CPNs can be used as reporters in a wide range of binding assays giving stable fluorescent signals that detect the molecule of interest with high sensitivity. CPNs have been validated in binding assays for proteins, nucleotides and small molecules. When CPNs are used in binding assays their magnetic properties can be used to increase the assay signal and detection window significantly, allowing for greater sensitivity in assays and therefore earlier detection of disease biomarkers.
Protein A/G – IgG binding assay. Unlinked CPNs and CPNs linked to IgG were incubated on plates coated with protein A/G. The IgG linked CPNs bound protein A/G and give a strong assay signal. When a magnet was positioned under the assay wells the assay signal was dramatically increased as CPNs were drawn to the bottom of the plate, locally increasing their concentration close to the target protein A/G. Non-specific binding was minimal and was further reduced by placing a magnet above the wells during the wash off steps, drawing off any loosely attached, non-specific bound, CPNs.