Novel Biosensor Based on Electrospun Nanofiber and Magnetic Nanoparticles for the Detection of E. coli O157:H7

A lateral-flow immunobiosensor is developed based on electrospun nanofibers and conductive magnetic nanoparticles (MNPs) for rapid detection of Escherichia coli O157:H7 bacteria. The magnetic nanoparticles are bioconjugated with antibody specific to E. coli O157:H7 to act as immunomagnetic separator to extract and purify the target from the sample solution. The cellulose nitrate nanofibers are synthesized using electrospinning technique to form unwoven biocompatible membrane with optimized nanoporous structure and excellent capillary properties. The nanofibrous membrane is biochemically functionalized with E. coli antibody to act as biosensor capture pad. Due to high surface area and unique nanostructure, the conductive pathogen/nanoparticle complex in the purified solution is effectively captured on the nanofiber membrane by antibody-antigen binding. The unbound nanoparticles and impurities are absorbed in the following cellulose membrane by capillary action. When the flow equilibrium is achieved, the resistance signal of the electrospun membrane is measured by a portable sensing platform, which indicates the pathogen concentration in the sample solution. This novel biosensor was capable to detect E. coli O157:H7 bacteria as low as 67 CFU/mL in a total detection time of 8 min. The test results demonstrate linear sensing response range of 10 ¹ -10 ⁴ CFU/mL, which is higher than that using nitrocellulose porous membrane under the same analytical conditions. This sensitive and low-cost biosensor fabricated using electrospun technology is fast and reliable, which can be used for on-field biodefense and food and water safety applications.