Sensitive bioassay for detection of PPARα potentially hazardous ligands with gold nanoparticle probe

There are so many kinds of peroxisome proliferator-activated receptor alpha (PPAR alpha) ligands with hazardous effect for human health in the environment, such as certain herbicides, plasticizers and drugs. Among these agonists, perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and mono(2-ethylhexyl) phthalate (MEHP) are mostly investigated due to their persistence and accumulation in environment and their potential toxicity via PPAR alpha. This investigation aims at developing a bioassay method to detect PPARa ligands based on the ligand-receptor interaction on microplate. PPAR alpha, which formed heterodimers with retinoid X receptor-alpha (RXR alpha), were activated by PPAR alpha ligands to form ligands-PPAR alpha-RXR alpha complexes. Then the complexes were transferred into a microplate and captured via monoclonal anti-PPAR alpha antibody. The PPAR alpha responsive elements (PPRE) modified-gold nanoparticle probes were captured by the ligand-PPAR alpha-RXR alpha complexes immobilized on the microplate, and then could be quantified through measuring the optical density after silver enhancement. The results showed that PFOS was quantified with a linear range from 100 pM to 1 mu M and the detection limit was 10 pM. In addition to PFOS, PFOA and MEHP were also quantified within a proper range through the proposed bioassay. This bioassay was compared with that of liquid chromatography tandem-mass spectrometry (LC-MS) for water spiked samples with a significant correlation (r = 0.9893). This study provides a high-throughput detection method for PPAR alpha ligands in microplate with high sensitivity and wide linear range. It may serve as an assistant of LC-MS for prescreening of PPAR alpha ligands like PFOS. (C) 2011 Elsevier B.V. All rights reserved.