Detection of parathion and patulin by quartz-crystal microbalance functionalized by the photonics immobilization technique.

Oriented antibodies are tethered on the gold surface of a quartz crystal microbalance through the photonics immobilization technique so that limit of detection as low as 50 nM and 140 nM are achieved for parathion and patulin, respectively. To make these small analytes detectable by the microbalance, they have been weighed down through a "sandwich protocol" with a second antibody. The specificity against the parathion has been tested by checking the immunosensor response to a mixture of compounds similar to parathion, whereas the specificity against the patulin has been tested with a real sample from apple puree. In both cases, the results are more than satisfactory suggesting interesting outlook for the proposed device.