Magnetic Fe3O4@Au composite-enhanced surface plasmon resonance for ultrasensitive detection of magnetic nanoparticle-enriched α-fetoprotein

► We report an amplification technique using Fe3O4@Au MNPs for an SPR bioassay. ► Fe3O4@Au MNPs can function as an amplifier to increase the SPR signal. ► Sensitive detection of AFP is achieved via the purification/amplification protocol. ► This strategy has great potential for detecting other biomolecules of interest.