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T-cell acute lymphoblastic leukemia (T-ALL) is a heterogeneous hematologic disease characterized by immature lymphoid cell proliferation in the bone marrow, peripheral blood and other organs [1]. C...

Sb-based nanocomposites are attractive anode materials for batteries as they exhibit large theoretical capacity and impressive working voltage. However, tardy potassium ion diffusion characteristics, unstable Sb/electrolyte interphase, and huge volume variation pose a challenge, hindering their practical use for potassium-ion batteries (PIBs). Now, a simple robust strategy is presented for uniformly impregnating ultrasmall Sb nanocrystals within carbon nanofibers containing an array of hollow nanochannels (denoted u-Sb@CNFs), resolving the issues above and yielding high-performance PIBs. u-Sb@CNFs can be directly employed as an anode, thereby dispensing with the need for conductive additives and binders. Such a judiciously crafted u-Sb@CNF-based anode renders a set of intriguing electrochemical properties, representing large charge capacity, unprecedented cycling stability, and outstanding rate performance. A reversible capacity of 225 mAh g-1 is retained after 2000 cycles at 1 A g-1 .

Summary Photoelectrochemical nitrogen reduction reaction can provide a useful source of ammonia and transportable carrier of hydrogen, but the process is limited by the photocathodes with poor conversion efficiency and low production rate. Here, we have designed a unique aerophilic-hydrophilic heterostructured Si-based photocathode for nitrogen-to-ammonia fixation in an acid electrolyte under mild conditions, achieving a high ammonia yield rate of ∼18.9 μg⋅cm−2⋅hr−1 and an excellent faradic efficiency of 37.8% at −0.2 V versus a reversible hydrogen electrode. The heterostructure based on the Au nanoparticles highly dispersed in poly(tetrafluoroethylene) porous framework enriches nitrogen molecular concentration at the Au active sites while manipulateing the proton activity with suppressed hydrogen evolution reactions. DFT calculation indicates that such heterostructure reduces the energy barrier for the nitrogen reduction reaction. The aerophilic-hydrophilic heterostructure provides a new insight on designing efficient and robust photocathodes for nitrogen fixation.

Tan Re Qing (TRQ), a traditional Chinese medicine formula, is composed of Scutellariae Radix and other four herbs (bear bile powder, Caprae Hircus Cornu, Lonicerae japonicae Flos and Forsythiae Fru...

Nonprecious highly active electrocatalysts in water splitting are essential for large-scale storage of renewable hydrogen energy. Two dimensional (2D) layered double hydroxides (LDHs) are commonly regarded as promising electrocatalysts for oxygen evolution reaction (OER), while they are not so efficient for hydrogen evolution reaction (HER). Herein, we propose the NiCo LDHs derived NiCoPx with 2D mesoporous ultrathin nanoplates structure in-situ grown on carbon paper (NiCoPx/CP). The special nanostructure and rich active sites endow the binder-free NiCoPx/CP with excellent bifunctional electrocatalytic performance toward HER and OER with very low overpotentials of 56 mV for HER at 10 mA cm−2 and 239 mV for OER at 30 mA cm−2. Moreover, the NiCoPx/CP can be directly used as electrodes for both anode and cathode to construct an efficient alkaline water electrolyzer with a cell votage of 1.58 V at 10 mA cm−2, which show even better performance than that of the best known commercial Pt-C&RuO2/CP catalysts. This work presented here can offer a novel guidance for the construction of non-noble metal-based electrocatalysts with 2D nanostructure in energy applications.

Tremendous efforts have been devoted to explore energy-efficient strategies of ammonia synthesis to replace Haber-Bosch process which accounts for 1.4% of the annual energy consumption. In this study, atomically dispersed Au1 catalyst is synthesized and applied in electrochemical synthesis of ammonia under ambient conditions. A high NH4+ Faradaic efficiency of 11.1% achieved by our Au1 catalyst surpasses most of reported catalysts under comparable conditions. Benefiting from efficient atom utilization, an NH4+ yield rate of 1,305 μg h−1 mgAu−1 has been reached, which is roughly 22.5 times as high as that by supported Au nanoparticles. We also demonstrate that by employing our Au1 catalyst, NH4+ can be electrochemically produced directly from N2 and H2 with an energy utilization rate of 4.02 mmol kJ−1. Our study provides a possibility of replacing the Haber-Bosch process with environmentally benign and energy-efficient electrochemical strategies.

