Highly sensitive trivalent copper chelate-luminol chemiluminescence system for capillary electrophoresis chiral separation and determination of ofloxacin enantiomers in urine samples

A simple,fast and sensitive capillary electrophoresis（CE） strategy combined with chemiluminescence（CL） detection for analysis of ofloxacin（OF） enantiomers was established in the present work.Sulfonated p-cyclodextrin（β-CD） was used as the chiral additive being added into the running buffer of luminol-diperiodatocuprate（Ⅲ）（K[Cu（HIO6）2],DPC） chemiluminescence system.Under the optimum conditions,the proposed method was successfully applied to separation and analysis of OF enantiomers with the detection limits（S/N=3） of 8.0 nM and 7.0 nM for levofloxacin and dextrofloxacin,respectively.The linear ranges were both 0.010-100 μM.The method was utilized for analyzing OF in urine;the results obtained were satisfactory and recoveries were 89.5-110.8%,which demonstrated the reliability of this method.This approach can also be further extended to analyze different commercial OF medicines.

Gold nanoparticles based digital color analysis for quinidine detection

In this contribution,we developed a novel digital color analysis of gold nanoparticles(AuNPs) for pharmaceutical detection by choosing quinidine as an example.It was found that the color of AuNPs colloid solution changed from red to blue in the presence of different concentrations of quinidine,and the color information of each solution could be digitalized with tricolor(RGB) system.Under the optimum conditions,the R value of the solution was found to be linear with the natural logarithm of concentration of quinidine in the range of 112 384 nmol/L.This method has the advantages of rapid,economical and simple,and can serve as a potential alternative to traditional spectrophotometry for practical use.

Multi-walled carbon nanotubes based catalyst plasmon resonance light scattering analysis of tetracycline hydrochloride

It was found that multi-walled carbon nanotubes (MWNTs) could catalyze the redox reaction between chlorauric acid (HAuCl4) and reductive drugs such as tetracycline hydrochloride (TC), producing gold nanoparticles (Au NPs). By measuring the plasmon resonance light scattering (PRLS) signals of the resulting Au NPs, tetracycline hydrochloride can be detected simply and rapidly with a linear range of 4―26 μmol/L, a correlated coefficient (r ) of 0.9955, and a limit of detection (3σ) of 6.0 nmol/L. This method has been successfully applied to the detection of tetracycline hydrochloride tablets in clinic with the recovery of 101.9% and that of fresh urine samples with the recovery of 98.3%―102.0%.

Selectively colorimetric detection of cysteine with triangular silver nanoprisms

Triangular silver nanoprisms were prepared and applied to make colorimetric detection of cysteine based on our findings that cysteine could lead to the blue shift of the dipole plasmon resonance absorption, but other 19 kinds of natural amino acids could not. Cysteine with a concentration 160 nmol/L can result in a color change that can be discerned with naked eyes.

The Effect of the Structure of Polychlorinated Biphenyls on their Hydroxylation, Oxidation,and Glutathionyl Conjugation Reactions

Objective To compare the nature of the metabolites formed from the phase I metabolism （hydroxylation and oxidation） and phase II metabolism （glutathionyl conjugation） of PCBs that have different chlorine substitution patterns. To discuss the structure-activity relationships and metabolic mechanisms of PCBs. Methods 4-CI-biphenyl （PCB3）, 4,4＇-CI-biphenyl （PCB15）, 3,4,3＇,4＇-Cl-biphenyl （PCB77） were used for in vitro metabolic study. LC/MS and UV-Vis studies were performed for metabolites identification. Results The cytochrome P-450 catalyzed hydroxylation rate decreased as the number of chlorine substitutions increased. In this reaction, PCB3 was fully metabolized, approximately half of the PCB15 was metabolized and PCB77 was not metabolized at all. The oxidation rate of PCB15-HQ was higher than that of PCB3-HO. under various oxidation conditions. The LC/MS and UV-Vis data suggest that in the conjugation reaction of PCB15-Q and GSH, the Michael addition reaction occurs preferentially over the displacement reaction. Conclusion The metabolic profiles of polychlorinated biphenyls （PCBs） are dramatically affected by chlorine substitution patterns. It is suggested that the metabolic profiles of PCBs are related to their chlorine substitution patterns, which may have implications for the toxicity of PCB exposure.

