An Electrochemiluminescent Method to Detect A Dipeptide Related to Diabetes / 分析化学

In this work, a simple and fast approach for dipeptide detection was developed. AuNPs were decorated onto the surface of indium tin oxide ( ITO ) glass to serve as the working electrode to trigger the electrochemiluminescence ( ECL) of luminol. The property of this electrode was characterized by transmission electron microscopy ( TEM ) , scanning electron microscopy ( SEM ) , electrochemistry and spectroscopic method. Under the optimum conditions, the dipeptide His-Ala could be detected within a linear range from 2. 44×10-11 mol/L to 1. 22×10-7 mol/L, with a detection limit of 2. 42×10-12 mol/L (S/N=3). In human body, the glucagon-like peptide 1(GLP-1) might lose activity during degradation under the enzymatic action of dipeptidyl peptidase IV (PDD-IV), meanwhile release same concentrated His-Ala dipeptide. Thus, the detection of His-Ala dipeptide was of great significance for investigation of diabetes not only for understanding the relation between GLP-1, PDD-IV and its inhibitor, but also the drug discovering because of its potential availability as the target to control the blood GLP-1 level of type II diabetics.

Electrochemiluminescence Performance of Poly(aniline_luminol) Composite Nanowires Synthesized by Chemical Oxidation / 分析化学

Poly ( aniline_luminol ) composite nanowires were synthesized by chemical oxidation using ammonium peroxydisulfate. In contrast to the maximum fluorescence emitting wavelength of luminol at 425 nm, the maximum fluorescence emitting wavelength of the polymeric luminol in the composite nanowires was red shifted to 465 nm obviously. The poly ( aniline_luminol) composite nanowires were modified on graphite electrode surface by drop coating, forming a stable poly ( aniline_luminol ) composite nanowires film. The composite nanowires film modified electrode presented favorable electrochemiluminescence ( ECL ) performances, and the ECL response could be enhanced by hydrogen peroxide. Under the optimized experimental conditions, the modified electrode provided a linear range of 5. 0×10-9-1. 0×10-5 mol/L for the detection of hydrogen peroxide with a detection limit of 2 ×10-9 mol/L.

Determination of Caffeic Acid Based on ZnO Nanoparticles Enhanced Luminol-EDTA Chemiluminescence / 分析化学

In the presence of ZnO nanoparticles ( ZnO NPs ) and EDTA, luminol could produce strong chemiluminescence ( CL) without any oxidant. Therefore, a new CL system was established based on luminol-EDTA-ZnO NPs. As caffeic acid could strongly inhibit the CL, a flow injection CL method for the determination of caffeic acid was proposed. Under the optimized conditions, the relative CL intensity was linear over the logarithm of concentration of caffeic acid ranging from 1 . 0í10-7 mol/L to 1 . 0í10-5 mol/L with the detection limit of 1. 8í10-8 mol/L (3σ). The relative standard deviation (RSD) for the determination of 4 . 0í10-7 mol/L caffeic acid was 3 . 5% ( n=11 ) . The new method was successfully applied to determine the caffeic acid content in the tablets with the recoveries in the range of 97%-101%.

Flow injection chemiluminescence determination of biapenem for injection / 国际药学研究杂志

Objective To establish a new method for the rapid and sensitive determination of biapenem. Methods A simple, rapid and sensitive flow injection chemiluminescence(CL) method for the determination of biapenem was developed based on the fact that biapenem could enhance the CL of the luminol (LMN)-potassium ferricyanide reaction system under an alkaline condition. Results Under the optimal experimental conditions, we obtained a linear relationship between the CL intensity and the concentration of biapenem in the range of 0.02~0.6 mg/L with a detection limit of 7.3×10-3 mg/L. The relative standard deviation was 1.76% for the eleven-time determination of 0.2 mg/L biapenem. Conclusion The method shows high sensitivity, low detection limit and good repeatability. It has been successfully applied to the determination of biapenem for injection and the results are satisfactory.

