Highly sensitive and interference-free simultaneous detection of two polycyclic aromatic hydrocarbons at parts-per-trillion levels using a surface plasmon resonance immunosensor

A novel surface plasmon resonance (SPR)-based flow immunosensor is fabricated for simultaneous detection of benzo(a)pyrene (BaP), a potential endocrine disrupter, and 2-hydroxybiphenyl (HBP), a carcinogen. Immunosensor chip for SPR imaging is fabricated using easily moldable, flexible, thin polydimethylsiloxane (PDMS) films. PDMS films having multi-microchannel structures are prepared by molding process and act as flow-cell module. With the use of multi-microchannel flow-cell systems, samples of as small as 300 RI are enough for SPR analysis of two different compounds present in a mixed analyte solution simultaneously. The SPR immunosensor working with indirect competitive immunoreaction method is demonstrated to detect the low molecular weight antigens, BaP and HBP, at ppt (parts-per-triIlion) levels. Monoclonal antibodies against BaP and HBP undergo competitive immunoreaction between the antigens, BaP and HBP, present in analyte solution and the antigen-protein conjugates immobilized on the SPR sensor chip. The SPR responses of the immunoreaction are followed to determine the concentration of BaP and HBP in mixed analyte solutions. The SPR immumosensor is demonstrated to detect BaP and HBP at the same time in the concentration range of 10 ppt-300 ppb and 10 ppt-1000 ppb, respectively, with a response time of approximately 15 min. The SPR immunosensor shows negligible cross-sensitivity between the two analytes. Regeneration of the sensor chip for repeated use is attained with the use of pepsin as the eluent. (C) 2004 Elsevier B.V. All rights reserved.