous and defects inside the grains, which increases the volume fraction of α″-Fe16N2 phase. The carbon effects were studied by the X-ray diffraction (XRD) and Wavelength-dispersive spectroscopy (WDS) to reveal the redistribution of carbon during the thermal treatment and its effects on nitridation. The microstructure variation during the thermal treatment for the Fe–C precursor was observed, which could be explained by the formation of non-uniform porous structure during the oxidation and reduction steps and also the migration of the carbon atoms.

In this work, the solvation of a nitrosyl ruthenium complex, [(CH3)4N][RuCl3(qn)(NO)] (with qn = deprotonated 8-hydroxyquinoline), which is a potential NO-releasing molecule in the bio-environment,...

Understanding lysosome-related physiology needs specific lysosome probes to track the biological processes of lysosome in living cells. Here, we report an azacyclo-modified fluorescent probe that has a large Stokes shift, good photostability and negligible cytotoxicity for highly specific labeling of lysosome and autolysosome in living cells. The probes with different kinds of azacyclo groups on parent dye dansyl are screened to show that dansyl-cycleanine (DNS-C) with four nitrogen atoms possesses the best lysosome-localized ability. And DNS-C as a universal tracker exhibits excellent ability for lysosome labeling in different cell lines with high overlap coefficients (≥0.90). Different from a commercially available LysoTracker, the Stokes shift of DNS-C up to 240 nm (λex/em = 330/570 nm), is much larger than that of LysoTracker ~20 nm (λex/em = 573/595 nm). More importantly, the fluorescence of DNS-C keeps still high brightness after a time-lapsed imaging for 40 min in living cells, implying its remarkable photostability for long-term tracking. In addition, DNS-C can also clearly image the autolysosome, a critical subcellular compartment, forming by the fusion of lysosome with autophagosome in autophagy. These results suggest the promising utility of our probe as a powerful tool to real-time trace physiological processes of lysosomes.

Two molecularly imprinted microspheres and two fluorescent tracers for benzimidazoles and pyrethroids were synthesized respectively. The two types of microspheres were coated in the wells of conventional microplate simultaneously. Then the sample extracts and the two traces were added for differential competition. The fluorescence intensities at two different emission wavelengths were excited and recorded for quantification of the two classes of drugs respectively. The optimized multiplexed fluorescence method could be used to determine 8 benzimidazoles and 10 pyrethroids in mutton and beef samples simultaneously. The limits of detection of the method for the 18 drugs were in the range of 5.2–17 ng/mL, and the recoveries from the standards fortified blank samples were in the range of 67.7%–109%. From the analysis of 60 real mutton and beef samples, this method could be used for multi-screening the residues of benzimidazoles and pyrethroids in meat samples.

In this study, a molecularly imprinted polymer based chemiluminescence array capable of simultaneous determining phenothiazines and benzodiazepines was first reported. Two polymers were coated in different wells of the conventional 96-well microtiter plate as the recognition reagents, and the added analytes competed with a horseradish peroxidase-labeled bi-hapten conjugate to bind the recognition reagents. The light signal was induced by using a highly effective luminol-H2O2-IMP system. The assay procedure consisted of only one sample-loading step prior to data acquisition. Then, the array was used to determine 4 phenothiazines and 5 benzodiazepines in pork simultaneously. The limits of detection for the 9 drugs were in a range of 0.001–0.01 ng/mL, and the recoveries from the fortified blank pork were in a range of 63.5%–94.1%. Furthermore, the array could be reused for 8 times. The detection results for some real pork samples were consistent with an ultra performance liquid chromatography method.

The spin-orbit torque (SOT) arising from materials with large spin-orbit coupling promises a path for ultra-low power and fast magnetic-based storage and computational devices. We investigated the SOT from magnetron-sputtered BixSe(1-x) thin films in BixSe(1-x)/CoFeB heterostructures by using a dc planar Hall method. Remarkably, the spin Hall angle (SHA) was found to be as large as 18.83, which is the largest ever reported at room temperature (RT). Moreover, switching of a perpendicular CoFeB multilayer using SOT from the BixSe(1-x) has been observed with the lowest-ever switching current density reported in a bilayer system: 2.3 * 105 A/cm2 at RT. The giant SHA, smooth surface, ease of growth of the films on silicon substrate, successful growth and switching of a perpendicular CoFeB multilayer on BixSe(1-x) film opens a path for use of BixSe(1-x) topological insulator (TI) material as a spin-current generator in SOT-based memory and logic devices.