A TiO2/CNTs Nanocomposites Enhanced Luminol Electrochemiluminescence Assay for Glucose Detection / 分析化学

Abstract A novel luminol electrochemiluminescence strategy based on titanium dioxide/carbon nanotubes ( TiO2/CNTs) nanocomposites for detection of glucose was developed. First, the TiO2/CNTs nanocomposites were prepared by a sol-gel method and modified on the glassy carbon electrode. The electrochemiluminescence ( ECL) signal could be greatly enhanced when the electrode was established by the nanocomposites, which finally resulted in the increased sensitivity. Glucose oxidase calalyzed the oxidation of glucose to form H2 O2 , and the H2 O2 reacted with luminol to produce the ECL signal. Thus the above system was proved to be efficient for glucose detection. The modified electrode exhibited excellent ECL signals and a good linear range of 1. 0í10-7-5. 0í10-6 mol/L with a detection limit of 5. 2í10-8 mol/L towards glucose detection. This strategy was successfully demonstrated as a sensitive, rapid, simple and cost-effective method to detect glucose. Meanwhile, the TiO2/CNTs nanocomposites offered a novel material for the signal enhancement in electrochemiluminescence sensor.

Flow injection chemiluminescence determination of biapenem for injection / 国际药学研究杂志

Objective To establish a new method for the rapid and sensitive determination of biapenem. Methods A simple, rapid and sensitive flow injection chemiluminescence(CL) method for the determination of biapenem was developed based on the fact that biapenem could enhance the CL of the luminol (LMN)-potassium ferricyanide reaction system under an alkaline condition. Results Under the optimal experimental conditions, we obtained a linear relationship between the CL intensity and the concentration of biapenem in the range of 0.02%0.6 mg/L with a detection limit of 7.3 x10-3 mg/L. The relative standard deviation was 1.76% for the eleven-time determination of 0.2 mg/L biapenem. Conclusion The method shows high sensitivity, low detection limit and good repeatability. It has been successfully applied to the determination of biapenem for injection and the results are satisfactory.

Electrochemiluminescence Behavior of Luminol at Closed Bipolar Electrode and Its Analytical Application / 分析化学

A new closed bipolar electrode electrochemiluminescence ( ECL)-based device was designed, and further used to investigate the ECL behaviors of luminol in this device. Our results showed that, while a suitable voltage was applied to the two poles of the closed bipolar electrode, both the positively charged ions and luminol-based anionic ions could be enriched on the two poles of the closed bipolar electrode, respectively. More importantly, the ECL signals, generated from the electro-oxidation of luminol on anodic pole, were found to be related to the total amount of positively charged ions on the cathodic pole of the closed bipolar electrode. Under the optimum experimental conditions, the ECL response was linearly to the concentration of analyte in the range of 1. 0×10-9-1. 0×10-8 mol/L with a detecting limit of 1. 1×10-10 mol/L. Based on this finding, a new ECL method for sensing the solution conductance was developed.

A highly sensitive chemiluminescence assay for superoxide detection and chronic granulomatous disease diagnosis

Reactive oxygen species (ROS) produced by neutrophils are crucial for defense against infectious diseases, and the adequate measurement of ROS levels is an important way to evaluate the possibility of infections. The fluorescent probe dihydrorhodamine 123 has been applied exclusively to the measurement of ROS thus far. We developed a novel method for detecting ROS, which utilizes the chemiluminescent probes Luminol and Diogenes. The new method quantitatively detects ROS produced by as few as 10 to 10⁴ neutrophils. Furthermore, this method can detect ROS levels in one microliter of whole blood or ROS produced by Epstein-Barr immortalized B lymphocytes. This method will be valuable for prompt diagnosis of neonatal chronic granulomatous diseases in which neutrophils aberrantly produce superoxide.

Direct Detection of Reactive Nitrogen Species in Experimental Autoimmune Uveitis

PURPOSE: Demonstrate unequivocally the generation of nitric oxide in experimental autoimmune uveoretinitis by electron spin resonance spectroscopy (ESR) using ferrous iron complex of N-methyl-D-glucamine dithiocarbamate, (MGD)2-Fe2+, as a spin trap. METHODS: Experimental autoimmune uveitis was induced in Lewis rats, and at the peak of the intraocular inflammation, the animals received intravitreous injections of the spin trap. The retina and choroid dissected from the enucleated globes were subjected to ESR. Similarly, the retina and choroid obtained at the peak of experimental autoimmune uveo-retinitis (EAU) were placed in a vial containing luminal, and chemiluminescence was counted on a Packard liquid scintillation analyzer. RESULTS: The ESR three-line spectrum (g=2.04; a(N)=12.5 G) obtained was characteristic of the adduct [(MGD)2-Fe2+-NO]. The majority of this signal was eliminated by the inducible nitric oxide synthase (iNOS) specific inhibitor aminoguanidine injected inflamed retina was detected when compared with that of the non inflamed controls. The chemiluminescent activity was further increased two-fold by the addition of bicarbonate to the inflamed retina; the phenomenon is attributable only to the presence of a high steady-state concentration of peroxynitrite. CONCLUSIONS: The study shows an unequivocal presence of nitric oxide in EAU retina and choroid and the generation of peroxynitrite. High levels of these reactive nitrogen species generated in the inflamed retina and choroids are certain to cause irreversible tissue damage, especially at the susceptible sites such as photoreceptors.

