Simple disposable microfluidic device for Salmonella typhimurium detection by magneto-immunoassay

Herein, we describe the construction of a simple, low-cost, and fully disposable microfluidic device (D mu FD) for ultrasensitive Salmonella typhimurium (S.typhi) detection. The D mu FD is based on unmodified carbon electrode array for rapid detection of S. typhi in milk samples by magneto-immunoassay using gold nanoparticles (AuNPs) as a label. In the method proposed, S. typhi was magnetically captured and separated from samples using magnetic beads modified with a monoclonal anti-Salmonella antibody followed by the addition of polyclonal anti-Salmonella antibody labeling with AuNPs. The magneto-immunoconjugate formed was injected into the D mu FD and captured on the electrode surface by placing magnets behind the unmodified working electrodes. The S. typhi detection was carried out by the electrochemical response of the gold from AuNPs. A single D mu FD was used for rapid and full S. typhi analysis by measuring standards and samples simultaneously. A low limit of detection (LOD) of 7.7 cells mL(-1) for S. typhi in a linear range from 10.0 to 100.0 cells mL(-1) was obtained. The D FD proved to be fast, accurate, and inexpensive for S. typhi detection and has great potential to multiplex detection of different food contaminants. (C) 2017 Elsevier B.V. All rights reserved.