Resonance Light Scattering Method for Determination of Amikacin with Potassium Ferrioxalate as a Probe

In a weak acid medium, potassium ferrioxalate（PF） can react with some aminoglycoside（AGs） antibiotics, such as amikacin（AMK）, kanamycin（KANA）, tobramycin（TOB） and gentamicin（GEN）, to form ion-association complexes. It results in the enhancement of resonance light scattering（RLS） in different degrees. The maximum scattering peaks are all located at 345 nm. Among them, the relative scattering intensity（AIRLs） of AMK system is much higher than that of KANA, TOB or GEN. Therefore the method is more propitious to the determination of trace amounts of AMK. The optimum reaction conditions, influencing factors, and the relationship between scattering intensity and concentration of antibiotics were investigated by means of the proposed method. The enhancement of RLS signals is directly proportional to the concentration of antibiotics in a certain range of concentration. A new resonance light scattering method for the determination of AMK and other aminoglycoside antibiotics with [Fe（C2O4）3]^3- as a probe is thus established based on it. The method exhibits high sensitivity and good selectivity. The detection limit（3σ） for AMK is 1.8 ng/mL. The method can be applied to the determination of AMK in clinical serum samples. The reaction mechanism and the reasons for RLS enhancement are discussed in this paper.

Cellular prion protein imaging analysis with aptamer-labeled Ru(bpy)_3^(2+)-doped silica nanoparticles

A new type of highly selective aptamer-labeled fluorescent silica nanoparticles[Apt-tris(2,20-bipyridyl)ruthenium(II)@SiO2NPs]were prepared through the reverse microemulsion method by using prolonged fluorescence lifetime ruthenium complexes of tris(2,20-bipyridyl)ruthenium(II)(Ru(bpy)32?)as the source of the fluorescence for cellular prion protein imaging.Investigations showed that the newly prepared Ru(bpy)32?@SiO2NPs possessed superior advantages of strong fluorescence,low toxicity,and easy surface modification for bioconjugation.Cell imaging experiments indicated that AptRu(bpy)32?@SiO2NPs had great tendency to human bone marrow neuroblastoma cells(SK-N-SH cells),since they can express large amount of prion protein on the surface of the cell,while in HeLa cells this phenomenon disappeared for the reason that HeLa cells cannot express prion proteins.

Determination of Matrine and Oxymatrine in Radix Sophorae Flavescentis by Resonance Rayleigh Scattering, Second-order Scattering and Frequency Doubling Scattering Technique

In 0.1 mol/L HCl medium, 12-tungstophosphoric（TP） acid reacted with matrine（Mat） and oxymatrine（Oxy） to form an ion-association complex. As a result, the new spectra of resonance Rayleigh scattering（RRS）, second-order scattering（SOS） and frequency doubling scattering（FDS） appeared and their intensities were enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS were located at 370, 670 and 390 nm, respectively. The in-crements of scattering intensity were directly proportional to the concentration of Mat and Oxy in a certain range. Based on this, the method for the determination of matrine and oxymatrine has been established. It has been applied to the determination of matrine and oxymatrine in samples of Radix sophorae flavescentis with satisfactory result. The reaction mechanism and reasons of RRS enhancement were discussed.

Resonance Rayleigh Scattering and Resonance Nonlinear Scattering Methods for Determination of Methylene Blue with 12-Tungstophosphoric Acid

In a pH=0.65―1.5 NaAc-HCl medium, methylene blue（MB） reacts with 12-tungstophosphoric acid （TPA） by virtue of electrostatic attraction and hydrophobic force to form a 3：2 ion-association complex. As a result, the intensities of resonance Rayleigh scattering（RRS）, second-order scattering（SOS） and frequency doubling scatte- ring（FDS） are enhanced greatly. The maximum scattering wavelengths of RRS, SOS and FDS are located at 316, 647 and 311 nm. The increments of scattering intensity（△I） are directly proportional to the concentration of MB in a certain range. The methods exhibited high sensitivity, and the detection limits（3s） for MB are 2.3 ng/mL（RRS method）, 5.6 ng/mL（SOS method） and 6.4 ng/mL（FDS method）, respectively. The effects of coexisting substances have been examined, and the results indicate that the methods have good selectivity. Based on the above researches, a new spectral method for the determination of trace amounts of MB has been developed. It can be applied to the determination of MB in human serum, and the recoveries are 97.5%―105.0%. The results are in good agreement with those obtained by the pharmacopoeia method. In this work, the optimum conditions of the reaction and the influencing factors were investigated. In addition, the reaction mechanism and the reasons of the enhancement of resonance light scattering were discussed.

