Development and comparative evaluation of two immunoassay platforms for bioanalysis of crizotinib: A potent drug used for the treatment of non-small cell lung cancer

This study describes, for the first time, the development of two platforms of competitive fluorescent immunoassays for bioanalysis of crizotinib (CZT), a potent drug used for the treatment of non-small cell lung cancer (NSCLC). These platforms were microwell-based heterogeneous fluoroimmunoassay (FIA) and a kinetic exclusion assay (KinExA) with KinExA™ 3200 immunosensor. Both FIA and KinExA were developed using same reagents; mouse anti-CZT antibody and a capturing reagent of CZT conjugated with bovine serum albumin (CZT-BSA). In the FIA, the CZT-BSA coated onto the microwells of the assay plate was present simultaneously in the assay mixture (CZT and its antibody). In the KinExA, the antibody was allowed to pre-equilibrate with CZT, and then the incubation mixture was rapidly passed through a microcolumn containing CZT-BSA coated onto polymethyl methacrylate (PMMA) beads. The analytical performances of both assays were comparatively evaluated in terms of assay working range, limit of detection, precision profile, and accuracy. The results revealed that KinExA yielded higher sensitivity and better precision than FIA; whereas, both assays had comparable accuracies. Both FIA and KinExA were superior to all the existing chromatographic methods for CZT in terms of the assay sensitivity, convenience, analysis throughputs. The proposed FIA and KinExA are anticipated to effectively contribute to the therapeutic drug monitoring (TDM) of CZT in clinical settings.

Automated flow fluorescent noncompetitive immunoassay for measurement of human plasma levels of monoclonal antibodies used for immunotherapy of cancers with KinExA™ 3200 biosensor

This study describes, for the first time, the development of an automated sensitive flow fluorescent noncompetitive immunoassay based on kinetic-exclusion analysis (KinExA) for the quantitative determination of human plasma levels of monoclonal antibodies (mAbs) used for cancer immunotherapy. The assay was adapted on KinExA™ 3200 biosensor and optimized and validated for bevacizumab (BEV) and cetuximab (CET), as representative examples of the mAbs, using their specific antigens. These antigens were the human vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) for BEV and CET, respectively. The limits of detection were 1.28 and 52.64 ng mL^-1 for BEV and CET, respectively. The accuracy of the assay was demonstrated with analytical recovery of analytes from spiked plasma at 96.2-104.3 and 96.8-105.3% for BEV and CET, respectively. The precision of the assay was satisfactory as shown by relative standard deviation (RSD) at 2.2-5.7 and 2.5-6.1% for assay of BEV and CET, respectively. The high sensitivity of the assay allowed the use of very small volumes (~ 1 µL) of plasma sample for analysis. Automated analysis by the proposed KinExA-based assay facilitates the processing of large numbers of mAbs-containing specimens in studies of pharmacokinetics (PK), pharmacodynamics (PD), and therapeutic drug monitoring (TDM) of therapeutic mAbs. The proposed assay can be used to overcome the problems encountered in the existing conventional immunoassays for mAbs.

Advances in human chorionic gonadotropin detection technologies: a review

Human chorionic gonadotropin (HCG) is a glycoprotein secreted by placental trophoblast cells in pregnancy. HCG is a heterodimer composed of two different α- and β-subunits, with the latter being unique to HCG. As well as being the most important diagnostic markers for pregnancy, HCG is also a tumor marker, therefore, quantitative detection of HCG is of great value. Numerous advanced technologies have been developed for HCG concentration detection including electrochemical immunoassay, chemiluminescent immunoassay, fluorescence immunoassay, resonance scattering spectrometry, atomic emission spectrometry, radioimmunoassay, MS and so on. Some have pursued simple and easy operation, while others have emphasized on accuracy and applications in clinical medicine. This review provides a comprehensive summary of various methods of detecting HCG.

Analytical Application of Flow Immunosensor in Detection of Thyroxine and Triiodothyronine in Serum

In this study, an immunosensor based on kinetic exclusion analysis (KinExA) was used for thyroxine (T4) and triiodothyronine (T3) estimation. A KinExA™ 3200 instrument was used for this analysis, which is an automated flow fluorimeter designed to separate free unbound antibody binding sites in reaction mixtures of antibody, antigen, and antibody-antigen complex. A T3-BSA- and T4-BSA-coated polymethyl methacrylate (PMMA) bead microcolumn is generated inside the flow cell of the instrument. A sample mixture containing T3 and T4 with their respective monoclonal antibodies and their complexes are drawn past the microbead column. The unbound T3 or T4 monoclonal antibody binding sites are captured by their respective T3 and T4 antigens coated on the PMMA beads as bovine serum albumin conjugates. Fluorescently labeled secondary antibodies bind to the T3 or T4 antigen-antibody complex to generate fluorescence intensity for analysis. The limit of detection for the T3 and T4 assays was found to be 0.06 and 1.9 ng mL^-1 with acceptable precision values. The convenience of the automated KinExA format may be valuable in medical diagnostic laboratories.

New analytical application of antibody-based biosensor in estimation of thyroid-stimulating hormone in serum

BACKGROUND

Conventionally, ELISA is used to measure thyroid-stimulating hormone (TSH) for diagnosis of thyroid disease. In this study, an immunosensor-based, kinetic-exclusion analysis (KinExA) was used for TSH estimation.

METHODOLOGY

A PMMA microbead column coated with TSH antigen is formed inside the flow cell. Samples consisting of mouse anti-TSH monoclonal antibody and TSH antigen complex in solution are passed over the beads and the unbound anti-TSH antibody is captured by the TSH-coated beads, followed by passing fluorescent-labeled antibody over the beads to generate signals for analysis. The limit of detection for the assay was 0.4 mIU l(-1) and the precision was acceptable.

CONCLUSION

The developed sensor was advantageous due to the automated nature and its convenience, without compromising the sensitivity for estimation of TSH.

A novel signal amplification strategy of an electrochemical immunosensor for human chorionic gonadotropin, based on nanocomposites of multi-walled carbon nanotubes–ionic liquid and nanoporous Pd

A novel electrochemical immunosensor using MWCNTs–BMIMPF₆/NP-Pd as a sensor platform to sequentially immobilize antibodies was developed for hCG detection.