Papers by Keyword: Fluorescence Spectroscopy

Abstract: The research on molecular devices, fluorescent labels and fluorescent probes based on the interaction between biomolecular DNA and fluorescent dyes has been paid more attention at home and abroad. In this paper, the luminescence properties of the [Ru(bpy)₃]Cl₂ complex itself were investigated, and the luminescence properties of the [Ru(bpy)₃]Cl₂ complex under the interaction of the solution and the film were observed by association of the DNA complex with the [Ru(bpy)₃]Cl₂ complex. The results showed that [Ru(bpy)₃]Cl₂ emitted red light with its main emission peak wavelength was 610nm, and its fluorescence intensity was the highest when the concentration of solution substance was 10mmol/L. When doped with DNA solution in [Ru(bpy)₃]Cl₂ complex, a small amount of fluorescent dye [Ru(bpy)₃]Cl₂ can be used to achieve a higher luminous intensity At the same time, the fluorescent dye [Ru(bpy)₃]Cl₂ doped with DNA solution reached a higher luminous intensity in the thin-film state. This experiment provides an important experimental basis for the application of fluorescent substance [Ru(bpy)₃]Cl₂ in luminescent thin films.

Abstract: The interaction of dibazol to serum was investigated by fluorescence and UV-vis spectroscopy. The fluorescence experiment results show that the fluorescence of human serum can be effectively induced by light wave. The maximum fluorescence intensity of serum is excited at 280 nm and the peak wavelength is about 334 nm. It can also be concluded that the fluorescence intensity gradually increase with the increasing excitation light wavelength. The range of the fluorescence spectroscopy of serum-dibazol system induced by excited at different wavelength is about 290 - 450 nm. The fluorescence intensity of the interaction system of dibazol-serum is significantly reduced, indicating that the fluorescence quenching of serum occurred strongly caused by dibazol and there is a new compound formed between dibazol and serum. The absorption spectra show that there is a large blue in the system of dibazol and serum, which reveal that there is a kind of new complex between dibazol and serum. It is very significance to study the interaction between dibazol and serum for understanding of drug’s toxicity and its distribution in the organism.

Abstract: Gentamicin is a kind of aminoglycoside antibiotics and widely used in the prevention and treatment of the duck diseases. A prediction model was established for the rapid detection of Gentamicin residue in duck meat using fluorescence analysis method according to the strong fluorescent characteristic of the generated derivative for Gentamicin and o-phthaldialdehyde (OPA) in the presence of emulsifier OP-10 and mercaptoethanol.The fluorescence spectra of the duck meat containing Gentamicin were analyzed, the optimum excitation wavelength of the material was 340 nm and the optimum emission wavelength was 442 nm. Fluorescence intensity and the concentration of the standard samples presented the good linear relationship, the linear correlation coefficient was 0.9963 and the limit of detection was 0.47 μg/mL in the dynamic rang of 0.5 ~6.5μg/mL. The correlation coefficient of regression equation was 0.9968 for the samples of duck meat extract. The experimental results showed that the fluorescence analysis method had a good performance and accuracy in detecting the Gentamicin residue in duck meat.

Abstract: A novel method has been developed to detect 1,2-benzisothiazolin-3-one (BIT) in paper for food packaging by hydrothermal extraction coupled with fluorescence spectroscopy in paper for food package. Parameters affecting fluorescence intensity have been evaluated, including the pH of solvents and the effect of surfactants. It turned out to be that fluorescent spectroscopy was a sensitive and easy method to determine BIT in paper package. The regression equation obtained was liner, and the correction coefficient was 99.9%, the limit detection (LOD) was 25.3μg/L, method detection limit (MDL) was 0.25mg/kg, which turned out that this method was sensitive and precise to determine BIT in food package.

Abstract: The inclusion complex formation between fluorescent sensor 3, 3’-benzidine/β-cyclodextrin derivative (BDCD) and pesticide carbaryl was studied and characterized by TEM, XRD and fluorescence spectroscopy. The stability constant and the stoichiometry of complex were determined. Based on the enhancement of the fluorescence intensity of carbaryl produced through complex formation, a new sensitive method for the determination of carbaryl was established. The linear relationship between the fluorescence intensity and carbaryl concentration was obtained in the range of 0.60-3.00 μmol/L with a correlation coefficient of 0.9946. The detection limit was 5.12 nmol/L. This method has been successfully applied to the determination of carbaryl pesticide residue in water, fruit and vegetable samples with satisfactory results, recoveries in the range of 94.12 % to 105.88 % were obtained. The method is rapid, simple, direct, economical, sensitive and useful for carbaryl analysis.