Determination of Hyoscine Butylbromide with Ag＋ and Dihalogenated Fluorescein Dyes in Capsules by Resonance Rayleigh Scattering Method Coupled with Flow Injection Analysis Techniquet

In pH 4.2-5.2 HOAc-NaOAc buffer solution, Ag＋ reacted with dihalogenated fluorescein （DHF） dyes to form a 1 ; 2 anionic complex. This anionic complex could further react with hyoscine butylbromide （HBB） to form 1 ： 1 ion-association complex, which resulted in the significant enhancement of resonance Rayleigh scattering （RRS） intensity. Therefore, a novel method for the determination of HBB by resonance Rayleigh scattering （RRS） coupled with flow injection analysis （FIA） technique has been established. The present method had been applied to determine HBB in capsules and the results were in good agreement with those obtained by the literature method.

Color-Tunable Hybrid White Organic Light-Emitting Diodes with Double Interlayers

An efficient color-tunable hybrid white organic light-emitting diode is demonstrated with double interlayers of 2,7-bis(carbazol-9-yl)-9,9-ditoylfluo- rene/2-(diphenylphosphoryl) spiroflu-orene (DMFL-CBP/SPPO1) inserted between blue fluorescent and yellow phosphorescent-emitting layers, and exhibits Commission Internationale de l’Eclairage (CIE1931) ranging from warm white (0.4368, 0.4497) to cool white (0.2781, 0.2896) with driving current density from 0.2 to 40 mA/cm2. The recombination of singlet and the triplet excitons in blue fluores-cent-emitting layer and yellow phosphorescent-emitting layer, respectively, can be modulated by both the thickness of these double interlayers and the applied current densities.

Highly selective recognition of adenosine 5′-triphosphate against other nucleosides triphosphate with a luminescent metal-organic framework of [Zn(BDC)(H_2O)_2]_n(BDC = 1,4-benzenedicarboxylate)

Selective recognition of adenosine 5＇-triphosphate （ATP） is of great significance owing to its indispensable functions to organisms. Also, it is a challenging task because other nucleosides triphosphate hold the same triphosphate group and structurally planar bases as ATP. It is known that metal-organic frameworks （MOFs） are a new type of sensing material. In this work, highly selective recognition of ATP against other nucleosides triphosphate is successfully achieved with a luminescent MOF of [Zn（BDC）（H2O）2]n （BDC2- = 1,4-benzenedicarboxylate）. [Zn（BDC）（H2O）2]n dispersed in water shows a remarkable redshift of the emission wavelength upon addition of ATP, while cytidine 5＇-triphosphate （CTP）, uridine 5＇-triphosphate （UTP） and guanosine 5＇-triphosphate （GTP）, as well as some inorganic anions such as P2074- or PO43- can＇t induce such spectral change as ATP. 1H NMR, 31p NMR and Raman spectra indicate that both π-π stacking interactions and the coordination of Zn（II） with adenine and the phosphate group are involved in the interaction of [Zn（BDC）（H2O）2],, with ATP. In addition, the experimental results showed that the redshift extent of the emission wavelength of [Zn（BDC）（HzO）2]n has the linear relation- ship with the concentration of ATP in the range of 0.3-1.8 mmol/L. Based on this, the detection of ATP content in the sample of ATP injection was made with satisfactory results. This system pioneers the application of MOFs in the recognition of nucle- otides, and testifies that the participation of base in the recognition process can improve the selectivity against the other nucleotides.

