Search

This study aimed to establish an efficient in vitro cell-based assay to measure the activity of teriparatide (PTH1–34). In this study, a rat osteosarcoma cell line (UMR-106) was treated with various concentrations of PTH1–34, and the biological activity of PTH1–34 was determined by quantitatively measuring intracellular cyclic adenosine monophosphate levels using a time-resolved fluoroimmunoassay. A four-parameter fitting analysis was used to calculate the relative potency of the samples. The experimental conditions were optimized. The method's specificity, relative accuracy, precision, and linearity were validated. Our data suggested that this method had good specificity, a relative bias of relative accuracy ranging from −0.8 to 1.4%, a correlation coefficient for the linear regression equation of 0.9953, a geometric coefficient of variation for intermediate precision ranges from 2.0 to 3.5%, and a linear range of 50 to 150%. This method significantly improves the quality control and release inspection efficiency of PTH1–34 and may be further developed and validated as an alternative to the existing United States Pharmacopeia and European Pharmacopoeia inclusion methods. This method also provides a platform for the high-throughput screening of PTH1–34 analogs.

In recent years, more and more functional peptide ligands have been identified from phage display libraries and served the immunoassay of small molecules. After the identification, the phage particle instead limits further application of peptide ligands, so it is of great significance to explore the peptide ligand as an independent detection reagent. In this work, the identified peptidomimetic of benzothiostrobin was synthesized and labelled with biotin, which was combined with Eu3+-labelled streptavidin to develop the peptide-based time-resolved fluoroimmunoassay (P-TRFIA). Under the optimal conditions, the half-maximum inhibitory concentration (IC50) of proposed P-TRFIA is 3.63 ng mL−1, which is similar to the TRFIA using phage-borne peptidomimetic and Eu3+-labelled anti-phage antibody (IC50: 4.55 ng mL−1), also more sensitive than previously reported immunoassays for benzothiostrobin. In addition, the proposed P-TRFIA shows excellent specificity and accuracy for analysis of spiked samples, and its detection results shows good consistency with high-performance liquid chromatography for the detection of environment and agro-products samples with unknown benzothiostrobin concentrations. [ABSTRACT FROM AUTHOR]

Background. The Kidney Disease Improving Global Outcomes (KDIGO) 2021 guidelines recommend Rituximab (RTX) as the first-line therapy and phospholipase A2 receptor (PLA2R) antibody as a biomarker for remission and prognosis in patients with idiopathic membranous nephropathy (IMN). Methods. This study was a retrospective analysis of 70 patients with IMN treated with either rituximab (RTX) or cyclophosphamide (CTX) and steroid. Quantitative detection of PLA2R-IgG and PLA2R-IgG4 antibodies at sixth month after treatment, determined using time-resolved fluoroimmunoassay (TRFIA), were used for treatment effectiveness analysis and prognostic evaluation in patients with IMN. Results. After 12 months of therapy, the remission rate of proteinuria, including complete remission (CR) and partial remission (PR) in the RTX group and the CTX group, were 74% versus 67.5% (P =0.114), respectively. Both PLA2R-IgG and PLA2R-IgG4 levels were decreased in patients with remission of proteinuria after 6 months of therapy. Receiver operating characteristic curve (ROC) curve analysis exhibited that the AUC of PLA2R-IgG4 and the PLA2R-IgG as laboratory criteria for proteinuria remission were 0.970 versus 0.886 (P =0.0516), respectively, after 6 months of treatment. The cut-off value of PLA2R-IgG4 was 7.67 RU/mL and the sensitivity and specificity of remission rate at 6th month were 90.9% and 100%, respectively. Furthermore, the AUC of the PLA2R-IgG4 and PLA2R-IgG to predict the outcome after 12 months of treatment were 0.922 versus 0.897 (P =0.3270), respectively. With the cut-off value of PLA2R-IgG4 being 22.985 RU/mL, the sensitivity and specificity of remission rate at 12th month were 100% and 87.1%, respectively. Logistic regression analysis revealed that the PLA2R-IgG4 level (P =0.023), the rate of decrease of PLA2R-IgG4 level (P =0.034), and eGFR level (P =0.012) were significantly associated with remission. Conclusions. We found that the patients in the RTX group and CTX group achieved effective remission of proteinuria after 12 months of treatment. PLA2R-IgG4 may be a more effective biomarker for treatment effectiveness analysis and prognostic assessment, compared with anti-PLA2R-IgG for PLA2R associated IMN. [ABSTRACT FROM AUTHOR]

Okadaic acid (OA) is a biotoxin from marine microalgae and widely present in shellfish, which severely affects the seafood safety. Therefore, it is essential to establish a highly sensitive OA analysis and detection method. In this study, a new type of immunoassay technology was established on the basis of the competition method using time-resolved fluoroimmunoassay (TRFIA). OA-bovine serum albumin (OA-BSA) coated on a 96-well plate competes with OA standard or samples to bind OA antibodies. A rare-earth ion-labeled secondary antibody, which fluoresces strongly under the effect of the enhancement solution, was then added as a tracer for detection. The established linear range of OA detected by TRFIA was 2.49 × 10-3 – 50 ng/ml, and the limit of detection was 2.49 × 10-3 ng/ml. The average coefficients of variation from intra-assay and inter-assay batches were 3.34% and 5.87%, respectively, and the recovery rate was 93.04%–111.66%. The OA in shellfish samples was determined by TRFIA and high-performance liquid chromatography (HPLC), and the results showed a good correlation. This study established a TRFIA to detect OA, which has the characteristics of simplicity, sensitivity, precision, and high accuracy, far exceeding the EU or the US standards for the detection of shellfish toxins. It is expected to make proper contribution in marine biotoxin detection.

Invasive Aspergillosis is a high-risk illness with a high death rate in immunocompromised people due to a lack of early detection and timely treatment. Based on immunology study, we achieved an efficient production of anti-galactomannan antibody by Chinese hamster ovary (CHO) cells and applied it to time-resolved fluoroimmunoassay for Aspergillus galactomannan detection. We first introduced dual promoter expression vector into CHO host cells, and then applied a two-step screening strategy to screen the stable cell line by methionine sulfoximine pressurization. After amplification and fermentation, antibody yield reached 4500 mg/L. Then we conjugated the antibodies with fluorescent microspheres to establish a double antibody sandwich time-resolved fluoroimmunoassay, which was compared with the commercial Platelia™ Aspergillus Ag by clinical serum samples. The preformed assay could obtain the results in less than 25 min, with a limit of detection for galactomannan of approximately 1 ng/mL. Clinical results of the two methods showed that the overall percent agreement was 97.7% (95% CI: 96.6%–98.4%) and Cohen's kappa coefficient was 0.94. Overall, the assay is highly consistent with commercial detection, providing a more sensitive and effective method for the rapid diagnosis of invasive aspergillosis. [Display omitted] • An efficient and stable cell line expression system was constructed to produce of anti-galactomannan monoclonal antibodies. • The antibody yield reached 4500 mg/L by scaling up fermentation, a 1.3-fold increase. • A time-resolved fluorescence immunoassay was established by conjugating the antibodies to detect aspergillosis. • The assay is highly consistent with commercial Platelia™ Aspergillus Ag according to clinical serum results. [ABSTRACT FROM AUTHOR]

