Determination of fibrinogen content in cryoprecipitated antihemophilic factor by fluorescence quenching method / 中国输血杂志

【Objective】 To establish a new method for the determination of fibrinogen content in cryoprecipitated antihemophilic factor. 【Methods】 Fibrinogen (Fib) could bind with sheep anti-human fibrinogen (anti-Fib) specifically and further form antigen-antibody complex. When the Fib was present in the solution, the fluorescence of fluorescein isothiocyanate (FITC) labeled on the anti-Fib (FITC-anti-Fib) was quenched due to the formation of immune complex. The fluorescence quenching degree of FITC-anti-Fib was positively correlated with Fib concentration (cFib) in a certain concentration range. 【Results】 The linear relationship between fluorescence quenching degree [(I0-I)/I0] of FITC-anti-Fib and ln(cFib) was (I0-I)/I0=15.53ln(cFib)+ 80.79 (R2=0.99) when the cFib was in the range of (0.007 8-0.560 0) g/L. The recovery of Fib was (96.77-102.43) %. When the method was applied to determine Fib at high, medium, and low concentrations, the obtained intra-day variation coefficients were 0.31%, 0.56%, and 0.49%, respectively, and the inter-day variation coefficients were 3.81%, 3.06%, and 4.13%, respectively. There was no significant difference between the results measured by fluorescence quenching method and coagulation method (t=-0.075, P>0.05). 【Conclusion】 In this work, a new fluorescence method for the determination of Fib in cryoprecipitated antihemophilic factor was successfully established based on the specific combination of fib and FITC-anti-Fib. The method is simple and rapid. The obtained results were accurate and reliable by using this method to determine Fib.

A novel technology to reduce astringency of tea polyphenols extract and its mechanism / 中草药·英文版

Objective: Tea polyphenols are natural extracts used widely throughout the world. However, the severe astringency of tea polyphenols has reduced patient compliance. Based on the analysis of the formation mechanism of astringency, this paper hopes to propose a new method to control the astringency of tea polyphenols and improve patient compliance without changing its effect. Methods: Artificial saliva was used to prepare the tea polyphenols solution with different pH, using β-casein to imitate salivary protein, and preparing 1.2 mg/mL β-casein solution. A fluorescence quenching test was used to study the interaction between tea polyphenols and β-casein, combined with the stability test results of the compound, we can choose the pH with weak binding but good stability as the best pH for masking astringency. The taste-masking tablets were prepared under the best pH conditions, and the Xinnaojian Original Tablets were prepared according to the conventional preparation method. The disintegration time limit and solubility were tested respectively. The astringency of Xinnaojian original tablets and taste-masking tablets was evaluated by visual analogue scale (VAS). Results: The result of the fluorescence quenching test prompted that the combination force was the weakest when the pH was 4.9. Further synchronous fluorescence analysis showed that an increase in pH resulted in a decrease of the binding sites between tea polyphenols and β-casein, and this decrease was closely related to changes in tryptophan residues in β-casein. Both original and taste-masking Xinnaojian Tablets were prepared. Volunteers’ VAS scores illustrated that the astringency improved significantly with the masking tablets (P < 0.05). Conclusion: This pH-adjusting masking treatment had little effect on the recovery of polyphenols from the tablets or the dissolution of the tablets. This study provides a novel and feasible astringency masking technology for tea polyphenols and its preparation.

A carbon nanoparticle-peptide fluorescent sensor custom-made for simple and sensitive detection of trypsin / 药物分析学报

Herein, we report a novel sensor to detect trypsin using a purpose-designed fluorescein-labelled peptide with negatively charged carbon nanoparticles (CNPs) modified by acid oxidation. The fluorescence of the fluorescein-labelled peptide was quenched by CNPs. The sensor reacted with trypsin to cleave the peptide, resulting in the release of the dye moiety and a substantial increase in fluorescence intensity, which was dose-and time-dependent, and trypsin could be quantified accordingly. Correspondingly, the biosensor has led to the development of a convenient and efficient fluorescent method to measure trypsin activity, with a detection limit of 0.7μg/mL. The method allows rapid determination of trypsin activity in the normal and acute pancreatitis range, suitable for point-of-care testing. Furthermore, the applicability of the method has been demonstrated by detecting trypsin in spiked urine samples.

