Abstract
A series of bis-quaternary ammonium compounds, 1, 4-dialky1-1, 4-dihydroxyethylpiperadinum diiodides (DAHP, bis-QACs), was immobilized on inorganic materials (glass beads and ferrite powder) using trimethoxysilane as a coupler to prepare the immobilized antimicrobial agents. GPA-n [with alkyl chain length (n) of 8 or 12 and a carrier of glass beads] and FPA-n [n =8, 12 and a carrier of ferrite] were developed. Their antimicrobial characteristics against Escherichia coil IFO 3301 or Staphylococcus aureus IFO 12732 were then investigated, and compared with those of [3-(trimethoxysilyl) propyl] octadecyldimethylammonium chloride (TPOAC, mono-QACs) immobilized on inorganic materials. The antibacterial activity of the immobilized DAHP against E. coli IFO 3301 was 30 times higher than that of the immobilized TPOAC. GPA-12 and FPA-12 had a higher antimicrobial activity than GPA-8 and FPA-8, and exhibited wide spectra of antibacterial activity against six strains of gram-negative and five strains of gram-positive bacteria. The antibacterial activity was hardly influenced by environmentalpH but was significantly affected by temperature. A concomitant substance, peptone, had a distinct effect on the antibacterial activity of GPA-12 and FPA-12.