Efecto del dimetilsulfóxido en la respuesta quimioluminiscente y el consumo de oxígeno de neutrófilos humanos activados / Effect of dimethylsulfoxide in the chemiluminescence answer and the consumption of the oxygen of active human neutrophils

El dimetil sulfóxido es un secuestrador inactivante del radical hidroxilo (úOH), e inhibe, de manera proporcional a la dosis, la quimioluminiscencia (QL) de luminol (QLU) y de lucigenina (QLC) en leucocitos polimorfonucleares neutrófilos (PMN) activados con estimulantes solubles y partículas de zimosán opsonizado (ZO). Los resultados indican la inhibición de la QLU en respuesta al ionóforo de calcio A23187 puede deberse al secuestro de úOH por DMSO, mientras que la inhibición de QLC sugiere que el DMSO afecta negativamente a la oxidasa de membrana de PMN. Ello se confirmó al observar el DMSO inhibió el consumo de O2 en PMN activados con FMLP y ZO. Cuando el DMSO se añadió luego de estimulación con FMLP y ZO, no hubo inhibición de la QLU, pero sí de la inducida por A23187. El labado de PMN expuestos a DMSO causó un incremento en la QLU en respuesta a la estimulació con FMLP y ZO. Ello es congruente con la hipótesis de que el DMSO interfiere con la activación de las subunidades de membrana de la oxidasa por las unidades reguladoras citoplasmáticas. Estos resultados implican que el DMSO puede inhibir la QL en fagocitos tanto mediante secuestro de úOH como por interferencia con la producción de superóxido por la oxidasa de membrana.

Dimethylsulfoxide (DMSO), a hydroxyl radical scavenger, exerted a dose dependent inhibition on the luminol and lucigenin-enhanced chemiluminiscent responses of human neutrophils activated with soluble and particulate stimulants. DMSO inhibition of the luminol chemiluminescence induced by calcium ionophore A23187 was probably due to .OH scavenging, whereas inhibition of the lucigenin chemiluminiscence suggested DMSO negatively affects the NADPH-dependent membrane oxidase of neutrophils. In agreement with this, DMSO moderately inhibited O2 consumption in PMN suspensions stimulated with chemotactic peptide and opsonized zymosan. DMSO inhibition of chemotactic peptide and opsonized zymosan-induced luminol chemiluminescence was observed only when added before or in conjunction with stimulants, whereas A23187-induced chemiluminescence was inhibited by DMSO regardless of time of addition. Washing of DMSO-treated PMN resulted in increased luminol enhanced chemiluminescence in response to chemotactic peptide and opsonized zymosan. This is consistent with the idea that DMSO may be interfering with activation of the membrane subunits of the oxidase by translocation and docking of the cytoplasmic, regulatory subunits...

Chemiluminescence Study of Pe roxynitrite in Experimental Autoimmune Uveitis

The purpose of this study is to evaluate the extent of peroxynitrite generation in the pool of radicals/oxidants from intraocular inflammation using luminol-dependent chemiluminescence(LDCL)method. S-antigen induced uveitis was produced in Lewis rats. The rats were killed at the peak of inflammation, and the retinas and choroids were collected for the LDCL. Sodium bicarbonate was used to confirm the peroxynitrite signal. Superoxide dismutase(SOD), N-nitro-L-arginine methyl ester(LNAME)and aminoguanidine(AG)were tried to evaluate the inhibitory effect of superoxide and nitric oxide. LDCL counts for 6 inflamed and 6 control retina/choroid preparations were 66, 429+/-413 cpm and 13, 941+/-105 cpm, respectively(p<0.01). In the presence of bicarbonate, emission was increased by 125.3+/-6.6%(n=6)and the signal was sustained for 2 hours. SOD, L-NAME and AG suppressed the LDCL by 39.8+/-6.1%(n=3), 20.4+/-4.4%(n=3) and 35.9+/-4.0 %(n=3), These observations suggest that peroxynitrite contributes considerably to the generation of the total pool of reactive species by the cellular infiltrate. The presence of a high level of peroxynitrite, a potent oxidizing and nitrating agent, in inflamed retina may cause irreversible tissue damage to the photoreceptors.

