Influence of reagent addition on carbodiimide-mediated amidation for poly(ethylene glycol) grafting
Influence of reagent addition on carbodiimide-mediated amidation for poly(ethylene glycol) grafting
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DOI：
10.1002/app.10549
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发表时间：
2002-08-08
影响因子：
3
通讯作者：
Magoshi, J
中科院分区：
文献类型：
--
作者：
Araki, J;Kuga, S;Magoshi, J
聚（乙二醇）是一种化学稳定的惰性聚合物，可溶于水和许多有机溶剂，1，2因此可用于胶体颗粒（包括生物聚合物）的化学改性。3-6用于此目的的最广泛使用的方法是二甲酰亚胺介导的酰胺结合，7特别是通过1-乙基-3-二甲基氨基丙基碳二亚胺（EDC）。Danishefsky等人描述了一种典型的方法，8谁把它应用到粘多糖。他们的反应条件（即在pH 4.75下混合羧基、胺和碳二亚胺）在许多研究中进行了研究5、9、10;一些报告声称成功形成了酰胺键，5、8，而另一些报告则报告了酰胺形成失败。9，10我们在纤维素空间稳定化方面的经验6也导致在Danishefsky条件下很少形成酰胺。最近，发现使用N-羟基琥珀酰亚胺（NHS）磺酸盐（一种羧基活化剂）对EDC介导的酰胺形成有效。10尽管NHS用于纤维素-PEG系统是有效的，6我们发现通过改变试剂添加的顺序，接枝的效率显著变化。在本研究中，我们通过四种不同的方法制备了PEG接枝的微晶，并通过重量增加、羧基含量减少和热解气相色谱-质谱（Py-GC/MS）来评估化学结合PEG的量。
Poly (ethylene glycol) is a chemically stable and inert polymer that is soluble in water as well as in many organic solvents, 1, 2 hence its use in chemical modification of colloidal particles, including biopolymers. 3–6 The most widely used method for this purpose is carbodiimide-mediated amide binding, 7 especially by 1-ethyl-3-dimethylaminopropyl carbodiimide (EDC). A typical procedure was described by Danishefsky et al., 8 who applied it to a mucopolysaccharide. Their reaction conditions (ie, mixing carboxyls, amines, and carbodiimide under pH 4.75) were followed in many studies5, 9, 10; some reports claimed successful formation of amide linkage, 5, 8 whereas others reported failure in amide formation. 9, 10 Our experience in steric stabilization of cellulose6 also resulted in scarce amide formation under the Danishefsky’s condition.Recently, the use of N-hydroxysuccinimide (NHS) sulfonate, an activating reagent for carboxyls, was found to be effective for the EDC-mediated amide formation. 10 Although the use of NHS for the cellulose-PEG system was effective, 6 we found the efficiency of grafting varied significantly by changing the order of reagent addition. In the present study, we prepared the PEG-grafted microcrystals by four different methods and evaluated the amount of chemically bound PEG by weight increase, decrease in carboxyl content, and pyrolytic gas chromatography with mass spectrometry (Py-GC/MS).