Optimization of ferromagnetic nanoparticles capture and concentration of Salmonella sp. from food samples

The aim of this study was to synthesize the amino-functionalized ferromagnetic nanoparticle (FMNs) by polyol method using polyol technique, surface modified with glutaraldehyde and monoclonal antibodies against Salmonella Typhimurium. The Ab-FMNs-Salmonella cells at different concentrations were evaluated using plating on XLD agar and FTIR techniques. FTIR unique peak(s) were identified to express presence of S. Typhimurium particles complex. In this experiment, the optimal proportions of each step were carried out. The selected condition was applied in the capturing and detection of S. Typhimurium in pure form and in spiked chicken samples. Limits of detection and inclusivity/exclusivity tests were also tested. It was found that Synthesized FMNs nanoparticle under oxygen - free condition and medium heat treatment in autoclave at 121 ˚C, 3 cycle 120 min for cycle were achieved. The average size of FMNs was about 50 nm. The surface of FMNs modified with Glutaraldehyde then conjugated with antibodies against S. Typhimurium was successful. Optimal FMNs particles to antibodies ratio was 1:32 where the highest %capture was 77.9% compared to other dilution levels (1:2 to 1:16). The FMNs concentration of 20 μl/ml was used for capturing S. Typhimurium was 1,000 μl. Limits of detection of Ab-FMNs for capturing S. Typhimurium were 10² CFU/ml with pure culture and 10³ CFU/ml in spiked chicken samples. Cross re-activities were not found in the inclusive/exclusive tests of target and non-target strains. The Ab-FMNs particles capture S. Typhimurium showed unique FTIR peak at wave number 2544.96 cm-1. Results of Ab-FMN-S. Typhimurium identification using unique peak comparison were consistent with that of the spread plate technique. The FTIR Ab-FMNs are promising for detection of Salmonella sp. This research shows that Ab-FMNs particles were powerful and efficient for capture, concentration and identify S. Typhimurium.