Abstract: The host-guest inclusion complex formation between 3, 3’-benzidine/β-cyclodextrin derivative (BDCD) and pesticide carbendazim was studied and characterized by TEM and XRD. The result showed that inclusion complex had hydrophobic small-molecule fluorophores. The fluorescence titration was performed to calculate binding constant, sensitivity factor and limit of detection of the resulting complex. Based on the enhancement of the fluorescence intensity of carbendazim produced throught complex formation, a new sensitive method for the determination of carbendazim was established. A linear relationship was obtained between the fluorescence intensity and carbendazim concentration in the range of 3.57 and 17.83 μmol/L. The correlation coefficient, the lowest limit of detection and RSD were 0.9916, 15.51 nmol/L and 2.13%, respectively. This method has better anti-interference ability and stability. The proposed method have been successfully applied to the determination of carbendazim pesticide residues in water, vegetable and fruit samples with satisfactory results, recoveries in the range of 87.56 % to 104.04 % were obtained.

Abstract: Bovine serum albumin (BSA) and human serum albumin (HSA) interaction with 4-nitroaniline was investigated by fluorescence spectroscopy respectively. 4-Nitroaniline can strongly quench intrinsic fluorescence of BSA and HSA. 4-Nitroaniline exhibits a high affinity to bovine and human serum albumins. The binding constants K and the number binding site n were obtained by double-log regression equation. Negative enthalpy (ΔH) and positive entropy (ΔS) values indicated that both hydrogen bond and hydrophobic forces played a major role in the binding of 4-nitroaniline and SA. The results of synchronous fluorescence showed the polarity around tryptophan residues was decreased and the hydrophobicity was increased.

Abstract: Comprehensive method for determining the fluorescent agents was studied through studying the fluorescence spectra of different concentration of VBL. The emission and excitation wavelength in the measurement was 275nm, and 434nm, respectively. When the concentrations of VBL are changing from 0 to 1.0 μg/mL, they have a linear relationship with the emitted fluorescence intensity. In this interval, the calibration curve is y= 1 6.713x+0.7879, showing strong correlation (correlation coefficient R² is 0.9979). The average percentage of recovery is 89.9%, which meets the measuring requirements. The interaction between VBL and CTAB is preliminary studied.

Abstract: Fluorescence spectroscopy was performed to investigate the composition changes and characteristics of the leachate DOM (dissolved organic matter) during UV-TiO₂ photocatalytic treatment process. The results showed that fulvic-like, tryptophan-like and humic acids-like matters were the main compounds in leachate. During photocatalytic treatment process, fluorescence spectroscopy of DOM changed considerably. The final products were mainly fulvic-like and tryptophan-like matters. In general, the fluorescence signals of humic acids-like matters had the most significant change, which disappeared entirely after 60 h treatment, implying that humic acids-like matters can be degraded preferentially by photocatalysis. The other notable change was in VIS fulvic-like matters region, which suggested that fulvic-like matters can be significantly degraded. In 72 h photocatalytic effluent, VIS fulvic-like, tryptophan-like and tyrosine-like matters were remained, and the last two matters were the dominant fractions. These results indicated that fulvic-like and humic acids-like matters with macromolecular can be degraded into protein-like matters with micro-molecular by photocatalysis.

Abstract: With water as the medium, PVP as stabilizer and ammonia as complexing agents and adjusting pH value of the solution, we report an all-aqueous synthesis of highly photoluminescent and stable ZnS quantum dots (QDs) by water-phase synthesis reaction between ZnCl2 and NaS at different temperatures and times. The optimal reaction conditions of PVP-capped ZnS QDs were obtained through experiment as follows: the concentration ZnCl2 and NaS solution both are 1 mM, (PVP):(ZnCl2) = 0.0167 (v/v), (NH3):(ZnCl2)=1:300 (v/v), the optimal reaction temperature is 40 °C, the optimal reaction time is 30 min. With ammonia as complexing agents, Zn(OH)2 can dissolve in ammonia and form to complex ions ((Zn(NH3)4)2+), which make Zn2+ release slowly to control the nucleus growth rate of ZnS, thus obtain small size of nanoparticles. The fluorescence spectra shows that the emission peaks of ZnS QDs around ~395 nm and ~470 nm on the emission spectra, which are consistent with literatures, so nano-ZnS QDs was synthesized successfully in this paper.