Used for detecting and measuring specific proteins, antibodies, or antigens in biological samples such as blood or serum. Commonly applied in medical diagnostics to identify infections like HIV, hepatitis, and Lyme disease. Also used in research to study immune responses and protein expression. Widely utilized in pharmaceutical development for quality control and biomarker analysis. Offers high sensitivity and specificity with relatively low sample volume requirements. Suitable for high-throughput screening in clinical and laboratory settings.