Trace level detections of abrin with high SNR piezoresistive cantilever biosensor

In this paper, sensitive detections on abrin are demonstrated in real-time by piezoresistive (PZR) cantilever sensors. With attempts to optimize the design and fabrication of the PZR cantilevers, the voltage fluctuation of the PZR sensors was decreased to 1 μV and the signal to noise ratio (SNR) was increased significantly. By using the biotin-streptavidin functionalized cantilevers, sensitive detections on abrin were realized. A linear relation between the concentration of abrin and the output voltage of PZR sensors was established within the range of 0.08-40 ng/mL (1.2-600 pM) and a limit of detection (LOD) of 80 pg/mL (1.2 pM) was obtained in PBS buffer. Meanwhile, detections on orange juice and skim milk samples spiked with abrin were also performed, and the detection sensitivity decreased by 6-17% compared with the one in PBS buffer at the same concentrations. At last, a model of pseudo-first-order kinetics was used to analyze the interaction mechanism of abrin and biotinylated polyclone antibody (bio-PcAb) against abrin, which was consistent with the detection results. The proposed PZR cantilever sensors provide an economical platform for on-site detections of food contaminants with the advantages of high SNR, portability, and rapid response.