Sulfonamide based pH-sensitive polymeric micelles: physicochemical characteristics and pH-dependent aggregation
Sulfonamide based pH-sensitive polymeric micelles: physicochemical characteristics and pH-dependent aggregation
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DOI：
10.1016/s0927-7757(02)00389-8
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发表时间：
2003-03-12
影响因子：
5.2
通讯作者：
Bae, YH
中科院分区：
文献类型：
--
作者：
Han, SK;Na, K;Bae, YH
研究了由聚l -丙交酯(PLLA)/聚乙二醇（PEG）嵌段共聚物组成的聚合物胶束，其末端用一种新的pH敏感元素磺胺，磺胺二甲氧嘧啶（SD; pKa 6.1）或其衍生物的聚合物（PSD; Mw: 3000）修饰。以2-氨基乙硫醇为链转移剂，通过乙烯化SD （SD单体；SDM）自由基聚合合成了PSD。将SD或PSD偶联至羧基PEG (Mw = 2000)/PLLA （Mw = 3500）嵌段共聚物。采用滤除法制备了聚合物胶束，并用动态光散射（DLS）和荧光光谱对其在水介质中的物理化学性质进行了表征。所有样品的平均直径均小于60 nm，尺寸呈单峰分布。硼酸盐缓冲液（pH 9.0）中PLLA/PEG-PSD胶束在一个疏水区域的临界胶束浓度（CMC）和平均聚块数略高于PLLA/PEG和PLLA/PEG- sd胶束，这是由于PSD电离后亲水性增强所致。通过测量ph依赖的溶液浊度和胶束聚集体的大小来检查ph敏感性。PLLA/PEG-PSD胶束在pH 7.0以下由于SDM的去离子化而聚集，而其他胶束则保持稳定。本研究中制备的聚合物胶束对生理pH值附近的pH值变化有明显的反应。(C) 2002 Elsevier Science B.V.版权所有。
Polymeric micelles composed of block copolymers of poly(L-lactide) (PLLA)/poly(ethylene glycol) (PEG) of which end was modified with a novel pH sensitive element of a sulfonamide, sulfadimethoxine (SD; pKa 6.1), or a polymer (PSD; Mw: 3000) of its derivative were investigated. PSD was synthesized by radical polymerization of a vinylated SD (SD monomer; SDM) using 2-aminoethanethiol as a chain transfer agent. SD or PSD was coupled to carboxylic PEG (Mw = 2000)/PLLA (Mw = 3500) block copolymer. The polymeric micelles were prepared by a diafiltration method and their physicochemical properties in aqueous media were characterized by dynamic light scattering (DLS) and fluorescence spectroscopy. The mean diameter of all samples was smaller than 60 nm with a unimodal size distribution. The critical micelle concentration (CMC) and mean aggregation number of PLLA block in one hydrophobic domain of PLLA/PEG-PSD micelle in borate buffer (pH 9.0) were slightly higher than those of PLLA/PEG and PLLA/PEG-SD micelles due to the enhanced hydrophilic nature of PSD when ionized. The pH-sensitive properties were examined by the measurement of pH-dependent solution turbidity and the size of micellar aggregates. The PLLA/PEG-PSD micelle aggregated below pH 7.0 due to deionized SDM on the surface, while the other micelles were stable. The polymeric micelle prepared in this study sharply responded to the change in pH around the physiological pH. (C) 2002 Elsevier Science B.V. All rights reserved.