Poly(amidoamine) (PAA) networks that are obtained by the use of cystamine as a cross-linking agent in the reaction with 2,2'-dithiodipyridine turn into linear PAAs with dithiopyridyl side groups that easily undergo an exchange reaction with thiocholesterol. The resultant products represent the first examples of amphiphilic PAA-cholesterol conjugates in which lipophilic cholesterol moieties are linked to the hydrophilic PAA chain by S-S bonds that are stable in blood but cleavable inside cells. In aqueous media, these conjugates self-assemble into nanoaggregates whose inner cores consist of lipophilic cholesterol domains. A series of PAA-cholesterol conjugates that are derived from two different bis-acrylamides, namely 2,2-bis(acrylamido)acetic acid and 1,4-bis(acryloyl)piperazine, and that have different cholesterol contents were obtained. All products were characterized by (1)H and (13)C NMR spectroscopy, and the average molecular weights of the soluble polymers were determined by size exclusion chromatography. In all instances, the segregation of cholesterol residues from the aqueous medium was revealed by the comparison of their NMR spectra in CDCl3 and D2O, respectively. The TEM analysis of the PAA-cholesterol aggregates in aqueous buffers revealed homogeneous round nanospheres whose dimensions and dimension distributions were determined by DLS. Preliminary cytocompatibility tests demonstrated that all prepared PAA-cholesterol samples are cytocompatible and thus show potential for biotechnological applications.

中文翻译：

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具有二硫键连接的胆固醇侧基的聚（酰胺基胺）共轭物可自组装成氧化还原敏感的纳米粒子。

在与2,2'-二硫代二吡啶反应中使用胱胺作为交联剂获得的聚（酰胺基胺）（PAA）网络转变为带有二硫代吡啶基侧基的直链PAA，该侧基很容易与硫代胆固醇进行交换反应。所得产物代表两亲PAA-胆固醇共轭物的第一个实例，其中亲脂性胆固醇部分通过在血液中稳定但可在细胞内裂解的SS键与亲水性PAA链连接。在水介质中，这些结合物自组装成纳米聚集体，其内核由亲脂性胆固醇结构域组成。获得了一系列衍生自两种不同的双丙烯酰胺，即2,2-双（丙烯酰胺基）乙酸和1,4-双（丙烯酰基）哌嗪的，具有不同胆固醇含量的PAA-胆固醇共轭物。所有产物均通过（1）H和（13）C NMR光谱表征，并且可溶性聚合物的平均分子量通过尺寸排阻色谱法测定。在所有情况下，通过分别比较其在CDCl3和D2O中的NMR谱图可以揭示胆固醇残留物从水性介质中的分离。水性缓冲液中PAA-胆固醇聚集体的TEM分析显示均匀的圆形纳米球，其尺寸和尺寸分布由DLS确定。初步的细胞相容性测试表明，所有制备的PAA-胆固醇样品均具有细胞相容性，因此具有生物技术应用潜力。在所有情况下，通过分别比较其在CDCl3和D2O中的NMR谱图可以揭示胆固醇残留物从水性介质中的分离。水性缓冲液中PAA-胆固醇聚集体的TEM分析显示均匀的圆形纳米球，其尺寸和尺寸分布由DLS确定。初步的细胞相容性测试表明，所有制备的PAA-胆固醇样品均具有细胞相容性，因此具有生物技术应用潜力。在所有情况下，通过分别比较其在CDCl3和D2O中的NMR谱图可以揭示胆固醇残留物从水性介质中的分离。水性缓冲液中PAA-胆固醇聚集体的TEM分析显示均匀的圆形纳米球，其尺寸和尺寸分布由DLS确定。初步的细胞相容性测试表明，所有制备的PAA-胆固醇样品均具有细胞相容性，因此具有生物技术应用潜力。