Platinum porous nanoparticles hybrid with metal ions as probes for simultaneous detection of multiplex cancer biomarkers

• PtPNPs absorbed metal ions were prepared as electrochemical probes.
• Ionic liquid functionalized reduced graphene oxide was used as a substrate.
• An electrochemical immunosensor simultaneously detected CEA and AFP.

In this work, platinum porous nanoparticles (PtPNPs) absorbed metal ions as electrochemical signals were fabricated. Clean-surface PtPNPs were prepared by a surfactant-free method and decorated with amino groups via 2-aminoethanethiol. Amino capped PtPNPs complexation with Cd2+ and Cu2+ to form PtPNPs-Cd2+ and PtPNPs-Cu2+ hybrids, respectively. Anti-CEA and Anti-AFP separately labeled with PtPNPs-Cd2+ and PtPNPs-Cu2+ were used as distinguishable signal tags for capturing antigens. The metal ions were detected in a single run through differential pulse voltammetry (DPV) without acid dissolution, electric potentials and peak heights of which reflected the identity and concentrations of the corresponding antigen. Ionic liquid reduced graphene oxide (IL-rGO) modified glassy carbon electrode (GCE) was used as a substrate, which was rich in amino groups to immobilize antibodies by glutaraldehyde through cross-link between aldehyde groups and amino groups. Using the proposed probes and platform, a novel sandwich-type electrochemical immunosensor for simultaneous detecting carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) was successfully developed. This immunoassay possessed good linearity from 0.05 ng mL−1 to 200 ng mL−1 for both CEA and AFP. The detection limit of CEA was 0.002 ng mL−1 and that of AFP was 0.05 ng mL−1 (S/N=3). Furthermore, analysis of clinical serum samples using this immunosensor was well consistent with the data determined by the enzyme-linked immunosorbent assay (ELISA). It suggested that the proposed electrochemical immunoassay provided a potential application of clinical screening for early-stage cancers.