ELISA assays are one of the most widely employed techniques at different stages of the drug discovery and development process. Besides, the ELISA method has applications in numerous other fields, including quality control and chemical and environmental sciences. Moreover, its applications in the bioanalytical space have given rise to its popularity among biomedical and pharmaceutical professionals. Hence, researchers always strive to modify ELISA assay protocols to increase their field of applications. Such interventions have made ELISA antibody assays a primary technique in biomarker analysis. The current article highlights five advances in ELISA assay technology and their impact on biomarker analysis.
Nanoparticle-conjugated ELISA
Standard ELISA assays have antibodies binding to the target antigen. Hence, incorporating nanoparticles attached to antibodies will enhance the sensitivity of ELISA assays. In a traditional ELISA assay, primary antibodies bind freely to the target receptor with limited binding sites for secondary antibodies. However, the introduction of nanoparticles increases the number of binding sites.
Nucleic amplification ELISA
RNA or DNA amplification methods can enhance the sensitivity of ELISA assays. Nucleic acids are attached to the optical signal and are vital in signaling responses during analyte detection. This method is also called CRISPR/Cas 13a signal amplification ELISA. Studies have confirmed that this method has at least 102-fold more sensitivity than traditional ELISA assays in detecting tumor markers and inflammatory markers.
Digital ELISA
For sensitivity, protein assays such as ELISA still lag behind nucleic acid assays, for example, polymerase chain reaction. Analyzing single protein molecules offer a promising platform for measuring proteins at very low concentrations. Digital ELISA is one such technique. Also known as Research status Single Molecule Array, digital ELISA employs an array of femtoliter-sized reaction chambers to differentiate and measure individual enzyme molecules. These individual enzymes are labeled to different protein molecules. Hence, digital ELISA can capture and detect enzymes conjugated to the target protein molecule.
Plasmonic ELISA
Plasmonic ELISA is another alternative. It combines traditional ELISA with nanomaterials. Plasmonic ELISA is highly sensitive and can be read openly without complex instruments. Hence, they are used increasingly in modern bioanalysis. Gold and silver nanoparticles have excellent local surface plasmonic resonance properties and are therefore, widely used in plasmonic nanosensors. In this particular assay setup, an antibody is labeled with an enzyme that catalyzes the substrate and triggers the shape change of the nanomaterial.
MSD (Meso Scale Discovery)
MSD protocol uses electrochemiluminescence detection and multi-array plates to measure protein biomarkers in complex study matrices. This technology employs similar principles of ELISA assays but has an advanced protocol to analyze multiple analytes via MSD-based assays. These assays include MSD PK assay and cytokine assays. MSD assays have higher sensitivity, selectivity, and a broader dynamic range. Hence, samples do not need multiple dilutions. Moreover, multiplexing capacities mean precious samples and reagents are saved during each analysis. A majority of MSD assays are sandwich-based assays. Each well of the microplate is coated with the capture antibodies. After incubation, Sulfo-Tag conjugate antibodies are added to measure multiple analytes of interest, making them an ideal assay for biomarker analysis.
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