Studies on the interaction between small organic molecules and DNA are important means to explore drug mechanism and new drugs. Quercetin is a polyhydroxy flavone compound with activities such as anti-cancer, anti-inflammatory, antibacterial, antiviral, hypoglycemic and anti-hypertensive, immunomodulation and cardiovascular protection. Experimental studies aim at confirming if an interaction exists between quercetin and DNA, and determining the type of interaction. The interaction between quercetin and herring DNA can be detected by fluorescence spectrometry and resonance scattering fluorescence spectrometry analysis. The mode of the interaction between quercetin and herring DNA can be detected by UV-Vis spectrophotometry and fluorescence polarization analysis. This review helps understand the in vitro interaction between quercetin and DNA, and assist the development of drugs for corresponding diseases.
DNA/genetics* ; Quercetin ; Spectrometry, Fluorescence

The current quantitative methods of bilirubin have disadvantages such as high cost and low sensitivity. Due to the negative correlation between the level of serum bilirubin and the risk of cardiovascular diseases, a fluorescent ratiometric film sensor was developed aiming at bilirubin detection at low level concentration. Blue-emitting and red-emitting gold nanoclusters were assembled into the same film using layer-by-layer self-assembly technology. Detection of bilirubin was achieved based on the intensity ratio of the two nanoclusters. Bilirubin exposure causes fluorescent quenching of the film. The fluorescence intensity ratio of the two cluster probes had quantitative relationship versus bilirubin concentration. Based on this film sensor, a portable fluorescence detection system was designed for the ratiometric sensing of bilirubin. The hardware of the system was mainly composed of main control chip STM32F407, TSL237 and TSL238T optical frequency sensor. A light-avoiding dark room and detection light path were designed through three-dimensional printing to reduce the interference from ambient light and improve detection accuracy. Experimental results showed that the proposed detection system had strong anti-interference, good stability and accuracy. The linear coefficient of bilirubin detected by this system was 0.987. The system presented good results in reproducible experiments and possessed a good linear relationship with the data obtained by standard spectrofluorometer. The portable system is expected to detect serum bilirubin at low levels.
Bilirubin ; Fluorescence ; Fluorescent Dyes ; Gold ; Metal Nanoparticles ; Spectrometry, Fluorescence/methods*

Humans ; Lead ; Spectrometry, Fluorescence ; Spectrophotometry, Atomic ; Uncertainty

The adsorption of proteins on the surface of glass slides is essential for construction of protein chips. Previously, we prepared a nickel-coated plate by the spin-coating method for immobilization of His-tagged proteins. In order to know whether the structural factor is responsible for the immobilization of His-tagged proteins to the nickel-coated glass slide, we executed a series of experiments. First we purified a His-tagged protein after expressing the vector in E. coli BL21 (DE3). Then we obtained the unfolding curve for the His-tagged protein by using guanidine hydrochloride. Fractions unfolded were monitored by internal fluorescence spectroscopy. The delta G(H20) for unfolding was 2.27 kcalmol +/- 0.52. Then we tested if unfolded His-tagged proteins can be adsorbed to the nickel-coated plate, comparing with Ni2+ -NTA (nitrilotriacetic acid) beads. Whereas unfolded His-tagged proteins were adsorbed to Ni2+ -NTA beads, they did not bind to the nickel-coated plate. In conclusion, a structural factor is likely to be an important factor for constructing the protein chips, when His-tagged proteins will immobilize to the nickel-coated slides.
Adsorption ; Fibrinogen ; Glass* ; Guanidine ; Immobilization ; Protein Array Analysis ; Spectrometry, Fluorescence

Botryococcus braunii is a unique colonial green microalga and a great potential renewable resource of liquid fuel because of its ability to produce lipids. Due to the dense cell colonies and rigidly thick cell wall of B. braunii, the traditional Nile red method is usually of low sensitivity and bad repeatability and hard for the determination of lipid content in the cells. By dispersing the colony with ultrasonic, assisting permeation of Nile red across the cell wall with dimethyl sulfoxide and optimizing the staining conditions, we established an improved detection method. The details were as follows: after the colonial algal sample was treated by ultrasonic at 20 kHz for 20 s, 100 W transmitting power and with 1 s on/1 s off intermittent cycle, the equivoluminal 15% (V/V) dimethyl sulfoxide and 3 microg/mL Nile red were successively added and mixed evenly, then the staining system was incubated in dark at 40 degrees C for 10 min, and subsequently was measured by fluorescence spectroscopy detection with an excitation wavelength of 490 nm. Compared with the traditional method, the improved one not only had higher detection sensitivity which was increased by 196.6%, but also had obviously better detection repeatability whose characteristic parameter - relative standard deviation (RSD) was decreased from 10.91% to 1.84%. Therefore, the improved method could provide a rapid and sensitive detection of lipid content for B. braunii breeding and cultivation.
Chlorophyta ; chemistry ; Lipids ; analysis ; Microalgae ; chemistry ; Spectrometry, Fluorescence ; methods ; Ultrasonics

