A single antibody sandwich electrochemiluminescence immunosensor based on protein magnetic molecularly imprinted polymers mimicking capture probes

A single antibody sandwich electrochemiluminescence (ECL) immunosensor for ultratrace detection of protein was developed using magnetic molecularly imprinted polymers (MMIPs) as an alternative to the first antibody as capture probes and antibodies labeled with Ru-silica (Ru(bpy)32+-doped silica) doped Au (Ru@SiO2@Au) nanocomposites as labels. Using MMIPs as capture probes will aid mass production, greatly reduce costs and avoid the loss of bioactivity associated with the use of conventional antibodies. Moreover, MMIPs can be easily immobilized on and washed off simply by adding or removing a magnet on the electrode, which will greatly simplify the preparation and allow regeneration of the sensor. Lastly, MMIPs can enrich ultratrace levels of antigens from sample solutions to produce more immunocomplex than the conventional capture probe, thus providing an ultrasensitive assay. The logarithm of ΔECL intensity depended linearly on the logarithm of the hemoglobin (Hb) concentration in the range from 0.1 to 4 × 104 pg mL−1 with a detection limit of 0.023 pg mL−1. This approach offers obvious advantages of low cost, high sensitivity and enhanced stability compared with other immunosensors, and therefore offers significant potential for protein detection in a clinical laboratory setting.