Study of the influence of silver nanoparticles on the second-order scattering and the fluorescence of the complexes of Tb(III) with quinolones and determination of the quinolones

Quinolones (Qs) can form the complex with Tb(III) ion, and the intramolecular energy transfer from Qs to Tb(III) takes place when excited. And thus the characteristic fluorescence of Tb(III) ion was enhanced and the maximum fluorescence peak locates at 545 nm. The second-order scattering (SOS) peak at 545 nm also appears for the Tb(III)-Qs complexes with the exciting wavelength of 274 nm. When the silver nanoparticles were added to the Tb(III)-Qs system, the luminescence intensity at 545 nm greatly increased. And the relative intensity is proportional to the amount of Qs. Based on this phenomenon, a novel method for determination of quinolones has been developed by using a common spectrofluorometer to measure the intensity of fluorescence and SOS. The luminescence intensity is greatly enhanced by silver nanoparticles in the pH range 5.5-6.2. The calibration graphs for pipemidic acid (PPA) and lomefloxacin (LMFX) are linear in the range 2.0 × 10⁻¹⁰ to 1.0 × 10⁻⁵ and 1.0 × 10⁻⁹ to 1.0 × 10⁻⁵ mol L⁻¹, respectively. The limits of detection are 4.7 × 10⁻¹¹ mol L⁻¹ for PPA and 1.1 × 10⁻¹⁰ mol L⁻¹ for LMFX. The method was applied satisfactorily to the determination of the two quinolones (Qs) in tablet, capsule, urine and serum samples. The experimental results showed that it is the certain size and certain concentration of silver nanoparticles that can greatly enhance the fluorescence -SOS intensity.     

Determination of ulifloxacin by terbium-sensitized fluorescence with second-order scattering and its applications.

This paper reports the determination of ulifloxacin (UFX) by terbium-sensitized fluorescence using a second-order scattering method. UFX and Tb(III) ion form a fluorescence complex in aqueous solution, and its maximum excitation and emission wavelengths are located at 273 and 545 nm, respectively. In optimum conditions, the relative intensity at 545 nm has a linear relationship to the concentration of UFX in the range of 2.0 x 10(-8) - 1.0 x 10(-5) mol L(-1) and the detection limit is 3.9 x 10(-9) mol L(-1). The proposed method was applied to the determination of UFX in spiked human serum and urine satisfactorily. The luminescence property of UFX is also discussed by comparing with norfloxacin (NFLX) and ofloxacin (OFLX).     

Spectrofluorometric determination of trace amounts of coenzyme II using norfioxacin-terbium complex as a fluorescent probe.

When terbium ion (Tb3+)-norfloxacin (NFLX) complex is issued a fluorescent probe, in a buffer solution of pH = 7.6, NADP can remarkably enhance the fluorescence intensity of the Tb3+ -NFLX complex at lambda = 545 nm. The enhanced fluorescence intensity of Tb3+ is in proportion to the concentration of NADP. The dynamic range for the determination of NADP is 1.11 x 10(-7) - 6.16 x 10(-5) mol l(-1), with a detection limit of 4.31 x 10(-8) mol l(-1). This method is simple, practical and relatively free of interference from coexisting substances, so it can be successfully applied to determination of NADP in synthetic water samples.     

Luminescence effect of silver nanoparticle in water phase

Yellow silver nanoparticles in water phase were prepared by microwave synthesis method. Study found that there is a fluorescence peak at 465 nm and a strongest resonance scattering peak at 460 nm for the nanoparticles. The resonance scattering intensity at 465 nm I(460 nm). fluorescence intensity at 465 nm F(465)(nm) and absorbance at 455 nm A(455 nm) were found linear to the concentration c(Ag) in the range from 0 to 3.5x10(-4)mol/L Ag, with linear regression equation for I(460 nm)=48.1x10(4) c(Ag)+3.69 and F(465 nm)=28.7x10(4)c(Ag)+3.50 and A(455 nm)1.23x10(4)c(Ag)+0.01, their regression coefficient for 0.9976, 0.9954 and 0.9957, respectively. When the c(Ag) was over 3.5x10(-4)mol/L, the resonance scattering peak and fluorescence peak of 465 nm take place red-shift and display luminescence quenching, but the absorption peak place does not change and the absorption intensity enhances. The paper reports the spectral properties of silver nanoparticles in water phase, and offers the principle of interface luminescence electron to state the luminescence effect of silver nanoparticles.     

Determination of trace terbium(III) with N, N', N"-tri(3-indolemethanal)triaminotriethylamine based on a new fluorescence enhancement system.