Animals ; Humans ; Reproducibility of Results ; Selenium ; analysis ; Spectrometry, Fluorescence ; Spectrophotometry, Atomic

Humans ; Mercury ; blood ; urine ; Spectrometry, Fluorescence ; methods ; Spectrophotometry, Atomic ; methods

In this review we summarize the progress made towards understanding the role of protein-protein interactions in the function of various bioluminescence systems of marine organisms, including bacteria, jellyfish and soft corals, with particular focus on methodology used to detect and characterize these interactions. In some bioluminescence systems, protein-protein interactions involve an "accessory protein" whereby a stored substrate is efficiently delivered to the bioluminescent enzyme luciferase. Other types of complexation mediate energy transfer to an "antenna protein" altering the color and quantum yield of a bioluminescence reaction. Spatial structures of the complexes reveal an important role of electrostatic forces in governing the corresponding weak interactions and define the nature of the interaction surfaces. The most reliable structural model is available for the protein-protein complex of the Ca(2+)-regulated photoprotein clytin and green-fluorescent protein (GFP) from the jellyfish Clytia gregaria, solved by means of Xray crystallography, NMR mapping and molecular docking. This provides an example of the potential strategies in studying the transient complexes involved in bioluminescence. It is emphasized that structural studies such as these can provide valuable insight into the detailed mechanism of bioluminescence.
Animals ; Anthozoa ; physiology ; Aquatic Organisms ; physiology ; Bacteria ; metabolism ; Binding Sites ; Calcium ; metabolism ; Crystallography, X-Ray ; Fluorescence Resonance Energy Transfer ; Green Fluorescent Proteins ; metabolism ; Hydrozoa ; physiology ; Imidazoles ; metabolism ; Luciferases ; metabolism ; Luminescent Measurements ; instrumentation ; methods ; Luminescent Proteins ; metabolism ; Models, Molecular ; Protein Binding ; Pteridines ; metabolism ; Pyrazines ; metabolism ; Scyphozoa ; physiology ; Spectrometry, Fluorescence

PURPOSE: The aim of this study was to evaluate the stability of arginine-glycine-aspartic acid (RGD) peptide coatings on implants by measuring the amount of peptide remaining after installation. MATERIALS AND METHODS: Fluorescent isothiocyanate (FITC)-fixed RGD peptide was coated onto anodized titanium implants (width 4 mm, length 10 mm) using a physical adsorption method (P) or a chemical grafting method (C). Solid Rigid Polyurethane Foam (SRPF) was classified as either hard bone (H) or soft bone (S) according to its density. Two pieces of artificial bone were fixed in a customized jig, and coated implants were installed at the center of the boundary between two pieces of artificial bone. The test groups were classified as: P-H, P-S, C-H, or C-S. After each installation, implants were removed from the SRPF, and the residual amounts and rates of RGD peptide in implants were measured by fluorescence spectrometry. The Kruskal-Wallis test was used for the statistical analysis (alpha=0.05). RESULTS: Peptide-coating was identified by fluorescence microscopy and XPS. Total coating amount was higher for physical adsorption than chemical grafting. The residual rate of peptide was significantly larger in the P-S group than in the other three groups (P<.05). CONCLUSION: The result of this study suggests that coating doses depend on coating method. Residual amounts of RGD peptide were greater for the physical adsorption method than the chemical grafting method.
Adsorption ; Dental Implants ; Isothiocyanates ; Microscopy, Fluorescence ; Oligopeptides ; Polyurethanes ; Spectrometry, Fluorescence ; Titanium ; Transplants

OBJECTIVETo develop a new high-performance liquid chromatographic (HLPC) method for determination of propofol in human serum.

METHODSHuman serum samples were precipitated with 20% perchloric acid and centrifuged to obtain 50 microl of the supernatant for analysis by HPLC coupled with fluorescence detection. The analysis was performed with a C(18) reversed-phase column using a acetonitrile-water (90:10) phase delivered at 1.0 ml/min, with the excitation wavelength of 276 nm and emission wavelength of 310 nm.

RESULTSThe calibration curves were linear (r=0.997 5) within the concentration range of 0.05-10 microg/ml, the limit of propofol quantification was 50 ng/ml and the intra- and inter-day precisions were between -/+15%.

CONCLUSIONSThe method is accurate, sensitive and simple for propofol determination in clinical anesthesia.

Anesthetics, Intravenous ; blood ; chemistry ; Chromatography, High Pressure Liquid ; methods ; Fluorescence ; Humans ; Propofol ; blood ; chemistry ; Reproducibility of Results ; Spectrometry, Fluorescence ; methods