Detection of copper ions and glutathione based on off-on fluorescent gra-phene quantum dots / 中国药科大学学报

We developed a rapid method to detect Cu2+and glutathione(GSH)based on the fluorescence quenching-recovery properties of graphene quantum dots(GQDs),which were synthesized by the gentle oxidation of graphite powder.The results revealed that the fluorescence intensity of GQDs versus concentration of Cu2+and GSH had good linearity, with the detection limits of 0.01 and 0.1 mmol/L, respectively.The fluorescence quenching was linearly proportional to the concentrations of Cu2+ranging from 1.0 to 10.0 mmol/L;the fluores-cence intensity was linearly enhanced with the concentrations of GSH ranging from 0.1 to 1.0 mmol/L.In addi-tion,the method was successfully applied to the determination of real samples with recoveries falling between 93％-101％ and 96％-107％,respectively.This method is simple,accurate and precise.There was no interference with other familiar co-existing metal ions and potential materials.

The Effect of 1-Propanol on the Rotational Mobility of n-(9-Anthroyloxy) stearic acid in Outer Monolayers of Neuronal and Model Membranes

The aim of this study was to provide a basis for the molecular mechanism underlying the pharmacological action of ethanol. We studied the effects of 1-propanol on the location of n-(9-anthroyloxy)palmitic acid or stearic acid (n-AS) within the phospholipids of synaptosomal plasma membrane vesicles (SPMV). The SPMV were isolated from the bovine cerebral cortex and liposomes of total lipids (SPMVTL) and phospholipids (SPMVPL). 1-Propanol increased the rotational mobility of inner hydrocarbons, while decreasing the mobility of membrane interface, in native and model membranes. The degree of rotational mobility varied with the number of carbon atoms at positions 16, 12, 9, 6 and 2 in the aliphatic chain of phospholipids in the neuronal and model membranes. The sensitivity of increasing or decreasing rotational mobility of hydrocarbon interior or surface by 1-propanol varied with the neuronal and model membranes in the following order: SPMV, SPMVPL and SPMVTL.

Analysis of penicillamine using Cu-modified graphene quantum dots synthesized from uric acid as single precursor / 药物分析学报

A simple methodology was developed to quantify penicillamine (PA) in pharmaceutical samples, using the selective interaction of the drug with Cu-modified graphene quantum dots (Cu-GQDs). The proposed strategy combines the advantages of carbon dots (over other nanoparticles) with the high affinity of PA for the proposed Cu-GQDs, resulting in a significant and selective quenching effect. Under the optimum conditions for the interaction, a linear response (in the 0.10–7.50 μmol/L PA concentration range) was observed. The highly fluorescent GQDs used were synthesized using uric acid as single precursor and then characterized by high resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence, and absorption spectroscopy. The proposed methodology could also be extended to other compounds, further expanding the applicability of GQDs.

Analysis of penicillamine using Cu-modified graphene quantum dots synthesized from uric acid as single precursor / 药物分析学报

A simple methodology was developed to quantify penicillamine (PA) in pharmaceutical samples, using the selective interaction of the drug with Cu-modified graphene quantum dots (Cu-GQDs). The proposed strategy combines the advantages of carbon dots (over other nanoparticles) with the high affinity of PA for the proposed Cu-GQDs, resulting in a significant and selective quenching effect. Under the optimum conditions for the interaction, a linear response (in the 0.10–7.50 μmol/L PA concentration range) was observed. The highly fluorescent GQDs used were synthesized using uric acid as single precursor and then characterized by high resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence, and absorption spectroscopy. The proposed methodology could also be extended to other compounds, further expanding the applicability of GQDs.

Detection of Ferric Iron Based on Fluorescence Quenching Effect of N-doped Carbon Quantum Dots / 分析化学

The photoluminescence properties of carbon quantum dots depend on their size and the properties of surface functional groups. The N-doped carbon dots ( using small molecular ethylenediamine ) with high quantum yield and excellent dispersibility were synthesized by one-step hydrothermal method with biomass tar that was generated in the reductive smelting process as a precursor. Rapid and accurate Fe3+ detection based on the selective fluorescence quenching effect of N-doped carbon quantum dots was achieved. The results showed that the as-synthesized N-doped carbon quantum dots were regular spherical, uniform in size with an average particle size of 2. 64 nm with a quantum yield of 26. 1%, and the crystal lattice spacing was 0. 25 nm, corresponding to the ( 100 ) facet of graphitic carbon structure. The functional groups on the surface of N-doped carbon quantum dots could interact with Fe3+ to form complex compound by coordination, leading to the fluorescence quenching effect. Fluorescence emission ratios kept a linear relationship with the concentrations of Fe3+ in the range of 0. 23-600 μmol/L with the detection limit of 230 nmol/L.

