Impedimetric nanoparticle aptasensor for selective and label free pesticide detection

An impedimetric label-free aptasensor for the simultaneous and highly selective detection of two pesticides is presented. The sensor is based on the combination of self-assembled platinum nanoparticle two-dimensional films (produced in room temperature via the magnetron sputtering technique) and target specific nucleic acids (a.k.a. aptamers). The platinum nanoparticle films have been deposited on top of SiO2 substrates previously patterned with interdigitated electrodes. The surface of the device has been chemically modified in order to enhance the subsequent aptamer deposition and immobilization. Two distinctive aptamer configurations have been employed in order to facilitate capturing and detection of two pesticides, namely acetamiprid and atrazine. Successful binding events between aptamer and target induce a shift in the impedance of the aptasensor which can be attributed in charge transport hindrance through the nanoparticle film. The incorporation of the nanoparticle film in the fabrication of the aptasensor significantly improves the performance of the device if compared to "naked" interdigitated based aptasensors, allowing the highly sensitive and selective detection of acetamiprid and atrazine down to 0.6 x 10- 11 M and 0.4 x 10- 10 M respectively.