One-step synthesis of fluorescent hydroxyls-coated carbon dots with hydrothermal reaction and its application to optical sensing of metal ions

Carbon dots (CDs) with average diameter of 3.1 ± 0.5 nm were facilely synthesized with candle soot through hydrothermal reaction in sodium hydroxide aqueous solution. The as-prepared CDs were covered with a lot of hydroxyls, possessed properties of good water-solubility, anti-photobleaching, salt tolerance, and low cytotoxicity, and had a fluorescence quantum yield (QY) of about 5.5%. The fluorescence of the hydroxyls-coated CDs could be selectively quenched by metal ions such as Cr3+, Al3+ and Fe3+, which is because these metals can easily combine with the hydroxyl groups on the surface of CDs and induce aggregation of hydroxyls-coated CDs. Experiments showed that the quenching of Cr3+ had a Sterm-Volmer constant of 1.03 × 107 M-1 with a liner range of 1.0-25.0 μM and detection limit of 60 nM (3σ).

Toxicity of graphene oxide and multi-walled carbon nanotubes against human cells and zebrafish

Graphene possesses unique physical and chemical properties, which have inspired a wide range of potential biomedical applications. However, little is known about the adverse effects of graphene on the human body and ecological environment. The purpose of our work is to make assessment on the toxicity of graphene oxide (GO) against human cell line (human bone marrow neuroblastoma cell line and human epithelial carcinoma cell line) and zebrafish (Danio rerio) by comparing the toxic effects of GO with its sister, multi-walled carbon nanotubes (MWNTs). The results show that GO has a moderate toxicity to organisms since it can induce minor (about 20%) cell growth inhibition and slight hatching delay of zebrafish embryos at a dosage of 50 mg/L, but did not result in significant increase of apoptosis in embryo, while MWNTs exhibit acute toxicity leading to a strong inhibition of cell proliferation and serious morphological defects in developing embryos even at relatively low concentration of 25 mg/L. The distinctive toxicity of GO and MWNTs should be ascribed to the different models of interaction between nanomaterials and organisms, which arises from the different geometric structures of nanomaterials. Collectively, our work suggests that GO does actual toxicity to organisms posing potential environmental risks and the result is also shedding light on the geometrical structure-dependent toxicity of graphitic nanomaterials.

Characterization of γ-Fe_2O_3 nanoparticles prepared by transformation of α-FeOOH

γ-Fe2O3 nanoparticles were successfully synthesized by a chemically induced transformation of α-FeOOH.In this method,the precursor(α-FeOOH)was prepared by chemical precipitation,and then treated with a mixed FeCl2/NaOH solution to produce the nanoparticles.X-ray diffraction indicated that when the precursor was treated with FeCl2(0.22 mol/L)and NaOH(0.19 mol/L),pure γ-Fe2O3 nanoparticles were obtained.However,when the concentration of FeCl2 was<0.22 mol/L or the concentration of NaOH was<0.19 mol/L,α-FeOOH and γ-Fe2O3 phases co-existed in the nanoparticles.Transmission electron microscopy observations showed that in the samples with co-existing phases,the nanoparticles did not have identical morphologies.The pure γ-Fe2O3 nanoparticles were polygonal rather than spherical.The volume ratio of α-FeOOH and γ-Fe2O3 was estimated for the two-phase samples from magnetization data obtained from a vibrating sample magnetometer.This chemically induced transformation is novel,and could provide an effective route for the synthesis of other metal oxide nanocrystallites.

Single scattering particles based analytical techniques

Single scattering particles,especially noble metal(plasmonic) nanoparticles,based analytical techniques are attractive recently and becoming the research focus of the light scattering analytical techniques.In this mini review,we summarize the single scattering particles based analytical techniques in the past decade including single scattering particles counting,single plasmonic nanoparticles sensing,and single plasmonic nanoparticles tracking/imaging.We emphasize the discussion on the single plasmonic nanoparticles sensing that combines with dark-field microscopy and resonant Rayleigh scattering spectroscopy.

Investigations of the interaction between cuprous oxide nanoparticles and Staphylococcus aureus

In this study, cuprous oxide nanoparticles of 30–50 nm in size were prepared in the presence of cetyltrimethylammonium bromide (CTAB). By taking Staphylococcus aureus (S.a), which always causes a variety of suppurative infections and toxinoses in humans, as a model bioparticle, the negative bioeffect of nano-Cu2O on S.a cells was evaluated, and minimal inhibitory concentration (MIC) was determined by imitating the MIC of antibiotics. Cellularity and bactericidal effect were measured by flow cytometry (FCM), dark field light scattering imaging and SEM photography. The results showed that nano-Cu2O particles may, by absorbing on the cell surface, impair the cell wall, damage the cell membrane, and finally increase permeability of the cell membrane, thus leading to a decrease in the viability of bacteria in the nano-Cu2O solution.