Fabrication of Nitrogen-doped Carbon Nanoparticles and Application in Detection of Free Chlorine / 分析化学

Nitrogen-doped carbon nanoparticles (N-CNPs) with a fluorescence quantum yield of 15.1％ were prepared from sucrose and urea in oleic acid medium by a one-pot solvothermal method.A new approach for quick,sensitive,and selective determination of free chlorine in water was developed based on fluorescence quenching of N-CNPs.There existed a good linear correlation between the fluorescence quenching and the concentration of ClO-in the range of 0.05-25.00 μmol/L.The limit of detection (LOD,S/N =3) was estimated to be 23 nmol/L.This method can be applied to the determination of free chlorine in real water samples.

Spectroscopic Study of Interaction of Harpagoside and Human Serum Albumin / 分析化学

Harpagoside (HAR) is believed to be a main compound in Scrophularia ningpoensis which possess a broad of biological activities.Human serum albumin (HSA) has important physiological roles in transportation, distribution and metabolism of many endogenous and exogenous substances in body.It is great significance in pharmacology to investigate the interaction mechanism of HAR and HSA.In this work, the interaction between HAR and HSA was investigated by fluorescence and ultraviolet absorption spectroscopy at different pH (pH=4.0, 7.4, and 9.0) and temperatures (297, 310 and 323 K).The experimental results showed that the HAR could cause the fluorescence quenching of HSA through a static quenching procedure, showing that the HAR regularly quenched the intrinsic fluorescence of HSA, and a decrease in the quenching constant was observed with an increase in temperature.Under different conditions, all the magnitude of binding constants (KA) was larger than 105 L/mol and the number of binding sites (n) in the binary system were approximate to 1.Base on the magnitude of enthalpy and entropy changes, the negative values of ΔG, ΔH and ΔS revealed that the binding of HAR with HSA was spontaneous and exothermic process, and the main interaction forces of the HAR with HAR were van der Waals forces and/or hydrogen bonding interaction.The binding distance (r) between the HAR and HSA was calculated to be about 4.2 nm based on the theory of F(o)rster′s nonradiation energy transfer, which indicated that the energy transfer from HSA to HAR occurred with high possibility.What was more, the synchronous florescence spectroscopy confirmed the conformational changes of HSA during the binding reaction.

Detection of Ferric Iron Based on Fluorescence Quenching Effect of N-doped Carbon Quantum Dots / 分析化学

The photoluminescence properties of carbon quantum dots depend on their size and the properties of surface functional groups. The N-doped carbon dots ( using small molecular ethylenediamine ) with high quantum yield and excellent dispersibility were synthesized by one-step hydrothermal method with biomass tar that was generated in the reductive smelting process as a precursor. Rapid and accurate Fe3+ detection based on the selective fluorescence quenching effect of N-doped carbon quantum dots was achieved. The results showed that the as-synthesized N-doped carbon quantum dots were regular spherical, uniform in size with an average particle size of 2. 64 nm with a quantum yield of 26. 1%, and the crystal lattice spacing was 0. 25 nm, corresponding to the ( 100 ) facet of graphitic carbon structure. The functional groups on the surface of N-doped carbon quantum dots could interact with Fe3+ to form complex compound by coordination, leading to the fluorescence quenching effect. Fluorescence emission ratios kept a linear relationship with the concentrations of Fe3+ in the range of 0. 23-600 μmol/L with the detection limit of 230 nmol/L.

CdS nanocrystals as fluorescent probe for detection of dolasetron mesylate in aqueous solution:Application to biomedical analysis / 药物分析学报

A simple and straightforward method for the determination of dolasetron mesylate (DM) in aqueous solution was developed based on the fluorescence quenching of 3-Mercaptopropionic acid (MPA) capped CdS quantum dots (QDs). The structure, morphology, and optical properties of synthesized QDs were characterized by using UV-Vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. Under the optimum conditions, the MPA-CdS QDs fluorescence probe offered good sensitivity and selectivity for detecting DM. The probe provided a highly specific selectivity and a linear detection of DM in the range of 2–40 μg/mL with detection limit (LOD) 1.512 μg/mL. The common excipients did not interfere in the proposed method. The fluorescence quenching mechanism of CdS QDs is also discussed. The developed sensor was applied to the quantification of DM in urine and human serum sample with satisfactory results.