Direct formic acid fuel cell (DFAFC) has been considered as a promising energy conversion device for stationary and mobile applications. Advanced platinum (Pt) electrocatalysts for formic acid oxidation reaction (FAOR) are critical for DFAFC. However, the oxidation of formic acid on Pt catalysts often occurs via a dual pathway mechanism, which hinders the catalytic activity owing to the CO poisoning. Herein, we directly exfoliate bulk antimony to 2D antimonene (Sb) and in situ load Pt nanoparticles onto antimonene sheets with the assistance of ethylenediamine. According to the Bader charge analysis, the charge transfer from antimonene to Pt occurs, confirming the electronic interaction between Pt and Sb. Interestingly, antimonene, as a cocatalyst, alters the oxidation pathway for FAOR over Pt catalyst and makes FAOR follow the more efficient dehydrogenation pathway. The density functional theory (DFT) calculation demonstrates that antimonene can activate Pt to be a lower oxidative state and facilitate the oxidation of HCOOH into CO 2 via a direct pathway, resulting in a weakened intermediate binding strength and better CO tolerance for FAOR. The specific activity of FAOR on Pt/Sb is 4.5 times, and the mass activity is 2.6 times higher than the conventional Pt/C.

Direct production of H2 from photocatalytic water splitting is a potential solution to environmental pollution and energy crisis, and tremendous efforts have been made to seek efficient photocatalysts that can split pure water (pH = 7) under visible light irradiation. Herein, by means of systematic density functional theory (DFT) computations, we demonstrated that the two-dimensional (2D) PdSeO3 monolayer is a promising candidate. The mechanical exfoliation of PdSeO3 monolayer from its bulk phase is experimentally feasible due to the rather small cleavage energy of ∼0.42 J/m2. Remarkably, PdSeO3 monolayer is semiconducting with a moderate indirect band gap of 2.84 eV, and its valence and conduction bands perfectly engulf the redox potentials of water. In particular, water oxidation and hydrogen reduction half reactions can both occur readily on the different active sites of PdSeO3 monolayer under the potentials solely provided by photogenerated electrons and holes. As PdSeO3 monolayer also has rather pron...

The oxygen evolution reaction (OER) is an ideal model to study the relationship between the activity and the surface properties of catalysts. Defect engineering has been extensively developed to tune the electrocatalytic activity for OER. Compared to the anion vacancies in metal oxides, cation vacancies are more challenging to selectively generate, and the insight into the structure and activity of cation vacancies-rich catalysts are lacked. Herein, using SnCoFe perovskite hydroxide as a precursor, abundant Sn vacancies on the surface were preferentially produced by Ar plasma. Sn vacancies could be preferentially produced as confirmed by the X-ray absorption spectra, probably owing to the lower lattice energy and weaker chemical bonds of Sn(OH)4 . The Sn vacancies promoted the exposure of active CoFe sites, resulting in an amorphous surface layer, modulated the conductivity, and thus enhanced the OER performance.

Despite wide applications of bimetallic electrocatalysis in oxygen evolution reaction (OER) owing to their superior performance, the origin of the improved performance remains elusive. The underlying mechanism was explored by designing and synthesizing a series of stable metal-organic frameworks (MOFs: NNU-21-24) based on trinuclear metal carboxylate clusters and tridentate carboxylate ligands. Among the examined stable MOFs, NNU-23 exhibits the best OER performance; particularly, compared with monometallic MOFs, all the bimetallic MOFs display improved OER activity. DFT calculations and experimental results demonstrate that introduction of the second metal atom can improve the activity of the original atom. The proposed model of bimetallic electrocatalysts affecting their OER performance can facilitate design of efficient bimetallic catalysts for energy storage and conversion, and investigation of the related catalytic mechanisms.

Defects modulation usually has great influence on the electronic structures and activities of photocatalysts. Here, porous structured graphitic carbon nitride materials with large amount of defects are obtained through facile 5 min thermal treatment in air without additional reactants. The resultant materials show remarkably extended light absorption in the visible light region. Theoretical calculations indicate that the distinctive origin of red-shifted intrinsic light absorption edge and newly occurred light absorption edge are attributed to cyano groups and nitrogen vacancies, respectively. Compared to pristine graphitic carbon nitride, the optimally modified material shows greatly enhanced photocatalytic hydrogen evolution rate by 21.5 times under λ > 440 nm and the responsive wavelength is extended from 450 nm to 650 nm. This work is expected to provide guidance for rational design of graphitic carbon nitride and inspire similar attempts for the modification of nanomaterials.