Effects of maximal exercise on blood leukocyte counts and neutrophil activity in athletes / 体力科学

Twenty endurance-trained athletes (five male speed-skaters, eleven male and four female cross-country skiers, 16-18 years) ran on a treadmill by a protocol of incremental graded increase in workload until exhaustion during an endurance training period in off-season summer. Immediately after exercise, all developed peripheral leukocytosis (1.9 times; p<0.01) due mainly to lymphocytosis (2.6 times; p<0.01) with a predominant effect on large granular lymphocyte (natural killer cell) count (5.9 times ; p<0.01) . Monocyte count was also enhanced 2.3 times (p<0.01) . These increases were transitory and returned to the pre-exercise levels 1 h later. Peripheral neutrophilia was also observed by 43% (p<0.01) immediately after exercise and remained elevated by 25% (p<0.01) 1 h after exercise, but a shift to the left did not take place. The capacity of isolated neutrophils to produce reactive oxygen species was assessed by luminol-dependent chemiluminescence which detects mainly myeloperoxidase (MPO) -mediated formation of such hyperreactive oxidants as HOCl. The maximum intensity of chemiluminescence (peak height) upon stimulation with opsonized zymosan was significantly enhanced following exercise (p<0.05) . Similar results were obtained when phorbol myristate acetate was employed as nonphagocytic soluble stimulus (p<0.01), suggesting that the capacity of neutrophils to degranulate MPO rather than phagocytosis was enhanced following exercise. In addition, the enhancements of chemiluminescence were positively correlated with the increase in segmented neutrophil count. These data indicate that maximal exercise not only mobilized mature neutrophils from the marginated pool into the circulation, but also augmented their capacity to generate reactive oxygen species of higher reactivity.

Effect of training on physical exersice-induced changes in non-specific humoral immunity / 体力科学

Although it is generally thought that habitual exercise protects an individual from infections, few careful scientific studies have been conducted. To clarify the influences of physical training on non-specific humoral immunity, both serum opsonic activity, which is a more direct indicator for the strength of non-specific humoral immunity to infections, and serum immunoglobulin and complement levels of 18 healthy male volunteers were assayed before and after a 10-week of training as indices of immuno defense.<BR>The serum levels of three immunoglobulins (IgG, IgA and 1gM) and one complement (C3) were compared prior to and immediately after exercise both before and after training. Paired t-test revealed that before training exercise-induced increases in IgG and C 3 were significant and after training increases in IgG, IgA, IgM and C 3 were significant. But baseline (prior to exercise) levels of these immunoglobulins and complement were significantly suppressed during the training period.<BR>Serum opsonic activity was compared with each other in the same way as serum protein levels. The noutrophilic chemiluminescence Peak Height (PH), which is one of the indicators of serum opsonic activity, was significantly decreased immediately after exercise at the beginning stage of the training. After the training period, serum opsonic activity showed no noteworthy exercise-induced variations and baseline levels were slightly increased during the training period.<BR>These findings suggest that resistance and reactivity to the physical stress are improved and the non-specific humoral immunity, self-defense ability against infections, is considered to be improved by the training.

Determination of selenium in serum with Luminol-H_2O_2-KMnO4 chemiluminescence system / 重庆医科大学学报

Objective: To study the quenchable effect of Selenium to Luminol-H2O2-KMnO4 Chemiluminescence system and to establish a method for the determination of Selenium in serum.Methods: Chemiluminescence system was used to determine the Chemiluminogenic strength of Luminol-H2O2-KMnO4 and the detection of Selenium in serum was realized.Results:A detection limit with 6.5?10-4?g/ml and a 1.5?10-3～6.5?10-1?g/ml linear range were obtained.The average recovery fraction was 94.21% and the relative standard deviation was 2.97%.Conclusion: A satisfactory result for the determination of Selenium in serum by this method is obtained.