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Agrobacterium rhizogenes-mediated transformation of sugar beet hairy roots expressing single-chain variable fragment (scFv) was exploited to evaluate the efficacy of four antibody-based constructs for interfering with the Beet necrotic yellow vein virus infection. The scFv specific to a major coat protein of virus, p21, was targeted to various cellular compartments including the cytosol (pIC and pICC constructs), apoplast (pIA), and mitochondrion (pIM). After mechanical virus inoculation, most of the hairy root clones expressing scFv in the cytosol displayed low virus titers while the majority of transgenic hairy root clones accumulated antibody in outer membrane of mitochondria or apoplast were infected. This hairy root system provided an efficient and rapid approach to initially investigating root disease resistance like rhizomania prior to transform whole recalcitrant plants such as sugar beet.

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A new enhancing fluorescent chemosensor was introduced for selective and sensitive determination of nickel ions based on 2-(1-H-benzo[d]imidazol-2yl)-N-phenyl hydrazine carbothioamide (L). L has an intrinsic fluorescent emission which enhances in presence of nickel ions in CH3CN/H2O (70:30, v/v) solution. The fluorescence enhancement of L is attributed to a 1:1 complex formation between L and Ni2+ ion which has been used for selective detection of Ni2+ ion. At the optimum conditions, the fluorescence intensity of L at 352 nm enhances linearly by the concentration of nickel ion from 1.6×10(-5) to 1.6×10(-7) M and detection limit of 7.9×10(-8) M. The new fluorescent probe exhibited high selectivity to Ni2+ ion over the other common mono, di-and trivalent cations.

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A turn-on fluorescent chemosensor is introduced for the detection of Lu(3+) ion using N-[3-methyl]-2-[pyridine-2-amido] phenyl] pyridine-2-carboxamide (L) molecule. Fluorescent emission intensity of L enhances after binding to Lu(3+) ions in ethanol-water solution (1:9, v/v). The observed enhancement is the result of a strong covalent binding between Lu(3+) ion and L (the binding constant value is 2.0×10(6) mol(-1) L). The proposed optical chemosensor can be applied for the analysis of Lu(3+) ion in a linear range of 3.3×10(-7) to 1.0×10(-5) mol L(-1). The limit of detection was obtained 8.6×10(-7) mol L(-1). The probe exhibits high selectivity toward Lu(3+) ion in comparison with common metal ions. The proposed fluorescent chemosensor was successfully used in the determination of Lu(3+) ion in some water samples.

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(E)-2-(1-(4-hydroxy-2-oxo-2H-chromen-3-yl)ethylidene)hydrazinecarbothioamide (L) has been used to detect trace amounts of praseodymium ion in acetonitrile-water solution (MeCN/H2O) by fluorescence spectroscopy. The fluorescent probe undergoes fluorescent emission intensity enhancement upon binding to Pr(3+) ions in MeCN/H2O (9/1:v/v) solution. The fluorescence enhancement of L is attributed to a 1:1 complex formation between L and Pr(3+), which has been utilized as the basis for selective detection of Pr(3+). The sensor can be applied to the quantification of praseodymium ion with a linear range of 1.6×10(-7) to 1.0×10(-5) M. The limit of detection was 8.3×10(-8) M. The sensor exhibits high selectivity toward praseodymium ions in comparison with common metal ions. The proposed fluorescent sensor was successfully used for determination of Pr(3+) in water samples.

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An overview of potentiometric sensors that are capable of detecting toxic heavy metal ions in environmental samples is presented and discussed. Notwithstanding the tremendous work performed so far, it is obvious that still several limitations do exist in terms of selectivity, limits of detection, dynamic ranges, applicability to specific problems, and reversibility. A survey on important advances in potentiometric sensors with regard to high selectivity, lower detection limit, fast response time, and on-line environmental analysis is presented in this review article. [Supplemental materials are available for this article. Go to the publisher's online edition of Critical Reviews in Analytical Chemistry to view the free supplemental file.].

