Biomedical subjects

Long-Di Li

Publications and source records attributed to Long-Di Li.

8 recordsLinked to original sources

PubMed2005

Solid-substrate room-temperature phosphorescence immunoassay based on an antibody labeled with nanoparticles containing dibromofluorescein luminescent molecules and analytical application.

Luminescent 20-nm silicon dioxide nanoparticles containing dibromofluorescein (D; particles denoted D-SiO(2)) were synthesized by the sol-gel method. In the presence of Pb(Ac)(2) as a heavy atom perturber, the particle can emit the intense and stable room temperature phosphorescence(RTP) signal on a polyamide membrane at the wavelength of lambdaex(max)/lambdaem(max) = 460/623 nm for D. Our research indicates that the specific immune reaction between goat-anti-human IgG antibody labeled with D-SiO(2) and human IgG can be carried out quantitatively on a polyamide membrane, and the phosphorescence intensity was evidently enhanced after the immunoreaction. Thus a new solid substrate-room temperature phosphorescence immunoassay (SS-RTP-IA) for determination of human IgG was established. The linear range of this method is 0.0624-20.0 pg spot(-1) of human IgG (corresponding to a concentration range of 0.156-50.0 ng ml(-1), sample volume: 0.40 microl spot(-1)). The regression equation of the working curve is DeltaIp = 94.39 + 17.00 m IgG (pg spot(-1)) (460/623 nm, r = 0.9998). Detection limit calculated as 3 Sb/k is 0.015 pg spot(-1). After elevenfold replicate measurement, RSD are 3.2% and 2.4% for samples containing 0.156 and 50.0 ng l(-1) IgG, respectively. This method is sensitive, accurate, and of high precision. And it has been applied to the determination of IgG in human serum with satisfactory results. Meanwhile, the mechanism of SS-RTP-IA based on an antibody labeled with nanoparticles containing dibromofluorescein luminescent molecules was discussed.

Animals↗

PubMed2005

Determination of traces of bismuth by quenching of solid-substrate room-temperature phosphorescence from morin-labeled silicon dioxide nano-particles.

Silicon dioxide nano-particles, diameter 50 nm, containing morin (morin-SiO2) have been synthesized by the sol-gel method. They emit strong and stable room-temperature phosphorescence (SS-RTP) on filter paper as substrate, and bismuth can quench the intensity of the SS-RTP. On this basis a new morin-SiO2 solid-substrate room-temperature phosphorescence-quenching method has been established for determination of traces of bismuth. Reduction of phosphorescence intensity (DeltaI(p)) is directly proportional to the concentration of bismuth in the working range 0.16-14.4 ag spot(-1) (sample volume 0.40 muL spot(-1), corresponding to the concentration range 0.40-36.0 fg mL(-1)). The regression equation of the working curve is DeltaI(p)=14.86+5.279x[Bi3+] (ag spot(-1)) (n=6, r=0.9982). The detection limit of this method is 0.026 ag spot(-1) (corresponding to a concentration of 6.5 x 10(-17) g mL(-1)).This sensitive, reproducible and accurate method has been used for successful analysis of real samples.

Journal Article↗

PubMed2005

Determination of human IgG by solid substrate room temperature phosphorescence immunoassay based on an antibody labeled with nanoparticles containing Rhodamine 6G luminescent molecules.

Luminescent silicon dioxide nanoparticles (R-SiO2) with size of 50 nm containing Rhodamine 6G (R) were synthesized by sol-gel method. In the presence of Pb(Ac)2 as a heavy atom perturber, the particle can emit intense and stable room temperature phosphorescence signal of R, respectively, on polyamide membrane, with the lambda(ex)(max)/lambda(em)(max) = 470/635 nm for R. Our research indicates that the specific immune reaction between goat-anti-human IgG antibody labeled with R-SiO2 and human IgG can be carried on polyamide membrane quantitatively, and the phosphorescence intensity was enhanced after the immunoreactions. Thus, a new method of solid substrate room temperature phosphorescence immunoassay (SS-RTP-IA) for the determination of human IgG was established basing on antibody labeled with the nanoparticles containing binary luminescent molecules. The linear range of this method is 0.0624-20.0 pg spot(-1) of human IgG (corresponding concentration, 0.156-50.0 ng mL(-1); sample volume, 0.40 microL spot(-1)). The regression equations of working curves are delta I(p) = 88.16. + 16.79 m(IgG) (pg spot(-1)) (485/646 nm, r = 0.9997). Detection limits calculated by 3Sb/k are 0.017 pg spot(-1). For samples containing 0.156 and 50.0 ng mL(-1) of IgG, we measured repeatedly for 11 times, RSDs are 3.9 and 2.8%, respectively. This method is sensitive, accurate and of high precision.

