A polydopamine-modified optical fiber SPR biosensor using electroless-plated gold films for immunoassays

A sensitive and stable electroless-plated gold film for the preparation of an optical fiber surface plasmon resonance (SPR) sensor is presented in this work, together with a facile antibody immobilization method. Gold nanoparticles were uniformly adsorbed onto the surface of an optical fiber forming a film with a thickness of approximately 56.3nm. The sensor had a high sensitivity with 2054nm/RIU and 3980nm/RIU in the refractive index ranges of 1.333–1.359 and 1.359–1.386, respectively. An SPR biosensor was developed based on polydopamine-modified gold film (PDA-Au), which was fabricated by a simple and quick spontaneous polymerization of dopamine (DA) on the gold film. When goat anti-human IgG antibodies were immobilized, the PDA-Au surface had a larger resonant wavelength shift of 66.21nm compared with the traditional 11-mercaptoundecanoic acid-modified gold film (MUA-Au) surface. In addition, the PDA-Au surface enabled the sensitive and selective determination of human IgG down to a concentration of 2μgmL−1 with a high sensitivity of 0.41nm per μgmL−1. The PDA-Au surface exhibited an approximately four fold higher sensitivity and an about seven fold lower LOD than the MUA-Au surface to human IgG. •An electroless-plated gold film was applied to fabricate a sensitive and stable optical fiber SPR sensor.•The gold film was functionalized by the spontaneous polymerization of dopamine.•Antibody immobilization on PDA-modified gold film was very effective.•The PDA- modified gold film displayed a high sensitivity in immunoassays.