Synthesis and Antibacterial Performance of Functional Organic–Inorganic Silica Nanocomposites Based on Novel Zwitterionic Polymer

Nano-sized silica particles (SiO 2 NPs) of 30 ± 5 nm were modified by the coupling agent of triethoxyvinylsilane and polymer 4-vinyl pyridine (P4VP) was “grafted” onto the surface of modified SiO 2 NPs by adopting the “grafting from” way. Then, the P4VP brush of SiO 2 NPs was quaternized by ethyl bromoacetate, iodoethane, 3-bromopropionic acid and 1,3-propanesulfonate to obtain four water-insoluble, functional and novel organic–inorganic silica nanocomposites (SiO 2 /P4VP-eb, SiO 2 /P4VP-ie, SiO 2 /P4VP-bpa and SiO 2 /P4VP-psl), respectively. The antibacterial performance of four functional silica nanocomposites above was investigated by using Escherichia coli ATTC25922 as model bacterium via the colony count method. When the sterilizing ratios of SiO 2 /P4VP-psl, SiO 2 /P4VP-bpa, SiO 2 /P4VP-eb and SiO 2 /P4VP-ie against E. coli with bacterium age of 4 h (OD600 nm = 2.5) reached 100%, the critical concentration value was 3, 5, 12 and 11 mg/mL, respectively. The results showed that although four functional silica nanocomposites all possessed excellent antibacterial ability, zwitterionic silica nanocomposites (SiO 2 /P4VP-psl, SiO 2 /P4VP-bpa) possessed stronger antibacterial ability than cationic silica nanocomposites (SiO 2 /P4VP-eb, SiO 2 /P4VP-ie). Graphical Abstract