As a common herbicide in farmland, there has been wide concern over quinclorac residue because of its potential risks to the environment and human health. For the detection and monitoring of quinclorac residue in the environment, enzyme-linked immunoassay (ELISA) and time-resolved fluoroimmunoassay (TRFIA) were established. The half-maximal inhibition concentrations (IC50) of ELISA and TRFIA were 0.169 mg/L and 0.087 mg/L with a linear range (IC20–IC80) of 0.020–1.389 mg/L and 0.004–1.861 mg/L, respectively. Compared with ELISA, the limit of detection (LOD, IC20) and IC50 of TRFIA improved approximately 5-fold and 2-fold. The cross-reaction rates for the quinclorac analogs were less than 2%. The average recoveries of quinclorac in river water, paddy water, paddy soil, and brown rice samples were 77.3–106.1%, with RSDs of 1.7–12.5%. More importantly, the results of the two methods were consistent with that of the referenced method of UPLC-MS/MS (R2 > 0.98). ELISA and TRFIA both showed good detection performance and could meet the requirements of the quantitative determination of quinclorac. Therefore, the proposed ELISA and TRFIA could be applied to the rapid and sensitive detection and monitoring of quinclorac residue in the environment. [ABSTRACT FROM AUTHOR]

Aims: Alternaria longipes is a causal agent of brown spot of tobacco, which remains a serious threat to tobacco production. Herein, we established a detection method for A. longipes in tobacco samples based on the principle of time‐resolved fluoroimmunoassay, in order to fulfil the requirement of rapid, sensitive and accurate detection in situ. Methods and Results: A monoclonal antibody against A. longipes was generated, and its purity and titration were assessed using western blot and ELISA. The size of europium (III) nanospheres was measured to confirm successful antibody conjugation. The method described here can detect A. longipes protein lysates as low as 0.78 ng ml−1, with recovery rates ranging from 85.96% to 99.67% in spiked tobacco. The specificity was also confirmed using a panel of microorganisms. Conclusions: The fluorescent strips allow rapid and sensitive onsite detection of A. longipes in tobacco samples, with high accuracy, specificity, and repeatability. Significance and Impact of the Study: This novel detection method provides convenience of using crude samples without complex procedures, and therefore allows rapid onsite detection by end users and quick responses towards A. longipes, which is critical for disease control and elimination of phytopathogens. [ABSTRACT FROM AUTHOR]

Abstract In this study, a novel dual-label time-resolved fluoroimmunoassay (TRFIA) is described for simultaneous quantification of human epidermal growth factor receptor 2 (HER-2) and human epididymis protein 4 (HE4) in serum to screen gynecologic cancers. A double-antibody sandwich TRFIA was introduced with europium and samarium chelates to simultaneously detect the concentrations of HER-2 and HE4. Under optimal conditions, the proposed method exhibited wide linear ranges for HER-2 of 0.07–500 ng ml−1 and for HE4 of 0.32–1000 pmol l−1 with the average coefficient of variation below 10%. The specificity was satisfied through determining the other common tumor markers. The recovery rates were 94.5% and 96.6% on average for HER-2 and HE4, respectively. Good correlations were observed in clinical samples between developed method and commercial chemiluminescence immunoassay kits. The results demonstrated that dual-label TRFIA for HER-2 and HE4 was rapid and precise, and therefore could have a promising use in large sample detection for gynecological cancer screening.

Aims: The aim of this study was to develop a new method for detecting anti-phospholipase A2 receptor-IgG4 to improve the sensitivity and specificity in the diagnosis of idiopathic membranous nephropathy (IMN). Methods: A highly sensitive quantitative assay was developed for the detection of serum anti-phospholipase A2 receptor-IgG4 with europium chelation by time-resolved fluoroimmunoassay (TRFIA), and a mouse anti-human IgG4 tracer was prepared using europium chelation for detection. The specificity and sensitivity of anti-phospholipase A2 receptor-IgG4 in the diagnosis of IMN were further assessed in patients with different kidney diseases. Results: The detection limit of anti-PLA2R-IgG4 was 0.69 ng/mL. The measurement range of anti-PLA2R-IgG4 TRFIA was 0.69–2,500 ng/mL. Mean serum anti-PLA2R-IgG4 was 21.27 ± 15.15 ng/mL in 45 healthy volunteers, 31.08 ± 18.17 ng/mL in 29 IgA nephropathy patients, 49.10 ± 34.32 ng/mL in 8 lupus nephropathy patients, and 10,324.11 ± 17,030.40 ng/mL in 30 IMN patients. The anti-PLA2R-IgG4 cutoff concentration was >161.2 ng/mL with the sensitivity of 90.0% and specificity of 100% in the diagnosis of IMN. However, the cutoff for other kidney diseases was lower than 161.2 ng/mL. Conclusion: The serum anti-phospholipase A2 receptor IgG4 detected with the method developed in this study has higher sensitivity and higher specificity than total IgG in the diagnosis of IMN.

As a common herbicide in farmland, there has been wide concern over quinclorac residue because of its potential risks to the environment and human health. For the detection and monitoring of quinclorac residue in the environment, enzyme-linked immunoassay (ELISA) and time-resolved fluoroimmunoassay (TRFIA) were established. The half-maximal inhibition concentrations (IC50) of ELISA and TRFIA were 0.169 mg/L and 0.087 mg/L with a linear range (IC20–IC80) of 0.020–1.389 mg/L and 0.004–1.861 mg/L, respectively. Compared with ELISA, the limit of detection (LOD, IC20) and IC50 of TRFIA improved approximately 5-fold and 2-fold. The cross-reaction rates for the quinclorac analogs were less than 2%. The average recoveries of quinclorac in river water, paddy water, paddy soil, and brown rice samples were 77.3–106.1%, with RSDs of 1.7–12.5%. More importantly, the results of the two methods were consistent with that of the referenced method of UPLC-MS/MS (R2 > 0.98). ELISA and TRFIA both showed good detection performance and could meet the requirements of the quantitative determination of quinclorac. Therefore, the proposed ELISA and TRFIA could be applied to the rapid and sensitive detection and monitoring of quinclorac residue in the environment.

Several studies have investigated the use of simple in vitro tests for the assessment of rabies antibody titers in serum samples from vaccinated human subjects, which would allow the effectiveness of rabies vaccination to be conveniently evaluated. To this end, a novel time-resolved fluoroimmunoassay (TRFIA) for the assessment of rabies antibody titers was established in this study for evaluating the effectiveness of protection against rabies. The TRFIA had a satisfactory limit of detection value (0.035 IU/mL) under optimal conditions. Additionally, the application of the TRFIA was demonstrated in 68 serum samples with satisfactory results. The coefficient variations (CVs) were all <10%, and the recoveries were in the range of 90–110%. The correlation coefficient of titer values obtained using the present TRFIA and the rapid fluorescent focus inhibition test (RFFIT) was 0.733, with a coincidence rate regarding the evaluation results (protected or not protected by vaccination) of 100%. The preliminary results confirmed that the TRFIA had a higher performance than an enzyme-linked immunosorbent assay (ELISA), and could potentially replace the ELISA. Based on these results, the novel TRFIA appears to be a convenient tool for the evaluation of rabies vaccination results based on serum samples from vaccinated human subjects. • A novel in vitro test for rabies antibody titers in the sera of vaccinated human subjects. • Application is demonstrated in practical samples, with satisfactory results. • Gets the advantages of simple operation, high stability and excellent accuracy than conventional ELISA method. [ABSTRACT FROM AUTHOR]

