Two Schiff base derivatives, 4-[(2, 5-dimethoxy phenylimino)-methyl] phenol, SB1 and 4-[(2-hydroxy benzylidine)-amino] phenolSB2, have been prepared and used as modifiers for polyvinyl chloride (PVC). Chemical modification of PVC was performed using these Schiff base sin presence ofAgNO3to obtain two modified PVC nanocomposite,PVC-SB1/AgNPs and PVC-SB2/AgNPs, and their chemical structures were confirmed by FTIR, 1 H-NMR, 13 C NMR and Mass spectroscopy. Scanning and transmission electron microscopy were performed for the modified polymer nanocomposites. The SEM and TEM micrographs of PVC-SB/AgNPs showed homogeneous surface polymeric matrix with uniform distribution of AgNPs, and their diameters are in the nanoscale. Moreover, thermal and photostabilities as well as mechanical properties of the modified polymer nanocomposites were also investigated. Moreover, mechanical properties of PVC-SB/AgNPs were also investigated. Antimicrobial activity of the modified PVC was evaluated against two Gram +ve bacteria (Bacillus subtitles and Staphylococcus aurous) and two Gram -ve bacteria (Escherichia coli and Pseudomonas aeruginosa) as well as Candida albicans as fungus.

Food safety is a worldwide health goal so foodborne diseases are a main health concern. A total 150 of dairy products samples (locally made yoghurt, ice cream and Talaga cheese) (50 for each type) were examined for E.coli O157:H7 detection and PCR confirmation using fliCH7 gene. E. coli O157:H7 was detected at 18%, 4%, 8% respectively, in samples. The isolates showed broad antibiotic resistance against vancomycin (84.6%), penicillin G (76.9%), cloxacillin (69.2%) and tetracycline (61.5%). Because of increasing number of microorganisms that are resistant to multiple antibiotics causing continuing economic losses in dairy manufacturing, there is an urgent need for development of alternative, cost-effective, and efficient antimicrobial agents to overcome antimicrobial resistance. Here, silver nanoparticle (AgNPs) solution was prepared, identified by transmission electron microscopy (TEM) with an average size 26.5 nm and examined for bactericidal activity against E. coli O157:H7 by using well diffusion assay. The mean inhibition zones of 25 and 50 µg/ml concentrations of Ag-NPs were 15.0±1.2 and 20.9±1.4 mm, respectively. In addition, the statistical analysis showed highly significant differences in the bactericidal effect of different Ag-NPs concentrations on E. coli O157:H7 strains. Bacterial sensitivity to nanoparticles is a key factor in manufacture, so nanoparticles were considered suitable for long life application in food packaging and food safety.

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