Biomedical subjects

Ru-Qin Yu

Publications and source records attributed to Ru-Qin Yu.

25 records · Page 2Linked to original sources

PubMed2002

An amperometric immunosensor based on a conducting immunocomposite electrode for the determination of Schistosoma japonicum antigen.

A renewable amperometric immunosensor based on a graphite-paraffin-Schistosoma japonicum antibody (SjAb) biocomposite electrode has been prepared for the detection of Schistosoma japonicum antigen (SjAg). Competitive ELISA was employed involving HRP-SjAg as a tracer and 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate. The product of an enzyme catalytic reaction was detected at +0.1 V (vs. Ag/AgCl reference electrode) for measuring the amount of HRP-labeled SjAg binding to the electrode surface. The assay conditions were optimized, including the amount of SjAb loading in the electrode and HRP-SjAg in the incubation solution, the pH of the measuring solution and the incubation time. The measuring range was 0.5-30 microg/ml under the optimum conditions. Rabbit serum samples of different infection degree were measured, which demonstrated that the immunosensor meets the demands of clinical analysis. It exhibits some advantages, such as simplicity of fabrication, rapidity of measurement, and satisfactory sensitivity and reproducibility.

Animals↗

PubMed2002

Spectrofluorometric resolution of closely overlapping drug mixtures using chemometrics methods.

A modified parallel factors analysis (PARAFAC) algorithm with a penalty diagonalization error (PDE), newly proposed by the present authors, was utilized to simultaneously resolve drug mixtures of propranolol (PRO), dipyridamole (DIP) and amiloride (AMI) without any loss of sensitivity. The analyses were performed in aqueous solution. The experimental results demonstrated that the profiles of the spectra and the concentrations could be accurately resolved using the PDE algorithm with a high sensitivity and stable repeatability. That is to say, the closely overlapping problem of the spectra could be easily solved. Furthermore, simultaneous determinations of three kinds of tablets, which contain PRO, AMI and DIP, respectively, were successfully performed with satisfactory results.

Algorithms↗

PubMed2002

Interaction of bis(ethylene)tin(bis(salicylidene)ethylenediamine) with DNA.

The fluorescence spectral characteristics and interaction of bis(ethylene)tin(bis(salicylidene)ethylenediamine) [Et2Sn(salen)] with DNA are described. The polarity of the solvent has a strong effect on the fluorescence characteristics of Et2Sn(salen). Et2Sn(salen) bound to DNA showed a marked decrease in the fluorescence intensity with a bathochromic shift of the excitation and emission peaks. A hypochromism in the UV absorption spectra was also observed. KI quenching and competitive binding to DNA between Et2Sn(salen) and ethidium bromide (EB) were studied in connection with other experimental observations to show that the interactive model between Et2Sn(salen) and DNA is an intercalative one. The pH and salt effect on the fluorescence properties was also investigated. The intrinsic binding constant was estimated to be 1.071 x 10(5) mol L(-1) in base pairs and the binding site number is 1.98, respectively. A linear relationship between F/F0 and the concentration of calf thymus DNA covers 5.1 x 10(-6) - 2.41 x 10(-4) mol L(-1), which can be utilized for determining traces of calf thymus DNA with a detection limit of 1.1 x 10(-7) mol L(-1) in base pairs.

Animals↗

PubMed2002

A novel piezoelectric biosensor for the detection of phytohormone beta-indole acetic acid.

A novel piezoelectric immunosensor has been developed for the determination of beta-indole acetic acid (IAA) in dilute solutions. The detection is based on competitive immunoreaction between a hapten (IAA) and an antigen (IAA-BSA, hapten-protein conjugation) bound to an anti-IAA antibody, immobilized on a quartz crystal microbalance (QCM). The frequency change (y) of the sensor caused by antigen is linearly related to the logarithm of the concentration of IAA (x) in the range of 0.5 ng/ml - 5 microg/ml with a regression equation of the form y = -23x + 151 (r = 0.9937).

Animals↗

PubMed2002

Glycosylated metalloporphyrins as neutral carriers for PVC membrane electrodes.

In this paper, the synthesis of a novel ionophore, chloro[5,10,15,20-tetrakis[2-(2,3,4,6-tetraacetyl-beta-D-glucopyranosyl)-1-O-phenyl]porphinato]manganese (MnT(o-glu)PPCl), and its application as a neutral carrier for a PVC membrane electrode are described. The MnT(o-glu)PPCl-based PVC membrane electrode shows a potentiometric responses to SCN- over a concentration range of 3.4 x 10(-7) - 1.0 x 10(-1) mol L(-1) with a Nernstian slope and a response time of 20 s. The electrode exhibits an anti-Hofmeister selectivity toward SCN- with respect to common coexisting anions. As active materials, MnT(o-glu)PPCl shows better selectivity toward SCN- than chloro(tetraphenylporphinato)manganese (MnTPPCl). The effect of the electrode membrane compositions has been studied and the experimental conditions were optimized. The electrode was applied to the determination of SCN- in body fluids with satisfactory results.

Biosensing Techniques↗

PubMed2002

Bacteria-modified amperometric immunosensor for a Brucella melitensis antibody assay.

A novel amperometric immunosensor setup is described which uses horseradish peroxidase (HRP) as a label in conjunction with a current-based Brucella sensor. The Bacteria modified immunosensor was constructed by using a biocomposite formed by dispersing graphite powder into a mixture of Brucella melitensis and silicate polymer gel. The enzyme-labeled antibody can readily diffuse toward the encapsulated antigen (Brucella melitensis), which retains its binding properties, and the association reaction is easily detected at the surface exposed to the solution. The use of an oaminophenol (o-AP) substrate and amperometric detection at -150 mV (vs. SCE) results in a relatively low detection limit of 3.5 ng/ml and a linear detection range of 3.5 ng/ml to 200 ng/ml. Based on an optimized parameter, the prepared sensor was used to detect the Brucella melitensis antibody in serum samples by using a competitive binding assay. The results demonstrate the feasibility of employing the proposed immunosensor for the detection for Brucella melitensis antibody in a clinical analysis.

Animals↗

PubMed2001

Covalently immobilized aminonaphthalimide as fluorescent carrier for the preparation of optical sensors.

By replacing the hydrogen of the 4-amino group of a 4-amino-1,8-naphthalimide derivative with an N-acryloxyethyl group, the fluorophore has been covalently immobilized on an optical sensor surface by UV photopolymerization. The optical sensor obtained can be used for the determination of picric acid. The linear range and detection limit of the sensor are 9.80x10(-7)-1.96x10(-4) mol L(-1) and 7.1x10(-7) mol L(-1), respectively. Leaching of the fluorophore from the membrane is effectively prevented by covalent immobilization, resulting in a sensor with a relatively long lifetime. The response time of the sensor is short, and the reproducibility and reversibility are good. The sensor has been used for the indirect determination of the chloroquine content of pharmaceutical tablets.

Journal Article↗