In this study, a novel dual-label time-resolved fluoroimmunoassay (TRFIA) is described for simultaneous quantification of human epidermal growth factor receptor 2 (HER-2) and human epididymis protein 4 (HE4) in serum to screen gynecologic cancers. A double-antibody sandwich TRFIA was introduced with europium and samarium chelates to simultaneously detect the concentrations of HER-2 and HE4. Under optimal conditions, the proposed method exhibited wide linear ranges for HER-2 of 0.07–500 ng ml−1 and for HE4 of 0.32–1000 pmol l−1 with the average coefficient of variation below 10%. The specificity was satisfied through determining the other common tumor markers. The recovery rates were 94.5% and 96.6% on average for HER-2 and HE4, respectively. Good correlations were observed in clinical samples between developed method and commercial chemiluminescence immunoassay kits. The results demonstrated that dual-label TRFIA for HER-2 and HE4 was rapid and precise, and therefore could have a promising use in large sample detection for gynecological cancer screening. [ABSTRACT FROM AUTHOR]

Veterinary drug residues have become a major source of environmental pollutants. To monitor trace salbutamol (SAL) in the environment, a highly sensitive and reliable time-resolved fluoroimmunoassay (TRFIA) was developed. Under the optimum parameters, the half-maximal inhibition concentration (IC 50) and the limit of detection (LOD, IC 10) were determined to be 0.08 μg/L and 0.66 ng/L with a linear range (IC 20 - IC 80) of 0.0028–2.25 μg/L for SAL. The IC 50 and LOD of the TRFIA improved approximately 5-fold and 31-fold, respectively, when compared with our previously reported ELISA data. When compared to most other conventional methods, the TRFIA also showed an excellent sensitivity and accuracy for the detection of SAL. Recoveries from 83.4 to 111.3% and standard deviations (RSDs) from 3.9 to 14.0% were observed in various environmental SAL-spiked samples, including river water, paddy water, livestock wastewater, vegetable field soil and rice paddy soil. In addition, the developed TRFIA showed largely consistent with analytic results from UPLC-MS/MS (R2 = 0.9825, n = 15). These results suggest that the proposed TRFIA can be applied as a sensitive and reliable monitoring method to detect trace SAL in environmental samples. Unlabelled Image • A highly sensitive time-resolved fluoroimmunoassay (TRFIA) for the detection of salbutamol was developed. • The TRFIA gave largely consistent results and showed good correlations with the referential method of UPLC-MSMS. • The developed TRFIA appears to be a useful method for monitoring trace salbutamol in environmental samples. [ABSTRACT FROM AUTHOR]

Aims: The aim of this study was to develop a new method for detecting anti-phospholipase A2 receptor-IgG4 to improve the sensitivity and specificity in the diagnosis of idiopathic membranous nephropathy (IMN). Methods: A highly sensitive quantitative assay was developed for the detection of serum anti-phospholipase A2 receptor-IgG4 with europium chelation by time-resolved fluoroimmunoassay (TRFIA), and a mouse anti-human IgG4 tracer was prepared using europium chelation for detection. The specificity and sensitivity of anti-phospholipase A2 receptor-IgG4 in the diagnosis of IMN were further assessed in patients with different kidney diseases. Results: The detection limit of anti-PLA2R-IgG4 was 0.69 ng/mL. The measurement range of anti-PLA2R-IgG4 TRFIA was 0.69–2,500 ng/mL. Mean serum anti-PLA2R-IgG4 was 21.27 ± 15.15 ng/mL in 45 healthy volunteers, 31.08 ± 18.17 ng/mL in 29 IgA nephropathy patients, 49.10 ± 34.32 ng/mL in 8 lupus nephropathy patients, and 10,324.11 ± 17,030.40 ng/mL in 30 IMN patients. The anti-PLA2R-IgG4 cutoff concentration was >161.2 ng/mL with the sensitivity of 90.0% and specificity of 100% in the diagnosis of IMN. However, the cutoff for other kidney diseases was lower than 161.2 ng/mL. Conclusion: The serum anti-phospholipase A2 receptor IgG4 detected with the method developed in this study has higher sensitivity and higher specificity than total IgG in the diagnosis of IMN. [ABSTRACT FROM AUTHOR]

Neutrophil gelatinase-associated lipocalin (NGAL) is a promising biomarker for diagnosing acute kidney injury (AKI). Currently, there are few assays for determining NGAL and they are complex, time-consuming or expensive. We aimed to establish an efficient immunoassay to measure NGAL in human urine simply and rapidly. A novel immunoassay for NGAL determination was established by combining a dissociation-enhanced-free time-resolved fluoroimmunoassay (TRFIA) and immunomagnetic separation. Based on a "sandwich"-type immunoassay format, analytes in samples were captured by a pair of monoclonal antibodies (mAb) in which one mAb was coated in magnetic beads and the other mAb was labeled with europium(III) chelate microparticles (CM-EUs) as "fluorescent reporters". NGAL concentrations were determined in a linear range (10–1500 ng mL−1) with a limit of detection of 0.32 ng mL−1. The reproducibility, recovery, and specificity of our TRFIA were acceptable. Our method was compared with that of a chemiluminescence immunoassay (CMIA) using 115 urine samples, and the results showed good correlation (R2 = 0.8677). We expect our novel method to be useful for the early diagnosis of AKI. • Europium (III) chelate microparticles was used as a label for the TRFIA. • Magnetic beads was used as the solid phase for the TRFIA. • Short analysis time and simplified procedure to accurately detect NGAL level • The linearity range was wider compared with ELISA. • This method could be developed for practical tool for early diagnosis of AKI in clinical. [ABSTRACT FROM AUTHOR]

Abstract The morbidity and mortality associated with acute kidney injury (AKI) remain obstinately high. Early diagnosis is urgently required and should be pursued in at-risk populations. Recently, a newly validated biomarker, matrix metalloproteinase-7 (MMP-7), was reported as a novel indicator for early AKI prediction and a noninvasive surrogate biomarker of kidney function. Monitoring urinary MMP-7 (uMMP-7) levels fills the gaps in early diagnosis of AKI at early onset. However, the lack of available reagents for its rapid detection limits its use. Herein, we established an ultrasensitive and rapid immunomagnetic microparticles-based time-resolved fluoroimmunoassay to measure urinary MMP-7 in AKI patients. The assay time is 30 min. The calibration curve showed high linear correlation (r = 0.9998) with a linearity of detection of 0.063–150 ng mL−1 and lower limit of detection of 0.039 ng mL−1. The coefficient variation of the intra- and inter-assay lower than 5.17%, and the analytical recovery was 99.06%–105.60%. Testing of clinical samples using the proposed assay and a DUOSET@ ELISA kit showed good correlations in the comparison of uMMP-7 levels (r = 0.9541) and uMMP-7/uCreatinine (r = 0.9595). The proposed assay has satisfactory analytical performance and may serve as a promising tool for early diagnosis of AKI. Highlights • First complete methodology report of rapid, ultrasensitive IMPs-TRF assay for measurement of uMMP-7 • Derivative research based on the latest findings-uMMP-7, promising noninvasive biomarker for risk prediction of early AKI • Method validation using clinical sample and method comparisons was carried out with a good correlation. • Addressing clinical needs on early diagnosis of AKI, IMPs-TRF may serve as a powerful tool in clinical use. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Modern Laboratory Medicine is the property of Journal of Modern Laboratory Medicine Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In clinical diagnosis of cancer, immunology assay with single tumor marker often lead to a false and missed inspection. A quantitative method with a high degree of accuracy, sensitivity, and effectiveness is required for its diagnosis. We developed a dual-label time-resolved fluoroimmunoassay (TRFIA) to simultaneously detect carbohydrate antigen 125 (CA125) and carcinoembryonic antigen (CEA) in human serum to aid the diagnosis and prognosis of gastric cancer. The method was based on a microplate sandwich immunoassay using europium-labeled anti-CA125 antibodies and samarium-labeled anti-CEA antibodies as fluorescent reporters. The assay detection range was widely, and the limit of detection was sufficiently for detecting clinical sample. The intra- and inter-assay coefficients of variation were below 6%, and recoveries ranged from 90% to 110%. No significant statistical difference in sensitivity or specificity was observed between dual label-TRFIA and commercial chemiluminescent immunoassays in serum samples. These results demonstrate the successful development of an effective, reliable, and convenient novel TRFIA method for the simultaneous detection of CA125 and CEA, which can be used for clinical blood screening to monitor the occurrence and development of tumors to facilitate early treatment. [ABSTRACT FROM AUTHOR]

