Basis of differentiation | ELISA | RIA |
Definition | An immunoassay that uses enzymes to detect antigen-antibody complex | An immunoassay that uses radioisotopes to detect antigen-antibody complex |
Principle | Based on the specific binding of an antibody or antigen to an immobilized counterpart on a solid surface | Based on the competitive binding between unlabeled antibodies or antigens and radioactive-labeled tracers |
Labeling molecule | Antibody is labeled with enzymes | Antigen is labeled with radioisotopes |
Sample preparation | Simpler and more straightforward | Laborious and time consuming |
Assay time | Relatively faster, with results within a few hours | Can take longer due to sample preparation time and radioactivity measurement |
Sensitivity | Lower sensitivity | Higher sensitivity, typically in the picogram-femtogram range |
Detection method | Fluorescent or colorimetric signal | Radioactivity measurement |
Automation | Can be easily automated with commercial kits widely available | Use of radioactive materials limits the extent of full automation |
Antibody cross-reactivity | Less prominent cross-reactivity | Higher potential for cross-reactivity issues |
Special protocol | No special arrangements required | Radioactive materials require special arrangements for storage, requisition, and disposal |
Cost | Cost-effective overall, especially with commercial kits | More expensive as it requires radioactive reagents and specialized equipment |
Applications | Widely used in research, diagnostics, and more | Used in limited applications such as specific hormone assays |
Radiation hazard reporting | Radiation hazards do not apply | Radiation hazards must be documented and reported |