A new Schiff-base ligand with a tripodal structure, N,N',N"-tri(3-indolemethanal)triaminotriethylamine (TTAIM), was synthesized. Its fluorescence intensity with terbium(III) was increased by about two orders of magnitude in the present of sodium acetate (NaAc). After the adding of the organic solvent dimethyl sulfoxide (DMSO) to the above system, leading to Tb3+ the fluorescence was further enhanced by about 16 fold. The spectrofluorimetric determination of a trace amount of Tb3+ based on this phenomenon was carried out. The excitation and emission wavelengths were 330 nm and 545 nm, respectively. Under the optimal conditions, the fluorescence intensities varied linearly with the concentration of Tb3+ in the range of 5.7 x 10(-11) - 6.3 x 10(-6) mol L(-1) with a detection limit of 5.0 x 10(-11) mol L(-1). The interferences of some rare earth metals and other inorganic ions were described. The method is a selective, sensitive, rapid and simple analytical procedure for the determination of terbium(III) in a high-purity yttrium oxide and synthetic sample. The mechanism for the fluorescence enhancement was also studied.     

Fluorimetric study of the interaction between human serum albumin and quinolones-terbium complex and its application

A highly sensitive spectrofluorimetric method is proposed for determination of human serum albumin (HSA) and some quinolone drugs. Using quinolones-terbium (Tb3+) complex as a fluorescent probe, in the buffer solution of pH 7.8, HSA can remarkably enhance the fluorescence intensity of the quinolones-Tb3+ complex at 545 nm and the enhanced fluorescence intensity of Tb3+ ion is in proportion to the concentration of HSA and quinolone drugs. Optimum conditions for the determination of HSA were also investigated. The linear ranges and limits of detection are 8.0 x 10(-9) to 8.0 x 10(-8) mol L(-1), 4.20 x 10(-9) mol L(-1) (for HSA); 1.0 x 10(-6) to 4.0 x 10(-6) mol L(-1), 1.87 x 10(-8) mol L(-1) (for norfloxacin) and 1.0 x 10(-7) to 1.0 x 10(-6) mol L(-1), 4.82 x 10(-8) mol L(-1) (for enoxacine), respectively. This method is simple, practical and relatively free interference from coexisting substances, as well as much more sensitive than most of the existing assays.     

The second-order scattering study of the Tb(III)-RNA and determination of RNA

The second-order scattering technique (SOS), using a common spectrofluorometer, was first developed as a sensitive instrumental analysis method for determination of the ribonucleic acid (RNA). The results indicate that RNA had a weak SOS peak and the Tb(III) ion can greatly enhance the SOS intensity of RNA with the maximum peak located at 612.0 nm. Mechanism study shows that the peak results from the long-range assembly of Tb(III) ion on the molecular surface of RNA. At the pH 7.50 and with cetyltrimethylammonium bromide (CTMAB) (6.0 x 10(-5)M), the enhanced SOS intensity was in proportion to the concentration of RNA in the range of 2.0 x 10(-8) to 2.0 x 10(-5)g/ml. The detection limit was 1.96 ng/ml. The relative standard deviation (five replicates) was within +/-5% in the linear range. This method has been used satisfactorily for the determination of both synthetic and real samples. In comparison with most other methods for the determination of ribonucleic acids, this method is more sensitive.     

Electrochemiluminescence of terbium (III)-two fluoroquinolones-sodium sulfite system in aqueous solution

The electrochemiluminescence (ECL) of Tb3+-enoxacin-Na2SO3 system (ENX system) and Tb3+-ofloxacin-Na2SO3 system (OFLX system) in aqueous solution is reported. ECL is generated by the oxidation of Na2SO3, which is enhanced by Tb3+-fluoroquinolone (FQ) complex. The ECL intensity peak versus potential corresponds to oxidation of Na2SO3, and the ECL emission spectra (the peaks are at 490, 545, 585 and 620 nm) match the characteristic emission spectrum of Tb3+, indicating that the emission is from the excited state of Tb3+. The mechanism of ECL is proposed and the difference of ECL intensity between ENX system and OFLX system is explained. Conditions for ECL emission were optimized. The linear range of ECL intensity versus concentrations of pharmaceuticals is 2.0 x 10(-10) -8.0 x 10(-7)mol l(-1) for ENX and 6.0 x 10(-10) -6.0 x 10(-7)mol l(-1) for OFLX, respectively. A theoretical limit of detection is 5.4 x 10(-11)mol l(-1) for ENX and 1.6 x 10(-10)mol l(-1) for OFLX, respectively. The ECL was satisfactorily applied to the determination of the two FQs in dosage form and urine sample.     