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BACKGROUND AND THE PURPOSE OF THE STUDY: Ofloxacin is a quinolone synthetic antibiotic, which acts against resistant mutants of bacteria by inhibiting DNA gyrase. This antibacterial agent is widely used in the treatment of respiratory tract, urinary tract and tissue-based infections, which are caused by Gram-positive and Gram-negative bacteria. In this work, an efficient modified ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction (M-IL-CIA-DLLME) was combined with spectrofluorimetry for trace determination of ofloxacin in real samples. METHODS: In this microextraction method, hydrophobic 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim] [PF(6)]) ionic liquid (IL) as a microextraction solvent was dispersed into a heated sample solution containing sodium hexafluorophosphate (NaPF(6)) (as a common ion) and the analyte of interest. Afterwards, the resultant solution was cooled in an ice-water bath and a cloudy condition was formed due to a considerable decrease of IL solubility. After centrifuging, the enriched phase was introduced to the spectrofluorimeter for the determination of ofloxacin. RESULTS AND MAJOR CONCLUSION: In this technique, the performance of the microextraction method was not influenced by variations in the ionic strength of the sample solution (up to 30% w/v). Furthermore, [Hmim][PF(6)] IL was chosen as a green microextraction phase and an alternative to traditional toxic organic solvents. Different parameters affecting the analytical performance were studied and optimized. At optimum conditions, a relatively broad linear dynamic range of 0.15-125 µg l(-1) and a limit of detection (LOD) of 0.029 µg l(-1) were obtained. The relative standard deviation (R.S.D.) obtained for the determination of five replicates of the 10 ml solution containing 50 µg l(-1) ofloxacin was 2.7%. Finally, the combined methodology was successfully applied to ofloxacin determination in actual pharmaceutical formulations and biological samples.

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A novel fluorescent chemosensor 2-(5-(dimethylamino)naphthalen-1-ylsulfonyl)-N-phenylhydrazinecarbothioamide (L) has been synthesized, which revealed an emission of 530 nm and when excited at 360 nm. The fluorescent probe undergoes a fluorescent emission intensity quenching upon binding to terbium ions in MeCN solution. The fluorescence quenching of L is attributed to the 1:1 complex formation between L and Tb(III) which has been utilized as the basis for the selective detection of Tb(III). The linear response range covers a concentration range of Tb(III) from 4.0 x 10(-7) to 1.0 x 10(-5) M and the detection limit is 1.4 x 10(-7) M. The association constant of the 1:1 complex formation for L-Tb(+3) was calculated to be 6.01 x 10(6) M(-1), and the fluorescent probe exhibits high selectivity over other common metal ions mono-, di-, and trivalent cations indicate good selectivity for Tb(III) ions over a large number of interfering cations.

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In this work, a highly selective and sensitive gadolinium (Gd) optical sensor based on immobilization of bis(thiophenal) pyridine-2,6-diamine (BPD), on a triacetylcellulose membrane has been reported. This optode exhibits a linear range of the Gd(III) ion concentration of 2.5 x 10(-6)M with a detection limit of 0.93 x 10(-8) M. Response time of the newly designed optode was within 1-2 min, depending on the Gd(III) ion concentration. Response of the sensor is independent of solution pH in the range of 2.0-9.0. It manifests advantages of: low detection limit, fast response time, and most significantly, very good selectivity with respect to a number of lanthanide ions (La, Ce, Sm, Tm, Ho, and Eu ions). The sensor was successfully regenerated with thiourea solutions and its response was reversible and reproducible (R.S.D. less than 1.4%). This optode was applied to determine Gd(III) in synthetic and water samples, and validated with certified reference materials (CRMs).

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Diltiazem was determined at the sub-nanomolar level for the first time by a new technique, involving fast Fourier continuous cyclic voltammetry in a flow-injection system. The best performance was achieved with the basic parameters being set at pH value of 2.0, scan rate value of 35 V/s, accumulation potential of 300 mV and accumulation time of 0.8 s. This paper additionally introduces a special computer based numerical method for the calculation of the analyte signal and the noise reduction. Concerning the electrode response calculations were carried out according to the partial and total charge exchanges on the electrode surface after subtraction of background current from that of noise. Furthermore, to obtain a sensitive determination, the currents integration range included all potential scan ranges, even oxidation and reduction of the Au surface electrode, during the measurements. In general, the potential waveform includes the potential steps for cleaning, accumulation and the step of the potential ramp of the analyte. This potential waveform was applied to an Au disk microelectrode in a continuous way. Finally, the method was found to be linear for the concentration range of 1-41450 pg/ml (r = 0.9986), while showing a limit of detection and quantitation of 0.29 and 1 pg/ml, respectively.

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The effects of DPG,IHP,GTP,GDP and GMP on the structure and stability of haemoglobin were electrochemically investigated with an iodide-modified silver electrode in 0.01 M KNO 3 at pH 7.0.Anodic and cathodic peaks of haemoglobin were observed at 250 mV and 12 mV with a formal potential value of 133 mV vs.Ag/AgCl.The effects of different concentrations of DPG,IHP,GTP,GDP and GMP on the anaerobic redox reaction were determined. The results showed that DPG and IHP can lead to a positive shift in the reduction peak of haemoglobin,indicating that the oxidation peak shift of haemoglobin was small as a result of stabilization of the reduced state and destabilization of the R-like state of haemoglobin.GTP elicited a more positive shift in the cathodic and anodic peaks of haemoglobin at a higher concentration,signifying that it has a low-affinity binding site on haemoglobin.The positive shift of the cathodic and anodic peaks revealed a slight variation in the structure and indicated the unfolding of haemoglobin in the presence of high concentrations of GTP.Our study also showed that GDP and GMP did not cause significant shift the cathodic and anodic peaks of haemoglobin even at high concentrations,refuting the existence of specific GDP-and GMP-binding sites on the protein.Moreover,the iodide-modified silver electrode method proved to be easy and useful in investigating the effects of ligands or other effectors on haemoglobin in solution.

