Development of a highly sensitive magnetic particle-based chemiluminescence enzyme immunoassay for thyroid stimulating hormone and comparison with two other immunoassays

Portable Chemiluminescence-Based Lateral Flow Assay Platform for the Detection of Cortisol in Human Serum

In this study, we developed the portable chemiluminescence (CL)-based lateral flow assay (LFA) platform for the detection of cortisol in human serum. Cortisol is well-known as a stress hormone due to its high relevancy for human mental and physical health, such as hypertension or depression. To date, a number of optical devices have provided the sensitive determination of levels of analytes. However, this modality type still requires costly optical modules. The developed CL platform is simply composed of two detection modules along with a loading part for the LFA strip. The LFA membrane contains gold nanoparticle probes conjugated with antibodies against cortisol and horseradish peroxidase (HRP), which can also efficiently increase the luminescent signal by providing many areas for anti-cortisol antibody and HRP. The measured voltage signals coming from the photodiode in a CL reader were compared with a standard microplate reader for the evaluation of accuracy. The linear range observed for cortisol was measured to be 0.78–12.5 μg/dL (R² = 0.99) with a limit of detection (LOD) of 0.342 μg/dL. In addition, the CL-LFA reader showed a high correlation (R² = 0.96) with the standard cortisol console (COBAS 8000, Roche), suggesting that our developed CL-based LFA platform can be usable in situ.

Label-free Paper-based Immunosensor with Graphene Nanocomposites for Electrochemical Detection of Follicle-stimulating Hormone

Follicle-stimulating hormone (FSH) is an important indicator of ovarian reserve function in women in clinical testing. In this work, a label-free paper-based immunosensor was developed for electrochemical rapid detection of FSH. A hydrophilic channel surrounded with hydrophobic barriers was firstly fabricated on the chromatography paper by wax printing technology. Then three electrodes were screen-printed on the circle zones of the channel, in which one carbon electrode further modified by reduced graphene-oxide /thionine /gold nanoparticles nanocomposites and FSH monoclonal antibody was used as the working electrode to provide sensitivity of the immunosensor. The detection of FSH is based on the decreased electrochemical current of Thi produced from the specific binding of the FSH and anti-FSH, and the decrease of the current is proportional to the concentration of the FSH. The experimental results exhibited that the immunosensor could be used to detect the standard FSH in range of 1-100 mIU/mL with the detection limit of 1 mIU/mL. And the proposed immunosensor had been successfully applied to detect FSH in serum samples.

Preparation of an Acridinium Ester-Labeled Antibody and Its Application in GoldMag Nanoparticle-Based, Ultrasensitive Chemiluminescence Immunoassay for the Detection of Human Epididymis Protein 4

An ultrasensitive and rapid sandwich-type chemiluminescence immunoassay (CLIA) was developed for the clinical determination of human epididymis protein 4 (HE4) in human serum, using GoldMag nanoparticles as solid phase and acridinium ester (AE) as chemiluminescence system (GMP-CLIA). The process of AE labeling antibodies was systematically studied and evaluated. The effect of varies factors such as molar ratio of AE to antibodies, labeling time, and the components of elution buffer and trigger solution were optimized. Under the selected conditions, AE labeling experiments were successfully performed with the average labeling efficiency of 1.92 ± 0.08, and antibody utilization rate of 69.77 ± 1.19%. Antibody activity remained unchanged after labeling. The established GMP-CLIA method can detect HE4 in the range of 0.25–50 ng·mL⁻¹ (10–2000 pM) with a detection limit of 0.084 ng·mL⁻¹ (3.36 pM). The sensitivity has reached a high level, comparable with the current commercial detection kits. This proposed method has been successfully applied to the clinical determination of HE4 in 65 human sera. The results showed a good correlation with a clinical method, microplate-based chemiluminescence enzyme immunoassay (CLEIA), with the correlation coefficient of 0.9594.

Evaluation of a magnetic particles-based chemiluminescence enzyme immunoassay for Golgi protein 73 in human serum

BACKGROUND

Golgi protein 73 (GP73) is regarded as a potential serum biomarker for early diagnosis of hepatocellular carcinoma (HCC). We developed a rapid magnetic particles-based chemiluminescence enzyme immunoassay (MPs-CLEIA) for the determination of serum GP73.

