Immunoassay technology is an analytical method that uses the specific reaction of antigen and antibody to detect. It is an important method for in vitro clinical diagnostic testing. Since the radioisotope I125 labeled immunoassay method was proposed in 1960, it has been developed to date. Depending on the labeling method, it can be The immunoassay is divided into radioimmunoassay, enzyme-linked immunoassay, fluorescence immunoassay and luminescence immunoassay.
Chemiluminescence immunoassay technology
Chemiluminescence (Chemiluminescence) is a phenomenon of light radiation accompanying substances in the process of chemical reactions. Combining chemiluminescence detection technology with immune response forms a chemiluminescence immunoassay technology, which can be divided into microplate type and microparticle type according to different fixed carrier phases. Nowadays, particle-based chemiluminescence immunoassay technology is the mainstream, including direct chemiluminescence immunoassay (CLIA), chemiluminescence enzyme immunoassay (CLEIA), electrochemiluminescence immunoassay (ECLIA) and photo-induced chemiluminescence immunoassay (LiCA); According to the luminescence time of the reaction system, it can be divided into flash type and glow type.
Figure 1. Classification of chemiluminescence immunoassay techniques
Advantages of chemiluminescence immunoassay technology
▶ High sensitivity
A study compared the sensitivity of chemiluminescence immunoassay (CLIA), enzyme-linked immunosorbent assay (ELISA) and lateral flow immunochromatography (LFIA) in detecting SARS-CoV-2 virus, which were 92% and 86%, respectively And 78% ; in a study on the antibody detection methodology of patients with vasculitis, the sensitivity of chemiluminescence enzyme immunoassay (CLEIA) can reach 100% .
▶ Wide linear range
The luminous intensity has a linear relationship with the concentration of the tested substance, and the detection concentration can reach 4 to 7 orders of magnitude [4,5].
▶ Short immune response time
CLIA based on magnetic microspheres has become the mainstream method of clinical automatic immunoassay. Magnetic microspheres are used as a fixed carrier phase, and the specific surface area of the microspheres is large, which can increase the chance of contact between immune antigens and antibodies; it can move freely under the action of a magnetic field. It has a mixing function; at the same time, the microspheres are cleaned more thoroughly, which greatly improves the reaction efficiency , and the immune response can be completed within 30 to 40 minutes [4,5].
Figure 2. Chemiluminescence immunoassay using magnetic microspheres as a solid phase carrier (taking alpha-fetoprotein (AFP) detection as an example )
▶ Long light signal duration
The light signal of the glow-type reaction system lasts for a long time, up to several hours or even one day, which simplifies the experimental operation and measurement.
▶ Stable results
No external light source is required in the detection process, which can avoid interference and other errors caused by other light sources.
▶ Yi Quan Automation
Equipped with fully automatic instruments, the analysis method is simple and fast.
Application of Chemiluminescence Immunoassay Technology
Chemiluminescence immunoassay is a commonly used method in clinical diagnosis at present. It can detect more than one hundred items, and it plays a very important role in disease screening in particular. For example, in the 2019 version of the "Blood Station Technical Operation Specifications", the detection methods for blood transfusion-related infectious disease markers clearly stipulate that the serological detection technology should use ELISA or chemiluminescence immunoassay (CLIA). In addition, chemiluminescence immunoassay has also been widely used in the diagnosis of tumors, infectious diseases, cardiovascular diseases, metabolism and other diseases. For the detection and research of bacteria and fungi [5,6], researchers have not stopped advancing. pace.
Figure 3. Chemiluminescence immunoassay application
Mekonnen D, et al. Diagnostic accuracy of serological tests and kinetics of severe acute respiratory syndrome coronavirus 2 antibody: A systematic review and meta-analysis[J]. Rev Med Virol. 2021,31(3):e2181.
Hirose O, et al. Comparison of a novel chemiluminescence enzyme immunoassay (CLEIA) with enzyme-linked immunosorbent assay (ELISA) for the determination of MPO-ANCA in patients with ANCA-associated vasculitis[J]. Mod Rheumatol. 2015,25(2):230-234.
Zhang QY, et al. Comparison of chemiluminescence enzyme immunoassay based on magnetic microparticles with traditional colorimetric ELISA for the detection of serum α-fetoprotein[J]. J Pharm Anal. 2012,2(2):130-135.
Candida albicans Germ-Tube Antibody: Evaluation of a New Automatic Assay for Diagnosing Invasive Candidiasis in ICU Patients[J]. Mycopathologia. 2017,182(7-8):645-652.