The prediction of new materials with peculiar topological properties is always desirable to achieve new properties and applications. In this work, by means of density functional theory computations, we extend the rule-breaking chemical bonding of planar pentacoordinate silicon (ppSi) into a periodic system: a C2v Ca4Si22− molecular building block containing a ppSi center is identified first, followed by the construction of an infinite CaSi monolayer, which is essentially a two-dimensional (2D) network of the Ca4Si2 motif. The moderate cohesive energy, absence of imaginary phonon modes, and good resistance to high temperature indicate that the CaSi monolayer is a thermodynamically and kinetically stable structure. In particular, a global minimum search reveals that the ppSi-containing CaSi monolayer is the lowest-energy structure in 2D space, indicating its great promise for experimental realization. The CaSi monolayer is a natural semiconductor with an indirect band gap of 0.5 eV, and it has rather strong optical absorption in the visible region of the solar spectrum. More interestingly, the unique atomic configuration endows the CaSi monolayer with an unusually negative Poisson's ratio. The rule-breaking geometric structure together with its exceptional properties makes the CaSi monolayer quite a promising candidate for applications in electronics, optoelectronics, and mechanics.

Two-dimensional (2D) crystals of atomic thickness with a band gap in the range of 0.3–1.5 eV, which corresponds to the solar spectrum range from mid-infrared to near-infrared and matches that of commercial silicon and III–V semiconductor materials, are highly sought for future electronic and optoelectronic technologies. In this study, by means of comprehensive density functional theory computations, we demonstrated that the recently synthesized 2D Pd2Se3 monolayer is a promising candidate. According to our computational results, Pd2Se3 monolayer is a semiconducting material with a moderate band gap of 0.45 eV and its carrier mobility (178.02 cm2 V−1 s−1) is comparable to that of the MoS2 monolayer. In particular, Pd2Se3 monolayer exhibits novel anisotropic transport properties and has a rather good current–voltage character. Moreover, Pd2Se3 monolayer shows a very pronounced optical absorption that covers almost the entire solar spectrum. With these excellent properties, Pd2Se3 monolayer would have wide applications in electronic and optoelectronic devices.

Photocatalytic water splitting represents the most promising approach to convert solar energy into chemical energy, and numerous efforts have been devoted to seeking photocatalysts that can work under visible-light irradiation to efficiently harvest solar energy. Here, by means of density functional theory computations, we predicted that the two dimensional germanium telluride (GeTe) monolayer can be easily exfoliated from the bulk phase by overcoming a small cleavage energy of ∼0.63 J m−2. The GeTe monolayer is semiconducting with a considerable band gap of 2.35 eV and shows suitable band edge positions for photocatalytic water splitting. Remarkably, the GeTe monolayer exhibits rather high electron and hole mobilities and has pronounced optical absorption in the visible region of the solar spectrum. These excellent properties render the GeTe monolayer a promising photocatalyst for water splitting.

By means of comprehensive density functional theory (DFT) computations, we designed a new two-dimensional (2D) structure of silicon, namely, tetra-silicene. In tetra-silicene, each silicon atom binds with four neighboring Si atoms to form a 2D network composed of only tetragons. Our DFT computations demonstrate that tetra-silicene is of rather high experimental feasibility, as indicated by its considerable cohesive energy, all positive modes in the phonon spectrum, and the well maintained structure after 10 ps first-principles molecular dynamics simulations at 500 K. Tetra-silicene has rather intriguing mechanical properties featured with unusual negative Poisson’s ratios. Remarkably, different from hexagonal silicene (hexa-silicene) which is semi-metallic without a band gap, tetra-silicene is semiconducting with an appreciable indirect band gap of 0.19 eV, and it has a considerable carrier mobility of 1639.07 cm2 V–1 s–1. Encouragingly, our simulations suggest that tetra-silicene can be flexibly produced...

Carbon dots (CDs) are raising a substantial amount of attention owing to their many unique and novel physicochemical properties. Herein one-pot synthesized CDs, to the best of our knowledge, were first served as the robust nanoprobe for detection tannic acid (TA) based on resonance Rayleigh scattering technique. The as-prepared CDs can combine with TA via hydrogen bond, resulting in remarkable enhancement of scattering signal with no changes in the fluorescence of CDs. Therefore, a novel protocol for TA determination was established and this strategy allowed quantitative detection of TA in the linear range of 0.2–10.0 μmol L − 1 with an excellent detection limit of 9.0 nmol L − 1 . Moreover, the CDs based nanoprobe can be applied to the determination of TA in water sample with satisfactory results. Our study can potentially influence our current views on CDs and particularly impressive and offers new insights into application of CDs beyond the traditional understanding of CDs.

