Antigens ; Immunoassay ; methods

Animals ; Antibody Affinity ; Electrophoresis, Capillary ; methods ; Humans ; Immunoassay ; methods

BACKGROUND: Cystatin C, a 13-kDa protein synthesized in all nucleated cells, has been proposed as a replacement for serum creatinine in assessments of renal function. The Gentian Cystatin C immunoassay (Gentian, Norway) was recently developed using particle enhanced turbidimetric immunoassay. In this study, we evaluated the analytical performance of the Gentian Cystatin C immunoassay on the Hitachi 7600 Automatic Analyzer (Hitachi Ltd., Japan). METHODS: We performed precision and linearity studies using Hitachi Clinical Analyzer 7600 with Gentian reagent and compared the results to those obtained with the N Latex Cystatin C (Siemens, Germany) using a particle enhanced nephelometric immunoassay method performed on the Behring Nephelometer II (Siemens, Germany). We also analyzed the traceability of Gentian reagent and Siemens reagent to Cystatin C standard reference material, ERM-DA471/IFCC. RESULTS: The coefficient of variations (CVs) for within-run imprecision at low and high levels were 1.58% and 1.06% and the CVs for total imprecision at low and high levels were 2.53% and 2.09%, respectively. In the linearity test, the coefficient of determination (R2) was 0.9997 (range, 0.23 to 7.50 mg/L), and comparison with the results obtained by Siemens reagent showed an excellent correlation coefficient of 0.9982. In the traceability test, Gentian reagent is more accurate than Siemens reagent and the total accuracy was 96.0%. CONCLUSIONS: Gentian reagent provides good analytic performance on the Hitachi 7600 Automatic Analyzer and can be used for the diagnosis, treatment, monitoring, and risk assessment of renal function.
Creatinine ; Cystatin C* ; Diagnosis ; Gentiana* ; Immunoassay ; Latex ; Methods ; Risk Assessment

Objective To compare the sensitivity and accuracy of amplified luminescent proximity homogeneous assay linked immunosorbent assay (AlphaLISA) and magnetic particles-based chemiluminescence immunoassay (MP-CLIA) for detection of staphylococcal enterotoxin C (SEC) in the simulated milk samples. Methods The AlphaLISA was constructed using goat anti-SEC polyclonal antibody-coupled receptor microspheres, biotin-labeled SEC monoclonal antibody and streptavidin-coupled donor microspheres. The MP-CLIA was constructed using goat anti-SEC polyclonal antibody conjugated alkaline phosphatase, biotin-labeled anti-SEC monoclonal antibody and streptavidin conjugated magnetic beads. Results The sensitivity of AlphaLISA to detect SEC content in simulated milk samples was 4.04 ng/L, and the coefficient of variation (CV) was 1.98%~9.82%. The sensitivity of MP-CLIA was 108.19 ng/L and CV was 4.63%~20.40%. Conclusion Compared with MP-CLIA, AlphaLISA is more sensitive and accurate to detecting SEC.
Animals ; Streptavidin ; Biotin ; Luminescence ; Milk ; Antibodies, Monoclonal ; Goats ; Immunoassay/methods*

In recent 10 years, microfluidic technology has developed rapidly. Hence the speed of analysis can be upgraded, the performance be improved and the consumption of sample and reagent be reduced. In this review, we introduce the design, fabrication and application of microfluidic immunoassay chip.
Humans ; Immunoassay ; methods ; Microfluidic Analytical Techniques ; trends ; Microfluidics ; trends

Maintaining immunosuppressant concentrations within the therapeutic range in organ recipients requires regular monitoring. The blood concentrations of immunosuppressants are routinely measured using one of several automated immunoassays, such as chemiluminescence immunoassays (CLIAs) and liquid chromatography-tandem mass spectrometry (LC-TMS). The ARCHITECT i2000 immunoassay analyzer (Abbott Diagnostics, USA) was developed as an automated CLIA analyzer for the measurement of cyclosporin A and tacrolimus in whole blood. Here, the precision and linearity of the ARCHITECT i2000 analyzer for the detection of cyclosporin A and tacrolimus in whole blood were evaluated according to Clinical and Laboratory Standards Institute guidelines and were compared with those of an LC-TMS detection method. The total coefficient of variation for the two drugs was less than 10%, and they showed linearity values of 0.97 or more, which was within the manufacturer's range. The measurements of both immunosuppressants by the ARCHITECT i2000 were closely correlated with measurements determined by LC-TMS. However, most measurements were lower with LC-TMS than with the ARCHITECT i2000. Measurement of cyclosporin A and tacrolimus in whole blood using the ARCHITECT i2000 showed very satisfactory performance in terms of precision and linearity as well as good correlation with the comparative method.
Cyclosporine ; Immunoassay ; Immunosuppressive Agents ; Luminescence ; Mass Spectrometry ; Methods ; Tacrolimus

