Dual Aptamer-Copper (II) Phosphate Nanocomposite-Based Point-of-Care Biosensor for the Determination of Escherichia coli O157:H7 through Pressure Monitoring with a Hand-Held Barometer

Abstract

Here, two types of aptamer (specific to E. coli O157:H7 pathogenic bacteria) Cu3(PO4)2 nanocomposites loaded with Fe3O4 nanoparticles (aptamer@Fe3O4, magnetic separation) and platinum nanoparticles (PtNPs) (aptamer@PtNP) were prepared in house via enzymatic hydrolysis of H2O2 to O2 through a one-step method. In the proposed point-of-care biosensor, these nanocomposites were used as capture and signal probes for the determination of pathogenic E. coli O157:H7 bacteria via hand-held barometers detecting gas pressure signals in a sealed bottle. The pressure signal was linear when the concentration of E. coli O157:H7 was from 103 to 108 CFU/mL. With the easily prepared dual aptamer-Cu3(PO4)2 nanocomposites and the hand-held barometer signal readout, the proposed point-of-care biosensor was shown to be a potential tool for the determination of pathogenic bacteria in underdeveloped areas.