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

• Pt@MnO 2 nanoflowers were synthesized for dual mimic enzymatic catalysis of H 2 O 2. • Piezoresistor was combined with smartphone to real-time monitor pressure change. • This pressure biosensor was able to detect Salmonella as low as 13 CFU/mL in 1.5 h. • The mean recovery of Salmonella in the spiked chicken samples was 96.8%96.8 %. 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 2 O 2 in a sealed centrifuge tube, H 2 O 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 × 101 to 1.5 × 105 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 2 O 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 2 O 2 into O 2 by the Pt@MnO 2 NFs on the target bacteria to determine pathogenic bacteria in food samples. [ABSTRACT FROM AUTHOR]