Preparation and antibacterial character of a water-insoluble antibacterial material of grafting polyvinylpyridinium on silica gel

Micron-sized silica gel particles were modified with the coupling agent of 3-methacryloylpropyl trimethoxysilane (MPS), then the copolymer of 4-vinyl pyridine and acrylamide (P (4VP-co-AM), PVA) was grafted onto the surface of modified silica gel particles by adopting the “grafting from” way, and the grafted particles PVA/SiO2 were obtained. Finally, PVA on the particles PVA/SiO2 were quaternarized by using benzyl chloride or dimethyl sulfate as quaternization reagents, and a kind of water-insoluble antibacterial material QPVA/SiO2 with pyridinium-type was prepared. In this paper, the antibacterial property of QPVA/SiO2 was mainly investigated by using Escherichia coli (E. coli) as model bacterium and by the colony count method, the effects of the grafting degree of pyridinium and the variety of quaternization reagents on the antibacterial property of QPVA/SiO2were examined, and the antibacterial mechanism of QPVA/SiO2 was explored using the method of measuring the activities of β-d-galactosidase and TTC-dehydrogenase. The experiment results show that QPVA/SiO2 possesses strong antibacterial ability, and the antibacterial ratio of QPVA/SiO2 with 2.3 mmol/g of grafting degree of pyridinium can reach 100% for bacterium suspension of 109 CFU/mL with the dosage of 20 g/L and for 10 min of contact time. The greater the grafting degree of pyridinium is, the stronger the antibacterial ability, and the antibacterial property of the QPVA/SiO2 prepared using benzyl chloride as quaternization reagent is stronger than that of the QPVA/SiO2 prepared using dimethyl sulfate. The experimental results of two kinds of enzyme activity measurements reveal that the antibacterial effect of QPVA/SiO2 is based on a sterilization process and not only based on a restraining action.