METHODS

Fluorescein isothiocyanate (FITC) and alkaline phosphatase (ALP) were used to label 2 different monoclonal antibodies to GP73. Serum GP73 was captured with labeled antibodies and formed a sandwiched immunoreaction. The magnetic particles (MPs) coated with anti-FITC antibody were used as a means of separation of the GP73 protein from other serum proteins. After adding the enzyme substrate solution, the relative light unit (RLU) was measured. A MPs-CLEIA for serum GP73 was established and evaluated.

RESULTS

The RLU was directly proportional to the concentration of GP73. The method linearity was 5-600 μg/l. Limit of the blank was 2.19 μg/l. The intra- and inter-assay imprecision was <3% and <5%, respectively. The average recoveries were between 95% and 105%. The proposed method showed a good correlation with a commercial ELISA assay (r=0.983, p<0.001). We also evaluated the efficiency of serum GP73 measurement for the diagnosis of HCC using this assay. The area under the receiver operating characteristic curve was 0.822 (95% CI, 0.73-0.89), and the sensitivity and specificity, with cut-off value of 115.6 μg/l, were 75.4% and 92.1%, respectively.

CONCLUSIONS

The proposed method demonstrates an acceptable performance for quantifying serum GP73. This assay could be appropriate for routine use in clinical laboratories.

Plasmonic metal scattering immunoassay by total internal reflection scattering microscopy with nanoscale lateral resolution

The total internal reflection scattering system incorporating a z-nanopositioner is introduced to explore the precise immunoassay on gold-nanopattemed chips by lateral resolution improvement.

Establishment and Evaluation of a One-Step Microplate Chemiluminescence Immunoassay to Detect IgG Antibody Against Treponema Pallidum

BACKGROUND

The serological detection of specific antibodies against Treponema pallidum is of particular importance in the diagnosis of syphilis. The chemiluminescence immunoassay (CLIA) has been widely used for clinical diagnosis because they remit no radical waste products, cause no enzyme precipitation, and exhibit an excellent sensitivity.

METHODS

A one-step CLIA was established to detect T. pallidum IgG antibody based on microplate coated with a mixture of recombinant T. pallidum antigens TpN15, TpN17, and TpN47. The Chinese national reference substances standard panel for T. pallidum diagnosis was applied to test the accuracy, stability, interference, and cross-reactivity of the established CLIA. The validation of efficacy for clinical application was performed by comparing the established method with the marketed T. pallidum particle agglutination (TPPA) kit and the Abbott ARCHITEC Auto System.

RESULTS

The established method met the requirement of the Chinese national reference substances standard for T. pallidum diagnosis. When compared with TPPA (n = 1,052), the specificity, sensitivity, and overall concordance were 99.7%, 99.0%, and 98.8% respectively, showing a great agreement with a kappa value of 0.81. When compared with the Abbott ARCHITEC Auto System (n = 352), the results showed that the specificity, sensitivity, and overall concordance were 98.6.0%, 96.6% and 98.6% respectively, and a high-degree agreement was observed (kappa value = 0.95).

CONCLUSION

The established rapid, specific, sensitive, and stable microplate CLIA method to detect IgG antibody against T pallidum will provide an efficient alternative to the treponemal tests and wide application in clinical laboratory.

Influence of the physical and chemical properties of magnetic nanoparticles on their performance in a chemiluminescence immunoassay

OBJECTIVES

Magnetic nanoparticles (MNPs) are important carriers in immunoassays. In this study, we investigated the influence of the physical and chemical properties of MNPs on their performance in a detection process.

DESIGN AND METHODS

A comparative study of the properties of two MNPs with sizes of 200nm and 1μm (MNP-200nm and MNP-1μm, respectively) was conducted using the following four aspects: nonspecific adsorption to proteins (IgG was used as a model protein), influence of magnetic nanoparticles on the chemiluminescence signal, response speed to an external magnetic field, and intensity of the detection signal.

RESULTS

MNP-1μm exhibited lower nonspecific adsorption to IgG in serum, a weaker interference with the chemiluminescence signal, and a higher response speed to the external magnetic field than the same amount of MNP-200nm. An automated chemiluminescence immunoassay system based on MNP-1μm was also established.

CONCLUSIONS

MNP-1μm acts as an excellent carrier in an automated chemiluminescence immunoassay system for the analysis of serum samples from clinical patients.