Label-free and ultra-low level detection of salmonella enterica serovar typhimurium using electrochemical impedance spectroscopy

An immunosensor for rapid and low level detection of the bacterial pathogen Salmonella enterica Serovar Typhimurium was designed and developed based upon label-free electrochemical impedance spectroscopy and correlated to viable cell counts. The immunosensor was fabricated by electroplating gold onto a disposable printed circuit board (PCB) electrode by immobilizing monoclonal antibody (MAb) specific against Salmonella typhimurium cell surface lipopolysaccharide (LPS) onto the surface of the electrode. Use of mass-fabricated and electroplated PCB electrodes allowed for disposable, highly sensitive, and rapid detection of Salmonella in an aqueous environment. Results demonstrate that in purified solution, Salmonella can be detected as low as 10 CFU in a 100 mL volume and label-free and rapid manner in fewer than 90 s. The cost effective approach described here can be used for detection of pathogens with relevance for healthcare, food, and environmental applications.