Enzyme-linked immunosorbent assays (ELISA) can be used to identify and quantify the presence of biological substances in a sample. This plate-based technique requires robust fluorescent read outs deep into a plate, making CPNs more applicable than conventional fluorophores.
Our bioimaging probes can be used in standard ELISA assays for the detection of proteins with improved performance. We have demonstrated how our CPNs increase the intensity of signals, while remaining stable for over days or weeks. Their outstanding stability and resistance to photo-bleaching allows assay plates to be read long after storage, without the need for further staining. The magnetic qualities of CPNs can also be exploited in ELISA using magnets, further increasing the propensity for binding at the plate surface and therefore dramatically increasing the detection window (see Binding assays).
ELISA can be undertaken from 4°C to room temperature. CPNs maintain brightness across this temperature range, which improves the sensitivity of the assay.
CPNs perform well in standard ELISA giving robust fluorescent read outs and little non-specific signal from negative control wells. The ELISA in the figure above was carried out with unlinked CPNs or CPNs linked to antibody to detect the presence/absence of analyte in a test sample. CPN-GAR+RIgG: CPNs linked to detection antibody with analyte present in sample. CPN-GAR -RIgG: CPNs linked to detection antibody with no analyte in sample. CPN +RIgG: unlinked CPNs with analyte present in sample. CPN -RIgG: unlinked CPNs with no analyte in sample.