Sensor system for detecting organophosphorus residues by inducing coagulation of gold nanoparticles

A method of detecting an organophosphorus pesticide, the method comprising:

• providing a sample suspected for comprising an organophosphorus pesticide selected from the group consisting of diazinon, edifenphos, iprobenfos, malathion, tebuconazole, parathion, acetamiprid, fenitrothion, and fenthion;
• adding, to the sample, gold nanoparticles and a reagent to provide a mixture, the reagent comprising a compound capable of binding with at least one gold nanoparticle and also capable of reacting with the organophosphorus pesticide such that, if the sample comprises the organophosphorus pesticide, a plurality of molecules of the compound are bonded to one molecule of the organophosphorus pesticide and at least part of the plurality of compound molecules bounded to the one organophosphorus pesticide molecule are bound to a plurality of gold nanoparticles, whereby in the mixture the plurality of gold nanoparticles are aggregated with the one organophosphorus pesticide molecule via the plurality of compound molecules, wherein the compound is at least one selected from the group consisting of imidazole, histidine, pyrozole, histamine, and green fluorescent protein (GFP);
• irradiating light beams to the mixture and measuring light absorbance for determining if aggregations of gold nanoparticles are formed in the mixture;
• and
• determining a presence of the organophosphorus pesticide in the sample when it is determined that aggregations are formed in the mixture.