A Paper-Chip-Based Phage Biosensor Combined with a Smartphone Platform for the Quick and On-Site Analysis of E. coli O157:H7 in Foods

The rapid and specific point-of-care (POC) analysis of virulent pathogenic strains plays a key role in ensuring food quality safety. In this work, paper-based fluorescent phage biosensor was developed for the detection E. coli O157:H7 strain (as mode pathogens) samples. Firstly, phages that can specifically combine with (E. coli) were stained SYTO-13 dye to prepare novel probe (phage@SYTO). Simultaneously, micro-porous membrane filter pore size 0.45 μm employed as paper chip so retain coli-phage@SYTO complex (>1.2 μm) on its surface. phage@SYTO (200 nm size) able pass through pores chip, could be retained using free probes. emit visual signal (excited at 365 nm; emitted 520 nm) onto which detected by smartphone reflect concentration coli. Under optimized conditions, limit low 50 CFU/mL (S/N = 3) exhibited wide linear range from 102 106 CFU/mL. sensor has potential application value quick POCT foods.