Study on Interaction Mechanism between 3 Kinds of Flavonoids Compounds and Human Serum Albumin by Fluorescence Spectrometry / 中国药房

OBJECTIVE:To study the interaction mechanism between flavonoids and human serum albumin (HSA),and to compare the effects of different B-ring substitutions(hydroxyl,methoxyl group)of flavonoids on macromolecular receptor. METH-ODS:The interaction regularity between three flavonoids with different B-ring substitutions(quercetin,hesperetin,methyl hespere-tin) and HSA was studied with fluorescence spectroscopy,the fluorescence quenching types between 3 flavonoids and HSA were determined and analyzed,and the velated binding constant,binding site and thermodynamic parameters were calculated. RE-SULTS:The quenching constants (Ksv) and binding constants (KA) were decreased with the increase of temperatures. The number of binding site(n)was approximately equal to one,and the thermodynamic parameters ΔH0,the binding interaction of these compounds with macromolecules was influenced because of the difference of the B-ring substituents. CONCLUSIONS:The quenching mechanism between three flavonoids and HSA was static quenching;the number of binding site was one;the interaction force of the three compounds with HSA was mainly static electricity,and hydroxyl group in the B-ring was likely the major active group and exerted stronger binding force than methoxyl group to connect with macromolecules.

Preparation and application of carbon dots in chloramphenicol determination / 中国药科大学学报

@#Carbon dots(CDs)were firstly prepared via a simple pyrolysis route using citric acid as the carbon precursor and glycine as modifier. The obtained CDs were further purified by n-butyl alcohol, which made the particle size more uniform and the fluorescence intensity stronger. When excited at 380 nm, the maximum emission wavelength of the CDs was about 480 nm, with a quantum yield of 47%. Based on fluorescence quenching, a novel method for chloramphenicol assay was developed with glycine-passivated CDs. This method is simple and rapid. A linear relationship between the change of fluorescence intensity and the concentration of chloramphenicol was obtained with a relation coefficient of 0. 999 7. The recovery was in the range of 99% to 101% with a relative standard deviation of 0. 3%, which shows CDs′ potential application in drug detection.

Non-covalent binding analysis of sulfamethoxazole to human serum albumin：Fluorescence spectroscopy, UV-vis, FT-IR, voltammetric and molecular modeling / 药物分析学报

This study was designed to examine the interaction of sulfamethoxazole (SMZ) with human serum albumin(HSA). Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of human serum albumin by SMZ was static mechanism. The binding constant values for the SMZ–HSA system were obtained to be 22,500 L/mol at 288 K, 15,600 L/mol at 298 K, and 8500 L/mol at 308 K. The distance r between donor and acceptor was evaluated according to the theory of F?ster energy transfer. The results of spectroscopic analysis and molecular modeling techniques showed that the conformation of human serum albumin had been changed in the presence of SMZ. The thermodynamic parameters, namely enthalpy change (ΔH0) -36.0 kJ/mol, entropy change (ΔS0) -41.3 J/mol K and free energy change (ΔG0) -23.7 kJ/mol, were calculated by using van’t Hoff equation. The effect of common ions on the binding of SMZ to HSA was tested.

Fluorescein Mercury Combined with Optical Sensing Micro Sequential Injection Lab_on_Valve for Determination of H2 S in Intestinal Perfusate / 分析化学

A fluorescence quenching method was established for the determination of H2 S in intestinal perfusate by optical fiber sensing technology combined with micro sequential injection lab_on_valve (μSIA_lov). In the experiment, 100 μL of 0. 1 mol/L NaOH was used as the carrier, and 50 μL of 5. 0×10-5 mol/L fluorescein mercury and 50 μL of sample were selected for the determination. The detection flow rate at the flowcell was 25 μL/s. According to H2 S quenching fluorescence at 521 nm, the concentration of H2 S in the sample was determined. The detected concentration range of H2S was 5. 0×10-6-8. 0×10-5 mol/L, and the detection limit was 5. 4×10-7 mol/L. Detection result of H2S in intestinal perfusion was 3. 8×10-5 mol/L with 3. 1% RSD (n=3). This method can be used for the determination of H2S effectively in the samples, which lay the foundation for real_time online measurement of H2 S in biological samples.

Study on the Interaction between Cefprozil and Bovine Serum Albumin by Spectrometry / 中国药房

OBJECTIVE:To study the interaction of cefprozil (CE) with bovine serum albumine (BSA). METHODS:Under the temperatures of 289,299 and 309 K,the interaction of CE with BSA for 50 min had been studied by fluorescence quenching, UV spectrometry and synchronous fluorescence spectroscopy. Quenching constant(KSV)and speed constant(Kq)were calculated by Stern-Volmer equation. Static quenching constant(KLB)was obtained by Lineweaver-Burk equation,and UV spectrogram was used to determine the type of quenching. Double logarithmic equation was used to calculate the binding constants (Kb) and the number of binding site(n). Thermodynamic equation was used to obtain ΔH,ΔS,ΔG. Hill's coefficients(nH)was obtained by Hill equa-tion. RESULTS:At three different temperatures,with CE concentration increasing,fluorescence intensity of BSA decreased regular-ly. The value of KSV,Kq,KLB,Kb and n and nH decreased with the temperature increasing. ΔH,ΔS and ΔG were lower than 0. The numbers of binding sites were approximately equal to 1 and nH<1. CONCLUSIONS:CE statically quench the fluorescence of BSA,and the binding of them have been found to certain extent. The process of binding is spontaneous exothermic process. The main binding forces include Hydrogen bonds and Van der Waals forces,and primary binding site for CE is located at sub-domain ⅡA of BSA. There was some negative cooperative effect. CE would not affect the conformation of BSA. The binding site of CE and BSA is near by tyrosine residue.

