The development of high sensitive alpha-fetoprotein immune-electrochemical detection method using an excellent conductivity 3D-CuFC-C nanocrystals synthesized by solution-grown at room temperature

A novel 3D C-based nano Cu2[Fe(CN)6]-C (C-CuFC) nanocrystals with unusually electrical-conductivity was synthesized based on reduced carboxylated graphene oxide (COOH-rGO) and copper nanoparticles (CuNPs) by using room temperature (RT) K3[Fe(CN)6]-solution growth. During the fabrication of C-CuFC electrode, rGO-COOH enabled the Cu2+ to tunnel the electrons, which contributed to form a 3D petal-liked structure (Flo.-C), meanwhile, the synthetic 3D Flo.-C induced crystal of the electroactive cubic CuFC-C in K3[Fe(CN)6] solution. Another, the [Cu(CN)4]2-, [Fe(CN)6]4- and quinones with high conductivity were produced, and the free Fe2+ and Cu2+ existed on solid (electrode)-liquid (electrolyte) interface also increased the electric signal directly, so this CuFC-C showed amazing electrochemical current, which was 29-folds larger than the current intensity of bare electrode. With attaching on electrode, CuFC-C nanomaterial can significantly improve the electrical conductivity of sensor. Impressively, such 3D-CuFC-C nanocrystals shows excellent anchoring ability toward the AFP-antibodies (Ab) ascribed to the unreduced COOH-group of CuFC-C. Hence, a 3D Ab/CuFC-C/GCE electrochemical immunosensor was constructed based the promising conductivity and biocompatibility. Meanwhile, the Ab/CuFC-C/GCE biosensor exhibited ultra-low detection limit (LOD: 1.40 × 10-8 ng mL-1) and a fast response time (0.4 min). Additionally, the developed biosensor displayed excellent stability and good recovery (92.07%-101.91%) for AFP in human serum. Therefore, this sensing-platform has great potential in rapidly and sensitively detecting biomarkers and the other race targets.