Antibodies↗

PubMed2004

Determination of human IgG by solid-substrate room-temperature phosphorescence immunoassay based on an antibody labeled with nanoparticles containing rhodamine 6G luminescent molecules.

Luminescent 50-nm silicon dioxide nanoparticles containing both types of rhodamine 6G (R; particles denoted R-SiO2) were synthesized by the sol-gel method. In the presence of Pb(Ac)2 as a heavy atom perturber the particle can emit the intense and stable room-temperature phosphorescence (RTP) signal of R on a polyamide membrane, with lambda(ex)max/ lambda(em)max=470/635 nm for R. Our research indicates that the specific immune reaction between goat-anti-human IgG antibody labeled with R-SiO2 and human IgG can be carried out quantitatively on a polyamide membrane, and the phosphorescence intensity was enhanced after the immunoreaction. Thus a new method for solid-substrate room-temperature phosphorescence immunoassay (SS-RTP-IA) for determination of human IgG was established on the basis of antibody labeled with the nanoparticles containing binary luminescent molecules. The linear range of this method is 0.0624-20.0 pg spot(-1) of human IgG (corresponding to a concentration range of 0.156-50.0 ng mL(-1), sample volume 0.40 microL spot(-1)). The regression equations of the working curves are DeltaIp = 71.27+7.208 m(IgG) (pg spot(-1)) (r = 0.9996). Detection limits calculated as 3 Sb/k are 0.022 pg spot(-1). Compared with the same IA using fluorescein isothiocyanate (FITC) as the marker the new method was more sensitive and had a wider linear range. After elevenfold replicate measurement RSD are 4.5 and 3.6% for samples containing 0.156 and 50.0 ng mL(-1) IgG, respectively. This method is sensitive, accurate, and of high precision.

Animals↗

PubMed2004

Determination of human complement3 by solid substrate room temperature phosphorescence immunoassay with a labelled avidin-biotin bridge.

A solid substrate room temperature phosphorescence immunoassay (SS-RTP-IA) for the determination of human complement3 (C3) based on a sandwich type assay and a labelled avidin-biotin (LAB) type assay was described. The anti-human complement3 and avidin were labeled with eosin5-isothiocyanate. On a polyamide membrane (PM), SS-RTP signals (lambda(ex)/lambda(em) = 535/678 nm) of immune complexes obtained by both assays were linear with the concentration of complement3 in the range of 6.25-100 ng/ml. The detection limits are 1.37 ng/ml for sandwich assay and 2.74 ng/ml for labeled avidin-biotin assay. (For a sample volume of 0.4 microl per spot, the mass detection limits are 0.546 and 1.09 pg/spot, respectively. If the molecular weight of human complement3 is 185,000, the detection limits are 2.95 and 5.91 amol per spot.) The results of determination of complement3 in 20 human sera obtained by labeled avidin-biotin SS-RTP-IA are correlated well with those obtained by ELISA. This study shows that SS-RTP-IA by whichever direct, sandwich or labeled avidin-biotin type assay can combine very well the characteristics of both the high sensitivity of SS-RTP and specificity of the immunoreaction.

Antibodies↗

PubMed2003

Medium effects on fluorescence of ciprofloxacin hydrochloride.