In this study, a novel dual-template molecularly imprinted polymer capable of simultaneously recognizing 4 phenothiazines and 5 benzodiazepines was synthesized. From the comparison of the 3D conformations of the two templates and the analytes, it was concluded that the shapes and sizes of the templates used in this study influenced the polymer's recognition ability. The polymer was used to prepare a solid phase extraction cartridge, which was used to purify the extract of the swine complete formula feed sample obtained with 10 mL acetonitrile/0.1% formic acid (3 : 7, v/v). The results were determined using ultra performance liquid chromatography. During the experiments, the flow rate, loading solvent, washing solvent and eluting solvent were optimized. The limits of detection for the 9 drugs were in the range of 1.5–10 ng g−1, and the recoveries from the fortified blank feed samples were in the range of 85.6–97.9%. This is the first study reporting the use of a molecularly imprinted polymer-based extraction method for determining the two classes of sedatives in animal feed.

The residues of amantadine and rimantadine in foods of animal origin are dangerous to consumers. This study used adamantane as the dummy template for the first time to synthesize a molecularly imprinted polymer capable of simultaneously recognizing amantadine and rimantadine. This polymer was used as the recognition reagent to prepare a chemiluminescence sensor on the conventional 96-well microtiter plate for the determination of the two drugs in chicken and pork samples. The results showed that one test could be finished within 20 min, and the sensor could be reused 6 times. Due to the 4-(imidazol-1-yl)phenol enhanced luminol–H2O2 signal system, the limit of detection for the two analytes was 1.0 pg mL−1. The recoveries of the two analytes from the standard fortified blank meat samples were in the range of 67.2–93.5%. Therefore, the sensor could be used as a simple, rapid, sensitive, specific and recyclable tool for the routine monitoring of the residues of amantadine and rimantadine in meat.

In this study, a dual-dummy-template molecularly imprinted polymer capable of simultaneous recognizing 8 fluoroquinolones and 8 sulfonamides was synthesized. Its recognition performance was investigated by comparing the 3D conformations of four dummy templates and the two classes of drugs based on computational simulation. Then a solid phase extraction column was prepared and optimized that was combined with ultra performance liquid chromatography for determination of the 16 drugs in pork and chicken. The column could be reused for at least eighty times, and it showed high absorbency capacities (34.9–74.2 μg) and high recoveries (92%–99%) to these drugs. The limits of detection of this method for the two classes of drugs in meat were in the range of 1.0–3.4 ng/g, and the recoveries from the standards fortified blank samples were in the range of 86.1%–109.4%. Therefore, this method could be used as a specific, sensitive and accurate method for determination of fluoroquinolones and sulfonamides in meat.

As an essential enzyme, alkaline phosphatase (ALP) has attracted considerable attention for its regulating effect to the dephosphorylation process in living organisms. Here, we present a colorimetric and surface enhanced Raman scattering (SERS) dual-readout approach for assaying ALP activity. The major advantage of dual-readout assay is the perfect combination of the merit of colorimetric and SERS, which not only allow rapid preliminary discrimination of ALP activity by the naked eye but also greatly improved the detection sensitivity by SERS. Specifically, 4-mercaptophenylboronic acid modified Ag coated gold nanoparticles (4-MPBA-Au@Ag NPs) are employed as the colorimetric and SERS bifunctional reporting nanoprobes. Upon the presence of ALP, the phosphate group in the ascorbic acid 2-phosphate (AAP) is cleaved to produce ascorbic acid (AA), which acted as boronic acid moieties receptors to control the aggregation of 4-MPBA-Au@Ag NPs. The color of 4-MPBA-Au@Ag NPs solutions had changed from bright orange to light brown to dark gray, simultaneously accompanied by a substantial enhancement of SERS-readouts for the strong Raman hot-spots between the aggregation of 4-MPBA-Au@Ag NPs. A distinguishable change in the color was observed at an ALP activity of 5.0 U/L, meanwhile, SERS-readout sensing method showed a good linear relationship from 0.50 to 10.0 U/L (R = 0.997) with an exciting detection limit of 0.10 U/L (signal-to-noise ratio of 3). In addition, the dual-readout approach developed here was applied for ALP inhibitor evaluation. With the simple, rapid/direct readout yet outstanding sensitivity, we anticipate that this method would greatly promote practical application in ALP-related early-stage diseases diagnosis.

