Rapid detection of pathogens by using functionalized nanoparticles coupled with antibodies provides advantages to detect bacterial pathogens in food and drinking water samples ¹. The study was aimed to develop an immuno-analytical assay to detect Salmonella by using magnetic iron oxide nanoparticles (IONPs) conjugated with the mouse anti-salmonella enteritidis LPS antibody. The IONPs were synthesized by reducing iron chloride and stabilized by using trisodium citrate. The morphophysical analysis of nanoparticles by using the TEM technique manifested that the nanoparticles are spherical and exist in the size range of 10-15 nm. A Williamson-Hall plot analysis of the XRD peaks gave a crystallite size of 9.9 nm. The magnetization of IONPs was recorded as 61 Am²kg^-1 at 1 T by performing the vibrating-sample magnetometer analysis. Magnetic iron oxide nanoparticles were carbodiimide conjugated to mouse antibody (8209-5349) by using N-Hydroxysuccinimide (NHS) and 1-Ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) at room temperature ². Size distribution analysis of IONPs, EDC-NHS associated IONPs and carbodiimide antibody conjugated nanoparticles showed the gradual increase in the hydrodynamic diameter of IONPs after their conjugation with NHS, EDC, mouse antibodies, and finally with the bacterial pathogens. A magnet was used to sequester the Salmonella conjugated immuno-functionalized nanoparticles from water samples. Confocal microscopic images of Salmonella conjugated immuno-functionalized IONPs showed the association of immuno-magnetic nanoparticles with Salmonella. The findings of the current study confirm the potential of immuno-functionalized IONPs to separate and detect Salmonella successfully from contaminated samples.

Dr Bilal Javed

Technological University Dublin

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