Novel Biocide Based on Cationic Derivative of Psyllium: Surface Modification and Antibacterial Activity
To circumvent the problems (such as volatilization, photolytic decomposition, chemical instability, easy permeability through the skin) associated with low molecular weight antimicrobial agents, our strategy employed graft copolymerization of cationic monomer with the polymeric substrate viz. psyllium husk. The surface graft concentration of quaternary ammonium ion on psyllium was optimized by measuring the extent of grafting in the microwave-induced process. The surface modification of graft copolymers was evident by different physico–chemical techniques like 13C nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffractometer (XRD), differential scanning calorimetry (DSC), Thermo gravimeteric analysis (TGA), and viscometric study. The synthesized water soluble product resulted good antibacterial activity against Gram positive Staphylococcus aureus and Bacillus anthracis but failed to produce any antibacterial activity against Gram negative Salmonella typhi and Escherichia coli. The reason to failure has been explained on the basis of differences in the electrokinetic property between Gram-positive and Gram-negative bacteria. Optimum minimum inhibitory concentration (MIC) for the polymeric grade which showed good biocidal effect evaluated by both zone of inhibition and absorbance is found at 1000 µg/ml.
KeywordsDADMAC Cationic graft copolymer Biocide Minimum inhibitory concentration
We sincerely thank Department of Science and Technology (DST), India, for providing the research Grant (Sanction Order No. SR/WOS-A/ET-13/2014). We are grateful to CIF-BIT, Mesra and Department of Botany, The University of Burdwan for their kind support. Aparna Banerjee is thankful for the financial assistance from the SRF (State Funded) [Fc (Sc.)/RS/SF/BOT./2014-15/103(3)] for the first phase of the research and to Vicerrectoría de Investigación y Posgrado (VRIP) of Universidad Católica del Maule for the Postdoctoral fellowship.
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