Molecular weight and pH effects of aminoethyl modified chitosan on antibacterial activity in vitro.
Molecular weight and pH effects of aminoethyl modified chitosan on antibacterial activity in vitro.
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DOI：
10.1016/j.ijbiomac.2012.01.018
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发表时间：
2012-05
影响因子：
8.2
通讯作者：
Xiangtao Meng;R. Xing;Song Liu;Huahua Yu;Kecheng Li;Yukun Qin;Pengcheng Li
中科院分区：
文献类型：
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作者：
Xiangtao Meng;R. Xing;Song Liu;Huahua Yu;Kecheng Li;Yukun Qin;Pengcheng Li
通过在不同分子量的壳聚糖和壳寡糖上接枝氨基乙基，合成了不同分子量的氨基乙基改性壳聚糖衍生物（AEMCSs）。FTIR、1H NMR、13C NMR、元素分析和电位滴定结果表明，合成了支化聚乙烯亚胺壳聚糖。采用美国临床实验室标准协会（CLSI）的方案测定了不同ph值下革兰氏阴性大肠杆菌菌株的MIC，与原始壳聚糖相比，衍生物的抑菌活性显著提高，其对大肠杆菌的MIC值随分子量和ph的不同而变化在4 ~ 64μg/mL之间，高分子量似乎有利于增强抑菌活性。在pH 7.4条件下，分子量大于27kDa的低聚糖壳聚糖衍生物具有相同的抗菌活性（16μg/mL），而分子量较低（~ 1.4kDa）的低聚糖壳聚糖衍生物的MIC降低了64μg/mL。pH值对抗菌活性的影响更为复杂。研究发现，在6.5左右的pH值可使HAEMCS的MIC低至4μg/mL，而较高或较低的pH值则会损害其活性。细胞完整性分析和扫描电镜图像显示明显的细胞破坏，表明膜破坏可能是抗菌活性的一种可能机制。
Aminoethyl modified chitosan derivatives (AEMCSs) with different molecular weight (Mw) were synthesized by grafting aminoethyl group on different molecular weight chitosans and chitooligosaccharide. FTIR,1H NMR,13C NMR, elemental analysis and potentiometric titration results showed that branched polyethylimine chitosan was synthesized. Clinical Laboratory Standard Institute (CLSI) protocols were used to determine MIC for Gram-negative strain of Escherichia coli under different pH. The antibacterial activity of the derivatives was significantly improved compared with original chitosans, with MIC values against E. coli varying from 4 to 64μg/mL depending on different Mw and pH. High molecular weight seems to be in favor of stronger antibacterial activity. At pH 7.4, derivatives with Mw above 27kDa exhibited equivalent antibacterial activity (16μg/mL), while oligosaccharide chitosan derivative with lower Mw (∼1.4kDa) showed decreased MIC of 64μg/mL. The effect of pH on antibacterial activity is more complicated. An optimal pH for HAEMCS was found around 6.5 to give MIC as low as 4μg/mL, while higher or lower pH compromised the activity. Cell integrity assay and SEM images showed evident cell disruption, indicating membrane disruption may be one possible mechanism for antibacterial activity.