Tehran University Medical Journal

Background: Nano scale dendrimers are macromolecules synthetic which frequently used in medical and health field. Because traditional antibiotics inevitably induce bacterial resistance, which is responsible for many treatment failures, there is an urgent need to develop novel antibiotic drugs. This study was aimed to examine Synthesis and the antibacterial effect of NanoPolyamidoamine-G7 (NPAMAM-G7) dendrimer on Escherichia Coli, Proteus Mirabilis, Salmonella Typhi, Bacillus Subtilis and Staphylococcus Aureus.

Methods: In this experimental study that has been conducted in June 2015 in the Laboratory of Microbiology, Iran University of Medical Science, NPAMAM-G7 dendrimers was synthesized by Tomalia’s divergent growth approach. The antibacterial effects of NPAMAM-G7 dendrimer were studied by disc diffusion and micro-dilution method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against gram-positive and gram-negative bacteria were determined according to Clinical and Laboratory Standards Institute (CLSI) guideline. Standard discs were prepared using different concentrations of dendrimer on Mueller-Hinton agar plates.

Results: Zone of inhibition in concentration 25 μg/ml of NPAMAM-G7 dendrimers for Escherichia Coli, Proteus Mirabilis, Salmonella Typhi, Bacillus Subtilis and Staphylococcus Aureus were 26, 38, 36, 22 and 25 mm, respectively. Regarding the zone of inhibition in gram negative bacteria with gram positive ones was P= 0.16 and was not significant difference. The MIC for Salmonella Typhi was 0.025, for Proteus Mirabilis, Bacillus Subtilis, Staphylococcus Aureus and Escherichia Coli was 0.25 μg/ml. The MBC for Salmonella Typhi was 25μg/ml, for Proteus Mirabilis and Bacillus Subtilis was 50 μg/ml and for Escherichia Coli and Staphylococcus Aureus was 100 μg/ml. The least of sensitivity against NPAMAM-G7 related to Escherichia Coli and Staphylococcus Aureus and the most of sensitivity related to Salmonella Typhi.

Conclusion: The NPAMAM-G7 dendrimer with end amine groups exhibited a positive impact on the removal of standard strains, gram-positive and gram-negative bacteria. Therefore, it is possible to use these nanodendrimers as antibacterial in the future.

Background: Poly(amidoamine) (PAMAM) dendrimer derivatives have been investigated for their biological applications, especially for delivery of drugs, including antimicrobial drugs to eukaryotic cells, but their effects on bacterial cells are largely unexplored. Nanotechnology and its application is one of the rapidly developing sciences. As demand of fresh drinking water is increasing, nanotechnology can contribute noticeable development and improvement to water treatment process. This study was aimed to examine synthesis and the antibacterial effect of Nanopolyamidoamine-G7 (NPAMAM-G7) dendrimer on Escherichia Coli (E. Coli), Klebsiella Oxytoca (K. Oxytoca), Pseudomonas Aeruginosa (P. Aeruginosa), Proteus Mirabilis (P. Mirabilis) and Staphylococcus Aureus (S. Aureus) from aqueous solution.
Methods: In this experimental study that has been conducted in August to December 2015 in the laboratory of microbiology of Iran University of Medical Sciences, initially dilution of 103 CFU/ml were prepared from each strain of bacteria. Then different concentrations of dendrimer (0.025, 0.25, 2.5 and 25 µg/ml) in the laboratory 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, 40, 50 and 60 min) and were cultured on nutrient agar medium. Samples were incubated for 24 hours at 37 °C and then number of colonies were counted.
Results: Antibacterial properties of dendrimers in aqueous solution by increasing the dendrimer concentration and contact time is directly related. At a concentration of 25 μg/ml at 60 minutes all bacteria except S. Aureus, and at 30 minutes, E. Coli and K. Oxytoca bacteria for 100% excluded. The concentration of 2.5 μg/ml at 60 minutes of bacteria, E. Coli, K. Oxytoca and P. Mirabilis are 100% excluded. All concentrations of dendrimers at different times were reduced bacteria in the PAMAM- G7 dendrimer effect on gram-negative bacteria, gram-positive bacteria was better.
Conclusion: The NPAMAM-G7 dendrimer with end amine groups exhibited a positive impact on the removal of standard strains, gram-positive and gram-negative bacteria. Therefore, it is possible to use these nanodendrimers as antibacterial in the future.