Study On The Synthesis And Properties Of Alkali Amine Antibacterial Materials

In recent years, microbial threats to human health and safety have become aserious public problem. Antibacterial materials that can effectively inhibit the growthof microorganisms have attracted significant research interests. Antibacterial materialshave been widely used in building material, resin, fiber, paper, rubber, paint, wood,clothing, medical treatment, water treatment, daily necessity, plastic, food packaging,sterilization of hygienic areas etc. To date, quaternary ammonium salts, quaternaryphosphonium salts, inorganic metal ions, N-halamines, etc., have been used in thedevelopment of antibacterial materials. Among them, N-halamine antibacterialmaterials have received intensive interest because of their unique properties, such aspowerful antibacterial efficacy, good stability in aqueous solution and in dry storage,safety to humans, and excellent regenerability. In this paper, three polymericN-halamine antibacterial materials were synthesized, and their antibacteiral eiffcacieswere deeply studied.(1) Synthesis, characterization, and antibacterial activity of polymeric N-halaminesnanoparticlesA series of poly (styrene-co-acrylate acid) nanoparticles(PSA NPs) weresynthesized by a copolymerization between styrene (St) and acrylic acid (AA) withdifferent St/AA mass ratios. The as-synthesized PSA NPs were characteirzed by fieldemission scanning electron microscopy (FE-SEM). It was found that St/AA mass ratiohas a dramatic impact on the morphology of PSA NPs. In order to get dispersive PSANPs with lower St/AA mass ratio, so relatively more carboxylic groups which can befinally transferred to N-halmine groups exist in PSA NPs, we chose a2:1St/AA massratio to synthesize PSA NPs. Then, the carboxylic groups (-COOH) in PSA NPs weretransferred to amide ones by an amination with tert-butylamine to form PSA-NH NPs.Finally, the amide groups in PSA-NH were transferred to antibacteiral N-halaminefunctional groups by exposure to a dilute sodium hypochlorite solution to form thetarget PSA-N-C1NPs. The as-prepared PSA-N-C1NPs were characterized by ifeldemission scanning electron microscopy (FE-SEM), specific surface area (BET), X-ray photoelectron spectra (XPS), and Fourier Transform infrared spectroscopy (FTIR).The antimicrobial activity of PSA-N-C1NPs was studied through the minimuminhibitory concentrations (MIC), the minimum bactericidal concentration (MBC), andthe effect of the contact time on the growth of Escherichia coli {E. coif) andStaphylococcus aureus (S. aureus). Antimicrobial tests showed that the as-preparedPSA-N-C1NPs possess powerful antimicrobial activity against both E. coli and S.aureus. MIC values of PSA-N-C1NPs against E. coli and S. aureus are5.00and10.00fxg/mL，respectively. Meanwhile,10)ig/mL PSA-N-C1NPs can completely kill E. coli(77.1x10CFU/mL) within90min，and the fractional survival rate of S.aureus(\.6x\07CFU/mL) is13.33%in120min. The results demonstrate thatPSA-N-C1NPs have higher antimicrobial activity against E. coli (gram-negative) thanS. aureus (gram-positive). The storage stability test indicated that PSA-N-C1NPs arevery stable under common storage conditions.(2)Synthesis, characterization, and antibacterial activity of polymeric N-halaminemagnetic nanoparticlesPolymeric N-halamine magnetic nanoparticles(PSA-N-Cl@Fe304NPs) wereprepared, and were characterized by a variety of testing methods. Antibacterial testsshowed that Fe304NPs, PSA@Fe3〇4NPs, and PSA-NH@Fe3〇4NPs have noinhibitory effect against E. coli and S. aureus. However, the as-preparedPSA-N-Cl@Fe304NPs have strong antibacteiral activity. MIC values ofPSA-N-Cl@Fe3C>4NPs against E. coli and S. aureus are15|xg/mL, and their MBCvalues against E. coli and S. aureus are20.00(ig/mL.15|ig/mL of the as-preparedPSA-N-Cl@Fe304NPs can completely kill E.coli (4.3x107CFU/mL) and S. aureus(17.9><10CFU/mL) within150and180min, respectively. The results demonstrate thatPSA-N-Cl@Fe3C>4NPs have higher antimicrobial activity against E, coli than S.aureus. Also, PSA-N-Cl@Fe3〇4NPs can be separated readily by the aid of anexternal magnetic field.(3)Synthesis, characterization, and antibacterial activity of macroporous crosslinkedN-halamine polymeric resinThe macroporous crossl inked PSA resin was synthesized via the suspension copolymerization of St and AA. In the copolymerization process, divinylbenzene wasadded as the crosslinking agent. By adjusting the ratio of AA and St, the ratio of waterphase to oil phase, and the amount of porogen, we achieved spheric macroporouscrosslinked PSA resin with a uniform morphology. Macroporous crosslinked PSA-NHresin was obtained by an amination reaction between PSA and t-Bu-NH〗. Finally, themacroporous crosslinked N-halamine polymeric resin, PSA-N-C1resin was achievedby a chlorination of amide functional groups in PSA-NH resin. BET analysis showedthat PSA-N-C1resin has a large surface area which can provide more N-halaminefunctional sites to contact the bacteria. The antibacterial results showed thatMacroporous crosslinked N-halamines PSA-N-C1has excellent antibacterial efficacyand can completely kill E.coli (8.9x107CFU/mL) and S. aureus (6.5X107CFU/mL)within lmin and3min, respectively.