This article summarizes biological detection techniques based on magnetic signal of magnetic nanoparticles and the research progress of these techniques in biomedicine. Biological detection based on magnetic nanoparticles is faster, more accurate and more convenient compared to traditional optical techniques and causes much attention. It can be classified into giant magneto resistive biosensor (GMR), magnetic relaxation switch (based on T2 relaxation time), AC susceptibility (based on Brownian relaxation) and magnetic lateral flow immunoassay. These techniques can be combined with nanotechnology, microfluidics, immunoassay and bio-chips and have wide application prospects in clinical diagnosis, biological detection, environmental monitoring and food security areas.
Biosensing Techniques ; instrumentation ; methods ; Immunoassay ; instrumentation ; methods ; Magnetic Phenomena ; Nanoparticles ; chemistry ; Nanotechnology ; instrumentation ; Point-of-Care Systems

Fiber-optic biosensor is now becoming a new research direction in biosensors. In recent 10 years it has got a compelling development and has been applied to medical pathogens, food toxicity, water pollution, biochemical weapons, fast detection for environmental samples, etc. In this paper its development is given out in detail.
Biosensing Techniques ; instrumentation ; methods ; Equipment Design ; Fiber Optic Technology ; Humans ; Immunoassay ; instrumentation ; methods ; Optical Fibers

We use direct-write laser micromachining technology to fabricate the microfluidic chip, and to establish a microfluidic chemiluminescence immunoassay system based on superparamagnetic microbeads, for detecting alpha- fetoprotein (AFP). The AFP analysis can be completed in 20 minutes with 5 microl sample and 5 microl reagent, and there is a good linear correlation in the range of 1-800 ng/ml.
Equipment Design ; Humans ; Immunoassay ; instrumentation ; methods ; Luminescent Measurements ; instrumentation ; methods ; Microfluidic Analytical Techniques ; instrumentation ; alpha-Fetoproteins ; analysis

Cytometric bead array (CBA) is a new analytical technique, which can achieve real-time and rapid detection of targeted components in a small amount of sample. With many advantages of high throughput screening, high specificity and sensitivity, low cost, easy operation and good repeatability, this CBA technique has been widely used for the detection of various components in foods, agricultural products and environmental samples. Recently, it has got significant development in rapid detection of small molecules. This review briefly introduced the theory of CBA technique, summarized the application in the analysis of small molecules, such as mycotoxins, pesticide residues, shellfish toxins, and then prospected the application of trace small molecules detection in the complex matrices of traditional Chinese medicine and the development trend of it.
Drug Contamination ; High-Throughput Screening Assays ; instrumentation ; methods ; Immunoassay ; instrumentation ; methods ; Microspheres ; Pesticides ; analysis ; Toxins, Biological ; analysis

In order to construct a new type of piezoelectric quartz immunosensor for the determination of carcino-embryonic antigen (CEA), the sensor detection pools were consisted of plastic loops and crystals that were 10 MHz quartz AT-cut with gold coated electrodes and the immobilization of the monoclonal antibody against CEA onto gold electrode surface of the quartz crystal was accomplished via Thiol method. Then the immunosensors were used in clinical laboratory. The experimental results showed that the piezoelectric immunosensor had good response to CEA, the frequency shifts were linearly dependent on CEA concentration in the range of 1.56 to approximately 50.00 ng/ml, other antigens such as alpha fetoprotein (AFP), prostate specific antigen (PSA), human chorionic gonadotropin (hCG) did not interfere with the sensor's response. The results obtained from this method were in satisfactory accordance with those obtained by radio immunoassay(P>0.05), The correlation coefficient was 0.90. Piezoelectric immunosensor for determination of CEA has the advantage of high sensitivity, high specificity, unnecessary labeling, simple performing, rapid analysis, low cost, real-time detection and repeated use, etc. It can be used for detecting serum CEA in clinical laboratory.
Antibodies, Monoclonal ; Carcinoembryonic Antigen ; blood ; immunology ; Electrodes ; Equipment Design ; Humans ; Immunoassay ; instrumentation ; methods ; Quartz ; Sensitivity and Specificity

Based on integrate circuit (IC) technology, an eight-channel gold electrodes (GEs) array was developed. The immunosensor array is prepared by co-immobilizing thionine and Hepatitis B (HB) antibody on the gold electrodes through covalently binding them to GEs with a cysteamine/glutaraldehyde linkage. Hepatitis B surface antigen (HBsAg) was detected qualitatively and quantitatively by the peak current decrease percentage of the thionine. HBsAg positive/negative standard serum was well defined by the array. 8-channel synchronous detection for HBsAg was noted to be of good accuracy and reliability. The results of its clinical application were in good agreement with the results from ELISA.
Biosensing Techniques ; instrumentation ; Electric Impedance ; Electrochemistry ; instrumentation ; methods ; Electrodes ; Hepatitis B Antibodies ; immunology ; Hepatitis B Surface Antigens ; analysis ; immunology ; Humans ; Immunoassay ; instrumentation ; methods

