季铵盐改性蒙脱土的抗菌活性及抗菌机理

采用离子交换法将不同季钱盐插层到钠基蒙脱土中制备了改性蒙脱土.改性蒙脱土对革兰氏阳性菌(S.aereus)和革兰氏阴性菌(E coli)均有很强的抗菌作用,并且随着季铵盐在蒙脱土中的质量分数增加其抗菌活性增强.不同季铵盐改性蒙脱土的抗菌活性不同,其中双季铵盐改性蒙脱土的抗菌活性最好,对S.aereus和E coli的最小抑菌浓度分别为6.25 mg/L和12.5 mg/L.用扫描电镜对与细菌接触不同时间后的改性蒙脱土进行观察,结果表明:细菌先吸附到改性蒙脱土的表面,然后慢慢的变形死亡.同时,对在0.9%的生理盐水中浸泡不同时间后的改性蒙脱土进行X射线衍射和热重分析.结果表明:随着浸泡时间的增加,蒙脱土中的有机物质量分数及层间距均逐渐减少,说明季铵盐能从蒙脱土的层间解吸出来,并进入溶液中直接杀死细菌.因而,改性蒙脱土的抗菌活性是吸附与释放到溶液中的季铵盐离子协同作用的结果.

ANTIMICROBIAL ACTIVITY AND ANTIMICROBIAL MECHANISM OF MODIFIED MONTMORILLONITE WITH QUATERNARY AMMONIUM SALTS

Sodium-montmorillonite was modified with different quaternary ammonium salts through the ion-exchange method. Through antimicrobial experiment, it is found that modified montmorillonite with different quaternary ammonium salts has excellent antimicrobial activity against gram-positive bacteria (S.aereus) and gram-negative bacteria (E.coli). The antimicrobial activities increase with the increase of the mass fraction of organic matter. Meanwhile, modified montmorillonite with bis-quaternary ammonium salts shows the best antimicrobial activity. Its minimal inhibitory concentration against S.aereus and E.coli is 6.25 mg/L and 12.5 mg/L, respectively. Modified montmorillonite after being in contact with bacteria for different time pe- riods was observed by a scanning electron microscope. The results show that the bacteria adhere to the surface of modified montmorillonite first and then they undergo slow cell-lysis. Meanwhile, the X-ray diffraction and thermogravimetric analysis of modified montmorillonite after soaking in 0.9% saline for different time were performed. The results show that interlayer spacing and mass fraction of organic matter of modified montmorillonite decrease with soaking time increasing. Namely, quaternary ammonium salts are dissociated from the interlayer of montmorillonite and directly exert an antimicrobial effect on the bacteria in suspension. Therefore, the antimicrobial activities of modified montmorillonite have a cooperative effect of surface absorption of modified montmorillonite and of releasing the quaternary ammonium salts from modified montmorillonite.