We developed a high-sensitivity C-reactive protein quantifiable chemiluminescent immunoassay (hs-CRP CLIA). The high-purity native CRP was purified from hepatic cirrhosis patient ascetic fluid by affinity and ion exchange chromatography and used as an immunogen to develop the monoclonal antibodies (mAbs) against CRP. Twenty-two mAbs were identified reactive with CRP in ELISA and 13 of them were reactive in the phosphorycholine ligand capture ELISA. The mAbs 10C5 and 10C11 were selected to develop the hs-CRP CLIA. The linearity and performance of the hs-CRP CLIA was characterized. It was showed not reactive when testing against other serum materials (IgG, hemoglobin and triglyceride). The reliable correlation (R2 > 0.993) was obtained between testing value (RLU/S) and the concentration of human serum CRP calibrator. The linearity fell in the range of 0.04-20.38 mg/L. The assay has good accuracy and reproducibility, the mean recovery was 99% and the precision of the intra- and inter assay was CVs (4.2%-5.8%) and (9.0%-11.5%), respectively. In testing of 90 human sera, this assay performed well and correlated comparably with a commercial hs-CRP ELISA kit. Thus, hs-CRP CLIA is an accurate, reliable, quantifiable assay for detection of high-sensitive C-reactive protein in serum, it may be useful to improve the risk assessment of cardiovascular disease and the prognosis of inflammatory bowel disease.
C-Reactive Protein ; analysis ; chemistry ; Humans ; Immunoassay ; methods ; Luminescent Measurements ; methods ; Sensitivity and Specificity

p-Nitrophenylphosphate (PNPP) is usually employed as the substrate for enzyme-linked immunosorbent assays. p-Nitrophenol (PNP), the product of PNPP, with the catalyst alkaline phosphatase (ALP), will passivate an electrode, which limits applications in electrochemical analysis. A novel anti-passivation ink used in the preparation of a graphene/ionic liquid/chitosan composited (rGO/IL/Chi) electrode is proposed to solve the problem. The anti-passivation electrode was fabricated by directly writing the graphene-ionic liquid-chitosan composite on a single-side conductive gold strip. A glassy carbon electrode, a screen-printed electrode, and a graphene-chitosan composite-modified screen-printed electrode were investigated for comparison. Scanning electron microscopy was used to characterize the surface structure of the four different electrodes and cyclic voltammetry was carried out to compare their performance. The results showed that the rGO/IL/Chi electrode had the best performance according to its low peak potential and large peak current. Amperometric responses of the different electrodes to PNP proved that only the rGO/IL/Chi electrode was capable of anti-passivation. The detection of cardiac troponin I was used as a test example for electrochemical immunoassay. Differential pulse voltammetry was performed to detect cardiac troponin I and obtain a calibration curve. The limit of detection was 0.05 ng/ml.
Electrochemical Techniques/methods* ; Electrodes ; Graphite ; Immunoassay/methods* ; Ink ; Microscopy, Electron, Scanning ; Troponin I/blood*

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

OBJECTIVETo evaluate chemiluminescent immunoassay (CLIA), electrochemiluminescent immunoassay (ECLIA) and ELISA in determination of low level HBsAg.

METHODSAccording to the standard of CLIA Architect i2000, 70 samples were divided into three groups by HBsAg concentration : <1 ng/ml, 1-5 ng/ml and >4 ng/ml. The samples were also determined by ECLIA MODULAR170 and ELISA, and the results were compared with those measured by CLIA Architect i2000.

RESULTSThe concordance rates of ECLIA MODULAR170 with Architect i2000 was 79.2% for <1 ng/ml group, 100% for 1-5 ng/ml group, 100% for >4 ng/ml group. And the concordance rates of ELISA with Architect i2000 was 0 % for <1 ng/ml group, 45.5% for 1-5 ng/ml group and 100 % for >4 ng/ml group.

CONCLUSIONFor determination of low level HBsAg,CLIA Architect i2000 and ECLIA MODULAR170 have high credibility. ELISA is also credible when HBsAg >5 ng/ml, but not for low level HBsAg, especially for HBsAg <1 ng/ml.