Study of magneto-optical effects in γ-Fe_2O_3/ZnFe_2O_4 nanoparticle ferrofluids, using circularly polarized light

When circularly polarized light travels through a ferrofluid film in the presence of an applied magnetic field, the transmitted light will behave as elliptically polarized light, because of magnetic birefringence and dichroism. The angular distribution of the relative intensity of the transmitted light can be obtained using a polarizer, so that the ratio of both the long and short ax- es-as well as the orientation angle of the ellipse, corresponding to the direction of the applied magnetic field--can be deter- mined, and whether the ferrofluids samples are stable during the measurement can be directly judged from the shape of the distribution curves. Thus, the ratio of the amplitudes Ax/Ay and the added phase difference A r can be resolved in the elliptically polarized light, and information on both the magnetic birefringence An and the dichroism Ak can be deduced for the ferrofluid sample. From the orientation angles of both right-handed and left-handed elliptically polarized transmitted light, the direction of the applied magnetic field can be accurately determined. Using circularly polarized light, the magnetic birefringence and dichroism of pure γ-Fe2O3 ferrofluids and γ--Fe2O3/ZnFe2O4 binary ferrofluids were studied. For the binary ferrofluids, a mod- ulating effect on the magnetic birefringence and dichroism was revealed.

Glucose oxidase as a blocking agent-based signal amplification strategy for the fabrication of label-free amperometric immunosensors

An effective electrochemical signal amplification strategy based on enzyme membrane modification and redox probe immobilization was proposed to construct an amperometric immunosensor.L-cysteine@ferrocene functionalized chitosan,which possessed not only efficient redox-activity but also excellent film-forming ability,was coated on the bare glass carbon electrode. Moreover,the thiol groups(SH)in the ferrocenyl compound were used for gold nanoparticles immobilization via the strong bonding interaction,which could further be utilized for the immobilization of antibody biomolecules with well-retained bioactivities.Finally,glucose oxidase(GOD)as the enzyme membrane was employed to block the possible remaining active sites and avoid the nonspecific adsorption.With the excellent electrocatalytic properties of GOD towards glucose,the amplification of antigen-antibody interaction and the enhanced sensitivity could be achieved.Under the optimal conditions,the linear range of the proposed immunosensor for the determination of carcinoembryonic antigen(CEA)was from 0.05 to 100 ng/mL with a detection limit of 0.02 ng/mL(S/N=3).Moreover,the immunosensor exhibited good selectivity,stability and reproducibility, which provided a promising potential for clinical immunoassay.

Mercuric ions induced aggregation of gold nanoparticles as investigated by localized surface plasmon resonance light scattering and dynamic light scattering techniques

With the development of nanosciences, both localized surface plasmon resonance light scattering （LSPR-LS） and dynamic light scattering （DLS） techniques have been widely used for quantitative purposes with high sensitivity. In this contribution, we make a comparison of the two light scattering techniques by employing gold nanoparticles （AuNPs） aggregation induced by mercuric ions. It was found that citrate-stabilized AuNPs got aggregated in aqueous medium in the presence of mercuric ions through a chelation process, resulting in greatly enhanced LSPR-LS signals and increased hydrodynamic diameter. The enhanced LSPR-LS intensity （A/） is proportional to the concentration of mercuric ions in the range of 0.4-2.5 laM following the linear regression equation of A/= -84.7＋516.4c, with the correlation coefficient of 0.983 （n = 6） and the limit of determi- nation （3o-） about 0.10 gM. On the other hand, the increased hydrodynamic diameter can be identified by the DLS signals only with a concentration of Hg2＋ in the range of 1.0-2.5 gM, and a linear relationship between the average hydrodynamic diame- ters of the resulted aggregates and the concentration of Hg2＋ can be expressed as d = -6.16 ＋ 45.9c with the correlation coeffi- cient of 0.994. In such case, LSPR-LS signals were further applied to the selective determination of mercuric ions in lake water samples with high sensitivity and simple operation.