A competitive time-resolved fluoroimmunoassay (TRFIA) using a biotin-streptavidin system was developed for the detection and quantification of the furaltadone metabolite 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ) in aquatic tissues. AMOZ-bovine serum albumin was coated to a solid phase and then competed with a free nitrophenyl derivative of AMOZ (2-NP-AMOZ) in standards or samples for binding with biotin-anti-AMOZ-ovalbumin polyantibody. Later, the complex was recognized by europium-labelled streptavidin, which was used as a novel tracer to amplify the signal, and it also reacted faster than europium-labelled second antibody in traditional TRFIA. After optimizing the reaction conditions, the method showed high sensitivity and specification to 2-NP-AMOZ with a half maximal inhibitory concentration of 0.190 μg/l and a sensitivity of 0.019 μg/l with a working range from 0.025 to 10 μg/l. The data from fish and shrimp samples indicated that the limit of detection was 0.021 μg/kg, and the recovery rates were 84.1-107.0% and 80.9-98.4%, respectively, with an average RSD below 10%. High correlation rates were observed in TRFIA, high performance liquid chromatography and universal enzyme-linked immunosorbent assay methods. The experiment above confirms that biotin-streptavidin-amplified TRFIA could be an ultrasensitive and accurate tool for screening large numbers of aquatic products for the determination of AMOZ residues. [ABSTRACT FROM AUTHOR]

BACKGROUND Aflatoxin B1 (AFB1) is a kind of toxic and carcinogenic mycotoxin. A time-resolved fluoroimmunoassay (TRFIA) was established for quantitative detection of AFB1 in feed using Eu3+-labeled IgG as tracer. RESULTS Monoclonal antibody (McAb) against AFB1 (9B11-D7) was prepared through immunization and cell fusion and was identified as high affinity, specificity and sensibility by enzyme-linked immunosorbent assay (ELISA). The 50% inhibition value (IC50) was 0.81 ng mL−1, the limit of detection (LOD) was 0.10 ng mL−1 and detection range was 0.10-3.94 ng mL−1. Goat anti-mouse immunoglobulin G (IgG) was modified by Eu3+-DATT, generating Eu3+-labeled IgG. Under optimal assay conditions, TRFIA was shown to be highly sensitive and specific in detection of AFB1. The IC50 and LOD were 94.73 pg mL−1 and 3.55 pg mL−1, respectively, and detection range was 3.55-1.11 × 103 pg mL−1. Cross-reactivity with AFM1, AFB2, AFG1 and AFG2 was 31.26%, 37.6%, 127.46% and 35.74%, respectively, but zero with other analogues. In determination of AFB1 spiked in feed sample, TRFIA showed high accuracy and precision. The average recoveries ranged from 93.71% to 97.80%, and coefficient of variation was 1.25-3.73%. Good correlation between TRFIA and HPLC was demonstrated for determination of AFB1 in feeds, confirming the reliability of the developed method. CONCLUSION The developed TRFIA exhibited good potential for employment in the ultrasensitive detection of AFB1 in feed and could be used to determine total aflatoxins. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Host cell proteins (HCPs) are the process-specific and inevitable impurities during the manufacture via a host cell, which affect the safety or efficacy of the bio-product. However, the commercial HCP enzyme-linked immunosorbent assay (ELISA) kits may not apply to specific products such as rabies vaccine from Vero cells. More advanced and process-specific assay methods are needed in the quality control of rabies vaccine throughout the whole manufacturing process. Therefore, a novel time-resolved fluoroimmunoassay (TRFIA) for the detection of process-specific HCP of Vero cells in rabies vaccine was established in this study. Liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) was used during the preparation of HCP antigen. Based on a sandwich-type immunoassay format, analytes in samples were captured by one antibody coating in the wells and "sandwiched" by another antibody labeled with europium chelates. Due to the complex composition of HCP, both the capture and detected antibodies are polyclonal antibodies from the same anti-HCP antibodies pool. Multiple experiments have identified the optimal conditions to allow the valid and reliable detection of HCP in rabies vaccine. The TRFIA had a satisfactory limit of detection value (0.011 μg/ml) under optimal conditions, with the linear range from 0.0375 to 2.4 μg/ml of HCP. The coefficient variations (CVs) were all < 10%, and the recoveries were in the range of 97.00–102.42%. All the test results of Vero cell protein reference substance were included in the expected concentration, which demonstrated that the present method was available for the test of HCP in rabies vaccine. Based on these results, the novel TRFIA to detect HCP appears to be important for application in modern vaccine quality control during the whole manufacturing process. • Establishment of HCP process-specific assay method. • LC-MS/MS analysis of self-made HCP antigen. • Excellent performance of the assay method. [ABSTRACT FROM AUTHOR]

A competitive indirect time-resolved fluoroimmunoassay (TRFIA) for detecting aflatoxin M1(AFM1) contamination in milk was developed, by using aflatoxin M1-bovineserum albumin conjugate, anti-AFM1 antibody, and Eu-labeled goat anti-rabbit antibody. To improve the sensitivity of the assay, the concentrations of the coating antigen and anti-AFM1 antibody were varied to optimize the condition of the immunological assay. The limit of detection values, limit of quantification values, and dynamic working range were 0.006, 0.022, and 0.022-1.334 μg/kg, respectively. Values of recovery within and between assays were 88.0-116.0% and 92.69-108.63%. The method was applicable for the full-cream, semi-skimmed, skimmed, and raw milk as well. Values of repeatability (intra-laboratory variability) and reproducibility (inter-laboratory variability) were 1.2-4.5% and 0.8-5.0%, respectively. The results of using AFM1-TRFIA to analyze samples of 23 brands of milk that were purchased in Wuxi revealed that AFM1 was absent from all studied samples. This study suggests that the novel method is a simple, sensitive, specific, reproducible, economic, and adequate method for screening large quantities of samples and has good prospects of application. [ABSTRACT FROM AUTHOR]

