Synthesis of ZnO nanoparticles supported on mesoporous SBA-15 with coordination effect -assist for anti-bacterial assessment

Abstract

Polyethyleneimine (PEI) was immobilized on SBA-15 for obtaining polyethyleneimine-modified silica PEI@SBA-15s (PEI@SBA-1.0, PEI@SBA-1.5, and PEI@SBA-2.0). With the coordination from PEI, zinc ions were impregnated on the PEI@SBA-15s, and then, Zn²⁺-PEI@SBA-15s were calcined at 550 ℃ to obtain the nano zinc oxide loaded on the mesoporous silica, ZnO-SBA-15s (ZnO-SBA-1.0, ZnO-SBA-1.5, and ZnO-SBA-2.0). The anti-bacterial activity of ZnO-loaded SBA-15 was; thereafter, assessed by the zone of inhibition and enzyme labeling methods. The results confirmed that the coordination ability of the imino groups in PEI helped adsorb more zinc ions during the process of impregnation so that more nano-ZnO could be supported on the surface of SBA-15. The modification did not change the mesostructure of the two-dimensional hexagonal phase and orderliness of SBA-15. At the mass ratio of PEI:SBA-15 = 1.0:1, 1.5:1, and 2.0:1, the concentration of zinc element (wt.%) was measured by inductively coupled plasma optical emission spectrometry as 2.5, 2.56, and 3.5% for ZnO-SBA-1.0, ZnO-SBA-1.5, and ZnO-SBA-2.0, respectively. The size of inhibition of SBA-15, ZnO-SBA-0, ZnO-SBA-1.0, ZnO-SBA-1.5, and ZnO-SBA-2.0 were 0, 1.14 ± 0.01, 2.56 ± 0.01, 2.58 ± 0.01, and 2.69 ± 0.02 cm, respectively. ZnO-SBA-15s suppressed the growth of Escherichia coli compared to blank SBA-15 in a ZnO dose-dependent manner.

Keywords: Anti-bacterial properties; Escherichia coli; Polyethyleneimine (PEI); SBA-15; nano-ZnO.