Surface functionalization of electrospun nanofibers for detecting E. coli O157:H7 and BVDV cells in a direct-charge transfer biosensor

Electrospinning is a versatile and cost effective method to fabricate biocompatible nanofibrous materials. The novel nanostructure significantly increases the surface area and mass transfer rate, which improves the biochemical binding effect and sensor signal to noise ratio. This paper presents the electrospinning method of nitrocellulose nanofibrous membrane and its antibody functionalization for application of bacterial and viral pathogen detection. The capillary action of the nanofibrous membrane is further enhanced using oxygen plasma treatment. An electrospun biosensor is designed based on capillary separation and conductometric immunoassay. The silver electrode is fabricated using spray deposition method which is non-invasive for the electrospun nanofibers. The surface functionalization and sensor assembly process retain the unique fiber morphology. The antibody attachment and pathogen binding effect is verified using the confocal laser scanning microscope (CLSM) and scanning electronic microscope (SEM). The electrospun biosensor exhibits linear response to both microbial samples, Escherichia coli O157:H7 and bovine viral diarrhea virus (BVDV) sample. The detection time of the biosensor is 8 min, and the detection limit is 61 CFU/mL and 103 CCID/mL for bacterial and viral samples, respectively. With the advantage of efficient antibody functionalization, excellent capillary capability, and relatively low cost, the electrospinning process and surface functionalization method can be implemented to produce nanofibrous capture membrane for different immuno-detection applications.