Surface plasmon resonance assay for chloramphenicol.

We report a rapid and ultrasensitive surface plasmon resonance (SPR) assay of chloramphenicol (CAP) by using large gold nanoparticles (40 nm) for signal enhancement on a mixed self-assembled monolayer (mSAM) sensor surface. After immobilization of the target antibiotic CAP through its ovalbumin (OVA) conjugates with an oligoethylene glycol (OEG) linker on the mSAM surface, sequential binding of anti-CAP antibody and IgG/nanogold (40 nm) onto the sensor surface afforded a rapid (<10 min) and ultrasensitive assay format for CAP. A limit of detection (LOD) for CAP as low as 0.74 fg/mL was achieved in aqueous buffer, and the linear working range was between 1-1000 fg/mL. While the LOD of CAP in a honey spiked-specimen is 17.5 fg/mL, the detection range is 80-5000 fg/mL. The mSAM sensor surface was also shown to be highly stable with over 400 binding/regeneration cycles performed.