Tb(III)与PNIPAM接枝核壳纳米微球相互作用的研究

利用透射电镜、X射线光电子能谱、动态激光光散射和荧光光谱技术对Tb(III)与聚N-异丙基丙烯酰胺(PNIPAM)接枝核壳纳米微球PNIPAM-g-P(NIPAM-co-St) (PNNS)的相互作用进行了研究. 结果表明: Tb(III)和热敏性的核壳纳米微球PNNS有显著的相互作用. 其一, Tb(III)可与PNNS中酰胺基团上的氧原子配位形成微球配合物Tb(III)-PNNS; 其二, Tb(III)-PNNS微球配合物兼具热敏性; 其三, 该配合物在545 nm处的荧光强度较Tb(III)增大了233倍, Tb(III)与PNNS分子间能量传递达到50%, 当Tb(III) 质量分数为12%时荧光强度最大.     

Simultaneous determination of trace of loxacin, ciprofloxacin, and sparfloxacin by micelle TLC-fluorimetry

The method of simultaneous determination of ofloxacin (OFLX), ciproflxacin (CPLX), and sparfloxacin (SPLX) by thin-layer chromatography is established, with micelle solutions as mobile phases. It is found that the optimum molar ratio of sodium dodecyl sulfate (SDS) to ethylene diamine tetraacetic acid is 0.01:0.1. On the polyamide thin-layer sheet, OFLX, CPLX, and SPLX are separated from each other, and the corresponding Rf values are 0.72, 0.55, and 0.32, respectively. The fluorescence spots are scanned with a spectrodensitometer at the excitation wavelength of 282 nm. The cut-off filter is set at 400 nm. The detection limits are 2 x 10(-6) mol/L for OFLX, 1.5 x 10(-6) mol/L for CPLX, and 1.6 x 10(-6) mol/L for SPLX, and the respective linear ranges correspondingly fell in the concentration of 1 x 10(-5) to 4 x 10(-4) mol/L for OFLX, 1 x 10(-5) to 4.5 x 10(-4) mol/L for CPLX, and 1 x 10(-5) to 4.2 x 10(-4) mol/L for SPLX. For all the three components, the relative standard deviations are in the range of 1.12-5.82%, and the recoveries are found to be 96.7-104.2% in urine and serum samples.     

Determination of heparin using ciprofloxacin-Tb3+ as a fluorescence probe.

A new spectrofluorometric method was developed for the determination of trace amounts of heparin (Hep). Using ciprofloxacin (CIP)-terbium (Tb3+) as a fluorescent probe, in a buffer solution of pH 7.20, Hep can remarkably enhance the fluorescence intensity of the CIP-Tb3+ complex at lambda = 545 nm; also, the enhanced fluorescence intensity the Tb3+ ion is proportional to the concentration of Hep. The optimum conditions for the determination of Hep were also investigated. The dynamic range for the determination of Hep is 0.1 - 1.2 microg ml(-1) with a detection limit of 6.89 ng ml(-1). This method is simple, practical and relatively free of interference from coexisting substances, and can be successfully applied to assess Hep in biological samples. By the Rosenthanl graphic method, the association constant and binding numbers of heparin with the probe are 2.44 x 10(5) l mol(-1) and 19.7. Moreover, the enhancement mechanisms of the fluorescence intensity in the CIP-Tb3+ system and the CIP-Tb3+-Hep system have also been considered.     

Spectrofluorimetric determination of trace heparin using lomefloxacin-terbium probe

A new spectrofluorimetric method was developed for determination of trace amount of heparin (Hep). Using lomefloxacin (LOM)-terbium ion (Tb3+) as a fluorescent probe, in the buffer solution of pH 8.70, Hep can remarkably enhance the fluorescence intensity of the LOM-Tb3+ complex at lambda = 545 nm and the enhanced fluorescence intensity of Tb3+ ion is in proportion to the concentration of Hep. Optimum conditions for the determination of Hep were also investigated. The linear range for the determination of Hep was 0.6-2.0 microg/ml and the detection limit was 45.22 ng/ml. This method is simple, practical and relatively free of interference from coexisting substances and can be successfully applied to assess Hep in biological samples. By the Rosenthanl graphic method, the association constant of Hep with the probe is 4.56 x 10(4) l/mol and binding numbers is 18.2. Moreover, the enhancement mechanism of the fluorescence intensity in the LOM-Tb3+ system and the LOM-Tb3+-Hep system have also been discussed.     

