Parallel Detection of Mixed Pesticides Based on Dual Quantum Dot/Porous Silicon Optical Biosensors

A dual-target molecular parallel detection method is proposed to detect multiple pesticides on a single sensor based on a double quantum dot/porous silicon optical biosensor. We fabricated porous silicon Bragg devices with broader forbidden bands to enhance the fluorescence from various quantum dots. Different quantum dots were labeled on complementary strands of nucleic acid aptamers and reacted with immobilized aptamers on the pore walls of the porous silicon pores. Finally, upon the addition of the pesticides of acetamiprid and profenofos, the complementary strands of the pesticides were replaced due to the stronger specific binding of the pesticides to their respective nucleic acid aptamers, and the fluorescence of the quantum dots was reduced. The detection of different pesticides was accomplished by monitoring the changes in the fluorescence of different quantum dots before and after the biological reaction. The detection limits were 2.64 nM for acetamiprid and 1.05 nM for profenofos. Our method was sensitive, cost-effective, and fast. Furthermore, our method could be applied to the efficient detection of multiple classes of chemical contaminants and nontargeted risk agent screening.