In vitro diagnosis of rapid test

Abstract

In vitro diagnosis refer to medical tests that are performed outside the human body, typically in a laboratory setting, to detect or diagnose diseases and conditions. These tests use samples such as blood, urine, saliva and tissue specimens to analyze the presence of specific molecules, cells or organisms that indicate a particular disease or condition. In vitro diagnosis tests are essential in healthcare because they help healthcare professionals diagnose diseases and conditions accurately and quickly. Early detection and diagnosis can improve patient outcomes and reduce healthcare costs by enabling earlier intervention and treatment. There are various types of IVD tests including immunoassays. These tests detect specific proteins or antibodies in a patient's blood, urine, or other bodily fluids. They are commonly used to diagnose infectious diseases, such as HIV, hepatitis, and COVID. All of them are worked on the principle of enzyme-linked immunosorbent assay. Enzyme-linked immunosorbent assay (ELISA) is a highly sensitive and specific laboratory technique used to detect and quantify the presence of an antigen (such as a protein, peptide, or antibody) in a sample. ELISA is widely used in clinical and research settings for diagnostic testing, disease monitoring and drug development. There are several types of ELISA, but the basic principles are the same. The demand for quantitative lateral flow immunoassays is growing steadily, however the development of these presents a challenging goal since quantitative assays require considerably more from the finished product in terms of reproducibility, stability, sensitivity and dynamic range than is needed from a qualitative assay. When a lateral flow immunoassay is run, the test sample is added to a sample application pad at the end of the strip. The sample then migrates to the conjugate release pad, where a detection particle (typically gold or latex) that has been conjugated to a biological component of the assay is held. Next the sample and the detection reagent migrate to the reaction membrane; a second biological component of the assay will have been immobilized here to function as a capture reagent. The capture reagent usually exists as a test line which spans the width of the membrane; a control reagent will be immobilized in a second line further along the membrane. The analyte is either captured at the test line, or continues to migrate until reaching the absorbent wicking pad at the other end of the strip. The detection reagent binds at the control line to indicate that the assay has run successfully.