Electrodeposition of a magnetic and redox-active chitosan film for capturing and sensing metabolic active bacteria

Abstract

Rapid and portable detection of viable pathogen is highly desired to minimize the risk of foodborne pathogen outbreaks. Here we report a proof-of-concept fabrication methodology of a multifunctional film that allows established methods from bacterial recognition (antibodies) and nanotechnology (magnetic nanoparticles) to be coupled with electrochemical signal processing methods for detection of viable bacteria. Specifically, we enlist a sequence of externally applied electrical and magnetic signals to: i) guide the self-assembly of stimuli-responsive biopolymer; ii) incorporate magnetic nanoparticles to form a magnetic layer; iii) electro-synthesize a signal processing layer (redox-capacitor). The function of the magnetic layer is collecting and concentrating MMP-bacteria through magnetic attractions between MMP-bacteria and the magnetic layer. The function of the signal processing layer is amplifying electrochemical detection of the collected bacteria by engaging the redox-active mediators with the redox capacitor. Importantly, the fabrication demonstrated here is simple, controllable, and reagentless.