Glypican-3(GPC3), an oncofetal protein, is a potential novel marker for hepatocellular carcinoma (HCC). In this study, we attempted to establish a new method to detect serum GPC3 using the antibodies identified in our previous research, and then evaluated its clinical application for the diagnosis of HCC. Herein, a sandwich time-resolved fluorescence immunoassay (TRFIA) for detecting serum GPC3 was developed. The detection limit, analytical recovery, specificity and precision of the proposed TRFIA assay were satisfactory. A total of 415 patients were collected and divided into seven groups: hepatocellular carcinoma (101), colorectal cancer (67), gastric cancer (44), esophageal cancer (15), cirrhosis (55), hepatitis (61), normal liver (72). Using this proposed method, the concentration of serum GPC3 in these clinical samples was detected. The results demonstrated that the levels of GPC3 in serum from HCC patients were significantly higher than that in others. Compared with the results of chemiluminescence immunoassay (CLIA), a high consistency (Kappa =0.84) was observed. Thus, an effective, sensitive and reliable TRFIA-GPC3 kit for diagnosing HCC was successfully developed. It offers a suitable alternative to existed methods of determining GPC3 and is expected to be used in clinic in the future. [ABSTRACT FROM AUTHOR]

Streptomycin (STR), used extensively in the treatment of bovine mastitis, may cause damage such as ototoxicity, allergic reaction, and increasing bacterial resistance to consumers on account of remnant in milk. A time-resolved fluoroimmunoassay (TRFIA) was developed to quantify STR for the first time to ensure food safety. Using secondary antibody labeled with europium (Eu) chelate as a tracer, the proposed TRFIA showed that the linear working range was 0.32-5.0 ng/mL under the optimal conditions. Milk samples were deproteinized by trichloroacetic acid and the limit of detection of STR in milk was 1.8 μg/kg. The recoveries of milk samples fortified with 4.0, 20, and 40 μg/kg of STR ranged from 86.2 to 96.3% with relative standard deviations less than 11%. Results of TRFIA for the authentic samples were coincided with those of UHPLC-MS/MS analyses. This study confirmed that the established TRFIA was sensitive as well as reliable and could be an alternative method to monitor STR residue in milk. [ABSTRACT FROM AUTHOR]

Thyrotropin or thyroid-stimulating hormone (TSH) is used as a marker for thyroid function. More precise and more sensitive immunoassays are needed to facilitate continuous monitoring of thyroid dysfunctions and to assess the efficacy of the selected therapy and dosage of medication. Moreover, most thyroid diseases are autoimmune diseases making TSH assays very prone to immunoassay interferences due to autoantibodies in the sample matrix. We have developed a super-sensitive TSH immunoassay utilizing nanoparticle labels with a detection limit of 60 nU L in preprocessed serum samples by reducing nonspecific binding. The developed preprocessing step by affinity purification removed interfering compounds and improved the recovery of spiked TSH from serum. The sensitivity enhancement was achieved by stabilization of the protein corona of the nanoparticle bioconjugates and a spot-coated configuration of the active solid-phase that reduced sedimentation of the nanoparticle bioconjugates and their contact time with antibody-coated solid phase, thus making use of the higher association rate of specific binding due to high avidity nanoparticle bioconjugates. [ABSTRACT FROM AUTHOR]

A direct quantum dots-based fluoroimmunoassay (QDFIA) and a time-resolved fluoroimmunoassay (TRFIA) for imidaclothiz (IMI) were developed by using the quantum dots (QDs)-labeled antibody and the europium (Eu 3 + )-labeled antibody, respectively. After optimization, the half-maximal inhibition concentration (IC 50 ) and the limit of detection (LOD, IC 10 ) are 20.41 and 0.52 μg L − 1 for the QDFIA, while 6.91 and 0.018 μg L − 1 for the TRFIA, respectively. The cross-reactivities (CRs) with the analogues are negligible except for imidacloprid with CRs of 29.0% for the QDFIA and 26.6% for the TRFIA. The spiked recoveries of IMI in paddy water, soil, pear, tomato, rice, apple, cabbage and cucumber are 72.7–117.6% with a standard deviation (RSD) of 2.4– 13.5% for the QDFIA, and 81.3–117.7% with a RSD of 1.6– 7.5% for TRFIA. The detection results of the analyses for the real paddy water and pear samples are markedly correlated with these of high-performance liquid chromatography (HPLC). [ABSTRACT FROM AUTHOR]

Immunochemical techniques exhibit great advantages of high efficiency, rapidness, reliability and low cost compared to instrumental methods for monitoring emerging organic contaminants (EOCs) in aquatic environments. This review covers recent advances in applying traditional and other antibody-like binders against these organic pollutants, and various antibody-based immunochemical methods such as enzyme-linked immunosorbent assays, time-resolved fluoroimmunoassay and immunosensors. Moreover, we also discuss the advantages and disadvantages of techniques for antibody production and analytical methods, and covers promising future prospects. [ABSTRACT FROM AUTHOR]

In this paper, a novel time-resolved fluorescence immunoassay (TRFIA) is described that allows the simultaneous quantitative detection of hepatitis B virus surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) in human serum to aid the diagnosis and monitoring of hepatitis B virus infection. The proposed method was developed based on a two-step sandwich immunoassay protocol in which monoclonal antibodies against HBsAg and HBeAg were co-coated in 96 microtitration wells, then tracer polyclonal antibodies against HBsAg labeled with samarium and tracer monoclonal antibodies against HBeAg labeled with europium chelates were used for detection. The detection range was 0.1-150 IU/mL for HBsAg and 0.5-160 PEIU/mL for HBeAg, and the detection limits were 0.03 IU/L and 0.09 PEIU/ml, respectively. The intra- and inter-assay coefficients of variation were below 8 % for both virus antigens. The dilution linearity and accuracy of the assay were satisfactory. No statistically significant differences were observed in sensitivity or specificity for the serum samples between the dual-label TRFIA and a commercial single-label TRFIA. These results demonstrate that an effective, reliable and convenient HBsAg/HBeAg dual-label TRFIA was successfully developed that may be clinically applicable for blood screening to monitor the course of hepatitis B virus infection and predict treatment responses. [ABSTRACT FROM AUTHOR]

Cylindrospermopsin (CYN) is a cyanotoxin that is of particular concern for its potential toxicity to human and animal health and ecological consequences due to contamination of drinking water. The increasing emergence of CYN around the world has led to urgent development of rapid and high-throughput methods for its detection in water. In this study, a highly sensitive monoclonal antibody N8 was produced and characterized for CYN detection through the development of a direct competitive time-resolved fluorescence immunoassay (TRFIA). The newly developed TRFIA exhibited a typical sigmoidal response for CYN at concentrations of 0.01–100 ng mL−1, with a wide quantitative range between 0.1 and 50 ng mL−1. The detection limit of the method was calculated to be 0.02 ng mL−1, which is well below the guideline value of 1 μg L−1 and is sensitive enough to provide an early warning of the occurrence of CYN-producing cyanobacterial blooms. The newly developed TRFIA also displayed good precision and accuracy, as evidenced by low coefficients of variation (4.1–6.5%). Recoveries ranging from 92.6% to 108.8% were observed upon the analysis of CYN-spiked water samples. Moreover, comparison of the TRIFA with an ELISA kit through testing 76 water samples and 15 Cylindrospermopsis cultures yielded a correlation r2 value of 0.963, implying that the novel immunoassay was reliable for the detection of CYN in water and algal samples.

