Development of CoFe2O4/SWCNT modified gold nanoparticle coated LAMP incorporated electrochemical DNA biosensor for Salmonella in contaminated water filtered samples

Abstract

Salmonella is a food, water, and soil-contaminating pathogen that is a major cause of foodborne infections worldwide. An efficient, effective, and reliable method for early monitoring of Salmonella is undoubtedly required. Even though there are established traditional methods, such as real-time polymerase chain reaction and culture plate, they require expensive laboratory equipment, trained personnel, and time-consuming processes. In this study, Salmonella was concentrated from contaminated water samples and its DNA was isolated by a developed DNA extraction method, which is reported in the literature for the first time. Loop-mediated isothermal amplification technique was incorporated into the process to amplify even the low concentrations of DNA. Methylene blue tethered, thiol functionalized, and specifically designed DNA probe was utilized as a biorecognition element. The cobalt/ferrite nanoparticles were in-situ synthesized on single wall carbon nanotubes (SWCNTs) by hydrothermal reaction and functionalized with TEOS and APTES, respectively. The nanocomposite material-modified electrodes were further modified with gold electrodeposition. The DNA biosensor system could distinguish full complementary DNA from 2-mismatch, 4-mismatch, and non-complementary DNA successfully. Moreover, the DNA biosensor system could also detect both genomic DNA and LAMP products, while it was not detected in colorimetric or gel electrophoresis methods. The developed sensor has a linear range between 1x10-15 to 1x10-6 M with a limit of detection of 0.234 x 10-15 M for complementary DNA sequences.