Metal-free carbon quantum dots (CQDs) have attracted great interest, but the rapid preparation of doped CQDs with tunable optical properties is still an urgent task. Herein, we report that covalent organic frameworks (covalent triazine-based frameworks, CTF-1) with layered structures can be rapidly exfoliated and cut into N-doped CQDs. The cutting mechanism involves triazine hydrolysis and breaking the bonds between the triazines and benzene rings. Experiments and density functional theory (DFT) calculations confirm that the fluorescence of the obtained CQDs mainly originates from the intrinsic state emission induced by localized π–π* transitions, despite the contribution of the defect state emission. Due to their unique chemical structure, the CQDs could be further utilized as an efficient PL probe for detecting Hg2+. This study may open up new avenues for developing new kinds of CQDs using covalent organic frameworks as the starting materials.

Using a norfloxacin (NFLX)-Nd3+ -cetyltrimethylammonium bromide (CTAB) system for the detection of NFLX, a simple and sensitive method based on fluorescence enhancement was developed.; Results: In pH 7.0 buffer solution, NFLX reacted with Nd3+ to form a complex, which resulted in fluorescence enhancement of NFLX, and the maximum emission peak shifted from 415 nm for NFLX to 450 nm for NFLX-Nd3+ . Moreover, the fluorescence intensity increased further when the surfactant CTAB was added to NFLX-Nd3+ . Under the optimum conditions, the fluorescence intensity of the NFLX-Nd3+ -CTAB system was linearly correlated with the NFLX concentration in the range 0.038-10 µmol L-1 , with a correlation coefficient (R2 ) of 0.9997. The detection limit (3σ/k) was 0.021 µmol L-1 , indicating that this method can be applied to detect trace NFLX levels. The mechanism of fluorescence enhancement is discussed. The method was used to detect NFLX in fish and chicken samples with satisfactory results.; Conclusion: The present results indicate that this method has the potential for fast and real-time determination of NFLX in food samples © 2016 Society of Chemical Industry.; © 2016 Society of Chemical Industry.

Herein, we report a heterogeneous single iron atom catalyst exhibiting excellent peroxidase, oxidase and catalase enzyme-like activities (defined as single atom enzymes, SAEs), exceeding those of Fe3O4 nanozymes by a factor of 40. Our findings open up a new family of artificial materials that mimic natural enzymes.

A simple and sensitive spectrofluorometry method for the determination of ascorbic acid was reported. In alkaline solution, the nonfluorescent thiamine was oxidized by potassium ferricyanide and formed the fluorescent thiochrome with an excitation maximum at 367 nm and an emission peak at 441 nm. However, the fluorescence intensity gradually decreased in the presence of ascorbic acid. The decreased fluorescence was linearly dependent under the optimum conditions with the concentration of ascorbic acid from 0.086–1.5 µmol L−1 with a correlation coefficient of 0.9996. The detection limit of 0.026 µmol L−1 was lower than many other methods. Additionally, the mechanism underlying the enhancement and quenching of this method was discussed. The protocol was used to determine ascorbic acid in tablets and juice with satisfactory results.

To establish a rapid and sensitive ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the determination of concentration of nintedanib and its metabolite BIBF 1202 in rat plasma. The nintedanib and its metabolite and the internal standard (diazepam) were separated on an Acquity UPLC BEH C18 chromatography column (2.1 mm×50 mm, 1.7 μm) using gradient elution with a mobile phase of acetonitrile and 0.1% formic acid in water at a flow rate of 0.30 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode to monitor the precursor-to-product ion transitions of m/z540.3→113.1 for nintedanib, m/z526.3→113.0 for BIBF 1202 and m/z285.3→193.1 for diazepam (IS) using a positive electrospray ionization interface. The method was validated for 1.0-200 ng/mL for nintedanib and 0.5-100 ng/mL for BIBF 1202 using 100 μL of plasma sample. Total time for each chromatograph was 3.0 min. The intra- and inter-day precision and accuracy of the quality control samples at low, medium, and high concentration levels exhibited relative standard deviations (RSD)

The aim of this study was to assess the influence of cantharidin on the activities of the drug-metabolizing enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 in rats. The activities of CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 were measured using specific probe drugs. After pretreatment for 1week with cantharidin or physiological saline (control group) by intraperitoneal injection, probe drugs phenacetin (5.0mg/kg; CYP1A2 activity), tolbutamide (1.0mg/kg; CYP2C9 activity), omeprazole (10mg/kg; CYP2C19 activity), metoprolol (20mg/kg; CYP2D6 activity) and midazolam (10mg/kg; CYP3A4 activity) were administered to rats by oral administration. The blood was then collected at different times for ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis. The data showed that cantharidin exhibits an inhibitory effect on CYP2D6 and CYP3A4 by increasing t1/2, Cmax and AUC(0-∞), and decreasing CL/F compared with those of the control group. In addition, cantharidin has induction effect on CYP2C9 activity. However, no significant changes in CYP1A2 and CYP2C19 activities were observed. In conclusion, the results indicated that cantharidin could inhibit CYP2D6 and CYP3A4, while induce CYP2C9, which may affect the disposition of medicines primarily dependent on these pathways. Our work may be the basis of related herb-drug interactions in the clinic.

