Biosensor with electrochemically active nanocomposites for signal amplification and simultaneous detection of three ovarian cancer biomarkers

The current trend in medical diagnostic methods is to simplify and accelerate diagnosis and bring testing closer to the patient while maintaining the existing analytical criteria. Point-of-care tests (POCT) allow improved screening of population and rapid decisions regarding patient care. In case of cancer, this is a very desirable and valuable factor affecting the survival rate. Biosensors exploiting the bioaffinity interaction of target molecules with specific antibodies, combined with screen-printed electrodes as detection units, meet these criteria perfectly. In this study, we present a new sandwich-type magneto-immunosensor with electrochemical signal generating nanocomposites that was designed for the simultaneous detection and quantification of three biomarkers associated with ovarian cancer, namely human epididymis protein 4 (HE4), alpha-fetoprotein (AFP), and cancer antigen 125 (CA-125). The simultaneous detection was enabled by three different electroactive nanomaterials, namely gold nanoparticles (AuNPs), and CdTe and PbS core-type quantum dots (QDs), which were conjugated with three specific antibodies. Mesoporous silica nanoparticles (SiNPs) were incorporated in nanocomposite for higher loading of electroactive labels, leading to substantial enhancement of electrochemical signal. Square-wave anodic/cathodic stripping voltammetry was used for the detection of metal ions released quantitatively from the captured bioconjugates. Combination of these three elements provided separate non interfering signals, hence enabling simultaneous detection. Using this multiplex immunosensor, up to three biomarkers within the linear concentration ranges of 0.02-20 pM for HE4, 0.45-450 IU L 1 for CA-125, and 0.1-500 ng L 1 for AFP could be detected and quantified. The analytical parameters obtained fit the requirements of early-stage disease detection.