Biomedical subjects

Zhifeng Fu

Publications and source records attributed to Zhifeng Fu.

7 recordsLinked to original sources

PubMed2006

Flow-through multianalyte chemiluminescent immunosensing system with designed substrate zone-resolved technique for sequential detection of tumor markers.

A novel flow-through immunosensing system for performing a multianalyte chemiluminescent determination in a single run was designed. A new analytical strategy of substrate zone-resolved technique was proposed. Using carcinoma antigen 125 (CA 125) and carcinoembryonic antigen (CEA) as model analytes, the capture antibodies for CA 125 and CEA were immobilized on an UltraBind aldehyde-activated membrane to act as an immunoreactor, to which the mixture of CA 125, CEA, and their corresponding tracers, horseradish peroxidase (HRP)-labeled anti-CA 125 and alkaline phosphatase (ALP)-labeled anti-CEA, was introduced for on-line incubation. The substrates for HRP and ALP were then delivered into the detection cell sequentially to perform substrate zone-resolved immunoassay by a sandwich format. Under optimal conditions, CA 125 and CEA could be assayed in the ranges of 5.0-100 units/mL and 1.0-120 ng/mL, respectively. The whole assay process including incubation, wash, detection, and regeneration could be completed in 35 min. The serum samples from the clinic were assayed with the proposed method, and the results were in acceptable agreement with the reference values. This method and the strategy of substrate zone-resolved technique could be further developed for high-throughput multianalyte immunoassay.

Biomarkers, Tumor↗

PubMed2006

Flow-injection chemiluminescent immunoassay for alpha-fetoprotein based on epoxysilane modified glass microbeads.

A flow-injection chemiluminescent immunoassay system based on a novel transparent immunoaffinity reactor is proposed for the quantitation of alpha-fetoprotein. The reactor prepared with alpha-fetoprotein immobilized epoxysilane modified glass microbeads was used as an immunosensor for chemiluminescent detection. With a non-competitive immunoassay format, the proposed immunosensor system is a low cost, flexible and rapid assay for alpha-fetoprotein. After an off-line incubation of the analyte alpha-fetoprotein with horseradish peroxidase-labeled alpha-fetoprotein antibody as enzyme tracer, the mixture was injected into the reactor, which led to trapping of the free enzyme tracer by the reactor. The trapped enzyme tracer was detected by the p-iodophenol-luminol-H2O2 chemiluminescence system. Under optimal conditions, the decrease in chemiluminescence intensity was proportional to the alpha-fetoprotein concentration in the range of 5.0-100 ng/ml with a detection limit of 2.7 ng/ml at a signal/noise ratio of 3. The immunosensor system showed an acceptable reproducibility and stability. Clinical serum samples were assayed with this method and the results were in acceptable agreement with those obtained from immunoradiometric assay.

Biosensing Techniques↗

PubMed2004

Flow-injection inhibition chemiluminescence determination of indapamide based on luminol-ferricyanide reaction.

A novel and sensitive chemiluminescence (CL) method for the determination of indapamide coupled with flow-injection analysis (FIA) technique is developed in this paper. It is based on the inhibition effect of the studied drug on the chemiluminescence emission of luminol-potassium ferricyanide system. Under the optimum conditions, the decreased CL intensity is proportional with the concentration of indapamide in the range of 1 x 10(-8) to 1.0 x 10(-6) g ml(-1). The detection limit is 3.4 x 10(-9) g ml(-1) (3sigma). A complete analysis could be performed in 45 s including washing and sampling, giving a throughout of about 90 h(-1). The relative standard deviation (R.S.D.) for 11 parallel measurements of 1.0 x 10(-7) g ml(-1) indapamide is 3.0%. The proposed method has been applied for the determination of indapamide in its pharmaceutical formulations. The results obtained compared well with those by an official method. The possible inhibition mechanism of indapamide on luminol-potassium ferricyanide CL system was discussed briefly.

Antihypertensive Agents↗

PubMed2004

N-bromosuccinimide-fluorescein based sensitive flow-injection chemiluminescence determination of phenformin.