The utilization of long-wave light (1000–2500 nm) in the solar spectrum is a difficulty in photocatalysis. Based on the Arrhenius equation, the activated carbon (AC)/graphitic carbon nitride (CN) composites were designed for photothermal-assisted photocatalytic water treatment. The short-wave solar energy can be converted to chemical energy on CN, and the long-wave solar energy to thermal energy by AC. The energetics and the interfacial charge transfer of activated carbon (AC)/graphitic carbon nitride (CN) composites (ACCN) were improved owing to the π bond between AC and CN. The excellent light absorption capacity (over 80%) led to higher photocatalytic reaction temperature due to the photothermal effect. The higher temperature accelerated the photocatalytic reaction and facilitates the charge transfer on ACCN. Hence, the optimal ACCN sample with good balance between photothermal and photocatalytic property could degrade 98% of sulfamerazine under simulated solar irradiation in 60 min. This work not only developed efficient and low-cost (~$1/kg) carbon-based photocatalysts with ultrahigh solar utilization, but also discussed the mechanism of photothermal effect on photocatalytic reaction.

While engineering the phase and structure of electrocatalysts could regulate the performance of many typical electrochemical processes, its importance to the carbon dioxide electroreduction has been largely unexplored. Herein, a series of phase and structure engineered copper-tin dioxide catalysts have been created and thoroughly exploited for the carbon dioxide electroreduction to correlate performance with their unique structures and phases. The copper oxide/hollow tin dioxide heterostructure catalyst exhibits promising performance, which can tune the products from carbon monoxide to formic acid at high faradaic efficiency by simply changing the electrolysis potentials from −0.7 VRHE to −1.0 VRHE. The excellent performance is attributed to the abundant copper/tin dioxide interfaces involved in the copper oxide/hollow tin dioxide heterostructure during the electrochemical process, decreasing the reaction free-energies for the formation of COOH* species. Our work reported herein emphasizes the importance of phase and structure modulating of catalysts for enhancing electrochemical CO2 reduction and beyond., While CO2 removal will play a crucial role in limiting climate change, it is challenging to understand the factors that control materials’ selectivity to convert CO2 to valuable products. Here, authors show copper and tin oxide interfaces to impact activities for CO2 reduction products.

As one of the most prominent metal-hydrides, beryllium hydride has received much attention over the past several decades, since 1978, and is considered as an important hydrogen storage material. By reducing the dimensionality from 3 to 2, the beryllium hydride monolayer is isoelectronic with graphene; thus the existence of its two-dimensional (2D) form is theoretically feasible and experimentally expected. However, little is known about its 2D form. In this work, by a global minimum search with the particle swarm optimization method via density functional theory computations, we predicted two new stable structures for the beryllium hydride sheets, named α–BeH2 and β–BeH2 monolayers. Both structures have more favorable thermodynamic stability than the recently reported planar square form (Nanoscale, 2017, 9, 8740), due to the forming of multicenter delocalized Be–H bonds. Utilizing the recently developed SSAdNDP method, we revealed that three-center-two-electron (3c–2e) delocalized Be–H bonds are formed in the α–BeH2 monolayer, while for the β–BeH2 monolayer, novel four-center-two-electron (4c–2e) delocalized bonds are observed in the 2D system for the first time. These unique multicenter chemical bonds endow both α– and β–BeH2 with high structural stabilities, which are further confirmed by the absence of imaginary modes in their phonon spectra, the favorable formation energies comparable to bulk and cluster beryllium hydride, and the high mechanical strength. These results indicate the potential for experimental synthesis. Furthermore, both α– and β–BeH2 are wide-bandgap semiconductors, in which the α–BeH2 has unusual mechanical properties with a negative Poisson's ratio of −0.19. If synthesized, it would attract interest both in experiment and theory, and be a new member of the 2D family isoelectronic with graphene.

