Synthesis of halogenated nanodendrimer as novel antimicrobial agents in water treatment

Abstract

Microbiological quality of drinking water is an important aspect of water quality. The aim of this research work was to fabricate and modify G2 and G4 dendrimers as novel antibacterial agent for local application. Poly(amidoamine) (PAMAM) (G 2 and G 4) dendrimers were fabricated and modified into quaternary ammonium salts using halogens groups (Cl, Br, I), and characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), and dynamic light scattering (DLS) analysis. The results of these analysis proved that nanostructure dendrimer and their quaternary ammonium salts are well fabricated. For evaluation of the antimicrobial property, the water samples were collected from rural drinking water resources, and the bacteria isolated and identified from these samples were Escherichia coli, Klebsiella oxytoca, Bacillus subtilis, and Staphylococcus aureus. The antimicrobial activities of PAMAM dendrimers (G 2 and G 4) and modified PAMAM dendrimers (G 2 Cl, G 2 Br, G 2 I, G 4 Cl, G 4 Br, and G 4 I) against gram-positive and gram-negative bacteria were examined by calculating minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and disc diffusion methods. Quaternary ammonium salts exhibited more antimicrobial efficacy against bacteria compared with unmodified ones. The most antibacterial effect was obtained by G 4 I with MIC: 52, 50, 55, and 57 μg/ml, and MBC: 64, 67, 71, and 75 μg/ml for Staphylococcus aureus, Bacillus subtilis, Klebsiella oxytoca, and Escherichia coli, respectively. The disc diffusion test of G 4 I (60 μM) on different bacteria showed inhibition zone diameters of 31, 28, 26, and 25 ml for Staphylococcus aureus, Bacillus subtilis, Klebsiella oxytoca, and Escherichia coli, respectively.