Immunoassay test is based on specific reaction between antibody and antigen to detect the existence or the concentration of specific substance in the sample. It could be used in a wide range of applications including hormone inspection, tumor detection, allergies, therapeutic drug monitoring and more. In this article, we would like to start with immunoassay drug test in order to know more about immunoassay test.
What is immunoassay drug test?
Immunoassay drug test is applied to determine the presence or absence of parent drugs or their metabolites by performing immunoassay testing. Antigen is a particular macromolecule which could bind with antibody. Therefore, we could take the antibody as reagent to identify the antigen, which is more common, or the antigen could be used to detect the antibody. Different from traditional laboratories testing, immunoassay drug test simplifies the process, obtains quickly the result and optimizes the efficiency. By the way , it’s cost-effective, so in our daily life, it can be used in different application scenarios, including entry examination of employers, police officers testing for the presence and concentration of alcohol (ethanol), detection for the suspected drug user, etc.
What is the difference between a drug test and a drug screen?
Drug screen means usually immunoassay drug testing which could be applied to all the samples, but the most common is urine. Drug screen has his advantages, like quick result, low cost, etc., but the false positive may appear. Therefore, to be more accurate, in the laboratories, operators may perform a second test as confirmation test, which is usually undertaken by a laboratory using highly specific chromatographic techniques and only applied to samples that test positive during the screening test.
How do drug immunoassays work?
Common drug samples include urine, blood, saliva, hair, etc. Among them, urine, blood, and saliva can reflect recent drug-related conditions, and hair can reflect the history of drug abuse. When performing on-site testing, urine, blood, and saliva do not require pre-processing for direct testing or simple processing, while hair samples need to be pre-processed in different ways before testing and then select appropriate methods for testing. We would like to introduce four kinds of immunoassay testing which are commonly used.
- Enzyme-linked immunosorbent assay (ELISA)
Immunoassay tests employ different methods, including labeled testing or label-free testing. Enzyme-linked immunosorbent assay (ELISA) applies heterogeneous immunoassay technique which takes enzyme as label.
The detection principle is to bind the antigen or antibody to the surface of a certain solid-phase carrier, and use enzymes to label the antigen or antibody. During the determination, the sample and enzyme-labeled antigen or antibody are allowed to react with the antigen or antibody on the surface of the solid-phase carrier in different steps. By washing, other substances can be separated, and the antigen-antibody complex formed on the solid phase carrier can be retained. Finally, the amount of enzyme bound to the solid phase carrier has a certain proportional relationship with the amount of the test object in the sample. After the enzyme substrate is added, the enzyme’s catalytic action turns it into a colored substance. Through the amount of this colored substance and the degree of color change, the components to be tested in the sample can be qualitatively or quantified.
- Collaurum Immunochromatography Assay (ICA)
Collaurum is an immunochromatographic technique that uses colloidal gold as a tracer to be applied to antigen/antibody. The test strip contains the specific synthetic antigen that is fixed in the test area on the membrane in advance, and the binding pad contains the labeled specific monoclonal antibody against specific drugs; during the test, the sample is dripped into the detection hole, and the sample is then under the capillary effect Chromatography upwards. If the drug concentration in the sample is lower than the threshold or there is no drug to be tested, the specific antibody labeled with colloidal gold cannot be fully bound by the drug in the sample. The remaining colloidal gold-labeled specific antibodies will be bound to the coated antigen immobilized on the test area (T) during the chromatography process, and a purple-red band will appear. If the concentration of the drug to be detected in the sample is higher than the critical value, the specific antibody labeled with colloidal gold is all bound by the drug in the sample. Therefore, the coating antigen on the test area (T) has no specific antibodies that can bind, so there will be no purple-red bands.
- Time resolved fluoroimmunoassay (TRFIA)
Time-resolved immunofluorescence technology is a new type of non-radioactive micro-immunoassay technology established by labeling antigens or antibodies with lanthanides and combining with time-resolved measurement technology. The technical principle is to use a chelating agent with a bifunctional group structure to label the lanthanide element on the antibody (or antigen), and form a complex after the immune reaction. Since the lanthanide element can emit fluorescence, the unbound components are separated and removed. After that, the fluorescence intensity can be measured by using a time-resolved fluorimeter to estimate the content of the analyte.
- Quantum dot immunofluorescence technology
Quantum dots have many advantages such as wide excitation spectrum, narrow emission peak, pleochroism and photobleaching resistance, making them important fluorescent markers for modern homogeneous immunoassay techniques.
