High demand for food and water means new water reuse programs are being explored; however, these sources could contain contaminants such as Escherichia coli spp., and consequently pose risks to public health. Here, we demonstrate a sensing mechanism for rapid, label-free detection of Escherichia coli spp. in real environmental samples using temperature-responsiveness of poly(N-isopropylacrylmide) (PNIPAAm) brushes. Sensors were fabricated based on a carbon-metal nanohybrid platform as the transducer layer with PNIPAAm brushes. Concanavalin A (ConA) or Anti-GroEL antibody were used as biorecognition agents. PNIPAAm actuation was tested and results revealed that 20 °C and 40 °C were the ideal temperatures for capturing and sensing bacteria, respectively. Actuation results show that PNIPAAm brushes in sensing can have numerous advantages, including enhanced target microorganisms capture, increased biorecognition agent loading, and increased electron transfer. PNIPAAm brushes sensor functionalized with ConA yielded a limit of detection of 6.5 ± 1.3 CFU mL-1 in PBS. ConA specificity to E. coli was tested in PBS with Salmonella Enteritidis and performance parameters were found to be similar (p > 0.05) to those with E. coli only. Response time for all sensors included 15 min for bacteria capture and 2 min to run the Electrochemical Impedance Spectroscopy. This study showed that there is great promise to use PNIPAAm brushes and carbon-metal nanostructure-based biosensors for on-farm water management, enabling farmers that do not have access to a nearby analytical lab to meet the Food Safety Modernization Act requirements for testing water quality within eight hours of sampling.
Cassie A. Giacobassi
Texas A&M University
Daniela A. Oliveira
Texas A&M University
Univeristy of Florida
Eric S. McLamore, Assistant Professor
Department of Architecture
University of Florida
Carmen Gomes, Associate Professor
Department of Mechanical Engineering
Iowa State University
This event is supported by the National Science Foundation, Award #1929601. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.