Quantum-dots-based electrochemical immunoassay for the chlorpyrifos and trichlopyr metabolite trichloropyridinol.
Liu-G; Riechers-SL; Timchalk-C; Yuehe-L
Toxicologist 2008 Mar; 102(1):360
Chlorpyfios and trichlopyr are two routinely utilized pesticides that share a common urinary metabolite, trichloropyridinol (TCPy), which can be used to biomonitor for exposure. To facilitate biomonitoring there is a need to develop simple, rapid and sensitive sensors to evaluate exposures utilizing readily obtainable biological fluids, like saliva. A quantum-dot (QD)-based electrochemical immunoassay was developed to detect TCPy. QD conjugated with TCP derivative, triclopyr, was used as a label in the competitive immunorecognition event. TCP and the QD-labeled triclopyr competitively bind with the limited TCP antibodies on the magnetic beads (TCP-Ab-MB). The captured QD labels on the magnetic beads were determined by highly sensitive stripping voltammetric measurement of the dissolved metallic component (cadmium) with a disposable-screen-printed electrode. The parameters (e.g., amount of triclopyr-QD, amount of TCP Ab-MB and immunoreaction time) that govern the sensitivity and reproducibility of the electrochemical immunoassay were optimized. The voltammetric response is inversely proportional to the TCP concentration in the sample solution and is linear over the range of 0.05 to 1 ng mL-1 TCP. The limit of detection is estimated to be 0.02 ng mL-1, which is 10 times lower than that of commercial enzyme linked immunosorbance assay kit (0.25 ng mL-1). The performance of the developed immunoassay system was successfully evaluated on rat saliva samples spiked with TCP. This technique could be readily used for detecting other environmental contaminants by developing specific antibodies against contaminants and is expected to open new opportunities for biological monitoring. This new QD-based electrochemical sensor represents a potential next generation sensor for noninvasive biomonitoring of exposure to commercially important insecticides.
Agricultural-chemicals; Insecticides; Organo-phosphorus-compounds; Organo-phosphorus-pesticides; Electrochemical-analysis; Electrochemical-reactions; Electrochemistry; Biological-effects; Laboratory-animals; Pesticide-residues; Pesticides-and-agricultural-chemicals; Chemical-agent-detectors; Chemical-analysis; Chemical-synthesis; Urinalysis; Urine-chemistry; Chemical-hypersensitivity; Chemical-properties
Agriculture, Forestry and Fishing
The Toxicologist. Society of Toxicology 47th Annual Meeting and ToxExpo, March 16-20, 2008, Seattle, Washington
Battelle Pacific Northwest Laboratories