Intrinsically inferior electrocatalytic activity of NiFe layered double hydroxides (LDHs) nanosheets is considered as a limiting factor to inhibit the electrocatalytic properties for oxygen evolution reaction (OER). Proper defect engineering to tune the surface electronic configuration of electrocatalysts may significantly improve the intrinsic activity. In this work, the selective formation of cation vacancies in NiFe LDHs nanosheets is successfully realized. The as-synthesized NiFe LDHs-VFe and NiFe LDHs-VNi electrocatalysts show excellent activity for OER, mainly attributed to the introduction of rich iron or nickel vacancies in NiFe LDHs nanosheets, which efficiently tune the surface electronic structure increasing the adsorbing capacity of OER intermediates. Density functional theory (DFT) computational results also further indicate that the OER catalytic performance of NiFe LDHs can be pronouncedly improved by introducing Fe or Ni vacancies.

A simple and sensitive resonance Rayleigh scattering (RRS) spectra method was developed for the determination of calf thymus DNA (ctDNA). The enhanced RRS signals were based on the interactions between ctDNA and aminoglycoside antibiotics (AGs) including kanamycin (KANA), tobramycin (TOB), gentamicin (GEN) and neomycin (NEO) in a weakly acidic medium (pH 3.3–5.7). Parameters influencing the method were investigated. Under optimum conditions, increments in the scattering intensity (∆I) were directly proportional to the concentration of ctDNA over certain ranges. The detection limit ranged from 12.2 to 16.9 ng/mL. Spectroscopic methods, including RRS spectra, absorption spectra and circular dichroism (CD) spectroscopy, coupled with thermo-denaturation experiments were used to study the interactions, indicating that the interaction between AGs with ctDNA was electrostatic binding mode. Copyright © 2015 John Wiley & Sons, Ltd.

A novel simple sensitive and inexpensive method based on the formation of Turnbull's blue nanoparticles using resonance Rayleigh scattering has been developed for the determination of hydroquinone (HQ). The results show that Fe3+ is deoxidized to Fe2+ by hydroquinone in pH 2.7 HCl (0.002 mol L−1) solution, then Fe2+ reacts with potassium ferricyanide to form a soluble Turnbull's blue (KFe[Fe(CN)6]), and further aggregates to form {KFe[Fe(CN)6]}n nanoparticles. These results induce a significant enhancement of resonance Rayleigh scattering (RRS). The maximum scattering wavelength of the ion-association complex is located at about 310 nm. The increment of scattering intensity (IRRS) is directly proportional to the concentration of HQ in the range of 0.46–50.0 μmol L−1. This method has high sensitivity and the detection limit (3σ/k) for HQ is 0.14 μmol L−1. In this work, the characteristics of absorption and RRS spectra of this reaction have been studied. The optimum reaction conditions and influencing factors have been investigated. Furthermore, the reaction mechanism and the reasons for the RRS enhancement have been explored. Additionally, the method is applied to the determination of HQ in local river water samples with satisfactory results.

A new method based on resonance Rayleigh scattering (RRS) was proposed for the determination of quinolones (QNS) at the nanogram level. In pH 3.3–4.4 Britton–Robinson buffer medium, quinolones such as ciprofloxacin, pipemidic acid (PIP), lomefloxacin (LOM), norfloxacin (NOR) and sarafloxacin (SAR) were protonated and reacted with methyl orange (MO) to form an ion-pair complex, which then further formed a six-membered ring chelate with Pd(II). As a result, new RRS spectra appeared and the RRS intensities were enhanced greatly. RRS spectral characteristics of the MO–QNS–Pd(II) systems, the optimum conditions for the reaction, and the influencing factors were investigated. Under optimum conditions, the scattering intensity (∆I) increments were directly proportional to the concentration of QNS with in certain ranges. The method had high sensitivity, and the detection limits (3σ) ranged from 6.8 to 12.6 ng/mL. The proposed method had been successfully applied for the determination of QNS in pharmaceutical formulations and human urine samples. In addition, the mechanism of the reaction system was discussed based on IR, absorption and fluorescence spectral studies. The reasons for the enhancement of scattering spectra were discussed in terms of fluorescence-scattering resonance energy transfer, hydrophobicity and molecular size. Copyright © 2014 John Wiley & Sons, Ltd.