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In this work a novel method for the fast monitoring of lidocaine in flow-injection systems has been developed. The fast Fourier transform continuous cyclic voltammetry (FFTCV) at gold microelectrode in flowing solution system was used for determination of lidocaine in its pharmaceutical formulation. The presented technique was very simple, precise, accurate, time saving and economical, compared with all of the previously reported methods. The recommended technique demonstrated some advantages over other reported methods. Firstly, there was no need for the oxygen removal from the test solution. Secondly, a picomolar detection limit was achieved, and additionally, the method was fast enough for the determination of any such compound, in a wide variety of chromatographic methods. The method was linear across the concentration range of 240-1.1 x 10(5) pg mL(-1) (r=0.996) with a limit of detection and quantitation 117.3 and 240 pg mL(-1), respectively. As a conclusion this system offers the requisite accuracy, sensitivity, precision and selectivity to assay lidocaine in injections.

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An easy and fast Fourier transform continuous cyclic voltammetric technique for monitoring of ultra trace amounts of naltrexone in a flow-injection system has been introduced in this work. The potential waveform, consisting of the potential steps for cleaning, stripping and potential ramp, was continuously applied on an Au disk microelectrode (with a 12.5 microm in radius). The proposed detection method has some of advantages, the greatest of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, this is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. The method was linear over the concentration range of 0.34-34000 pg/mL (r = 0.9985) with a limit of detection 8.0 x 10(-4) nM. The method has the requisite accuracy, sensitivity, precision, and selectivity to assay naltrexone in tablets. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the naltrexone were considered.

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In this work, a novel La(III) membrane sensor based on 8-amino-N-(2-hydroxybenzylidene)naphthylamine (AIP) is presented. This electrode reveals good selectivity for La(3+) over a wide variety of lanthanides metal ions. Theoretical calculations and conductance study of AIP to lanthanum and some other metal ions were carried out and confirmed selectivity toward La(III) ions. The electrode comprises 7% AIP, 30% PVC, 61% NPOE and 2% KTpClPB. The sensor displays a linear dynamic range between 1.0 x 10(-7) and 1.0 x 10(-1) M, with a nice Nernstian slope of 20.3+/-0.3 mV per decade and a detection limit of 8.0 x 10(-8) M. The potentiometric response is independent of pH in the range of 4.0-9.0. The proposed sensor posses the advantage of short response time, and especially, very good selectivity towards a large number of cations, such as Sm(III), Ce(III, Pr(III), Yb(III) and Hg(II), low detection limit and wide linear dynamic range in comparison with former ones. The electrode can be used for at least seven weeks without any considerable divergence in the potentials. It was used as an indicator electrode in the potentiometric titration of La(III) ions with EDTA. The sensor was applied to the determination of La(III) ions concentration in binary mixtures. It was also applied for the determination of fluoride ions in mouth wash preparations.

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Otosclerosis (otospongiosis) occurs when the hard endochondral bone of the otic capsule is replaced by spongy vascular foci of haversian bone. Using computed tomography (CT), we studied the ears of 32 selected patients with mixed or sensorineural hearing loss (one patient had normal hearing); 24 were suspected of having otosclerosis. CT proved valuable in detecting cochlear otosclerosis, foci of demineralization, and changes in bony texture and enables the easy recognition of subtle radiographic findings. Our paper also reports the CT findings of temporal bones in osteogenesis imperfecta and Paget disease.

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Otosclerosis (otospongiosis) is a primary focal disease of the labyrinthine capsule. The stapes footplate is fixed when the spongiotic focus expands and invades the oval window. Persons with stapedial otosclerosis experience a progressive conductive hearing loss. In many cases, cochlear degeneration is observed, in which a mixed hearing loss occurs. Using computed tomography (CT), we studied the ears of 45 selected patients with conductive or mixed hearing loss. CT proved valuable in determining otosclerotic changes of the oval window and otic capsule. Spongiotic changes of the otic capsule are better appreciated by CT than complex motion tomography. The usefulness of CT in diagnosing other causes of conductive or mixed hearing loss is also described.

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