温度对铽（III）-转铁蛋白溶液构象的影响

在pH 7.4,0.01 mol/L N-2-羟乙基哌嗪-N’-2-乙磺酸（Hepes）条件下,铽 （III）与N,N’-二（2-羟苄基）乙二胺-N,N’-二乙酸（HBED）结合并发生交换 相互作用使铽（III）荧光增强10~4倍,通过监测铽（III）545 nm荧光强度的变化 测定了Tb-HBED配合物的条件稳定常数是lgK = 14.30 ± 0.49;Tb-HBED配合物中 配体、铽（III）荧光强度均随着温度的升高而降低。在pH 7.4,0.01 mol/L Hepes条件下,Tb_N-apoTf-Tb_C配合物中蛋白质的荧光强度随着温度的升高而降 低,而能量受体铽（III）的荧光强度随着温度的升高而增强,主要源于铽（III） 与螺旋5色氨酸残基间的无辐射能量转移;当温度由0 ℃上升到55 ℃时,平均能量 转移效率AE值增加了29%,给体、受体间距离R有约4.2%的减小,温度变化引起 Tb_N-apoTf-Tb_C配合物大的构象变化;铽（III）与人血清脱铁转铁蛋白的结合使 蛋白质的变性温度降低。同样条件下,Tb_N-apoOTf-Tb_C配合物与Tb_N-apoTf- Tb_C配合物有所不同,虽然能量给体的荧光强度随着温度的增加而减小,但铽（ III）荧光强度没有明显的增强;铽（III）对蛋白质的变性温度几乎没有影响。     

Photochemical fluorescence enhancement of the terbium-lomefloxacin complex and its application

The sensitized fluorescence intensity of the terbium ion (Tb(3+)) can be notably enhanced after the Tb(3+)-lomefloxacin(LFLX) complex system was irradiated by 365nm ultraviolet light. A photochemical reaction occurs to the irradiated Tb(3+)-LFLX complex. A new Tb(3+)system with intense fluorescence is obtained. On this basis a new sensitive and selective photochemical fluorimetry for the determination of LFLX was established. Under the optimal experimental conditions, the linear range of the determination is 2.0-500x10(-8) mol l(-1) for LFLX, and the detection limit is 6.0x10(-9) mol l(-1).Without any pre-treatment the recoveries of LFLX in human urine and serum were determined.     

Method for determination of fluoroquinolones based on the plasmonic interaction between their fluorescent terbium complexes and silver nanoparticles

We report on a fluorometric method for the determination of the fluoroquinolones levofloxacin (LEV) and moxifloxacin (MOXI). It is based on the Tb(III)-sensitized luminescence that is plasmonically enhanced by silver nanoparticles (Ag NPs). The emission of the Tb(III) complexes has maximum at 545?nm after excitation at 284?nm and is strongly enhanced in the presence of the colloidal Ag NPs. Under optimum experimental conditions, luminescence intensity increases linearly with the concentration in the range from 4.16?×?10^-17-3.59?×?10^-15?M of LEV, and from 4.98?×?10^-17-2.49?×?10^-15?M for MOXI with correlation coefficients of 0.9996 and 0.9996, respectively. The limits of detection are 7.19?×?10^-18?M and 8.47?×?10^-18?M, respectively, and the relative standard deviations are 1.3 and 1.5% for 5 replicate measurements at 6.08?×?10^-14?M of LEV and 5.48?×?10^-14?M of MOXI. The method was successfully applied to the determination of LEV and MOXI in pharmaceutical samples, in urine and in serum.

Study on interaction between Tb(III) and poly(N-isopropylacrylamide)-g-poly(N-isopropylacrylamide-co-styrene) core-shell nanoparticles

Based on the synthesis of poly(N-isopropylacrylamide-co-styrene) P(NIPAM-co-St) and poly(N-isopropylacrylamide) (PNIPAM) grafted P(NIPAM-co-St) core-shell nanoparticle, a new kind of thermoresponsive and fluorescent complex of Tb(III) and PNIPAM-g-P(NIPAM-co-St) (PNNS) was successfully prepared. The PNNS-Tb(III) complex was characterized with the different techniques. It was found that when PNNS with the core-shell structure interact with Tb(III), Tb(III) mainly bonded to O of the carbonyl groups of PNNS, forming the novel PNNS-Tb(III) complex. After forming the complex, the emission fluorescence intensity of Tb(III) in the complex is significantly enhanced. Especially, the maximum emission intensity of the PNNS-Tb(III) complex at 545 nm is enhanced about 223 times comparing to that of the pure Tb(III) because the effective intramolecular energy transfer from PNNS to Tb(III). The intramolecular energy transfer efficiency from PNNS to Tb(III) reaches 50%. The fluorescence intensity is related the weight ratio of Tb(III) and PNNS in the PNNS-Tb(III) complex. When the weight ratio of Tb(III) and the PNNS is 12 wt%, the enhancement of the emission fluorescence intensity at 545 nm is highest. This novel fluorescence characterization of the PNNS-Tb(III) complex may be useful in the fluorescence systems and the biomedical field.     