In this study, a photoaffinity labeled activity-based protein profiling probe for tetracycline drugs was first synthesized that was used to capture a type of natural TetR protein from Escherichia coli. The TetR simultaneously recognized 10 tetracycline drugs. Then it was used as recognition reagent to develop a direct competitive chemiluminescence immunoassay for detection of the 10 drugs in milk. The IC50 values for these drugs were in the range of 0.084–0.32 ng/mL, and the limits of detection were in the range of 2.0–9.0 pg/mL. Their recoveries from the standards fortified blank milk samples were in the range of 68.4%-91.3%. After comparison, the natural TetR protein and the developed method showed better performances than the previous TetR proteins and the related immunoassays. Therefore, this method could be used as a practical tool for routine screening the residues of tetracycline drugs in milk. Furthermore, this type of probe could also be used to produce the receptors and develop different immunoassays for other classes of drugs.

In this study, 105 broiler chickens were fed with dietary feeds containing different contents of Dichroae Radix extract for 10 consecutive days. Then the residue depletions of its main alkaloids (febrifugine and isofebrifugine) in muscle, kidney and liver samples at different withdrawal times were determined by an ultra-performance liquid chromatography method. Results showed that the 2 alkaloids were mainly at tissue-bound formation. At withdrawal period of 0 d, their concentrations in all samples were high but decreased rapidly after 1 day of cessation (35–91%). After 5 to 7 days of cessation, their residues in muscle and kidney were not detectable, and after at least 10 days of cessation they were not detectable in liver. These results indicated that an appropriate withdrawal time for Dichroae Radix preparation was required if it is licensed as a new drug, and the best target tissue for monitoring its residue was liver.

As a metabolic disease, fatty liver hemorrhagic syndrome (FLHS) has become the major factor responsible for the noninfectious cause of mortality in laying hens, which lead to huge economic losses to poultry industry. However, the pathogenesis of FLHS remains unclear. The aim of present study was to identify novel liver metabolites associated with FLHS. Twenty healthy Chinese commercial Jing Fen laying hens aged 90 d were used in present study. After acclimatization for 2 wk, the hens were divided into 2 treatments (n = 10): control group (normal diet) and FLHS group (high-energy low-protein diet). The experiment lasted for 48 d, and the laying hens were killed for blood and liver sampling at the end of the experiment. Blood biochemical indicators and liver pathological changes were examined. Meanwhile, the changes in liver metabolic profile were investigated with the application of metabolomics approach. Significant increased levels of alanine aminotransferase, aspartate aminotransferase, low density lipoprotein, total cholesterol and triglycerides, decreased high density lipoprotein (P < 0.01), and hepatic steatosis were observed in hens of FLHS group, which suggested FLHS was successfully established in this study. Distinct changes in metabolite patterns in liver between control and FLHS group were observed by partial least-squares discriminant analysis. In total, 42 liver metabolites including tyrosine, glutathione, carnitine, linoleic acid, uric acid, arachidonic acid (ARA), lactate and lysophosphatidylcholine (14: 0) were identified and considered to be related with pathogenesis of FLHS. Pathway analysis revealed that these metabolites were mainly involved in amino acid metabolism, fatty acid metabolism, ARA metabolism, glucose metabolism and glycerophospholipid metabolism. Furthermore, targeted metabolomics found that ARA metabolites such as prostaglandins and hydroxyeicosatetraenoic acids were significantly increased in FLHS group (P < 0.05). In conclusion, our data showed that liver metabolites and ARA metabolism were linked to the pathophysiology of FLHS, which provided a basis for understanding the pathogenesis of FLHS in laying hens.

Organic molecule incorporation into inorganic halide brings up a series of variable optical physics and applications. Here, we report a new zero-dimensional Mn-based hybrid metal halide of C4H14N2MnBr4 single crystals by using bi-amine group organic ions incorporation, which shows bright orange emission at room temperature. Interestingly, it exhibits unique dual-emission bands at 516 nm and 623 nm, both bands are related to the polaronic exciton or selftrapped exciton(STE1) and the bipolaronic exciton(STE2) due to the enhanced charged electron-phonon coupling by the incorporation of bi-amine-group molecular ions in the manganese halide lattice, which are also combined with the d-d transition of single Mn and Mn pair at a Mn-Mn distance close to a critical number of about 6.6 A. This distance is found to be the critical distance between Mn ions for their paramagnetic and pair ferromagnetic phases in the manganese halides. The temperature-dependent photoluminescence (PL) spectra show that the C4H14N2MnBr4 single crystals have a sensitive reversible thermo-induced PL characteristic, i.e., its orange and green PL colors can be converted back and forth through the temperature dependent electron-phonon coupling coefficient variations, during which there are different phase transitions.