In this work, second order scattering (SOS), frequency double scattering (FDS), the overlapping method of the two (SFOM), and resonance Rayleigh scattering (RRS) method had been developed for sensitive determination of trace 6-benzyladenine (BA) in bean sprout samples. In pH 1.6 HCl-NaAc medium, Pd(II) reacted with BA to form a 1:1 chelate complex, and then, the complex further self-aggregated into nanoparticles [Pd(II)-BA]n. This resulted in a remarkable enhancement of resonance Rayleigh-scattering (RRS), second-order scattering (SOS), and frequency-double scattering (FDS) spectra. The maximum wavelengths were located at 312 nm (RRS), 632 nm (SOS), and 323 nm (FDS), respectively. The increments of scattering intensities ΔI were directly proportional to the concentration of BA in certain ranges. The detection limits were 7.0 nmol L−1 (0.79 μg/kg, RRS), 10.3 nmol L−1 (1.16 μg/kg, SOS), 39.4 nmol L−1 (4.44 μg/kg, FDS), and 8.6 nmol L−1 (0.96 μg/kg, SFOM). In addition, the optimum conditions of the reaction, and the effects of coexisting substances were investigated. The results showed that these methods exhibited a high selectivity. The reaction mechanism and the reasons for the enhancement of scattering were also discussed. Moreover, the feasibility for the SFOM method was illustrated in this paper. The proposed method had been successfully applied to determine a trace amount of BA in bean-sprout samples with the recoveries of 97.0–103.0 %.

In this work, a synthetic meso-tera (4-sulfophenyl) porphyrin (TPPS4) was used as a probe to determine daunorubicin (DNR) by fluorescence quenching and spectrophotometric methods. At pH 4.6 potassium acid phthalate-NaOH buffer solution, a 1:1 complex of DNR interacted with TPPS4 formed via the electrostatic attractions and hydrophobic interactions, thus resulted in TPPS4 fluorescence quenching and absorption spectra change. The maximum excitation wavelength (λex) and the maximum emission wavelength (λem) are 435 nm and 672 nm, respectively. The fluorescence quenching values (ΔF) are the good linear relationship to the concentration of DNR in the range of 0.8-6.0 mgL(-1). The method exhibits high sensitivity with the detection limit (3σ) being 27.0 ng mL(-1). Meanwhile, a decrease of absorbance is detected at 433 nm with the appearance of a new absorption peak at 420 nm. The optimum reaction conditions, influencing factors and the effect of coexisting substances have been investigated in our experiment. The results showed that the method had a good selectivity and could be applied to determine DNR in serum and urine samples. In addition, the combine ratio between DNR and TPPS4 was measured and the charge distribution before and after reaction was calculated by quantum chemistry calculation AM1 method. The type of fluorescence quenching was discussed by the absorption spectra change, Stern-Volmer plots and fluorescence lifetime determination.

A method is presented for the sensitive and selective determination of trace allura red (AR) with ethyl violet (EV) in drink samples, based on triple-wavelength overlapping resonance Rayleigh scattering (TWO-RRS). At pH 10.0 in a Britton–Robinson (BR) buffer medium, AR combined with EV to form an ion-association complex, which resulted in the RRS intensity getting enhanced significantly with new RRS peaks appearing at 341, 508 and 666 nm. The scattering intensities of the three peaks were proportional to the concentration of AR in the range of 0.057–5.0 μmol L−1 (0.028–2.48 μg mL−1). The detection limits for the three single peaks were 0.048 μmol L−1 (0.024 μg mL−1), 0.050 μmol L−1 (0.025 μg mL−1), and 0.057 μmol L−1 (0.028 μg mL−1), while that of the TWO-RRS method was 0.017 μmol L−1 (0.008 μg mL−1), indicating that the TWO-RRS method could detect trace AR with high sensitivity. In addition, the optimum reaction conditions and the effects of foreign substances were studied. The composition of the ion-association complex, and the reasons for the enhancement of RRS were also investigated. The proposed method was successfully applied in a real sample analysis with satisfactory results.

Fluorescent carbon dots was prepared by heating N-(2-hydroxyethyl)ethylene diaminetriacetic acid in air. The carbon dots were not only highly soluble in water but also uniform in size, and possessed strong blue fluorescence and excitation wavelength-dependent emission properties with the maximum excitation and emission wavelength at 366 nm and 423 nm, respectively. Food colorant sunset yellow whose excitation and emission wavelength at 303 nm and 430 nm could selectively quench the fluorescence of carbon dots, efficient fluorescent resonance energy transfer between the carbon dots and sunset yellow is achieved. This was exploited to design a method for the determination of sunset yellow in the concentration range from 0.3 to 8.0 μmol L− 1, with a limit of detection (3 σ/k) of 79.6 nmol L− 1. Furthermore the fluorimetric detection method was established and validated for sunset yellow in soft drinks samples with satisfactory results.