Study on the new fluorescence enhancement system of Tb-1,10-bis(2′-carboxylphenyl)-1,4,7,10-tetraoxadecane in silver chloride collosol and its analytical application

A new salicylic-based open-chain crown ether ligand, 1,10-bis(2′-carboxylphenyl)-1,4,7,10-tetraoxadecane (BCPTD) was synthesized. Solutions of its complex with Tb³⁺ can emit the intrinsic fluorescence of Tb³⁺. The fluorescence intensity of the complex in KCl solution was enhanced by the addition of silver(I), leading to a new fluorescence enhancement phenomenon. The spectrofluorimetric determination of traces of silver(I) based on the above phenomenon was carried out. The excitation and emission wavelengths are 298 and 545 nm, respectively. Under optimal conditions, the differential value of fluorescence intensity in the absence and presence of Ag⁺ was proportional to the concentration of silver(I) in the range 0.5-20 μg ml⁻¹. The method was applied to the determination of silver(I) in a standard ore sample. The analytical performance is investigated in detail by using common aromatic carboxylic acids or synthetic analogues of BCPTD as ligands to replace BCPTD. It was found that Tb-aromatic acid complexes did not result in fluorescence enhancement of Tb³⁺ in AgCl collosol. The phenomenon was only observed in Tb(III) with BCPTD or its open-chain crown ether analogues solutions.In addition, the enhancement of the fluorescence intensity of terbium(III) in these complexes depends on the extent of formation of the AgCl collosol.     

A tripod ligand as new sensitiser for the enzyme amplified lanthanide luminescence determination of esterase

Screening of a small library of tripod ligands resulted in the discovery of bis(2-pyridylmethyl)-(2-hydroxybenzyl)amine (HL1) as a new sensitiser, which is able to transfer its excitation energy to terbium(III). After synthesis of the acetic acid ester of HL1, a highly selective method for the determination of porcine liver esterase by means of enzyme amplified lanthanide luminescence (EALL) was developed. Enzyme-catalysed cleavage of the ester results in the formation of HL1. After excitation at 297 nm, the characteristic emission of Tb(III) at 545 nm is observed and used to determine the esterase concentration. In contrast to existing EALL methods, this method may be carried out at neutral pH and without further additives. Limit of detection for porcine liver esterase is 10(-9) mol l(-1) and limit of quantification is 3 x 10(-9) mol l(-1). A linear calibration range of two decades starting at the limit of quantification is observed.     

Spectrofluorimetric determination of trace amounts of Tb(III) using acetylacetone in ethanol solution

Summary The spectrofluorimetric determination of terbium(III) in ethanol (95%) solution of acetylacetone (3×10^–4 mol/l) was studied. Intensive fluorescence of terbium(III) (=545 nm) was observed after excitation of the system (=310 nm). The method proposed is satisfactory for the determination of terbium(III) in the range of 4 to 40 ng/ml (2.5×10^–8 to 2.5×10^–7 mol/l). The effect of other rare earths, common metal ions and anions upon the intensity of the fluorescence emitted by terbium(III) is discussed.

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Spektrofluorimetrische Bestimmung von Tb(III)-Spuren mit Acetylaceton in Ethanollösung

     

The new fluorescence enhancement system Tb-N-(2-pyridinyl) ketoacetamide-Et(3)N-Zn and its application

A sensitive fluorescence enhancement system was developed for the determination of terbium. The fluorescence intensity of the Tb-N-(2-pyridinyl) ketoacetamide (PKAA) system was greatly enhanced by the addition of triethylamine (Et(3)N) and zinc nitrate in the methanol solution. The excitation and emission wavelengths were 329 and 546 nm, respectively. Under optimal conditions, the fluorescence intensities varied linearly with the concentration of Tb(3+) in the range of 7.5 x 10(-8)-8.2 x 10(-6)M with a detection limit of 6.4 x 10(-8)M. The interferences of some rare earth ions were described. This method was applied to the determination of trace amounts of terbium (III) in a synthetic rare earth oxide and a high purity Y(2)O(3) matrix. The mechanism of fluorescence enhancement was also studied.