A fast and ultrasensitive indirect competitive time-resolved fluoroimmunoassay (TRFIA) was developed for the analysis of paclobutrazol in environmental water and soil samples. Paclobutrazol hapten was synthesized and conjugated to bovine serum albumin (BSA) for producing polyclonal antibodies. Under optimal conditions, the 50% inhibitory concentration (IC 50 value) and limit of detection (LOD, IC 20 value) were 1.09 μg L − 1 and 0.067 μg L − 1 , respectively. The LOD of TRFIA was improved 30-fold compared to the already reported ELISA. There was almost no cross-reactivity of the antibody with the other structural analogues of triazole compounds, indicating that the antibody had high specificity. The average recoveries from spiked samples were in the range from 80.2% to 104.7% with a relative standard deviation of 1.0–9.5%. The TRFIA results for the real samples were in good agreement with that obtained by high-performance liquid chromatography analyses. The results indicate that the established TRFIA has potential application for screening paclobutrazol in environmental samples. [ABSTRACT FROM AUTHOR]

Europium (Eu 3+ ) and samarium (Sm 3+ ) were used as fluorescent labels to develop a highly sensitive dual-labeled time-resolved fluoroimmunoassay (TRFIA) for detect clothianidin and diniconazole in food samples. Under the optimized assay conditions, 50% inhibition concentration (IC 50 ) and the limit of detection (LOD, IC 10 ) of clothianidin were 5.08 and 0.021 μg/L, and 13.14 and 0.029 μg/L for diniconazole. The cross-reactivities (CRs) were negligible except dinotefuran (9.4%) and uniconazole (4.28%). The recoveries of clothianidin and diniconazole ranged from 79.3% to 108.7% in food samples. The results of TRFIA for the authentic samples were validated by gas chromatography (GC) analyses, and a satisfactory correlations were obtained. These results indicated that the method was an alternative tool for simultaneous detection of clothianidin and diniconazole in food samples. [ABSTRACT FROM AUTHOR]

A dual-label time-resolved fluoroimmunoassay (TRFIA) was introduced for the simultaneous quantification of chlortetracycline (CTC) and doxycycline (DOX) in edible animal tissues. Europium- and samarium-labelled antibodies were used, because lanthanides have higher stabilities and narrower emission spectra than most fluorescent dyes. The limits of detection for simultaneous determination of CTC and DOX were 0.03 ng ml−1and 0.04 ng ml−1, respectively. The average recoveries and the intra- and inter-assay coefficients of variation were 85.8–102.4%, 4.3–8.4% and 5.5–8.9%, respectively, and 85.3–101.6%, 4.5–9.2% and 5.3–9.6% for DOX, respectively. The proposed TRFIA for spiked samples was confirmed by high-performance liquid chromatography with a high correlation coefficient (R2) of 0.9933–0.9969. Therefore, the TRFIA may be an alternative sensitive and fast quantitative method for the high-throughput simultaneous screening of CTC or DOX in edible animal tissues. [ABSTRACT FROM AUTHOR]

A highly sensitive direct dual-labeled time-resolved fluoroimmunoassay (TRFIA) to detect parathion and imidacloprid simultaneously in food and environmental matrices was developed. Europium (Eu) and samarium (Sm) were used as fluorescent labels by coupling separately with L-Ab and AP-Ab. Under optimal assay conditions, the half-maximal inhibition concentration (IC) and limit of detection (LOD, IC) were 10.87 and 0.025 μg/L for parathion and 7.08 and 0.028 μg/L for imidacloprid, respectively. The cross-reactivities (CR) were negligible except for methyl-parathion (42.4 %) and imidaclothiz (103.4 %). The average recoveries of imidacloprid ranged from 78.9 to 104.2 % in water, soil, rice, tomato, and Chinese cabbage with a relative standard deviation (RSD) of 2.4 to 11.6 %, and those of parathion were from 81.5 to 110.9 % with the RSD of 3.2 to 10.5 %. The results of TRFIA for the authentic samples were validated by comparison with gas chromatography (GC) analyses, and satisfactory correlations (parathion: R = 0.9918; imidacloprid: R = 0.9908) were obtained. The results indicate that the dual-labeled TRFIA is convenient and reliable to detect parathion and imidacloprid simultaneously in food and environmental matrices. [ABSTRACT FROM AUTHOR]

To measure the concentration of C-reactive protein (CRP) in serum, a portable, scanningfluorescence reader based on time-resolved fluoroimmunoassays was developed. The scanningfluorescence reader integrates with the AD7707 converter, which performs at a high accuracy. The photosensitive diode acts as the photoelectric conversion device, an optical module based on optical fibers, which is able to concentrate the excitation light from an LED into a line-shape beam, was designed to sendand receive the optical signal. The device subsequently addresses waveform data using a gradient, smoothing, and binarization method. When the device measures the CRP fluorescence test strip, the results exhibited a good linearity (0.99998) and the CVs (coefficient of variation) were below 5%, which indicate high accuracy. At the same time the system is low cost and small size. [ABSTRACT FROM AUTHOR]

Enzyme-linked immunosorbent assays (ELISA) specific for anti-HSV glycoprotein G (gG) are most commonly used in the clinical diagnosis of HSV infection. But most of them are qualitative and with narrow detection ranges. A novel time-resolved fluoroimmunoassay (TRFIA) methodology was developed for the quantitative determination of HSV IgG in human serum. The assay was based on an indirect immunoassay format, and performed in 96-well microtiter plates. HSV-1 and HSV-2 were used as the coating antigens. Eu3+-labeled goat anti-(human IgG) polyclonal antibodies were used as tracers. The fluorescence intensity of each well was measured and serum HSV IgG levels quantified against a calibration curve. The detection range of the novel TRFIA was between 5 and 500 AU/mL. Assay sensitivity was 0.568 AU/mL. The intra- and inter-assay coefficients of variation were 0.59-3.63% and 3.65-6.81%, respectively. Analytical recovery, dilution tests and serum panel tests were performed using TRFIA and the results proved satisfactory. There were no statistically significant differences in sensitivity and specificity between the TRFIA and commercial ELISAs. An effective, sensitive and accurate quantitative HSV type 1 and type 2 IgG TRFIA was successfully developed and provided diagnostic value in clinical use. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Summary Tuberculous pleural effusion is the second most common form of extrapulmonary tuberculosis, which is very difficult to rapidly distinguish from malignant pleural effusion in the clinical setting. A time-resolved fluoroimmunoassay (TRF) of CFP-10, a low molecular weight protein secreted by pathogenic Mycobacterium tuberculosis, was developed to differentiate tuberculous pleural effusion from malignant one. The measuring range was 0.3–187.5 ng/ml with the dose–response coefficient of 0.9998 and detection limit of 0.036 ng/ml. The intra-assay and inter-assay coefficients of variation were 3.6–9.2% and 10.0–12.4%, respectively. The concentration of CFP-10 in malignant pleural effusion was less than 0.8 ng/ml. The negative predictive value was 93.1% in malignant pleural effusion (n = 247) while the positive predictive value was 83.0% in tuberculous pleural effusion (n = 235). Moreover, there was a statistically significant difference in the CFP-10 concentration of pleural effusion between the groups before and after clinical therapy of tuberculosis (P < 0.001, n = 81). In addition, the stability of the diagnostic reagents lasted at least 1 year at 4 °C. Therefore, the TRF of CFP-10 may be used for the rapid diagnosis of tuberculous pleural effusion and further monitoring the clinical therapeutic efficacy of tuberculosis. [ABSTRACT FROM AUTHOR]