The medium (pH, organic solvents, cyclodextrin (CD) or surfactants) effects on the fluorescence of ciprofloxacin hydrochloride (CPFX.HCl) were studied in detail. It is found that the three acid constants of ciprofloxacin (CPFX) are near to each other. Therefore the relation curve between pH and fluorescence intensity has no strident change and keeps relative stable in the pH range of 2-7. When pH was in the range of 5.5-6.0, the fluorescence intensity of CPFX reached the max. The kind and amount of organic solvent added to the luminescent system have various effects. Ethanol quenched fluorescence and the fluorescence excitation wavelength is red shift at first and then blue shift. Acetone has complicated effects on the fluorescence properties of CPFX.HCl solution. The experiment result shows that acetone is really a quencher when its volume content in the system is from 0 to 20%, but when its content is 90%, the signal intensity is unexpectedly one and a half times as much as that of no acetone. This means that there is a strong interaction between the acetone and CPFX; CPFX.H(+) could be included into the gamma-CD but the capping effect is not notable. The effect of cationic surfactant cetyltrimethylammonium bromide and non-ionic surfactant TX-100 and TX-80 on CPFX fluorescence was unimpressive, but the anionic surfactant's effect is aberrant. The fluorescence intensity of CPFX.HCl solution experiences three stages of increasing, decreasing and increasing in turn, as sodium dodecyl sulfate is adding gradually. But for sodium lauryl sulfonate, there are only two stages of decreasing and increasing with the concentration increasing. It is problematic to illustrate clearly the effect mechanism of acetone and anionic surfactant at present. Undoubtedly, the experimental results in this paper should be useful in practice works and the research is worth studying still further.

Ciprofloxacin↗

PubMed2002

Studies on properties and application of non-protected room temperature phosphorescence of propranolol.

A direct and simple non-protected room temperature phosphorimetry (NP-RTP) for determine propranolol, which using I- as a heavy atom perturber and sodium sulfite as a deoxygenator, has been developed. The phosphorescence peak wavelength maxima lambda(ex)/lambda(em) = 288/494, 522 nm. The analytical curve of propranolol gives a linear dynamic range of 8.0 x 10(-8)-2.0 x 10(-5) mol l(-1) and a detection limit of 3 x 10(-8) mol l(-1). The influence of I- concentration on RTP lifetime of propranolol was studied and the luminescence kinetic parameters were calculated. It is found that the relation between I- concentration (x) and RTP lifetime (tau) can be expressed as tau = 1.25e(-0.477x) and the rate constants of phosphorescence emission k(p) was 0.800 per ms. The method was applied directly to determination of propranolol in urine and drug tablets with a satisfactory result. The recoveries were 96.6-97.4% and the relative standard deviation was 2% for the 1.00 x 10(-6)-4.00 x 10(-6) mol l(-1) propranolol in spiked urine sample.

Humans↗

PubMedDate not supplied

Comparison of properties on non-protected fluid room temperature phosphorescence of some tetra-ring aromatic hydrocarbons.

A comparative study of the photoluminescence properties of three kinds of tetra-ring aromatic hydrocarbon (1-sodium pyrenesulphonate, benz[alpha]anthracene and chrysene) solution in the absence of any protecting medium is described. It was found that a room temperature phosphorescence signal with different intensities can be induced for these solutions, using only TlNO3 or KI as a heavy atom perturber (HAP) and Na2SO3 as a deoxygenator. An appropriate amount of organic solvent added to the systems of pyrene, benz[alpha]anthracene and chrysene is necessary for increasing the solubility and phosphorescence intensity, and the preferable solvent is acetonitrile. For the pyrene, pyrenesulphonate and chrysene systems, a delayed excimer fluorescence accompanied with the room temperature phosphorescence (RTP) emission can be observed, but that for benz[alpha]anthracene cannot. The ratio of delayed excimer fluorescence and phosphorescence signals for pyrene, pyrenesulphonate and chrysene systems can be controlled by adjusting the concentration of luminophor, kinds and amount of both organic solvents and HAP. Under the optimal conditions, the RTP signals are proportional to the concentration of the four aromatic hydrocarbons, which means that the RTP properties of the four tetra-ring aromatic hydrocarbons can be used for quantitative analysis.

Cyclization↗