A novel and highly sensitive method for the determination of phenformin over the range of 6 x 10(-9) - 1 x 10(-5) g ml(-1) in pharmaceutical formulations with flow-injection chemiluminescence (CL) detection is proposed. The method is based on the CL produced during the oxidation of N-bromosuccinimide (NBS) in an alkaline medium in the presence of fluorescein as an effective energy transfer agent. The use of cetyltrimethylammonium bromide (CTAB) as a sensitizer enhances the signal magnitude by about 100 times. The detection limit is 2 x 10(-9) g ml(-1) (3sigma) with a relative standard deviation of 2.3% (n = 11) at 1 x 10(-7) g ml(-1) phenformin. Ninety samples can be determined per hour. The method was evaluated by carrying out a recovery study and by the analysis of commercial formulations. The obtained results compared well with those by an official method, and demonstrated good accuracy and precision. The possible CL mechanism of the proposed system was also briefly analyzed.

Bromosuccinimide↗

PubMed2003

Sensitive flow-injection chemiluminescence determination of terbutaline sulfate based on enhancement of the luminol-permanganate reaction.

A novel and highly sensitive chemiluminescence (CL) method for the determination of terbutaline sulfate, coupled with flow-injection analysis (FIA), is described in this paper. The method is based on enhancement by terbutaline sulfate of the chemiluminescence emission of the luminol-permanganate system under alkaline conditions. Under the conditions selected the concentration of terbutaline sulfate is proportional to CL intensity in the range 5 x 10(-10)-5 x 10(-7) g mL(-1), with a detection limit of 1.7 x 10(-10) g mL(-1) (3 sigma). The relative standard deviation is 2.8% for 1 x 10(-8) g mL(-1) terbutaline sulfate ( n=11). Ninety samples can be determined per hour. The proposed method has been used to determine terbutaline sulfate in pharmaceutical preparations and in plasma and urine samples with satisfactory results. The possible mechanism of the chemiluminescence reaction is discussed briefly.

Calibration↗

PubMed2003

Flow-injection chemiluminescence detection for studying protein binding of terbutaline sulfate with on-line microdialysis sampling.

The binding of terbutaline sulfate to bovine serum albumin was studied in vitro using the technique of microdialysis sampling combined with flow-injection chemiluminescence analysis (FIA-CL). In the presence of formaldehyde, terbutaline sulfate can be oxidized by KMnO(4) to produce high chemiluminescence emission in sulfate acid media. The concentration of terbutaline sulfate is proportional with the CL intensity in the range of 1 x 10(-7)-2 x 10(-5) mol l(-1) with a detection limit of 3 x 10(-8) mol l(-1). The drug and protein were mixed in different molar ratios in 0.067 mol l(-1) phosphate buffer, pH 7.4, and incubated at 37 degrees C in a water bath. The microdialysis probe was utilized to sample the mixed solution at a perfusion rate of 5 microl min(-1) and the dialytic efficiency of terbutaline sulfate under the experimental conditions was 26.3%. The data obtained by proposed microdialysis flow-injection chemiluminescence method was analyzed with Scrathard analysis and Klotz plot. The estimated association constant (K) and the number of the binding site (n) on one molecule of BSA by Scrathard analysis were 4.11 x 10(4) l mol(-1) and 1.06, respectively. The proposed system proved that FIA-CL coupled with on-line microdialysis sampling is a simple and reliable technique for the study of drug-protein interaction.

Animals↗

PubMed2003

A flow-injection ultrafiltration sampling chemiluminescence system for on-line determination of drug-protein interaction.

A flow-injection ultrafiltration sampling chemiluminescence system for on-line determination of cimetidine-bovine serum albumin (BSA) interaction is proposed in this paper. Cimetidine can be oxidized by N-bromosuccinimide (NBS) and sensitized by fluorescein to produce high chemiluminescence emission in basic media. The concentration of cimetidine is linear with the CL intensity in the range 3 x 10(-7) - 1 x 10(-4) mol L(-1) with a detection limit of 1 x 10(-7) mol L(-1) (3 sigma). The drug and protein were mixed in different molar ratios in 0.067 mol L(-1) phosphate buffer, pH 7.4, and incubated at 37 degrees C in a water bath. The ultrafiltration probe was utilized to sample the mixed solution at a flow rate of 5 micro L min(-1). The data obtained by the proposed ultrafiltration flow-injection chemiluminescence method was analyzed with Scrathard analysis and a Klotz plot. The estimated association constant ( K) and the number of the binding site ( n) on one molecule of BSA by Scrathard analysis and Klotz plot were 3.15 x 10(4) L mol(-1) and 0.95, 3.25 x 10(4) L mol(-1) and 0.92, respectively. The proposed system proved that flow-injection chemiluminescence analysis coupled with on-line ultrafiltration sampling is a simple and reliable technique for the study of drug-protein interaction.

Binding Sites↗