An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and time-resolved fluoroimmunoassay (TR-FIA) based on an anti- N -butylquinoxaline-2-carboxamide (BQCA) monoclonal antibody were standardized and validated for quinoxaline-2-carboxylic acid (QCA) screening in animal tissues and its performance were compared to HPLC. The sensitivities obtained for edible tissue extracts were 1.62 and 1.12 ng ml −1 for ic-ELISA and TR-FIA detection, respectively. Two samples were spiked with QCA and analyzed by both methods. The recovery values ranged from 92.6% to 112.2% and the coefficients of variation were less than 15% for QCA spiking into swine tissue samples at concentrations of 2.5–50.0 μg kg −1 . Excellent correlations ( r 2 = 0.987–0.996) of the ic-ELISA/HPLC and TR-FIA/HPLC data were observed for processed samples. The results demonstrated that the ic-ELISA and TR-FIA methods were rapid and accurate for the residue detection of QCA in animal tissues. [ABSTRACT FROM AUTHOR]

We developed a TR-FIA kit for quantitative detection of CA50. This study aims to evaluate the analytical and clinical performances of this kit. Precision, accuracy, specificity, sensitivity, stability, and endogenous interference of this kit are evaluated. Reference range is established. Coincidence rate and correlation between TR-FIA and RIA are evaluated. ROC is adopted to evaluate the diagnostic performance. This kit shows excellent precision with a coefficients of variation (CVs) ranged from 2.2–9.3%, accuracy (average recovery, 98.5%), sensitivity (minimum detectable concentration is 0.2 U/mL), specificity (all cross-reactivity is less than 0.1% except CA199, which is 0.175%), and storage stability (recoveries, 90.8–100.4%). Bilirubin, hemoglobin, and triglyceride dose not interfere with CA50 detection (recovery, 97.13–109.1%). The range from 0–25 U/mL is chosen as the reference range. There are good correlation (r = 0.804) and coincidence (p = 0.608, kappa = 0.924) between TR-FIA and RIA. Diagnostic performance of this kits, which based on RIA results, is perfect (AUC = 0.996), and the diagnostic accuracy for malignancy diagnosis is in moderate degree (AUC, 0.802–0.861). The TR-FIA (CA50) kit performs well in analytical and clinical performances, and can be employed in the clinical diagnosis of malignancy. [ABSTRACT FROM PUBLISHER]

An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and a time-resolved fluoroimmunoassay (TR-FIA) for the determination of the furazolidone metabolite 3-amino-2-oxazolidinone (AOZ) were developed. 3-Amino-2-oxazolidinone was detected using its derivative, 3-[[(2-nitrophenyl)-methylene]-amino]-2-oxazolidinone (NPAOZ). 3-([(3-Carboxyphenyl)methylene]-amino)-2-oxazolidinone (CPAOZ) was used as the immunizing hapten for the production of monoclonal antibodies against NPAOZ. The ic-ELISA had a 50 percent inhibition (IC50) value of 0.82 microgram per liter and a detection limit of 0.11 microgram per liter. The recoveries from animal tissues spiked with AOZ from 0.2 to 5 micrograms per kilogram were 82.3–112.8 percent with coefficients of variation values of 3.5–12.5 percent. The time-resolved fluoroimmunoassay (TR-FIA) showed a 50 percent inhibition of 0.56 microgram per liter and a detection limit of 0.07 microgram per liter. The recoveries and coefficients of variation were 87.2–117.4 percent and 3.6–8.5 percent, respectively. The analysis of fortified samples by both methods provided similar results to those obtained by a standard high-performance liquid chromatography-tandem mass spectrometry method. These results indicate the ic-ELISA and TR-FIA methods are suitable for the determination of 3-amino-2-oxazolidinone in animal tissue. [ABSTRACT FROM PUBLISHER]

A sensitive, rapid and novel measurement method for cytokeratin 19 fragment (CYFRA 21-1) in human serum by magnetic particle-based time-resolved fluoroimmunoassay (TRFIA) is described. Built on a sandwich-type immunoassay format, analytes in samples were captured by one monoclonal antibody coating onto the surface of magnetic beads and 'sandwiched' by another monoclonal antibody labeled with europium chelates. The coefficient variations of the method were lower than 7 %, and the recoveries were in the range of 90-110 % for serum samples. The lower limit of quantitation of the present method for CYFRA 21-1 was 0.78 ng/ml. The correlation coefficient of CYFRA 21-1 values obtained by our novel TRFIA and CLIA was 0.980. The present novel TRFIA demonstrated high sensitivity, wider effective detection range and excellent reproducibility for determination of CYFRA 21-1 can be useful for early screening and prognosis evaluation of patients with non-small cell lung cancer. [ABSTRACT FROM AUTHOR]

Sensitive, precise and rapid detection tests are needed in the quality control of rabies vaccine for rabies virus nucleoprotein. Previous studies for quantitation of rabies virus nucleoprotein focused on enzyme-linked immunosorbent assay (ELISA). A novel immunoassay for rapid determination of rabies virus nucleoprotein in rabies vaccine was first established by time-resolved fluoroimmunoassay (TRFIA). Based on a sandwich-type immunoassay format, analytes in samples were captured by one monoclonal antibody coating in the wells and "sandwiched" by another monoclonal antibody labeled with europium chelates. The immunocomplex was retained after washing, and then adopted treatment with enhancement solution; fluorescence was then measured according to the number of europiumions dissociated. Levels of the rabies virus nucleoprotein were measured in a linear range (5-2500 mEU/mL) with a lower limit of quantitation (0.95 mEU/mL) under optimal conditions. The repeatability, recovery, and linearity of the immunoassay were demonstrated to be acceptable. The correlation coefficient of nucleoprotein values obtained by novel TRFIA method and ELISA method was 0.981. These results showed good correlation and confirmed that this sensitive, precise and rapid TRFIA was feasible and could be more suitable for the quality control in the process of rabies vaccine production than ELISA. [ABSTRACT FROM AUTHOR]

Current clinically assays, such as enzyme‐linked immunosorbent assay and chemiluminescence immunoassay, for hepatitis B surface antigen (HBsAg) are inferior in terms of either sensitivity and accuracy or rapid and high‐throughput analysis. A novel assay based on magnetic beads and time‐resolved fluoroimmunoassay was developed for the quantitative determination of HBsAg in human serum. HBsAg was captured using two types of anti‐HBsAg monoclonal antibodies (B028, S015) immobilized on to magnetic beads and detected using europium‐labeled anti‐HBsAg polyclonal detection antibody. Finally, the assay yielded a high sensitivity (0.02 IU/mL) and a wide dynamic range (0.02–700 IU/mL) for HBsAg when performed under optimal conditions. Satisfactory accuracy, recovery and specificity were also demonstrated. The intra‐ and interassay coefficients of variation were 4.7–8.7% and 3.8–7.5%, respectively. The performance of this assay was further assessed against a well‐established commercial chemiluminescence immunoassay kit with 399 clinical serum samples. It was revealed that the test results for the two methods were in good correlation (Y = 1.182X – 0.017, R = 0.989). In the current study, we demonstrated that this novel time‐resolved fluoroimmunoassay could be used: as a highly sensitive, automated and high‐throughput immunoassay for the diagnosis of acute or chronic hepatitis B virus infection; for the screening of blood or organ donors; and for the surveillance of persons at risk of acquiring or transmitting hepatitis B virus. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In an effort to enhance the linear range of anti-CCP we developed a new immunoassay based on time-resolved fluoroimmunoassay. The precision, sensitivity, specificity, and stability of the assay were evaluated ELISA set as control. The anti-CCP IgG TRFIA kit we established had a wider detectable range than commercial ELISA ones. With regard to intra- and inter-assay precision, the TRFIA kit was better than threee commercial ELISA ones. The mean recovery rate was 101.0%. The TRFIA we developed for anti-CCP IgG detection yielded a more sensitive and reliable method for RA diagnosis and large-scale screening programs as well. [ABSTRACT FROM PUBLISHER]

