Background: Dendrimers are macromolecules with regular three-dimensional structure that have many branches. The aim of this study was to investigate the fficiency of Nano Polyamidoamine–G5 (NPAMAM-G5) dendrimers in removal of Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa, Proteus mirabilis and Staphylococcus aureus from aqueous solution.

Materials and Methods: In this experimental study, initially, dilution of 10³ CFU/ml was prepared from each strain of bacteria. Then, different concentrations of dendrimers (0.025, 0.25, 2.5 and 25 µg/ml) in the ambient temperature (23-25°C) was added to water. In order to determine the efficiency of dendrimers in removal of bacteria, samples were taken at different times (0, 10, 20, 30, 50 and 60 min) and were cultured on nutrient agar medium. Samples were incubated for 24 hours at 37 ° C and then the number of colonies was counted.

Results: There is a direct relation between antibacterial properties of dendrimers in aqueous solution and increasing the dendrimer concentration and contact time. At a concentration of 25 μg/ml and 60 minutes, all kinds of bacteria except Staphylococcus aureus, and at 30 minutes, E. coli and Klebsiella bacteria, were removed by 100% The concentration of 2.5 μg/ml at 60 minutes of  bacteria, Escherichia coli, Klebsiella and Proteus mirabilis, 100% Were removed. All concentrations of dendrimer at different times were reduced bacteria.

Conclusion: Results of this study indicated that NPAMAM–G5 dendrimer is able to remove Escherichia coli, Klebsiella oxytoca, Pseudomonas aeruginosa, Proteus mirabilis and Staphylococcus aureus from aqueous solution.