Interaction and Molecular Simulation between Gossypol and Human Serum Albumin / 中国药师

Objective:To explore the interaction between gossypol and human serum albumin ( HSA) . Methods:The interaction of gossypol and HSA under physiological conditions was studied by fluorescence spectroscopy, and the molecular docking software was used to simulate the interaction. Results:The binding constant of gossypol and HSA at 293K and 303K was 2. 390 6 × 105 L·mol-1 and 3. 576 8 × 103 L·mol-1 , respectively. There was one binding site on HSA for gossypol. Hydrogen bond and Van Der Waals inter-actions were involved in the binding process. The binding of gossypol and HAS was closer to tyrosine residue in HSA. The molecular simulation analysis verified the above results. Conclusion: The gossypol-induced fluorescence quenching of HSA belongs to a static quenching procedure.

Study on Interaction betweenYan-Hu-Ning and Bovine Serum Albumin by Spectrometry / 世界科学技术-中医药现代化

The interaction betweenYan-Hu-Ning (YHN) and bovine serum albumin (BSA) was investigated in order to provide further theoretical evidences on action mechanism study between YHN and proteins within the organism. Under optimal conditions, the interaction between YHN and BSA was studied by fluorescence quenching, ultraviolet absorption spectrometry and synchronous fluorescence spectroscopy. At the temperature of 283.15 K, 298.15 K and 313.15 K, quenching constant (KSV) and speed constant (Kq) were calculated by S-V curves. Static quenching constant (KLB) was obtained by L-B double reciprocal equation. Double logarithmic equation was used to calculate the binding constants (Kb) and the number of binding site (n). Thermodynamic equation was used to obtainΔH,ΔS,ΔG. Hill’s coefficients (nH) was obtained by Hill equation. The results showed that at three different temperatures, along with the increasing of YHN concentration, the fluorescence intensity of BSA decreased regularly. The value of KSV, Kq, KLB, Kb, n and nH decreased with the increasing of temperature;ΔG 1. It was concluded that YHN-BSA complex quenched the intrinsic fluorescence of BSA. The mechanism of fluorescence quenching was static quenching. The main binding forces were deduced as hydrogen bonds and Van der Waals forces from calculated values of thermodynamic parameters. YHN and BSA can form a binding site, which indicated certain binding interaction between YHN and BSA. YHN can be stored and transported by protein within the body. Free energy was produced to transformΔG into negative value. It showed that the process of binding between YHN and BSA was spontaneous. The nH was more than 1. It indicated that YHN had positive cooperative effect. The primary binding site was located at subdomainⅡA. The synchronous fluorescence spectra showed certain influence on the conformation of BSA by YHN. It led to the weakening of polarity within BSA and the binding site to be closer to the tyrosine.

Deciphering the binding modes of hematoporphyrin to bovine serum albumin.

Interaction of proteins with small molecules is important in understanding delivery and transport of different therapeutic agents, including drugs. In the present study, we investigated the interaction between hematoporphyrin (HP), the principal component of photosensitizing drug with bovine serum albumin (BSA) in aqueous buffer solution using UV-Vis absorption spectroscopy and fluorescence measurements. The results were further substantiated by molecular docking and molecular dynamics (MD) simulation. Our results revealed that fluorescence of BSA was dominantly quenched by the ground-state complex formation with HP accompanied by the electronic energy transfer (EET) to the later. We experimentally determined the thermodynamic parameters such as G0, H0, and S0 for the HP-BSA system which were -35.5 kJ mole-1, -56.4 kJ mole-1 and -0.06 kJ mole-1 K-1, respectively. These parameters suggested hydrogen-bonding and Van der Waals forces playing major role in the complexation. This was also supported by the binding energy parameters calculated by molecular docking. Moreover, the experimentally determined G0 nicely correlated with those determined by molecular docking and MD-simulation. Further, computational results clearly showed that the binding of HP with BSA in the subdomains IB and IIA.