Quantum dot immunochromatography technology uses quantum dot fluorescent probes as markers, which not only fully embodies the advantages of simplicity, speed and specificity of immunochromatography, but also demonstrates the high sensitivity of quantum dots and its fluorescence characteristics, Showing great development potential and broad application prospects. However, there are some problems in the application of quantum dots. The conversion of quantum dots between different states will cause them to appear fluorescent flicker, which will affect the detection results of a single quantum dot. Secondly, with the gradual excitation of quantum dots, the intensity of its fluorescence will gradually become stronger, affecting quantitative detection. In addition, during the quantitative detection process, the stability of the luminous intensity is required, and the change of the intensity will affect the accuracy of the detection result. Effective solutions to these problems can greatly promote the application of quantum dot fluorescence immunoassay technology.
Are immunoassays presumptive tests?
Presumptive test is different from confirmatory tests, the former could determine that the sample is definitely not a certain substance or probably the substance without confirming the analysis. Immunoassay drug testing could be presumptive test by detecting the suspicious substance, material etc. Presumptive substance testing could find the trace of drug without participation of suspicious individual.
Immunoassay could not only perform drug testing, but also help individual health care by tracing antigen/antibody in human body in order to monitor or prevent diseases. We would like to introduce an excellent automated immunoassay analyzer— BLZ FL-400 Immunofluorescence Quantitative Analyzer.
What’s the principle of BLZ FL-400 Immunofluorescence Quantitative Analyzer?
BLZ FL-400 Immunofluorescence Quantitative Analyzer is a kind of POCT (point-of care) product, which is based on specific antigen-antibody reaction, uses double antibody sandwich method to detect the existence or calculate the value of certain antigen. We drop the serum sample into the cassette, the sample will flow to the conjugate pad and bind will fluorescent labeled antibody. And then the liquid will move naturally in the cassette and arrive at test line where the complexes will combine again with the capture antibody. This automated device is equipped with light-emitting device which is capable to project light in certain wave to the test line, and the optical sensor will detect the light energy absorbed by the combination and calculate the concentration of analyte in the sample.
Double antibody could combine more completely with antigen, therefore the result will be more reliable.
Application of BLZ FL-400 Immunofluorescence Quantitative Analyzer
BLZ FL-400 Immunofluorescence Quantitative Analyzer is able to perform many kinds of testing, test items are including 5 categories: diabetes markers, cardiac markers, infection markers, tumor markers, and hormone markers.
- Diabetes markers: Glycated hemoglobin (HbA1c) concentration provides a better estimate of average hyperglycemia; Assays for proinsulin, insulin and C-peptide are widely used in the monitoring of hypoglycemia, pathogenesis and treatment of diabetes mellitus.
- Cardiac markers: Cardiac markers are biomarkers measured to evaluate heart function. They can be useful in the early prediction or diagnosis of disease.
- Infection markers: To define, diagnosis of inflammation, and to monitor the process of treatment.
- Tumor markers: Tumor markers are substances made by cancer cells or by normal cells in response to cancer in the body. Help monitoring if cancer has spread, whether treatment is working, or if cancer back after treatment.
- Hormone markers: Endocrine glands, make hormones. The major endocrine glands are the pituitary, pineal, thymus, thyroid, adrenal glands, and pancreas. Hormones are your body’s chemical messengers.
There are more than 40 parameters could be detected.
Advantages of BLZ FL-400 Immunofluorescence Quantitative Analyzer
- Compact Size, easy to carry and easy to use: the operation do not require professional experience, specialized facilities etc. The value will be displayed within 3-15 minutes, the TAT(turn-around-time) is greatly reduced. Simplify the complex.
- Reliable results: the result has a high consistance with international leading product manufacturer. With In-built automatic calibration and independent quality control, the device could maintain accuracy.
- Maintenance free: the device could realize internal calibration by standard curves stored inside ID chips, it can be shipped and stored in room temperature without cold storage, and BLZ Medical offers maintenance totally free with 2 years’ warranty and free change policy.
- Quantitative platform: different from collaurum technique, the immunofluorescence could achieve quantitative analysis with higher sensitivity.
BLZ FL-400 Immunofluorescence Quantitative Analyzer could detect multiple parameters in a full platform, it will definitely improve experience of patient care.
References
Patel, Bhavna & patel, hiral. (2013). INTRODUCTION TO DIFFERENT TYPES OF IMMUNO ANALYZERS AND ITS USEFULNESS IN DIFFERENT TYPES OF IMMUNO ASSAYS. International Journal of Pharmacy and Biological Sciences. 3. 95-98.