Nanosilver/hyperbranched polyester (HBPE): synthesis, characterization, and antibacterial activity

HBPE of different generations were synthesized using 4-hydroxybenzoic acid and 2,2',2aEuro(3)-nitrilotriethanol via the A(2) + B-3 method. The reaction was carried out in a dry nitrogen atmosphere using p-toluene sulfonic acid (p-TSA) as an acid catalyst. The chosen molar ratios of 2,2',2aEuro(3)-nitrilotriethanol to 4-hydroxybenzoic acid were 1:3, 1:6, and 1:21 for the G(1), G(2), and G(5) generations, respectively. The G(5) stage of HBPE was further coupled with acrylic acid to modify the terminal hydroxyl groups. The resulting products were analyzed using H-1 NMR, C-13 NMR, FTIR spectroscopy, and GPC. Silver nanoparticles were prepared by a reductive technique using HBPEs of the G(5) generation as the matrix. XRD and TEM analysis indicated the formation of highly spherical and stable nanosilver in the HBPE. The antibacterial activity of the nanosilver/HBPE was evaluated against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria.