ELISA Kits for almost All Your Targets: Cytokines, Biomarkers, Veterinary Analytes and More.

In a sandwich ELISA, one antibody captures the target protein and a second antibody detects it. The signal is proportional to the analyte concentration. In a competitive ELISA, the sample analyte competes with a labelled antigen for a fixed number of antibody binding sites. Here, the signal decreases as the analyte concentration increases. Sandwich formats suit large proteins. Competitive formats suit small molecules.

Most sandwich ELISA kits are validated for serum and EDTA or heparin plasma. Many also accept cell culture supernatant. Cell lysate is required for transcription factor and nuclear protein kits. Always check the kit's sample type validation table. Matrix effects from lipemic or haemolysed samples can affect accuracy.

Start with the species and sample type. Then confirm the detection range covers the concentrations you expect, whether physiological or experimental. Check whether the kit is validated for your application. If you need to measure the same protein across species, choose a cross-reactive validated kit. This helps you avoid switching formats mid-study.

Include the kit's standard curve, run in duplicate. Add a blank well with no sample to define background. Include at least one positive control at a known concentration to check kit performance. For biological samples, add a pooled reference sample across all plates to assess inter-assay variation. Spiked recovery controls help you spot matrix effects in complex biological fluids.