A sensitive Salmonella biosensor using platinum nanoparticle loaded manganese dioxide nanoflowers and thin-film pressure detector

摘要

Salmonella is the leading factor for microbial food poisoning. In this study, a facile pressure biosensor was developed for rapid and sensitive detection of Salmonella using magnetic nanobeads (MNBs) to separate target bacteria, platinum nanoparticle loaded manganese dioxide nanoflowers (Pt@MnO_2 NFs) to amplify detection signal, and a thin-film piezoresistor based pressure detector to monitor pressure change. First, the capture antibodies (CAbs) modified MNBs were used to specifically separate Salmonella from sample to form MNB-CAb-Salmonella complexes (magnetic bacteria). Then, the detection antibodies (DAbs) modified Pt@MnO_2 NFs were used for labelling magnetic bacteria to form MNB-CAb-Salmonella-DAb-Pt@MnO_2 NF complexes (nanoflower bacteria). After nanoflower bacteria were resuspended with H_2O_2 in a sealed centrifuge tube, H_2O_2 was catalyzed by Pt@MnO_2 NFs to produce O_2, resulting in the increase on pressure. Finally, the pressure increase was real-timely monitored by piezoresistor based pressure detector and transferred to smartphone App via Bluetooth for analysis and determination of Salmonella. This biosensor could quantitatively detect Salmonella from 1.5 × 10~1 to 1.5 × 10~5 CFU/mL in 1.5 h with low detection limit of 13 CFU/mL. The Pt@MnO_2 NFs with high loading capacity of platinum nanoparticles were demonstrated as dual mimic enzymatic catalyst of H_2O_2 to greatly enhance the sensitivity. More importantly, it is the first time to combine a thin-film piezoresistor with a smartphone App for realtime monitoring of the pressure change resulting from the mimic enzymatic catalysis of H_2O_2 into O_2 by the Pt@MnO_2 NFs on the target bacteria to determine pathogenic bacteria in food samples.