High sensitivity microgravimetric biosensor far qualitative and quantitative diagnostic detection of polychlorinated dibenzo-p-dioxins

A piezoelectric immunosensor system was developed for the rapid detection o f polychlorinated dibenzo-p-dioxins (PCDDs). The system uses a competitive inhibition enzyme immunoassay (EIA) based on a mouse monoclonal antibody th at is specific for 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and a conjugate of a dioxin-like competitor coupled to the enzyme horseradish pe roxidase (HRP). The anti-dioxin antibody was deposited on a 10 MHz AT-cut q uartz crystal resonator modified with a self-assembly monolayer of dithiobi s-N-succinimidyl propionate. PCDDs at different concentrations in the range 0.001-10 ng mL(-1) were mixed with a constant amount of HRP-conjugated com petitor. The frequency responses due to the adsorption of the mixed samples on the biosensor surface were measured. The results show that 2,3,7;8-TCDD can be quantitatively detected with the developed immunosensor in the conc entration range 0.01-1.3 ng mL(-1). Cross-reactivities of the biosensor to various PCDD congeners were also investigated. The sensitivity and selectiv ity of the quartz crystal microbalance (QCR) biosensor is comparable to EIA and ELISA methods in the detection of polychlorinated dibenzo-p-dioxins. T he developed QCM immunosensing system offers significant improvements in sp eed, sample throughout and cost for the qualitative and quantitative detect ion of PCDDs compared with GC-MS.