Cu2O rhombic dodecahedra as a superexcellent electroactive substance for ultrasensitive electrochemical immunosensors

A novel biomolecular immobilization strategy based on a Cu2O rhombic dodecahedra–polydopamine–gold nanoparticle nanocomposite was used for the detection of alpha-fetoprotein (AFP). Cu2O rhombic dodecahedra, a new kind of Cu2O nanocrystal with excellent catalytic properties, were coated with bio-functional polydopamine (PDA) using a simple self-polymerization in mild basic solution. Then, highly loaded and uniformly dispersed gold nanoparticles (Au NPs) were deposited on Cu2O–PDA through in situ deposition. Under optimal conditions, a linear relationship between the CV peak current and the logarithm of the AFP concentration was obtained from 0.001 to 100 ng mL−1 with a detection limit of 0.6 pg mL−1 at a signal-to-noise ratio of 3. The high sensitivity and stability, low cost and simplicity in the fabrication procedures of the proposed immunosensor provide potential applications for clinical immunoassays.