Based on l -tryptophan-Pd(II) system, a sensitive and selective fluorimetric assay for the quantification of ceftriaxone (CTRX) had been developed. The experimental results showed that in pH 4.0 Britton–Robinson (BR) buffer medium, the fluorescence of l -tryptophan ( l -Trp) ( λ ex / λ em = 276 nm/352 nm) could be efficiently quenched by Pd(II). When CTRX was added to the mixed solution of the l -tryptophan and Pd(II), the fluorescence of l -Trp recovered. The reaction mechanism and the reasons for the fluorescence recovery were also discussed. Pd(II) reacted with l -Trp to form a 1:1 chelate complex, and then, after CTRX was added in l -Try-Pd(II) system, the ligand exchange reaction occurred between l -Trp and CTRX, which resulted in the fluorescence recovery. Under the optimized experimental conditions, the recovered fluorescence intensities at 352 nm showed excellent linear relationship with the concentration of CTRX over the range of 6.0 × 10 − 8 –2.4 × 10 − 6 mol L − 1 (0.040–1.59 μg mL − 1 ). The correlation coefficient (R) was 0.9997 and the detection limit was 1.8 × 10 − 8 mol L − 1 (11.9 ng mL − 1 ). Furthermore, the assay had been applied to determine trace amount of CTRX human urine samples with satisfactory results.

In the present study, a novel triple-wavelength overlapping resonance Rayleigh scattering (TWO-RRS) method had been well established to detect perfluorooctane sulfonate (PFOS). We found that crystal violet (CV) could react with PFOS to form 1:1 ion-association complex by electrostatic attraction and hydrophobic effect over a wide pH range (5.0∼11.0) in less than 60 s. The complexes would further self-aggregated into nanoparticles [CV-PFOS]n. Based on this phenomenon, not only the absorption and Raman spectra were changed but also the resonance Rayleigh scattering (RRS) intensities were significantly enhanced. And three new RRS peaks located at 327, 492, and 654 nm were clearly observed, respectively. At the same time, it was found that both the enhanced single-wavelength resonance Rayleigh scattering (SW-RRS) and TWO-RRS intensities against the concentration of PFOS showed an excellent correlation. The detection limits for the three single peaks were 27.4 nmol L(-1) (13.7 μg L(-1), 327 nm), 27.5 nmol L(-1) (13.8 μg L(-1), 492 nm), and 31.4 nmol L(-1) (15.7 μg L(-1), 654 nm), and for TWO-RRS method was 5.9 nmol L(-1) (3.0 μg L(-1)). Moreover, it could be applied to determine PFOS water samples successfully.

In this study, a simple, sensitive, and robust analytical method based on ultra-performance liquid chromatography (UPLC) has been developed for the determination of apatinib in rat plasma using carbamazepine as internal standard (IS). After sample preparation by a simple liquid-liquid extraction, chromatography was performed on an Acquity UPLC BEH C18 column (2.1 × 50 mm, 1.7 µm particle size) and total run time was 2.0 min. The method was linear over the concentration range 5-1000 ng/mL with a lower limit of quantification of 5 ng/mL. Inter- and intraday precision were all within 6.5% and the accuracy was ≤3.5%. Recoveries of apatinib and IS were >80%. Stability studies showed that apatinib was stable under a variety of storage conditions. The method was successfully applied to a pharmacokinetic study involving oral administration of apatinib to rats.

An enhanced spectrofluorimetric method for highly selective and sensitive determination of nmol L−1 of hypochlorite has been performed. In alkaline medium, ferrocyanide was specifically oxidized by hypochlorite to form ferricyanide, which further reacted with non-fluorescent thiamine, resulting in the formation of blue fluorescent thiochrome. Notably, the fluorescence intensities were positively correlated with the concentration of hypochlorite over the range of 0.02–12.5 μmol L−1. The detection limit was 6.1 nmol L−1, which was lower than for most of the recently published methods. The experimental conditions were optimized and effects of coexisting substances were evaluated and the results showed excellent priority since a certain amount of other anions, including ClO3−, BrO3−, IO3−, Cr2O72− and other acid radicals, would not interfere with the measurement.

A simple and very selective spectrofluorimetric method for the detection of ng mL−1 levels of inorganic selenium species in infant formulas has been performed. It is based on the oxidation of micelle-capped nile blue A (MCNBA) by sodium selenite under neutral conditions (pH 7.0). A specific quenching of the fluorescence of MCNBA was observed and the response signals were linearly correlated with the concentration of sodium selenite over the ranges of 4.17 × 10−9 to 4.5 × 10−6 mol L−1 (0.73–787.1 ng mL−1). The limit of detection was 1.25 nmol L−1 (0.22 ng mL−1). Different parameters such as selectivity, recovery, linearity, limits of detection and quantification of the measurements were evaluated in order to validate the proposed method. Then, the new method was applied to the analysis of several infant formula samples with satisfactory results.