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Xanthan gum has been modified by carboxymethylation to hamper its slow dissolution and then grafted with 4-vinyl pyridine (4-VP) in the aqueous phase using potassium persulphate (KPS) as an initiator aiming to obtain new biopolymer-synthetic hybrid materials with desirable Physico-chemical properties and antimicrobial activity. The influence of reaction parameters on grafting yield (G), grafting efficiency (GE), and homopolymer (H) percentage was investigated.
Maximum %G and low %H were obtained at concentrations of 1 mol L-1 4VP and 12 × 10-2 KPS, respectively. The optimum temperature and reaction period were 60 °C and 120 (min.), respectively. FTIR, XRD, TGA and SEM techniques were used to confirm the structure, morphology and thermal stability of the prepared copolymers. TGA revealed that the CMX-g-P4VP is thermally more stable than the neat CMX. The influence of P4VP content in the copolymers and pH of the aqueous media on the swelling capacity was examined and the results revealed that swellability increased with the increasing P4VP content. The highest swelling capacity was achieved at pH = 2.5 and %G of 420 % reaching 7300 %. The antimicrobial activity of the grafted copolymer was investigated against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as Gram-negative and Gram-positive bacteria, respectively, in addition, Candida albicans (C. albicans) as fungus. The effect of P4VP content in the copolymers on the minimum inhibitory concentration (MIC) was evaluated and the results showed that the graft copolymer exhibited better biological activity compared with neat CMX and the MIC values decreased with increasing the P4VP content. Additionally, cytotoxicity of the graft copolymer was estimated against normal lung cell lines and found to be non-toxic and exhibiting IC50 > 500 µg/mL
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•Successful synthesis of carboxymethyl xanthan-graft- poly(4-vinyl pyridine).•Optimization of reaction condition on grafting %.•Elucidation of the copolymer structure via various analysis techniques.•Synthesized copolymers showed pH-dependent swelling behavior.•Compared to xanthan, the copolymers exhibited better antimicrobial activity.•Cytotoxicity assay showed excellent biocompatible property for grafted sample.