To research piezoelectric immunosensor array for rapid detecting HIV(1+2), piezoelectric immunosensor array matrix was designed. HIV(1+2)C1 antigen was immobilized onto the silver electrodes of quartz-crystal microbalance, which was modified with adsorption and cross-linked method. In the clean air flow and monitoring environment, standard quality control and clinical serum sample were detected. The linear range for the measurement of HIV(1+2) was 0.01-0.2 NCU/ml. The sensitivity, specificity and accuracy of HIV(1+2) piezoelectric protein sensor array were 91.7%, 93.3% and 92.7% respectively.
Biosensing Techniques ; instrumentation ; methods ; Electrodes ; HIV ; isolation & purification ; HIV Antibodies ; blood ; Humans ; Immunoassay ; methods ; Protein Array Analysis ; instrumentation ; methods ; Quartz ; Reproducibility of Results ; Sensitivity and Specificity

A sensitive antibody-based lateral flow dipstick was developed for ginsenoside Re (GRe) detection. The stick consisted of a sample pad, a conjugate pad, membrane and an absorbent pad. The membrane was coated with two capture reagents, GRe-BSA conjugate and goat anti-mouse antibodies, forming a test line and a control line, respectively. The conjugate pad was saturated with colloidal gold particles coated with affinity purified monoclonal anti-GRe antibody. The visual detection limit was 200 microg x L(-1) of GRe and the reaction time was 10 min. The Panax ginseng roots were identified after these samples (10 mg) were extracted with 5 mL tap water for 30 min at room temperature, and the extracts were tested by the dipsticks and ELISA kit. The true and false P. ginseng could be distinguished with dipsticks. The dipstick could be used to detect the quality of the P. ginseng samples when the extract was diluted 100-folds. The results were compared with those obtained using an indirect competitive enzyme-linked immunosorbent assay (icELISA). The dipstick assay proved to be a sensitive and rapid tool for quality control of P. ginseng.
Animals ; Antibodies, Monoclonal ; immunology ; Counterfeit Drugs ; analysis ; Ginsenosides ; analysis ; Immunoassay ; instrumentation ; methods ; Mice ; Panax ; chemistry ; Reagent Strips ; Time Factors

BACKGROUND: The importance and usefulness of therapeutic drug monitoring (TDM) have been emphasized, and analysis of drugs has been increased in clinical laboratories. We evaluated the analytical performance and clinical usefulness of a recently introduced enzyme multiplied immunoassay instrument, Viva-E Drug Testing System (Dade Behring Inc., USA). METHODS: Using patients' samples and quality control material, we evaluated the analytical performance of Viva-E for a total of 11 drugs (cyclosporine, tacrolimus, mycophenolic acid, valproic acid, digoxin, theophylline, carbamazepine, phenytoin, phenobarbital, vancomycin, and gentamicin) with respect to linearity, precision, and correlations with other methods according to CLSI guidelines. Cobas Integra 800 (Roche Diagnostics, Switzerland) and API 4000 LC-MS/MS System (Applied Biosystems, USA) were used to make a comparison. In addition, we analyzed analysis time. RESULTS: Viva-E showed a good linearity (r2 > or = 0.97) for all items. Within-run CVs were within 5% and total CVs were within 10% for all drugs except for tacrolimus and digoxin at low concentrations. The system correlated well with the other methods (r=0.9283-0.9778). The time required for reporting the first sample was 11 min and the analysis time was 1.1 min. CONCLUSIONS: Since Viva-E showed a good analytical performance required for TDM in its linearity, precision, and accuracy with its wide drug menus including cyclosporine, tacrolimus, and mycophenolic acid, stat and random accessing functions, and the consolidation to a single workstation, it could be very useful in the clinical laboratory for various needs.
Data Interpretation, Statistical ; Drug Monitoring/*instrumentation/methods ; Enzyme Multiplied Immunoassay Technique/*instrumentation ; Humans ; Immunoenzyme Techniques ; Pharmaceutical Preparations/*analysis ; Quality Control ; Reference Standards ; Reproducibility of Results

We utilized polyethylenimine (PEI) and Glu solution to immobilize the antibody of Treponema Pallidum on the silver electrode of piezoelectric quartz crystal and detect the standard antigen solution at different concentration. The antibody keeps the intrinsic Y type molecular structure revealed by AFM. The resonant range of the sensor is between 5 x 10(-5) - 1.25 x 10(-4) g/mL and the correlation coefficient is 0.9976, the optimal resonance pH is 7.5. We found the sensor having good selectivity in comparison with the method using BSA. At last, a discussion on the reproducibility of the sensor is presented.
Antibodies, Bacterial ; immunology ; Antigens, Bacterial ; analysis ; Biosensing Techniques ; instrumentation ; Equipment Design ; Immunoassay ; instrumentation ; methods ; Microelectrodes ; Polyethyleneimine ; Quartz ; Treponema pallidum ; immunology ; isolation & purification