Europium (Eu)-labeled antibody was used as a fluorescent label to develop a highly sensitive time-resolved fluoroimmunoassay (TRFIA) for determination of clothianidin residues in agricultural samples. Toward this goal, the Eu-labeled polyclonal antibody and goat anti-rabbit antibody were prepared for developing and evaluating direct competitive TRFIA (dc-TRFIA) and indirect competitive TRFIA (ic-TRFIA). Under optimal conditions, the half-maximal inhibition concentration (IC) and the limit of detection (LOD, IC) of clothianidin were 9.20 and 0.0909 μg/L for the dc-TRFIA and 2.07 and 0.0220 μg/L for the ic-TRFIA, respectively. The ic-TRFIA has no obvious cross-reactivity with the analogues of clothianidin except for dinotefuran. The average recoveries of clothianidin from spiked water, soil, cabbage, and rice samples were estimated to range from 74.1 to 115.9 %, with relative standard deviations of 3.3 to 11.7 %. The results of TRFIA for the blind samples were largely consistent with gas chromatography ( R = 0.9902). The optimized ic-TRFIA might become a sensitive and satisfactory analytical method for the quantitative monitoring of clothianidin residues in agricultural samples. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: Diabetes mellitus is a chronic disease affecting millions of people globally and resulting in significant death rates each year. A fast, inexpensive alternative to traditional testing and monitoring techniques is desirable, since secretion of insulin and C-peptide is impaired in diabetes mellitus. Design and methods: A highly sensitive immunoassay was developed for the simultaneous measurement of C-peptide and insulin levels in human serum, utilizing dual-label time-resolved fluoroimmunoassay (TRFIA) and magnetic particle technologies. This assay was characteristic for a single-step sandwich-type immunoassay, wherein antibody-coated magnetic particles were used as the solid phase and Eu3+ and Sm3+ chelate labels were used for detection. Results: Antibody-coated magnetic particles in a TRFIA format performed well in addressing a number of quantitative needs. Conclusions: The results of this assay correlated well with commercial chemiluminescence assays and provided a number a advantages, including reduced sample volume, reduced reagent and personnel costs and reduced assay time, while maintaining the required clinical sensitivity. [Copyright &y& Elsevier]

A time-resolved fluoroimmunoassay for the specific determination of methyl-3-quinoxaline-2-carboxylic acid in animal tissues, a marker residue of olaquindox, was developed. The IC50of the assay was found to be 1.46 ± 0.19 ng/mL of methyl-3-quinoxaline-2-carboxylic acid in phosphate-buffered saline samples and the detection limit was 0.16 ± 0.03 ng/mL. For porcine liver and muscle samples spiked with 5, 10, and 15 ng/g, the recovery ranges were 95.7–112.3% and 98.5–116.2% and the coefficients of variation were 9.3–11.5% and 8.9–14.2%, respectively. The time-resolved fluoroimmunoassay results correlated well with high performance liquid chromatography results (correlation coefficients of 0.991 for liver and 0.988 for muscle). This study suggests that this method is simple, fast, and sensitive for the high-throughput determination of methyl-3-quinoxaline-2-carboxylic acid in animal tissues. [ABSTRACT FROM AUTHOR]

Pregnancy-associated plasma protein A (PAPP-A) is an important serum marker for first trimester screening. Its weekly median value varies with ethnicity. A one-step time-resolved fluoroimmunoassay (TRFIA) using two monoclonal antibodies against PAPP-A with Eu3+chelates as labels has been developed. Using the assay described here, we evaluated 5,301 normal serum samples from Chinese women at 7–13 weeks of gestation. The detection limit using this assay was 1.2 mIU/L, and the maximum detection range was up to 10,000 mIU/L. The intra-assay and inter-assay coefficients of variation were <3.0% and <5.0%, respectively, and the mean recovery rate was 98.0%. PAPP-A concentrations measured in 516 maternal serum samples correlated well with those obtained by Dissociation-Enhanced Lanthanide Fluorescent Immunoassay (DELFIA) PAPP-A assay (r = 0.988, P < 0.001). The medians for 7–13 weeks of maternal serum PAPP-A were higher in the women from China compared to reports from other countries. The present assay possesses accuracy and high sensitivity and exhibits great potential for the clinical analysis of PAPP-A. Our investigation on the median concentrations of PAPP-A will help establish reference values that are specific for China and study the importance of ethnic factors in biochemical screening. [ABSTRACT FROM AUTHOR]

In an effort to improve the quantitative detection of aCL IgM, we develop a new immunoassay to improve aCL IgM detection based on TRFIA using the complex of cardiolipin plus bovine β2GPI as antigen and Sm3+-labeled rabbit anti-human IgM as conjugate. The precision, sensitivity, specificity, coefficient of recovery, and stability of the assay were evaluated and comparison with the classical ELISA was also made. The aCL IgM TRFIA kit we established had a wider detectable range than commercial ELISA ones when diluted a specimen with strong positive from 1:2.5–1:40960. We observed that for the established TRFIA kit there was a good liner range within 1:2.5–1:40960, whereas it was within 1:20–1:1280 when using ELISA kits. The intraassay precision rate and the interassay precision rate were <5% for 3 different concentrations. The sensitivity was 0.1MPL U/mL and the clinical diagnostic specificity was 98%. Average recovery rate was 101.13%. The established assay kit also behaved better in stability. Additionally, the immunoassay we established correlated well with the ELISA and the correlation coefficient was 0.956. We thus conclude that the TRFIA we developed for aCL IgM detection gives promise to a more sensitivity and reliable diagnosis of APS and has potential value for large-scale screening programs. [ABSTRACT FROM AUTHOR]

A dual-label time-resolved fluoroimmunoassay (TRFIA) was introduced for the simultaneous quantification of sulfamethazine (SM2) and sulfaquinoxaline (SQX). Lanthanide (Eu3+and Sm3+)-labelled antibodies were used because lanthanides have higher stabilities and narrower emission spectra than most fluorescent dyes. The sensitivity of the TRFIA for SM2was 0.02 ng ml−1, and the average recoveries and the intra- and inter-assay CVs were 77.2–107.6%, 5.4–10.5%, and 6.0–11.2%, respectively. The sensitivity of the TRFIA for SQX was 0.04 ng ml−1; and the average recoveries and the intra- and inter-assay CVs were 74.1–102.8%, 4.6–10.9%, and 8.7–11.2%, respectively. The method was used to analyse chicken tissue and egg samples, and the results agreed well with the results of HPLC and enzyme-linked immunosorbent assay (ELISA) analyses, with correlation coefficients (R2) of 0.9415–0.9724. The TRFIA developed is a simple, fast and sensitive method for the high-throughput simultaneous screening of SM2and SQX in edible animal tissues. [ABSTRACT FROM AUTHOR]